From 5182f7f30fad87023ae5e5a4e1f660fb513fb469 Mon Sep 17 00:00:00 2001 From: Andrzej Krzemienski Date: Sat, 24 Mar 2018 00:04:15 +0100 Subject: [PATCH 01/13] Added has_value() --- doc/27_ref_optional_synopsis.qbk | 4 ++ doc/28_ref_optional_semantics.qbk | 2 + doc/91_relnotes.qbk | 5 +++ doc/html/boost_optional/acknowledgements.html | 2 +- .../dependencies_and_portability.html | 2 +- ...emplace_operations_in_older_compilers.html | 2 +- .../optional_reference_binding.html | 2 +- doc/html/boost_optional/quick_start.html | 2 +- ...sing_unnecessary_default_construction.html | 2 +- .../optional_automatic_variables.html | 2 +- .../quick_start/optional_data_members.html | 2 +- .../quick_start/storage_in_containers.html | 2 +- ...ost_optional_bad_optional_access_hpp_.html | 2 +- .../detailed_semantics.html | 2 +- .../header__boost_optional_hpp_.html | 2 +- ...der__boost_optional_optional_fwd_hpp_.html | 2 +- .../detailed_semantics___free_functions.html | 2 +- ...ailed_semantics___optional_references.html | 5 ++- .../detailed_semantics___optional_values.html | 5 ++- .../header_optional_in_place_init.html | 2 +- .../header_optional_optional_refs.html | 4 +- .../header_optional_optional_values.html | 4 +- .../boost_optional/reference/io_header.html | 2 +- .../reference/io_header/io_semantics.html | 2 +- doc/html/boost_optional/relnotes.html | 41 +++++++++++++++---- .../tutorial/design_overview.html | 2 +- .../design_overview/the_interface.html | 2 +- .../design_overview/the_semantics.html | 2 +- .../tutorial/exception_safety_guarantees.html | 2 +- doc/html/boost_optional/tutorial/gotchas.html | 2 +- ...e_positive_with__wmaybe_uninitialized.html | 2 +- .../gotchas/mixed_relational_comparisons.html | 2 +- .../gotchas/moved_from__optional_.html | 2 +- .../tutorial/in_place_factories.html | 2 +- .../boost_optional/tutorial/io_operators.html | 2 +- .../tutorial/optional_references.html | 2 +- ...for_assignment_of_optional_references.html | 2 +- .../tutorial/performance_considerations.html | 15 +++---- .../tutorial/relational_operators.html | 2 +- .../tutorial/type_requirements.html | 2 +- .../tutorial/when_to_use_optional.html | 2 +- doc/html/index.html | 4 +- doc/html/optional/reference.html | 2 +- .../header__boost_optional_optional_hpp_.html | 2 +- doc/html/optional/tutorial.html | 2 +- .../detail/optional_reference_spec.hpp | 1 + include/boost/optional/optional.hpp | 4 +- test/optional_test.cpp | 2 +- ...st_common.cpp => optional_test_common.hpp} | 12 ++++++ 49 files changed, 119 insertions(+), 59 deletions(-) rename test/{optional_test_common.cpp => optional_test_common.hpp} (94%) diff --git a/doc/27_ref_optional_synopsis.qbk b/doc/27_ref_optional_synopsis.qbk index f93076e..1a6a849 100644 --- a/doc/27_ref_optional_synopsis.qbk +++ b/doc/27_ref_optional_synopsis.qbk @@ -182,6 +182,8 @@ They are empty, trivially copyable classes with disabled default constructor. T const* get_ptr() const ; ``[link reference_optional_get_ptr __GO_TO__]`` T* get_ptr() ; ``[link reference_optional_get_ptr __GO_TO__]`` + bool has_value() const noexcept ; ``[link reference_optional_operator_bool __GO_TO__]`` + explicit operator bool() const noexcept ; ``[link reference_optional_operator_bool __GO_TO__]`` bool operator!() const noexcept ; ``[link reference_optional_operator_not __GO_TO__]`` @@ -256,6 +258,8 @@ They are empty, trivially copyable classes with disabled default constructor. T* get_ptr() const noexcept ; ``[link reference_optional_ref_get_ptr __GO_TO__]`` + bool has_value() const noexcept ; ``[link reference_optional_ref_operator_bool __GO_TO__]`` + explicit operator bool() const noexcept ; ``[link reference_optional_ref_operator_bool __GO_TO__]`` bool operator!() const noexcept ; ``[link reference_optional_ref_operator_not __GO_TO__]`` diff --git a/doc/28_ref_optional_semantics.qbk b/doc/28_ref_optional_semantics.qbk index 7e2740c..8c1397f 100644 --- a/doc/28_ref_optional_semantics.qbk +++ b/doc/28_ref_optional_semantics.qbk @@ -754,6 +754,7 @@ __SPACE__ [#reference_optional_operator_bool] [: `explicit optional::operator bool() const noexcept ;`] +[: `bool optional::has_value() const noexcept ;`] * [*Returns:] `get_ptr() != 0`. * [*Notes:] On compilers that do not support explicit conversion operators this falls back to safe-bool idiom. @@ -1040,6 +1041,7 @@ __SPACE__ __SPACE__ [#reference_optional_ref_operator_bool] +[: `bool has_value() const noexcept;`] [: `optional::operator bool () const noexcept;`] * [*Returns:] `bool(ref)`. diff --git a/doc/91_relnotes.qbk b/doc/91_relnotes.qbk index d34861b..93e9799 100644 --- a/doc/91_relnotes.qbk +++ b/doc/91_relnotes.qbk @@ -11,6 +11,11 @@ [section:relnotes Release Notes] +[heading Boost Release 1.68] + +* Added member function `has_value()` for compatibility with `std::optional` ([@https://github.com/boostorg/optional/issues/52 issue #52]). + + [heading Boost Release 1.67] * Fixed [@https://github.com/boostorg/optional/issues/46 issue #46]. diff --git a/doc/html/boost_optional/acknowledgements.html b/doc/html/boost_optional/acknowledgements.html index 9d07002..f91a9f2 100644 --- a/doc/html/boost_optional/acknowledgements.html +++ b/doc/html/boost_optional/acknowledgements.html @@ -3,7 +3,7 @@ Acknowledgements - + diff --git a/doc/html/boost_optional/dependencies_and_portability.html b/doc/html/boost_optional/dependencies_and_portability.html index 24d0038..ca54b86 100644 --- a/doc/html/boost_optional/dependencies_and_portability.html +++ b/doc/html/boost_optional/dependencies_and_portability.html @@ -3,7 +3,7 @@ Dependencies and Portability - + diff --git a/doc/html/boost_optional/dependencies_and_portability/emplace_operations_in_older_compilers.html b/doc/html/boost_optional/dependencies_and_portability/emplace_operations_in_older_compilers.html index 2354e2e..afa139f 100644 --- a/doc/html/boost_optional/dependencies_and_portability/emplace_operations_in_older_compilers.html +++ b/doc/html/boost_optional/dependencies_and_portability/emplace_operations_in_older_compilers.html @@ -3,7 +3,7 @@ Emplace operations in older compilers - + diff --git a/doc/html/boost_optional/dependencies_and_portability/optional_reference_binding.html b/doc/html/boost_optional/dependencies_and_portability/optional_reference_binding.html index cffa160..9038cb2 100644 --- a/doc/html/boost_optional/dependencies_and_portability/optional_reference_binding.html +++ b/doc/html/boost_optional/dependencies_and_portability/optional_reference_binding.html @@ -3,7 +3,7 @@ Optional Reference Binding - + diff --git a/doc/html/boost_optional/quick_start.html b/doc/html/boost_optional/quick_start.html index d7dde63..18ea040 100644 --- a/doc/html/boost_optional/quick_start.html +++ b/doc/html/boost_optional/quick_start.html @@ -3,7 +3,7 @@ Quick Start - + diff --git a/doc/html/boost_optional/quick_start/bypassing_unnecessary_default_construction.html b/doc/html/boost_optional/quick_start/bypassing_unnecessary_default_construction.html index 7ccdb1b..2b38395 100644 --- a/doc/html/boost_optional/quick_start/bypassing_unnecessary_default_construction.html +++ b/doc/html/boost_optional/quick_start/bypassing_unnecessary_default_construction.html @@ -3,7 +3,7 @@ Bypassing unnecessary default construction - + diff --git a/doc/html/boost_optional/quick_start/optional_automatic_variables.html b/doc/html/boost_optional/quick_start/optional_automatic_variables.html index e135be1..b292f0a 100644 --- a/doc/html/boost_optional/quick_start/optional_automatic_variables.html +++ b/doc/html/boost_optional/quick_start/optional_automatic_variables.html @@ -3,7 +3,7 @@ Optional automatic variables - + diff --git a/doc/html/boost_optional/quick_start/optional_data_members.html b/doc/html/boost_optional/quick_start/optional_data_members.html index 93682f8..8402401 100644 --- a/doc/html/boost_optional/quick_start/optional_data_members.html +++ b/doc/html/boost_optional/quick_start/optional_data_members.html @@ -3,7 +3,7 @@ Optional data members - + diff --git a/doc/html/boost_optional/quick_start/storage_in_containers.html b/doc/html/boost_optional/quick_start/storage_in_containers.html index 4861178..36e3191 100644 --- a/doc/html/boost_optional/quick_start/storage_in_containers.html +++ b/doc/html/boost_optional/quick_start/storage_in_containers.html @@ -3,7 +3,7 @@ Storage in containers - + diff --git a/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_.html b/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_.html index 4269965..56d43fc 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_.html +++ b/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_.html @@ -3,7 +3,7 @@ Header <boost/optional/bad_optional_access.hpp> - + diff --git a/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_/detailed_semantics.html b/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_/detailed_semantics.html index ba66f61..e85abc9 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_/detailed_semantics.html +++ b/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_/detailed_semantics.html @@ -3,7 +3,7 @@ Detailed semantics - + diff --git a/doc/html/boost_optional/reference/header__boost_optional_hpp_.html b/doc/html/boost_optional/reference/header__boost_optional_hpp_.html index 2a81a82..f3a3649 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_hpp_.html +++ b/doc/html/boost_optional/reference/header__boost_optional_hpp_.html @@ -3,7 +3,7 @@ Header <boost/optional.hpp> - + diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_fwd_hpp_.html b/doc/html/boost_optional/reference/header__boost_optional_optional_fwd_hpp_.html index f053e06..96f41a2 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_optional_fwd_hpp_.html +++ b/doc/html/boost_optional/reference/header__boost_optional_optional_fwd_hpp_.html @@ -3,7 +3,7 @@ Header <boost/optional/optional_fwd.hpp> - + diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___free_functions.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___free_functions.html index 1a48614..5b0780b 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___free_functions.html +++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___free_functions.html @@ -3,7 +3,7 @@ Detailed Semantics - Free Functions - + diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html index ffe1733..4400216 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html +++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html @@ -3,7 +3,7 @@ Detailed Semantics - Optional References - + @@ -422,6 +422,9 @@ space

+ bool has_value() const noexcept; +

+

optional<T&>::operator bool () const noexcept; diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html index b18c618..fd94a67 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html +++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html @@ -3,7 +3,7 @@ Detailed Semantics - Optional Values - + @@ -1592,6 +1592,9 @@ const noexcept ;

+

+ bool optional<T>::has_value() const noexcept ; +

  • Returns: get_ptr() != 0. diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_in_place_init.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_in_place_init.html index 8f1560e..d94a2b2 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_in_place_init.html +++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_in_place_init.html @@ -3,7 +3,7 @@ Initialization tags - + diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html index ee518a4..f02cdb5 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html +++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html @@ -3,7 +3,7 @@ Optional References - + @@ -75,6 +75,8 @@ T* get_ptr() const noexcept ; R + bool has_value() const noexcept ; R + explicit operator bool() const noexcept ; R bool operator!() const noexcept ; R diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html index 172da40..7780abd 100644 --- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html +++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html @@ -3,7 +3,7 @@ Optional Values - + @@ -108,6 +108,8 @@ T const* get_ptr() const ; R T* get_ptr() ; R + bool has_value() const noexcept ; R + explicit operator bool() const noexcept ; R bool operator!() const noexcept ; R diff --git a/doc/html/boost_optional/reference/io_header.html b/doc/html/boost_optional/reference/io_header.html index 675e598..78bcfd9 100644 --- a/doc/html/boost_optional/reference/io_header.html +++ b/doc/html/boost_optional/reference/io_header.html @@ -3,7 +3,7 @@ Header <boost/optional/optional_io.hpp> - + diff --git a/doc/html/boost_optional/reference/io_header/io_semantics.html b/doc/html/boost_optional/reference/io_header/io_semantics.html index d286c9d..13b7477 100644 --- a/doc/html/boost_optional/reference/io_header/io_semantics.html +++ b/doc/html/boost_optional/reference/io_header/io_semantics.html @@ -3,7 +3,7 @@ Detailed semantics - + diff --git a/doc/html/boost_optional/relnotes.html b/doc/html/boost_optional/relnotes.html index 9881def..7eb48e0 100644 --- a/doc/html/boost_optional/relnotes.html +++ b/doc/html/boost_optional/relnotes.html @@ -3,7 +3,7 @@ Release Notes - + @@ -28,6 +28,29 @@

+ Boost + Release 1.68 +

+
  • + Added member function has_value() for compatibility with std::optional (issue + #52). +
+

+ + Boost + Release 1.67 +

+
    +
  • + Fixed issue + #46. +
    • +
  • + Fixed -Wzero-as-null-pointer-constant warnings. +
    • +
+

+ Boost Release 1.66

@@ -45,7 +68,7 @@

- + Boost Release 1.63

@@ -69,7 +92,7 @@

- + Boost Release 1.62

@@ -77,7 +100,7 @@ Fixed Trac #12179.

- + Boost Release 1.61

@@ -120,7 +143,7 @@

- + Boost Release 1.60

@@ -131,7 +154,7 @@ #11203.

- + Boost Release 1.59

@@ -145,7 +168,7 @@

- + Boost Release 1.58

@@ -181,7 +204,7 @@

- + Boost Release 1.57

@@ -191,7 +214,7 @@ to fix C++03 compile error on logic_error("...")".

- + Boost Release 1.56

diff --git a/doc/html/boost_optional/tutorial/design_overview.html b/doc/html/boost_optional/tutorial/design_overview.html index 5d2a7a0..fe959b6 100644 --- a/doc/html/boost_optional/tutorial/design_overview.html +++ b/doc/html/boost_optional/tutorial/design_overview.html @@ -3,7 +3,7 @@ Design Overview - + diff --git a/doc/html/boost_optional/tutorial/design_overview/the_interface.html b/doc/html/boost_optional/tutorial/design_overview/the_interface.html index 6b860a7..5c7d153 100644 --- a/doc/html/boost_optional/tutorial/design_overview/the_interface.html +++ b/doc/html/boost_optional/tutorial/design_overview/the_interface.html @@ -3,7 +3,7 @@ The Interface - + diff --git a/doc/html/boost_optional/tutorial/design_overview/the_semantics.html b/doc/html/boost_optional/tutorial/design_overview/the_semantics.html index d84118a..cdbd9e6 100644 --- a/doc/html/boost_optional/tutorial/design_overview/the_semantics.html +++ b/doc/html/boost_optional/tutorial/design_overview/the_semantics.html @@ -3,7 +3,7 @@ The semantics - + diff --git a/doc/html/boost_optional/tutorial/exception_safety_guarantees.html b/doc/html/boost_optional/tutorial/exception_safety_guarantees.html index 925eca6..6d57a52 100644 --- a/doc/html/boost_optional/tutorial/exception_safety_guarantees.html +++ b/doc/html/boost_optional/tutorial/exception_safety_guarantees.html @@ -3,7 +3,7 @@ Exception Safety Guarantees - + diff --git a/doc/html/boost_optional/tutorial/gotchas.html b/doc/html/boost_optional/tutorial/gotchas.html index fab4d53..45c9435 100644 --- a/doc/html/boost_optional/tutorial/gotchas.html +++ b/doc/html/boost_optional/tutorial/gotchas.html @@ -3,7 +3,7 @@ Gotchas - + diff --git a/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html b/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html index 299b211..2352db7 100644 --- a/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html +++ b/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html @@ -3,7 +3,7 @@ False positive with -Wmaybe-uninitialized - + diff --git a/doc/html/boost_optional/tutorial/gotchas/mixed_relational_comparisons.html b/doc/html/boost_optional/tutorial/gotchas/mixed_relational_comparisons.html index a0c4eb0..187e457 100644 --- a/doc/html/boost_optional/tutorial/gotchas/mixed_relational_comparisons.html +++ b/doc/html/boost_optional/tutorial/gotchas/mixed_relational_comparisons.html @@ -3,7 +3,7 @@ Mixed relational comparisons - + diff --git a/doc/html/boost_optional/tutorial/gotchas/moved_from__optional_.html b/doc/html/boost_optional/tutorial/gotchas/moved_from__optional_.html index 2be1f77..0e1b772 100644 --- a/doc/html/boost_optional/tutorial/gotchas/moved_from__optional_.html +++ b/doc/html/boost_optional/tutorial/gotchas/moved_from__optional_.html @@ -3,7 +3,7 @@ Moved-from optional - + diff --git a/doc/html/boost_optional/tutorial/in_place_factories.html b/doc/html/boost_optional/tutorial/in_place_factories.html index 1f4e145..f00e5ed 100644 --- a/doc/html/boost_optional/tutorial/in_place_factories.html +++ b/doc/html/boost_optional/tutorial/in_place_factories.html @@ -3,7 +3,7 @@ In-Place Factories - + diff --git a/doc/html/boost_optional/tutorial/io_operators.html b/doc/html/boost_optional/tutorial/io_operators.html index 874f5ac..bbfc1f7 100644 --- a/doc/html/boost_optional/tutorial/io_operators.html +++ b/doc/html/boost_optional/tutorial/io_operators.html @@ -3,7 +3,7 @@ IO operators - + diff --git a/doc/html/boost_optional/tutorial/optional_references.html b/doc/html/boost_optional/tutorial/optional_references.html index 702733c..417ff36 100644 --- a/doc/html/boost_optional/tutorial/optional_references.html +++ b/doc/html/boost_optional/tutorial/optional_references.html @@ -3,7 +3,7 @@ Optional references - + diff --git a/doc/html/boost_optional/tutorial/optional_references/rebinding_semantics_for_assignment_of_optional_references.html b/doc/html/boost_optional/tutorial/optional_references/rebinding_semantics_for_assignment_of_optional_references.html index 219fd61..f12fb59 100644 --- a/doc/html/boost_optional/tutorial/optional_references/rebinding_semantics_for_assignment_of_optional_references.html +++ b/doc/html/boost_optional/tutorial/optional_references/rebinding_semantics_for_assignment_of_optional_references.html @@ -3,7 +3,7 @@ Rebinding semantics for assignment of optional references - + diff --git a/doc/html/boost_optional/tutorial/performance_considerations.html b/doc/html/boost_optional/tutorial/performance_considerations.html index f54e49e..6a6667d 100644 --- a/doc/html/boost_optional/tutorial/performance_considerations.html +++ b/doc/html/boost_optional/tutorial/performance_considerations.html @@ -3,7 +3,7 @@ Performance considerations - + @@ -56,12 +56,13 @@

We call it a direct storage. This makes optional<T> a trivially-copyable type for scalar Ts. - This only works for compilers that support defaulted functions. On compilers - without defaulted functions we still use the direct storage, but optional<T> is - no longer recognized as trivially-copyable. Apart from scalar types, we leave - the programmer a way of customizing her type, so that it is reconized by - optional as candidate for - optimized storage, by specializing type trait boost::opitonal_config::optional_uses_direct_storage_for: + This only works for compilers that support defaulted functions (including + defaulted move assignment and constructor). On compilers without defaulted + functions we still use the direct storage, but optional<T> + is no longer recognized as trivially-copyable. Apart from scalar types, we + leave the programmer a way of customizing her type, so that it is reconized + by optional as candidate + for optimized storage, by specializing type trait boost::opitonal_config::optional_uses_direct_storage_for: 

struct X // not trivial
 {
diff --git a/doc/html/boost_optional/tutorial/relational_operators.html b/doc/html/boost_optional/tutorial/relational_operators.html
index 744120d..8aa9234 100644
--- a/doc/html/boost_optional/tutorial/relational_operators.html
+++ b/doc/html/boost_optional/tutorial/relational_operators.html
@@ -3,7 +3,7 @@
 
 Relational operators
 
-
+
 
 
 
diff --git a/doc/html/boost_optional/tutorial/type_requirements.html b/doc/html/boost_optional/tutorial/type_requirements.html
index 8a9eb7f..191f5fe 100644
--- a/doc/html/boost_optional/tutorial/type_requirements.html
+++ b/doc/html/boost_optional/tutorial/type_requirements.html
@@ -3,7 +3,7 @@
 
 Type requirements
 
-
+
 
 
 
diff --git a/doc/html/boost_optional/tutorial/when_to_use_optional.html b/doc/html/boost_optional/tutorial/when_to_use_optional.html
index 675bd3f..b56a8c0 100644
--- a/doc/html/boost_optional/tutorial/when_to_use_optional.html
+++ b/doc/html/boost_optional/tutorial/when_to_use_optional.html
@@ -3,7 +3,7 @@
 
 When to use Optional
 
-
+
 
 
 
diff --git a/doc/html/index.html b/doc/html/index.html
index 1429a21..b9ec32a 100644
--- a/doc/html/index.html
+++ b/doc/html/index.html
@@ -3,7 +3,7 @@
 
 Boost.Optional
 
-
+
 
 
 
@@ -146,7 +146,7 @@
 
 
 
-
+
Last revised: May 17, 2017 at 23:01:39 GMT
Last revised: March 23, 2018 at 23:01:17 GMT

 

 

 

diff --git a/doc/html/optional/reference.html b/doc/html/optional/reference.html
index fe13339..da63269 100644
--- a/doc/html/optional/reference.html
+++ b/doc/html/optional/reference.html
@@ -3,7 +3,7 @@
 
 Reference
 
-
+
 
 
 
diff --git a/doc/html/optional/reference/header__boost_optional_optional_hpp_.html b/doc/html/optional/reference/header__boost_optional_optional_hpp_.html
index 24626e3..fdfb029 100644
--- a/doc/html/optional/reference/header__boost_optional_optional_hpp_.html
+++ b/doc/html/optional/reference/header__boost_optional_optional_hpp_.html
@@ -3,7 +3,7 @@
 
 Header <boost/optional/optional.hpp>
 
-
+
 
 
 
diff --git a/doc/html/optional/tutorial.html b/doc/html/optional/tutorial.html
index b3260b9..6d1122b 100644
--- a/doc/html/optional/tutorial.html
+++ b/doc/html/optional/tutorial.html
@@ -3,7 +3,7 @@
 
 Tutorial
 
-
+
 
 
 
diff --git a/include/boost/optional/detail/optional_reference_spec.hpp b/include/boost/optional/detail/optional_reference_spec.hpp
index 012e91a..8e9974c 100644
--- a/include/boost/optional/detail/optional_reference_spec.hpp
+++ b/include/boost/optional/detail/optional_reference_spec.hpp
@@ -159,6 +159,7 @@ public:
     void reset() BOOST_NOEXCEPT { ptr_ = 0; }
 
     bool is_initialized() const BOOST_NOEXCEPT { return ptr_ != 0; }
+    bool has_value() const BOOST_NOEXCEPT { return ptr_ != 0; }
     
 #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES   
  
diff --git a/include/boost/optional/optional.hpp b/include/boost/optional/optional.hpp
index 74ef49c..17c8f89 100644
--- a/include/boost/optional/optional.hpp
+++ b/include/boost/optional/optional.hpp
@@ -375,7 +375,7 @@ class optional_base : public optional_tag
     pointer_const_type get_ptr() const { return m_initialized ? get_ptr_impl() : 0 ; }
     pointer_type       get_ptr()       { return m_initialized ? get_ptr_impl() : 0 ; }
 
-    bool is_initialized() const { return m_initialized ; }
+    bool is_initialized() const BOOST_NOEXCEPT { return m_initialized ; }
 
   protected :
 
@@ -1333,6 +1333,8 @@ class optional
       }
 #endif
       
+    bool has_value() const BOOST_NOEXCEPT { return this->is_initialized() ; }
+    
     bool operator!() const BOOST_NOEXCEPT { return !this->is_initialized() ; }
     
     BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT()
diff --git a/test/optional_test.cpp b/test/optional_test.cpp
index 017d4ff..3354430 100644
--- a/test/optional_test.cpp
+++ b/test/optional_test.cpp
@@ -32,7 +32,7 @@
 
 #include "boost/core/lightweight_test.hpp"
 
-#include "optional_test_common.cpp"
+#include "optional_test_common.hpp"
 
 void test_implicit_construction ( optional opt, double v, double z )
 {
diff --git a/test/optional_test_common.cpp b/test/optional_test_common.hpp
similarity index 94%
rename from test/optional_test_common.cpp
rename to test/optional_test_common.hpp
index acb935c..943e646 100644
--- a/test/optional_test_common.cpp
+++ b/test/optional_test_common.hpp
@@ -194,6 +194,9 @@ inline void check_uninitialized_const ( optional const& opt )
   BOOST_TEST( !opt ) ;
   BOOST_TEST( !get_pointer(opt) ) ;
   BOOST_TEST( !opt.get_ptr() ) ;
+  BOOST_TEST( !opt.has_value() ) ;
+  BOOST_TEST( !opt.is_initialized() ) ;
+  BOOST_TEST( opt == boost::none ) ;
 }
 template
 inline void check_uninitialized ( optional& opt )
@@ -204,6 +207,9 @@ inline void check_uninitialized ( optional& opt )
   BOOST_TEST( !opt ) ;
   BOOST_TEST( !get_pointer(opt) ) ;
   BOOST_TEST( !opt.get_ptr() ) ;
+  BOOST_TEST( !opt.has_value() ) ;
+  BOOST_TEST( !opt.is_initialized() ) ;
+  BOOST_TEST( opt == boost::none ) ;
 
   check_uninitialized_const(opt);
 }
@@ -220,6 +226,9 @@ inline void check_initialized_const ( optional const& opt )
   BOOST_TEST ( !!opt ) ;
   BOOST_TEST ( get_pointer(opt) ) ;
   BOOST_TEST ( opt.get_ptr() ) ;
+  BOOST_TEST ( opt.has_value() ) ;
+  BOOST_TEST ( opt.is_initialized() ) ;
+  BOOST_TEST ( opt != boost::none ) ;
 }
 
 template
@@ -234,6 +243,9 @@ inline void check_initialized ( optional& opt )
   BOOST_TEST ( !!opt ) ;
   BOOST_TEST ( get_pointer(opt) ) ;
   BOOST_TEST ( opt.get_ptr() ) ;
+  BOOST_TEST ( opt.has_value() ) ;
+  BOOST_TEST ( opt.is_initialized() ) ;
+  BOOST_TEST ( opt != boost::none ) ;
 
   check_initialized_const(opt);
 }

From e47a01700940654f3f9e461ac422f55a8d0ed0c8 Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Sat, 23 Jun 2018 18:27:14 +0200
Subject: [PATCH 02/13] added o.map()

---
 doc/00_optional.qbk                           |   2 +-
 doc/27_ref_optional_synopsis.qbk              |   4 +
 doc/28_ref_optional_semantics.qbk             |  19 +++
 doc/91_relnotes.qbk                           |   1 +
 doc/html/boost_optional/acknowledgements.html |   3 +-
 .../dependencies_and_portability.html         |   3 +-
 ...emplace_operations_in_older_compilers.html |   3 +-
 .../optional_reference_binding.html           |   3 +-
 doc/html/boost_optional/quick_start.html      |   3 +-
 ...sing_unnecessary_default_construction.html |   3 +-
 .../optional_automatic_variables.html         |   3 +-
 .../quick_start/optional_data_members.html    |   3 +-
 .../quick_start/storage_in_containers.html    |   3 +-
 ...ost_optional_bad_optional_access_hpp_.html |   3 +-
 .../detailed_semantics.html                   |   3 +-
 .../header__boost_optional_hpp_.html          |   3 +-
 ...der__boost_optional_optional_fwd_hpp_.html |   3 +-
 .../detailed_semantics___free_functions.html  |   3 +-
 ...ailed_semantics___optional_references.html |   3 +-
 .../detailed_semantics___optional_values.html |  47 ++++-
 .../header_optional_in_place_init.html        |   3 +-
 .../header_optional_optional_refs.html        |   3 +-
 .../header_optional_optional_values.html      |   7 +-
 .../boost_optional/reference/io_header.html   |   3 +-
 .../reference/io_header/io_semantics.html     |   3 +-
 doc/html/boost_optional/relnotes.html         |  12 +-
 .../tutorial/design_overview.html             |   3 +-
 .../design_overview/the_interface.html        |   3 +-
 .../design_overview/the_semantics.html        |   3 +-
 .../tutorial/exception_safety_guarantees.html |   3 +-
 doc/html/boost_optional/tutorial/gotchas.html |   3 +-
 ...e_positive_with__wmaybe_uninitialized.html |   3 +-
 .../gotchas/mixed_relational_comparisons.html |   3 +-
 .../gotchas/moved_from__optional_.html        |   3 +-
 .../tutorial/in_place_factories.html          |   3 +-
 .../boost_optional/tutorial/io_operators.html |   3 +-
 .../tutorial/optional_references.html         |   3 +-
 ...for_assignment_of_optional_references.html |   3 +-
 .../tutorial/performance_considerations.html  |   3 +-
 .../tutorial/relational_operators.html        |   3 +-
 .../tutorial/type_requirements.html           |   3 +-
 .../tutorial/when_to_use_optional.html        |   3 +-
 doc/html/index.html                           |   5 +-
 doc/html/optional/reference.html              |   3 +-
 .../header__boost_optional_optional_hpp_.html |   3 +-
 doc/html/optional/tutorial.html               |   3 +-
 .../detail/optional_reference_spec.hpp        |  11 +-
 include/boost/optional/optional.hpp           |  51 +++++-
 test/Jamfile.v2                               |   1 +
 test/optional_test_map.cpp                    | 160 ++++++++++++++++++
 50 files changed, 343 insertions(+), 91 deletions(-)
 create mode 100644 test/optional_test_map.cpp

diff --git a/doc/00_optional.qbk b/doc/00_optional.qbk
index 02e21f4..00b6096 100644
--- a/doc/00_optional.qbk
+++ b/doc/00_optional.qbk
@@ -2,7 +2,7 @@
     [quickbook 1.4]
     [authors [Cacciola Carballal, Fernando Luis]]
     [copyright 2003-2007 Fernando Luis Cacciola Carballal]
-    [copyright 2014-2017 Andrzej Krzemieński]
+    [copyright 2014-2018 Andrzej Krzemieński]
     [category miscellaneous]
     [id optional]
     [dirname optional]
diff --git a/doc/27_ref_optional_synopsis.qbk b/doc/27_ref_optional_synopsis.qbk
index 1a6a849..8454218 100644
--- a/doc/27_ref_optional_synopsis.qbk
+++ b/doc/27_ref_optional_synopsis.qbk
@@ -179,6 +179,10 @@ They are empty, trivially copyable classes with disabled default constructor.
         template T value_or_eval( F f ) const& ; ``[link reference_optional_value_or_call __GO_TO__]``
         template T value_or_eval( F f ) && ; ``[link reference_optional_value_or_call_move __GO_TO__]``
 
+        template auto map( F f ) const& -> ``['see below]``; ``[link reference_optional_map __GO_TO__]``
+        template auto map( F f ) & -> ``['see below]``; ``[link reference_optional_map __GO_TO__]``
+        template auto map( F f ) && -> ``['see below]``; ``[link reference_optional_map_move __GO_TO__]``
+
         T const* get_ptr() const ; ``[link reference_optional_get_ptr __GO_TO__]``
         T*       get_ptr() ; ``[link reference_optional_get_ptr __GO_TO__]``
 
diff --git a/doc/28_ref_optional_semantics.qbk b/doc/28_ref_optional_semantics.qbk
index 8c1397f..320da2d 100644
--- a/doc/28_ref_optional_semantics.qbk
+++ b/doc/28_ref_optional_semantics.qbk
@@ -685,6 +685,25 @@ __SPACE__
 
 __SPACE__
 
+[#reference_optional_map]
+
+[: `template auto optional::map(F f) const& -> ``['see below]`` ;`]
+[: `template auto optional::map(F f) & -> ``['see below]`` ;`]
+
+* [*Effects:] `if (*this) return f(**this); else return none;`
+* [*Notes:] The return type of these overloads is `optional`. On compilers that do not support ref-qualifiers on member functions, these two (as well as the next one) overloads are replaced with good old const and non-const overloads. 
+
+__SPACE__
+
+[#reference_optional_map_move]
+
+[: `template auto optional::map(F f) && -> ``['see below]`` ;`]
+
+* [*Effects:] `if (*this) return f(std::move(**this)); else return none;`
+* [*Notes:] The return type of this overload is `optional`.
+
+__SPACE__
+
 [#reference_optional_get_value_or_value]
 
 [: `T const& optional::get_value_or( T const& default) const ;`]
diff --git a/doc/91_relnotes.qbk b/doc/91_relnotes.qbk
index 93e9799..79bb200 100644
--- a/doc/91_relnotes.qbk
+++ b/doc/91_relnotes.qbk
@@ -14,6 +14,7 @@
 [heading Boost Release 1.68]
 
 * Added member function `has_value()` for compatibility with `std::optional` ([@https://github.com/boostorg/optional/issues/52 issue #52]).
+* Added member function `map()` for transforming `optional` into `optional` using a function of type `U(T)`.
 
 
 [heading Boost Release 1.67]
diff --git a/doc/html/boost_optional/acknowledgements.html b/doc/html/boost_optional/acknowledgements.html
index f91a9f2..c6f9f2f 100644
--- a/doc/html/boost_optional/acknowledgements.html
+++ b/doc/html/boost_optional/acknowledgements.html
@@ -116,8 +116,7 @@
 
 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/dependencies_and_portability.html b/doc/html/boost_optional/dependencies_and_portability.html
index ca54b86..bc235f8 100644
--- a/doc/html/boost_optional/dependencies_and_portability.html
+++ b/doc/html/boost_optional/dependencies_and_portability.html
@@ -77,8 +77,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/dependencies_and_portability/emplace_operations_in_older_compilers.html b/doc/html/boost_optional/dependencies_and_portability/emplace_operations_in_older_compilers.html
index afa139f..a35c4a2 100644
--- a/doc/html/boost_optional/dependencies_and_portability/emplace_operations_in_older_compilers.html
+++ b/doc/html/boost_optional/dependencies_and_portability/emplace_operations_in_older_compilers.html
@@ -76,8 +76,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/dependencies_and_portability/optional_reference_binding.html b/doc/html/boost_optional/dependencies_and_portability/optional_reference_binding.html
index 9038cb2..7a191d2 100644
--- a/doc/html/boost_optional/dependencies_and_portability/optional_reference_binding.html
+++ b/doc/html/boost_optional/dependencies_and_portability/optional_reference_binding.html
@@ -93,8 +93,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/quick_start.html b/doc/html/boost_optional/quick_start.html
index 18ea040..0ef16bc 100644
--- a/doc/html/boost_optional/quick_start.html
+++ b/doc/html/boost_optional/quick_start.html
@@ -155,8 +155,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/quick_start/bypassing_unnecessary_default_construction.html b/doc/html/boost_optional/quick_start/bypassing_unnecessary_default_construction.html
index 2b38395..e039e0c 100644
--- a/doc/html/boost_optional/quick_start/bypassing_unnecessary_default_construction.html
+++ b/doc/html/boost_optional/quick_start/bypassing_unnecessary_default_construction.html
@@ -61,8 +61,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/quick_start/optional_automatic_variables.html b/doc/html/boost_optional/quick_start/optional_automatic_variables.html
index b292f0a..f7b6664 100644
--- a/doc/html/boost_optional/quick_start/optional_automatic_variables.html
+++ b/doc/html/boost_optional/quick_start/optional_automatic_variables.html
@@ -61,8 +61,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/quick_start/optional_data_members.html b/doc/html/boost_optional/quick_start/optional_data_members.html
index 8402401..a06aa10 100644
--- a/doc/html/boost_optional/quick_start/optional_data_members.html
+++ b/doc/html/boost_optional/quick_start/optional_data_members.html
@@ -80,8 +80,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/quick_start/storage_in_containers.html b/doc/html/boost_optional/quick_start/storage_in_containers.html
index 36e3191..4c145f1 100644
--- a/doc/html/boost_optional/quick_start/storage_in_containers.html
+++ b/doc/html/boost_optional/quick_start/storage_in_containers.html
@@ -50,8 +50,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_.html b/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_.html
index 56d43fc..363379c 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_.html
@@ -49,8 +49,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_/detailed_semantics.html b/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_/detailed_semantics.html
index e85abc9..b182324 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_/detailed_semantics.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_bad_optional_access_hpp_/detailed_semantics.html
@@ -46,8 +46,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_hpp_.html b/doc/html/boost_optional/reference/header__boost_optional_hpp_.html
index f3a3649..c8d6b9e 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_hpp_.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_hpp_.html
@@ -33,8 +33,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_fwd_hpp_.html b/doc/html/boost_optional/reference/header__boost_optional_optional_fwd_hpp_.html
index 96f41a2..ee81dd9 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_fwd_hpp_.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_fwd_hpp_.html
@@ -52,8 +52,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___free_functions.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___free_functions.html
index 5b0780b..b46bcce 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___free_functions.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___free_functions.html
@@ -507,8 +507,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
index 4400216..3101217 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
@@ -504,8 +504,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
index fd94a67..46fe0a8 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
@@ -1471,6 +1471,50 @@
               ref-qualifiers on member functions this overload is not present.
             
 

+

+          space
+        

+

+            template<class F> auto optional<T>::map(F f) const& ->
+            ['see below] ;
+          

+

+            template<class F> auto optional<T>::map(F f) & -> ['see below]
+            ;
+          

+
    
+
  • 
+              Effects: if
+              (*this) return f(**this); else return
+              none;
+            
    • 
+
  • 
+              Notes: The return type of these overloads
+              is optional<decltype(f(**this)>.
+              On compilers that do not support ref-qualifiers on member functions,
+              these two (as well as the next one) overloads are replaced with good
+              old const and non-const overloads.
+            
    • 
+

+

+          space
+        

+

+            template<class F> auto optional<T>::map(F f) &&
+            -> ['see below]
+            ;
+          

+
    
+
  • 
+              Effects: if
+              (*this) return f(std::move(**this)); else return
+              none;
+            
    • 
+
  • 
+              Notes: The return type of this overload
+              is optional<decltype(f(istd::move(**this))>.
+            
    • 
+

 

           space
         

@@ -1654,8 +1698,7 @@
 
 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_in_place_init.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_in_place_init.html
index d94a2b2..be67b67 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_in_place_init.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_in_place_init.html
@@ -47,8 +47,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
index f02cdb5..3934957 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
@@ -102,8 +102,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html
index 7780abd..5e960f1 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html
@@ -105,6 +105,10 @@
     template<class F> T value_or_eval( F f ) const& ; R
     template<class F> T value_or_eval( F f ) && ; R
 
+    template<class F> auto map( F f ) const& -> see below; R
+    template<class F> auto map( F f ) & -> see below; R
+    template<class F> auto map( F f ) && -> see below; R
+
     T const* get_ptr() const ; R
     T*       get_ptr() ; R
 
@@ -132,8 +136,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/io_header.html b/doc/html/boost_optional/reference/io_header.html
index 78bcfd9..fd8599f 100644
--- a/doc/html/boost_optional/reference/io_header.html
+++ b/doc/html/boost_optional/reference/io_header.html
@@ -58,8 +58,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/reference/io_header/io_semantics.html b/doc/html/boost_optional/reference/io_header/io_semantics.html
index 13b7477..2e8ed56 100644
--- a/doc/html/boost_optional/reference/io_header/io_semantics.html
+++ b/doc/html/boost_optional/reference/io_header/io_semantics.html
@@ -98,8 +98,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/relnotes.html b/doc/html/boost_optional/relnotes.html
index 7eb48e0..b596e38 100644
--- a/doc/html/boost_optional/relnotes.html
+++ b/doc/html/boost_optional/relnotes.html
@@ -31,10 +31,15 @@
       Boost
       Release 1.68
     
-
  • 
+
      
+
    • 
           Added member function has_value() for compatibility with std::optional (issue
           #52).
-        
    
+        
    • 
+
  • 
+          Added member function map() for transforming optional<T> into optional<U> using a function of type U(T).
+        
    • 
+

 

 
       Boost
@@ -271,8 +276,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/design_overview.html b/doc/html/boost_optional/tutorial/design_overview.html
index fe959b6..31a192b 100644
--- a/doc/html/boost_optional/tutorial/design_overview.html
+++ b/doc/html/boost_optional/tutorial/design_overview.html
@@ -170,8 +170,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/design_overview/the_interface.html b/doc/html/boost_optional/tutorial/design_overview/the_interface.html
index 5c7d153..0bb4a96 100644
--- a/doc/html/boost_optional/tutorial/design_overview/the_interface.html
+++ b/doc/html/boost_optional/tutorial/design_overview/the_interface.html
@@ -173,8 +173,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/design_overview/the_semantics.html b/doc/html/boost_optional/tutorial/design_overview/the_semantics.html
index cdbd9e6..dbc1ab0 100644
--- a/doc/html/boost_optional/tutorial/design_overview/the_semantics.html
+++ b/doc/html/boost_optional/tutorial/design_overview/the_semantics.html
@@ -107,8 +107,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/exception_safety_guarantees.html b/doc/html/boost_optional/tutorial/exception_safety_guarantees.html
index 6d57a52..c75dab0 100644
--- a/doc/html/boost_optional/tutorial/exception_safety_guarantees.html
+++ b/doc/html/boost_optional/tutorial/exception_safety_guarantees.html
@@ -161,8 +161,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/gotchas.html b/doc/html/boost_optional/tutorial/gotchas.html
index 45c9435..c11cad2 100644
--- a/doc/html/boost_optional/tutorial/gotchas.html
+++ b/doc/html/boost_optional/tutorial/gotchas.html
@@ -98,8 +98,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html b/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html
index 2352db7..240ee0f 100644
--- a/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html
+++ b/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html
@@ -63,8 +63,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/gotchas/mixed_relational_comparisons.html b/doc/html/boost_optional/tutorial/gotchas/mixed_relational_comparisons.html
index 187e457..8d25f0d 100644
--- a/doc/html/boost_optional/tutorial/gotchas/mixed_relational_comparisons.html
+++ b/doc/html/boost_optional/tutorial/gotchas/mixed_relational_comparisons.html
@@ -45,8 +45,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/gotchas/moved_from__optional_.html b/doc/html/boost_optional/tutorial/gotchas/moved_from__optional_.html
index 0e1b772..7a4e444 100644
--- a/doc/html/boost_optional/tutorial/gotchas/moved_from__optional_.html
+++ b/doc/html/boost_optional/tutorial/gotchas/moved_from__optional_.html
@@ -49,8 +49,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/in_place_factories.html b/doc/html/boost_optional/tutorial/in_place_factories.html
index f00e5ed..5f0c426 100644
--- a/doc/html/boost_optional/tutorial/in_place_factories.html
+++ b/doc/html/boost_optional/tutorial/in_place_factories.html
@@ -183,8 +183,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/io_operators.html b/doc/html/boost_optional/tutorial/io_operators.html
index bbfc1f7..713b283 100644
--- a/doc/html/boost_optional/tutorial/io_operators.html
+++ b/doc/html/boost_optional/tutorial/io_operators.html
@@ -73,8 +73,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/optional_references.html b/doc/html/boost_optional/tutorial/optional_references.html
index 417ff36..fb0fb56 100644
--- a/doc/html/boost_optional/tutorial/optional_references.html
+++ b/doc/html/boost_optional/tutorial/optional_references.html
@@ -103,8 +103,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/optional_references/rebinding_semantics_for_assignment_of_optional_references.html b/doc/html/boost_optional/tutorial/optional_references/rebinding_semantics_for_assignment_of_optional_references.html
index f12fb59..6e827d0 100644
--- a/doc/html/boost_optional/tutorial/optional_references/rebinding_semantics_for_assignment_of_optional_references.html
+++ b/doc/html/boost_optional/tutorial/optional_references/rebinding_semantics_for_assignment_of_optional_references.html
@@ -133,8 +133,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/performance_considerations.html b/doc/html/boost_optional/tutorial/performance_considerations.html
index 6a6667d..19fe1ed 100644
--- a/doc/html/boost_optional/tutorial/performance_considerations.html
+++ b/doc/html/boost_optional/tutorial/performance_considerations.html
@@ -251,8 +251,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/relational_operators.html b/doc/html/boost_optional/tutorial/relational_operators.html
index 8aa9234..376bdcc 100644
--- a/doc/html/boost_optional/tutorial/relational_operators.html
+++ b/doc/html/boost_optional/tutorial/relational_operators.html
@@ -99,8 +99,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/type_requirements.html b/doc/html/boost_optional/tutorial/type_requirements.html
index 191f5fe..d213a4f 100644
--- a/doc/html/boost_optional/tutorial/type_requirements.html
+++ b/doc/html/boost_optional/tutorial/type_requirements.html
@@ -95,8 +95,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/boost_optional/tutorial/when_to_use_optional.html b/doc/html/boost_optional/tutorial/when_to_use_optional.html
index b56a8c0..3caec24 100644
--- a/doc/html/boost_optional/tutorial/when_to_use_optional.html
+++ b/doc/html/boost_optional/tutorial/when_to_use_optional.html
@@ -128,8 +128,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/index.html b/doc/html/index.html
index b9ec32a..a37010c 100644
--- a/doc/html/index.html
+++ b/doc/html/index.html
@@ -26,8 +26,7 @@
 Fernando Luis Cacciola Carballal
 

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal

-
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2014-2018 Andrzej Krzemieński

 

 

         Distributed under the Boost Software License, Version 1.0. (See accompanying
@@ -146,7 +145,7 @@
 

 

 
-
+
Last revised: March 23, 2018 at 23:01:17 GMT
Last revised: June 23, 2018 at 16:25:31 GMT

 

 

 

diff --git a/doc/html/optional/reference.html b/doc/html/optional/reference.html
index da63269..d3b0ab7 100644
--- a/doc/html/optional/reference.html
+++ b/doc/html/optional/reference.html
@@ -75,8 +75,7 @@
 
 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/optional/reference/header__boost_optional_optional_hpp_.html b/doc/html/optional/reference/header__boost_optional_optional_hpp_.html
index fdfb029..c416301 100644
--- a/doc/html/optional/reference/header__boost_optional_optional_hpp_.html
+++ b/doc/html/optional/reference/header__boost_optional_optional_hpp_.html
@@ -97,8 +97,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/doc/html/optional/tutorial.html b/doc/html/optional/tutorial.html
index 6d1122b..972f9f7 100644
--- a/doc/html/optional/tutorial.html
+++ b/doc/html/optional/tutorial.html
@@ -139,8 +139,7 @@
 

 
-

 
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2017 Andrzej
-      Krzemieński

+
Copyright © 2003-2007 Fernando Luis Cacciola Carballal
Copyright © 2014-2018 Andrzej Krzemieński

         Distributed under the Boost Software License, Version 1.0. (See accompanying
         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       

diff --git a/include/boost/optional/detail/optional_reference_spec.hpp b/include/boost/optional/detail/optional_reference_spec.hpp
index 8e9974c..2e08e30 100644
--- a/include/boost/optional/detail/optional_reference_spec.hpp
+++ b/include/boost/optional/detail/optional_reference_spec.hpp
@@ -1,4 +1,4 @@
-// Copyright (C) 2015-2016 Andrzej Krzemienski.
+// Copyright (C) 2015-2018 Andrzej Krzemienski.
 //
 // Use, modification, and distribution is subject to the Boost Software
 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -161,6 +161,15 @@ public:
     bool is_initialized() const BOOST_NOEXCEPT { return ptr_ != 0; }
     bool has_value() const BOOST_NOEXCEPT { return ptr_ != 0; }
     
+    template 
+    optional::type> map(F f) const
+    {
+      if (this->has_value())
+        return f(this->get());
+      else
+        return none;
+    }
+
 #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES   
  
     optional(T&& /* rhs */) BOOST_NOEXCEPT { detail::prevent_binding_rvalue(); }
diff --git a/include/boost/optional/optional.hpp b/include/boost/optional/optional.hpp
index 17c8f89..8ee259c 100644
--- a/include/boost/optional/optional.hpp
+++ b/include/boost/optional/optional.hpp
@@ -1,5 +1,5 @@
 // Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal.
-// Copyright (C) 2014 - 2017 Andrzej Krzemienski.
+// Copyright (C) 2014 - 2018 Andrzej Krzemienski.
 //
 // Use, modification, and distribution is subject to the Boost Software
 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -53,6 +53,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -1304,7 +1305,7 @@ class optional
 #endif
 
 
-#ifndef BOOST_NO_CXX11_REF_QUALIFIERS
+#if (!defined BOOST_NO_CXX11_REF_QUALIFIERS) && (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) 
     template 
     value_type value_or_eval ( F f ) const&
       {
@@ -1322,6 +1323,34 @@ class optional
         else
           return f();
       }
+
+    template 
+    optional::type> map(F f) &
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
+
+    template 
+    optional::type> map(F f) const&
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
+    
+    template 
+    optional::type> map(F f) &&
+      {
+        if (this->has_value())
+          return f(boost::move(this->get()));
+        else
+          return none;
+      }
+    
 #else
     template 
     value_type value_or_eval ( F f ) const
@@ -1331,6 +1360,24 @@ class optional
         else
           return f();
       }
+
+    template 
+    optional::type> map(F f)
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
+
+    template 
+    optional::type> map(F f) const
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
 #endif
       
     bool has_value() const BOOST_NOEXCEPT { return this->is_initialized() ; }
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index edc2e14..f181ec7 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -23,6 +23,7 @@ import testing ;
     [ run optional_test_convert_from_T.cpp ]
     [ run optional_test_empty_braces.cpp ]
     [ run optional_test_make_optional.cpp ]
+    [ run optional_test_map.cpp ]
     [ run optional_test_tie.cpp ]
     [ run optional_test_ref_assign_portable_minimum.cpp ]
     [ run optional_test_ref_assign_mutable_int.cpp ]
diff --git a/test/optional_test_map.cpp b/test/optional_test_map.cpp
new file mode 100644
index 0000000..9a9aab2
--- /dev/null
+++ b/test/optional_test_map.cpp
@@ -0,0 +1,160 @@
+// Copyright (C) 2018 Andrzej Krzemienski.
+//
+// Use, modification, and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/lib/optional for documentation.
+//
+// You are welcome to contact the author at:
+//  akrzemi1@gmail.com
+
+#include "boost/optional/optional.hpp"
+
+#ifdef __BORLANDC__
+#pragma hdrstop
+#endif
+
+#include "boost/core/ignore_unused.hpp"
+#include "boost/core/is_same.hpp"
+#include "boost/core/lightweight_test.hpp"
+#include "boost/core/lightweight_test_trait.hpp"
+
+
+using boost::optional;
+using boost::make_optional;
+using boost::core::is_same;
+
+template 
+void verify_type(Deduced)
+{
+  BOOST_TEST_TRAIT_TRUE(( is_same ));
+}
+  
+#if (!defined BOOST_NO_CXX11_REF_QUALIFIERS) && (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) 
+struct MoveOnly
+{
+  int value;
+  explicit MoveOnly(int i) : value(i) {}
+  MoveOnly(MoveOnly && r) : value(r.value) { r.value = 0; }
+  MoveOnly& operator=(MoveOnly && r) { value = r.value; r.value = 0; return *this; }
+  
+private:
+  MoveOnly(MoveOnly const&);
+  void operator=(MoveOnly const&);
+};
+
+MoveOnly makeMoveOnly(int i)
+{
+  return MoveOnly(i);
+}
+
+optional makeOptMoveOnly(int i)
+{
+  return optional(MoveOnly(i));
+}
+
+int get_val(MoveOnly m)
+{
+  return m.value;
+}
+
+void test_map_move_only()
+{
+  optional om (makeMoveOnly(7)), om2 (makeMoveOnly(8));
+  verify_type>(boost::move(om).map(get_val));
+  optional oi = boost::move(om2).map(get_val);
+  BOOST_TEST(bool(oi));
+  BOOST_TEST_EQ(8, *oi);
+
+  optional oj = makeOptMoveOnly(4).map(get_val);
+  BOOST_TEST(bool(oj));
+  BOOST_TEST_EQ(4, *oj);
+  
+  optional o_;
+  optional oi_ = boost::move(o_).map(get_val);
+  BOOST_TEST(!oi_);
+}
+
+#endif // no rvalue refs
+
+struct Int
+{
+  int i;
+  explicit Int(int i_) : i(i_) {}
+};
+
+struct convert_t
+{
+  Int operator()(int i) { return Int(i); }
+};
+
+int& get_int_ref(Int& i)
+{
+  return i.i;
+}
+
+struct get_ref
+{
+  int& operator()(int& i) { return i; }
+};
+
+void test_map()
+{
+  optional oi (1);
+  verify_type>(oi.map(convert_t()));
+  optional oI = oi.map(convert_t());
+  BOOST_TEST(bool(oI));
+  BOOST_TEST_EQ(1, oI->i);
+}
+
+void test_map_with_lambda()
+{
+#ifndef BOOST_NO_CXX11_LAMBDAS
+  optional oi (1), oj(2);
+  verify_type>(oi.map([](int i){ return i == 1; }));
+  optional ob = oi.map([](int i){ return i == 1; });
+  optional oc = oj.map([](int i){ return i == 1; });
+  BOOST_TEST(bool(ob));
+  BOOST_TEST_EQ(true, *ob);
+  BOOST_TEST(bool(oc));
+  BOOST_TEST_EQ(false, *oc);
+#endif // lambdas
+}
+
+void test_map_to_ref()
+{
+  optional oi (2);
+  verify_type>(oi.map(get_ref()));
+  optional ori = oi.map(get_ref());
+  BOOST_TEST(bool(ori));
+  *ori = 3;
+  BOOST_TEST(bool(oi));
+  BOOST_TEST_EQ(3, *oi);
+  BOOST_TEST_EQ(3, *ori);
+}
+
+void test_map_optional_ref()
+{
+  Int I (5);
+  optional ori (I);
+  verify_type>(ori.map(get_int_ref));
+  optional orii = ori.map(get_int_ref);
+  BOOST_TEST(bool(orii));
+  BOOST_TEST_EQ(5, *orii);
+  *orii = 6;
+  BOOST_TEST_EQ(6, I.i);
+}
+
+int main()
+{
+#if (!defined BOOST_NO_CXX11_REF_QUALIFIERS) && (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) 
+  test_map_move_only();
+#endif
+  test_map_with_lambda();
+	test_map();
+  test_map_to_ref();
+  test_map_optional_ref();
+
+  return boost::report_errors();
+}

From 51d1bc843d4df61e881026e4d01373f9e1e2c5f1 Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Sat, 23 Jun 2018 20:53:16 +0200
Subject: [PATCH 03/13] test and doc update for .map()

---
 doc/27_ref_optional_synopsis.qbk              |  2 ++
 doc/28_ref_optional_semantics.qbk             | 17 +++++++----
 ...ailed_semantics___optional_references.html | 15 ++++++++++
 .../detailed_semantics___optional_values.html | 10 +++----
 .../header_optional_optional_refs.html        |  2 ++
 doc/html/index.html                           |  2 +-
 test/optional_test_map.cpp                    | 30 +++++++++++++++++++
 7 files changed, 67 insertions(+), 11 deletions(-)

diff --git a/doc/27_ref_optional_synopsis.qbk b/doc/27_ref_optional_synopsis.qbk
index 8454218..5d4c2e4 100644
--- a/doc/27_ref_optional_synopsis.qbk
+++ b/doc/27_ref_optional_synopsis.qbk
@@ -260,6 +260,8 @@ They are empty, trivially copyable classes with disabled default constructor.
         
         template T& value_or_eval( F f ) const ; ``[link reference_optional_ref_value_or_eval __GO_TO__]``
 
+        template auto map( F f ) const -> ``['see below]``; ``[link reference_optional_ref_map __GO_TO__]``
+
         T* get_ptr() const noexcept ; ``[link reference_optional_ref_get_ptr __GO_TO__]``
 
         bool has_value() const noexcept ; ``[link reference_optional_ref_operator_bool __GO_TO__]``
diff --git a/doc/28_ref_optional_semantics.qbk b/doc/28_ref_optional_semantics.qbk
index 320da2d..b615e35 100644
--- a/doc/28_ref_optional_semantics.qbk
+++ b/doc/28_ref_optional_semantics.qbk
@@ -687,20 +687,20 @@ __SPACE__
 
 [#reference_optional_map]
 
-[: `template auto optional::map(F f) const& -> ``['see below]`` ;`]
-[: `template auto optional::map(F f) & -> ``['see below]`` ;`]
+[: `template auto optional::map(F f) const& -> `['see below]` ;`]
+[: `template auto optional::map(F f) & -> `['see below]` ;`]
 
 * [*Effects:] `if (*this) return f(**this); else return none;`
-* [*Notes:] The return type of these overloads is `optional`. On compilers that do not support ref-qualifiers on member functions, these two (as well as the next one) overloads are replaced with good old const and non-const overloads. 
+* [*Notes:] The return type of these overloads is `optional`. On compilers that do not support ref-qualifiers on member functions, these two (as well as the next one) overloads are replaced with good old const and non-const overloads. 
 
 __SPACE__
 
 [#reference_optional_map_move]
 
-[: `template auto optional::map(F f) && -> ``['see below]`` ;`]
+[: `template auto optional::map(F f) && -> `['see below]` ;`]
 
 * [*Effects:] `if (*this) return f(std::move(**this)); else return none;`
-* [*Notes:] The return type of this overload is `optional`.
+* [*Notes:] The return type of this overload is `optional`.
 
 __SPACE__
 
@@ -1053,6 +1053,13 @@ __SPACE__
 
 __SPACE__
 
+[#reference_optional_ref_map]
+[: `template auto optional::map( F f ) const -> `['see below]`;`]
+* [*Effects:] Equivalent to `if (*this) return f(**this); else return none;`.
+* [*Remarks:] The return type of this function is `optional`.
+
+__SPACE__
+
 [#reference_optional_ref_get_ptr]
 [: `T* optional::get_ptr () const noexcept;`]
 * [*Returns:] `ref`.
diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
index 3101217..acb6775 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
@@ -407,6 +407,21 @@
               is ill-formed.
             
 

+

+          space
+        

+

+            template<class F> auto optional<T&>::map( F f ) const -> see below;
+          

+
    
+
  • 
+              Effects: Equivalent to if (*this) return f(**this); else return none;.
+            
    • 
+
  • 
+              Remarks: The return type of this function
+              is optional<decltype(f(**this))>.
+            
    • 
+

 

           space
         

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
index 46fe0a8..127df4c 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
@@ -1476,10 +1476,10 @@
         

 

             template<class F> auto optional<T>::map(F f) const& ->
-            ['see below] ;
+            see below ;
           

 

-            template<class F> auto optional<T>::map(F f) & -> ['see below]
+            template<class F> auto optional<T>::map(F f) & -> see below
             ;
           

 
    
@@ -1490,7 +1490,7 @@
             
 
  • 
               Notes: The return type of these overloads
-              is optional<decltype(f(**this)>.
+              is optional<decltype(f(**this))>.
               On compilers that do not support ref-qualifiers on member functions,
               these two (as well as the next one) overloads are replaced with good
               old const and non-const overloads.
@@ -1501,7 +1501,7 @@
         
    
 
    
             template<class F> auto optional<T>::map(F f) &&
-            -> ['see below]
+            -> see below
             ;
           
    
 
      
@@ -1512,7 +1512,7 @@
             
 
    • 
               Notes: The return type of this overload
-              is optional<decltype(f(istd::move(**this))>.
+              is optional<decltype(f(istd::move(**this)))>.
             
      • 
 
    
 
    
diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
index 3934957..77906eb 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
@@ -73,6 +73,8 @@
 
     template<class F> T& value_or_eval( F f ) const ; R
 
+    template<class F> auto map( F f ) const -> see below; R
+
     T* get_ptr() const noexcept ; R
 
     bool has_value() const noexcept ; R
diff --git a/doc/html/index.html b/doc/html/index.html
index a37010c..44e9bc0 100644
--- a/doc/html/index.html
+++ b/doc/html/index.html
@@ -145,7 +145,7 @@
 

 
 
-
+
Last revised: June 23, 2018 at 16:25:31 GMT
Last revised: June 23, 2018 at 18:49:36 GMT

 

 

 

diff --git a/test/optional_test_map.cpp b/test/optional_test_map.cpp
index 9a9aab2..19348bd 100644
--- a/test/optional_test_map.cpp
+++ b/test/optional_test_map.cpp
@@ -106,6 +106,34 @@ void test_map()
   optional oI = oi.map(convert_t());
   BOOST_TEST(bool(oI));
   BOOST_TEST_EQ(1, oI->i);
+
+  optional o_ = optional().map(convert_t());
+  BOOST_TEST(!o_);
+}
+
+optional make_opt_int(int i)
+{
+  if (i != 0)
+    return Int(i);
+  else
+    return boost::none;
+}
+
+void test_map_optional()
+{
+  optional o9 (9), o0 (0), o_;
+  verify_type>>(o9.map(make_opt_int));
+  optional> oo9 = o9.map(make_opt_int);
+  BOOST_TEST(bool(oo9));  
+  BOOST_TEST(bool(*oo9));  
+  BOOST_TEST_EQ(9, (**oo9).i);
+
+  optional> oo0 = o0.map(make_opt_int);
+  BOOST_TEST(bool(oo0));  
+  BOOST_TEST(!*oo0);  
+  
+  optional> oo_ = o_.map(make_opt_int);
+  BOOST_TEST(!oo_);  
 }
 
 void test_map_with_lambda()
@@ -153,7 +181,9 @@ int main()
 #endif
   test_map_with_lambda();
 	test_map();
+  test_map_optional();
   test_map_to_ref();
+  test_map_optional();
   test_map_optional_ref();
 
   return boost::report_errors();

From 250806d029f99f4ce4d4f04de9c7421df4b691f2 Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Sun, 24 Jun 2018 15:22:56 +0200
Subject: [PATCH 04/13] fixed >> int C++03 templates

---
 test/optional_test_map.cpp | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/test/optional_test_map.cpp b/test/optional_test_map.cpp
index 19348bd..42878da 100644
--- a/test/optional_test_map.cpp
+++ b/test/optional_test_map.cpp
@@ -62,7 +62,7 @@ int get_val(MoveOnly m)
 void test_map_move_only()
 {
   optional om (makeMoveOnly(7)), om2 (makeMoveOnly(8));
-  verify_type>(boost::move(om).map(get_val));
+  verify_type >(boost::move(om).map(get_val));
   optional oi = boost::move(om2).map(get_val);
   BOOST_TEST(bool(oi));
   BOOST_TEST_EQ(8, *oi);
@@ -102,7 +102,7 @@ struct get_ref
 void test_map()
 {
   optional oi (1);
-  verify_type>(oi.map(convert_t()));
+  verify_type >(oi.map(convert_t()));
   optional oI = oi.map(convert_t());
   BOOST_TEST(bool(oI));
   BOOST_TEST_EQ(1, oI->i);
@@ -122,17 +122,17 @@ optional make_opt_int(int i)
 void test_map_optional()
 {
   optional o9 (9), o0 (0), o_;
-  verify_type>>(o9.map(make_opt_int));
-  optional> oo9 = o9.map(make_opt_int);
+  verify_type > >(o9.map(make_opt_int));
+  optional > oo9 = o9.map(make_opt_int);
   BOOST_TEST(bool(oo9));  
   BOOST_TEST(bool(*oo9));  
   BOOST_TEST_EQ(9, (**oo9).i);
 
-  optional> oo0 = o0.map(make_opt_int);
+  optional > oo0 = o0.map(make_opt_int);
   BOOST_TEST(bool(oo0));  
   BOOST_TEST(!*oo0);  
   
-  optional> oo_ = o_.map(make_opt_int);
+  optional > oo_ = o_.map(make_opt_int);
   BOOST_TEST(!oo_);  
 }
 
@@ -140,7 +140,7 @@ void test_map_with_lambda()
 {
 #ifndef BOOST_NO_CXX11_LAMBDAS
   optional oi (1), oj(2);
-  verify_type>(oi.map([](int i){ return i == 1; }));
+  verify_type >(oi.map([](int i){ return i == 1; }));
   optional ob = oi.map([](int i){ return i == 1; });
   optional oc = oj.map([](int i){ return i == 1; });
   BOOST_TEST(bool(ob));
@@ -153,7 +153,7 @@ void test_map_with_lambda()
 void test_map_to_ref()
 {
   optional oi (2);
-  verify_type>(oi.map(get_ref()));
+  verify_type >(oi.map(get_ref()));
   optional ori = oi.map(get_ref());
   BOOST_TEST(bool(ori));
   *ori = 3;
@@ -166,7 +166,7 @@ void test_map_optional_ref()
 {
   Int I (5);
   optional ori (I);
-  verify_type>(ori.map(get_int_ref));
+  verify_type >(ori.map(get_int_ref));
   optional orii = ori.map(get_int_ref);
   BOOST_TEST(bool(orii));
   BOOST_TEST_EQ(5, *orii);

From 42445e94aa8c9a68fce4af0d4980dc6cf8226e4a Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Sun, 24 Jun 2018 17:12:38 +0200
Subject: [PATCH 05/13] Fix for C++03 tests for .map() using result_of

---
 test/optional_test_map.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test/optional_test_map.cpp b/test/optional_test_map.cpp
index 42878da..f16c733 100644
--- a/test/optional_test_map.cpp
+++ b/test/optional_test_map.cpp
@@ -86,6 +86,7 @@ struct Int
 
 struct convert_t
 {
+  typedef Int result_type;
   Int operator()(int i) { return Int(i); }
 };
 
@@ -96,6 +97,7 @@ int& get_int_ref(Int& i)
 
 struct get_ref
 {
+  typedef int& result_type;
   int& operator()(int& i) { return i; }
 };
 

From 01694601943ca316bb73f5bcbebfec12e3a1c665 Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Mon, 25 Jun 2018 22:50:00 +0200
Subject: [PATCH 06/13] fixed tests and maybe
 std::is_trivially_default_constructible

---
 include/boost/optional/detail/experimental_traits.hpp    | 4 ++--
 test/optional_test_map.cpp                               | 2 +-
 test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp | 9 ++++++++-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/boost/optional/detail/experimental_traits.hpp b/include/boost/optional/detail/experimental_traits.hpp
index 6eded58..4ac8bc6 100644
--- a/include/boost/optional/detail/experimental_traits.hpp
+++ b/include/boost/optional/detail/experimental_traits.hpp
@@ -15,8 +15,6 @@
 #include 
 #include 
 #include 
-
-namespace boost { namespace optional_detail {
   
 // The condition to use POD implementation
 
@@ -52,10 +50,12 @@ namespace boost { namespace optional_detail {
 #ifndef BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
 #  define BOOST_OPTIONAL_DETAIL_HAS_TRIVIAL_CTOR(T) BOOST_HAS_TRIVIAL_CONSTRUCTOR(T)
 #else
+#  include 
 #  define BOOST_OPTIONAL_DETAIL_HAS_TRIVIAL_CTOR(T) std::is_trivially_default_constructible::value
 #endif
   
   
+namespace boost { namespace optional_detail {
   
 #ifndef BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
 template 
diff --git a/test/optional_test_map.cpp b/test/optional_test_map.cpp
index f16c733..288249c 100644
--- a/test/optional_test_map.cpp
+++ b/test/optional_test_map.cpp
@@ -140,7 +140,7 @@ void test_map_optional()
 
 void test_map_with_lambda()
 {
-#ifndef BOOST_NO_CXX11_LAMBDAS
+#if !defined BOOST_NO_CXX11_LAMBDAS && !defined BOOST_NO_CXX11_DECLTYPE_N3276
   optional oi (1), oj(2);
   verify_type >(oi.map([](int i){ return i == 1; }));
   optional ob = oi.map([](int i){ return i == 1; });
diff --git a/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp b/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
index e6b6ba0..aa21cf5 100644
--- a/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
+++ b/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
@@ -1,4 +1,4 @@
-// Copyright (C) 2015 Andrzej Krzemienski.
+// Copyright (C) 2015 - 2018 Andrzej Krzemienski.
 //
 // Use, modification, and distribution is subject to the Boost Software
 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -11,6 +11,7 @@
 
 #include "boost/core/lightweight_test.hpp"
 #include "boost/optional/detail/optional_config.hpp"
+#include "boost/predef.h"
 #include 
 
 int main()
@@ -37,5 +38,11 @@ int main()
   BOOST_TEST_EQ(empty, __GNUC_PATCHLEVEL__);
   BOOST_TEST_EQ(empty, __cplusplus);
 #endif
+
+  BOOST_TEST_EQ(empty, BOOST_COMP_GNUC);
+  BOOST_TEST_EQ(empty, BOOST_LANG_STDCPP);
+  BOOST_TEST_EQ(empty, BOOST_LIB_C_GNU);
+  BOOST_TEST_EQ(empty, BOOST_LIB_STD_CXX);
+
   return boost::report_errors();
 }

From 35ca7c1ff116af09a3ed34bf3e9e3a46bb80fc1a Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Mon, 25 Jun 2018 23:59:19 +0200
Subject: [PATCH 07/13] added a hack test to check compiler setup

---
 test/Jamfile.v2 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index f181ec7..bb9acd4 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -72,6 +72,7 @@ import testing ;
     [ run optional_test_static_properties.cpp ]
     [ compile optional_test_maybe_uninitialized_warning.cpp ]
     [ compile optional_test_deleted_default_ctor.cpp ]
+    [ run optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp ]
     [ run optional_xconfig_NO_PROPER_ASSIGN_FROM_CONST_INT_pass.cpp ]
     [ run-fail optional_xconfig_NO_PROPER_ASSIGN_FROM_CONST_INT_fail.cpp ]
     [ run optional_xconfig_NO_PROPER_CONVERT_FROM_CONST_INT_pass.cpp ]

From 51a46f95c6789dc6667018155c24764db72d36db Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Tue, 26 Jun 2018 00:04:33 +0200
Subject: [PATCH 08/13] testing clang v.

---
 test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp b/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
index aa21cf5..f8cf269 100644
--- a/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
+++ b/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
@@ -40,6 +40,7 @@ int main()
 #endif
 
   BOOST_TEST_EQ(empty, BOOST_COMP_GNUC);
+  BOOST_TEST_EQ(empty, BOOST_COMP_CLANG);
   BOOST_TEST_EQ(empty, BOOST_LANG_STDCPP);
   BOOST_TEST_EQ(empty, BOOST_LIB_C_GNU);
   BOOST_TEST_EQ(empty, BOOST_LIB_STD_CXX);

From 7320dd54e89d29f8aec536becb1e501db898551e Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Wed, 27 Jun 2018 22:23:57 +0200
Subject: [PATCH 09/13] one more test hack macro to check

---
 test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp b/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
index f8cf269..202c7ef 100644
--- a/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
+++ b/test/optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp
@@ -43,6 +43,7 @@ int main()
   BOOST_TEST_EQ(empty, BOOST_COMP_CLANG);
   BOOST_TEST_EQ(empty, BOOST_LANG_STDCPP);
   BOOST_TEST_EQ(empty, BOOST_LIB_C_GNU);
+  BOOST_TEST_EQ(empty, BOOST_LIB_STD_GNU);
   BOOST_TEST_EQ(empty, BOOST_LIB_STD_CXX);
 
   return boost::report_errors();

From d13623884a4dcca5091129f50be4861d6f5f9abb Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Thu, 28 Jun 2018 02:10:57 +0200
Subject: [PATCH 10/13] hopefully fixed the libstdc++ 4.9 problem (thanks
 Jonathan)

---
 include/boost/optional/detail/experimental_traits.hpp | 8 +++++++-
 test/Jamfile.v2                                       | 3 ++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/boost/optional/detail/experimental_traits.hpp b/include/boost/optional/detail/experimental_traits.hpp
index 4ac8bc6..556aa99 100644
--- a/include/boost/optional/detail/experimental_traits.hpp
+++ b/include/boost/optional/detail/experimental_traits.hpp
@@ -14,6 +14,7 @@
 
 #include 
 #include 
+#include 
 #include 
   
 // The condition to use POD implementation
@@ -38,11 +39,16 @@
 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
 #endif
 
+// GCC 5 or higher, or clang with libc++ or clang with libstdc++ 5 or higher
 #if __cplusplus >= 201103L
 #  if BOOST_WORKAROUND(BOOST_GCC, >= 50000)
 #    define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
 #  elif (defined BOOST_CLANG)
-#    define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
+#    if BOOST_LIB_STD_CXX > 0
+#      define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
+#    elif BOOST_LIB_STD_GNU >= 441200023 && BOOST_LIB_STD_GNU != 450600023 && BOOST_LIB_STD_GNU != 450600026 && BOOST_LIB_STD_GNU != 460800003
+#      define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
+#    endif
 #  endif
 #endif  
 
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index bb9acd4..e1690d2 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -23,6 +23,7 @@ import testing ;
     [ run optional_test_convert_from_T.cpp ]
     [ run optional_test_empty_braces.cpp ]
     [ run optional_test_make_optional.cpp ]
+    #[ run optional_test_flat_map.cpp ]
     [ run optional_test_map.cpp ]
     [ run optional_test_tie.cpp ]
     [ run optional_test_ref_assign_portable_minimum.cpp ]
@@ -72,7 +73,7 @@ import testing ;
     [ run optional_test_static_properties.cpp ]
     [ compile optional_test_maybe_uninitialized_warning.cpp ]
     [ compile optional_test_deleted_default_ctor.cpp ]
-    [ run optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp ]
+    #[ run optional_xconfig_HACK_TO_LIST_PREDEFINED_MACROS.cpp ]
     [ run optional_xconfig_NO_PROPER_ASSIGN_FROM_CONST_INT_pass.cpp ]
     [ run-fail optional_xconfig_NO_PROPER_ASSIGN_FROM_CONST_INT_fail.cpp ]
     [ run optional_xconfig_NO_PROPER_CONVERT_FROM_CONST_INT_pass.cpp ]

From 701afd43a4452af5c42ef1d0de3223a36f7fd31b Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Thu, 28 Jun 2018 21:17:07 +0200
Subject: [PATCH 11/13] fixed strange verisons of libstdc++

---
 include/boost/optional/detail/experimental_traits.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/boost/optional/detail/experimental_traits.hpp b/include/boost/optional/detail/experimental_traits.hpp
index 556aa99..b51f5f1 100644
--- a/include/boost/optional/detail/experimental_traits.hpp
+++ b/include/boost/optional/detail/experimental_traits.hpp
@@ -46,7 +46,7 @@
 #  elif (defined BOOST_CLANG)
 #    if BOOST_LIB_STD_CXX > 0
 #      define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
-#    elif BOOST_LIB_STD_GNU >= 441200023 && BOOST_LIB_STD_GNU != 450600023 && BOOST_LIB_STD_GNU != 450600026 && BOOST_LIB_STD_GNU != 460800003
+#    elif BOOST_LIB_STD_GNU >= 441200023 && BOOST_LIB_STD_GNU != 450600023 && BOOST_LIB_STD_GNU != 450600026 && BOOST_LIB_STD_GNU != 460800003 && BOOST_LIB_STD_GNU != 450400026 && BOOST_LIB_STD_GNU != 460700026
 #      define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
 #    endif
 #  endif

From 71d797b9ee132b381c2d4f3b5bcca2078b0a5062 Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Thu, 28 Jun 2018 23:27:42 +0200
Subject: [PATCH 12/13] added implementation and tests of flat_map()

---
 .../detail/optional_reference_spec.hpp        |   9 +
 include/boost/optional/optional.hpp           |  55 ++++
 test/Jamfile.v2                               |   2 +-
 test/optional_test_flat_map.cpp               | 275 ++++++++++++++++++
 4 files changed, 340 insertions(+), 1 deletion(-)
 create mode 100644 test/optional_test_flat_map.cpp

diff --git a/include/boost/optional/detail/optional_reference_spec.hpp b/include/boost/optional/detail/optional_reference_spec.hpp
index 2e08e30..4be140c 100644
--- a/include/boost/optional/detail/optional_reference_spec.hpp
+++ b/include/boost/optional/detail/optional_reference_spec.hpp
@@ -170,6 +170,15 @@ public:
         return none;
     }
 
+    template 
+    optional::type>::type> flat_map(F f) const
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
+    
 #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES   
  
     optional(T&& /* rhs */) BOOST_NOEXCEPT { detail::prevent_binding_rvalue(); }
diff --git a/include/boost/optional/optional.hpp b/include/boost/optional/optional.hpp
index 8ee259c..ff39dad 100644
--- a/include/boost/optional/optional.hpp
+++ b/include/boost/optional/optional.hpp
@@ -758,7 +758,16 @@ class optional_base : public optional_tag
     storage_type m_storage ;
 } ;
 
+template 
+struct optional_value_type
+{
+};
 
+template 
+struct optional_value_type< ::boost::optional >
+{
+  typedef T type;
+};
 
 #include 
 
@@ -1351,6 +1360,33 @@ class optional
           return none;
       }
     
+    template 
+    optional::type>::type> flat_map(F f) &
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
+    
+    template 
+    optional::type>::type> flat_map(F f) const&
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
+    
+    template 
+    optional::type>::type> flat_map(F f) &&
+      {
+        if (this->has_value())
+          return f(boost::move(get()));
+        else
+          return none;
+      }
+    
 #else
     template 
     value_type value_or_eval ( F f ) const
@@ -1378,6 +1414,25 @@ class optional
         else
           return none;
       }
+
+    template 
+    optional::type>::type> flat_map(F f)
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
+    
+    template 
+    optional::type>::type> flat_map(F f) const
+      {
+        if (this->has_value())
+          return f(get());
+        else
+          return none;
+      }
+    
 #endif
       
     bool has_value() const BOOST_NOEXCEPT { return this->is_initialized() ; }
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index e1690d2..4a758da 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -23,7 +23,7 @@ import testing ;
     [ run optional_test_convert_from_T.cpp ]
     [ run optional_test_empty_braces.cpp ]
     [ run optional_test_make_optional.cpp ]
-    #[ run optional_test_flat_map.cpp ]
+    [ run optional_test_flat_map.cpp ]
     [ run optional_test_map.cpp ]
     [ run optional_test_tie.cpp ]
     [ run optional_test_ref_assign_portable_minimum.cpp ]
diff --git a/test/optional_test_flat_map.cpp b/test/optional_test_flat_map.cpp
new file mode 100644
index 0000000..409e111
--- /dev/null
+++ b/test/optional_test_flat_map.cpp
@@ -0,0 +1,275 @@
+// Copyright (C) 2018 Andrzej Krzemienski.
+//
+// Use, modification, and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/lib/optional for documentation.
+//
+// You are welcome to contact the author at:
+//  akrzemi1@gmail.com
+
+#include "boost/optional/optional.hpp"
+
+#ifdef __BORLANDC__
+#pragma hdrstop
+#endif
+
+#include "boost/core/ignore_unused.hpp"
+#include "boost/core/is_same.hpp"
+#include "boost/core/lightweight_test.hpp"
+#include "boost/core/lightweight_test_trait.hpp"
+
+
+using boost::optional;
+using boost::make_optional;
+using boost::core::is_same;
+
+template 
+void verify_type(Deduced)
+{
+  BOOST_TEST_TRAIT_TRUE(( is_same ));
+}
+
+struct Int
+{
+  int i;
+  explicit Int(int i_) : i(i_) {}
+};
+
+struct convert_t
+{
+  typedef optional result_type;
+  optional operator()(int i) { if (i != 0) return Int(i); else return boost::none; }
+};
+
+void test_flat_map_on_mutable_optional_with_function_object()
+{
+  {
+    optional oi (1);
+    verify_type< optional >(oi.flat_map(convert_t()));
+    optional oI = oi.flat_map(convert_t());
+    BOOST_TEST(bool(oI));
+    BOOST_TEST_EQ(1, oI->i);
+  }
+  {
+    optional oi (0);
+    optional oI = oi.flat_map(convert_t());
+    BOOST_TEST(!oI);
+  }
+  {
+    optional oi;
+    optional oI = oi.flat_map(convert_t());
+    BOOST_TEST(!oI);
+  }
+}
+
+void test_flat_map_on_const_optional_with_function_object()
+{
+  {
+    const optional oi (1);
+    verify_type< optional >(oi.flat_map(convert_t()));
+    optional oI = oi.flat_map(convert_t());
+    BOOST_TEST(bool(oI));
+    BOOST_TEST_EQ(1, oI->i);
+  }
+  {
+    const optional oi (0);
+    optional oI = oi.flat_map(convert_t());
+    BOOST_TEST(!oI);
+  }
+  {
+    const optional oi;
+    optional oI = oi.flat_map(convert_t());
+    BOOST_TEST(!oI);
+  }
+}
+
+void test_flat_map_with_lambda()
+{
+#if !defined BOOST_NO_CXX11_LAMBDAS && !defined BOOST_NO_CXX11_DECLTYPE_N3276
+  {
+    optional oi (1);
+    verify_type< optional >(oi.flat_map([](int i){ return optional(i == 0, Int(i)); }));
+    optional oI = oi.flat_map([](int i){ return optional(i != 0, Int(i)); });
+    BOOST_TEST(bool(oI));
+    BOOST_TEST_EQ(1, oI->i);
+  }
+  {
+    optional oi (0);
+    optional oI = oi.flat_map([](int i){ return optional(i != 0, Int(i)); });
+    BOOST_TEST(!oI);
+  }
+  {
+    optional oi;
+    optional oI = oi.flat_map([](int i){ return optional(i != 0, Int(i)); });
+    BOOST_TEST(!oI);
+  }
+#endif // lambdas
+}
+
+struct get_opt_ref
+{
+  typedef optional result_type;
+  optional operator()(int& i) { return i != 0 ? optional(i) : optional(); }
+};
+
+void test_flat_map_obj_to_ref()
+{
+  {
+    optional oi (2);
+    verify_type< optional >(oi.flat_map(get_opt_ref()));
+    optional ori = oi.flat_map(get_opt_ref());
+    BOOST_TEST(bool(ori));
+    BOOST_TEST_EQ(2, *ori);
+    *ori = 3;
+    BOOST_TEST(bool(oi));
+    BOOST_TEST_EQ(3, *oi);
+    BOOST_TEST_EQ(3, *ori);
+  }
+  {
+    optional oi (0);
+    optional ori = oi.flat_map(get_opt_ref());
+    BOOST_TEST(!ori);
+  }
+  {
+    optional oi;
+    optional ori = oi.flat_map(get_opt_ref());
+    BOOST_TEST(!ori);
+  }
+}
+
+optional get_opt_int_ref(Int& i)
+{
+  return i.i ? optional(i.i) : optional();
+}
+
+void test_flat_map_ref_to_ref()
+{
+  {
+    Int I (5);
+    optional orI (I);
+    verify_type< optional >(orI.flat_map(get_opt_int_ref));
+    optional ori = orI.flat_map(get_opt_int_ref);
+    BOOST_TEST(bool(ori));
+    BOOST_TEST_EQ(5, *ori);
+    *ori = 6;
+    BOOST_TEST_EQ(6, *ori);
+    BOOST_TEST_EQ(6, I.i);
+  }
+  {
+    Int I (0);
+    optional orI (I);
+    optional ori = orI.flat_map(get_opt_int_ref);
+    BOOST_TEST(!ori);
+  }
+  {
+    optional orI;
+    optional ori = orI.flat_map(get_opt_int_ref);
+    BOOST_TEST(!ori);
+  }
+}
+
+optional< optional > make_opt_int(int i)
+{
+  if (i == 0)
+    return boost::none;
+  else if (i == 1)
+    return boost::make_optional(optional());
+  else
+    return boost::make_optional(boost::make_optional(Int(i)));
+}
+
+void test_flat_map_opt_opt()
+{
+  {
+    optional oi (9);
+    verify_type > >(oi.flat_map(make_opt_int));
+    optional > ooI = oi.flat_map(make_opt_int);
+    BOOST_TEST(bool(ooI));
+    BOOST_TEST(bool(*ooI));
+    BOOST_TEST_EQ(9, (**ooI).i);
+  }
+  {
+    optional oi (1);
+    optional > ooI = oi.flat_map(make_opt_int);
+    BOOST_TEST(bool(ooI));
+    BOOST_TEST(!*ooI);
+  }
+  {
+    optional oi (0);
+    optional > ooI = oi.flat_map(make_opt_int);
+    BOOST_TEST(!ooI);
+  }
+  {
+    optional oi;
+    optional > ooI = oi.flat_map(make_opt_int);
+    BOOST_TEST(!ooI);
+  }
+}
+
+#if (!defined BOOST_NO_CXX11_REF_QUALIFIERS) && (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES)
+struct MoveOnly
+{
+  int value;
+  explicit MoveOnly(int i) : value(i) {}
+  MoveOnly(MoveOnly && r) : value(r.value) { r.value = 0; }
+  MoveOnly& operator=(MoveOnly && r) { value = r.value; r.value = 0; return *this; }
+
+private:
+  MoveOnly(MoveOnly const&);
+  void operator=(MoveOnly const&);
+};
+
+MoveOnly makeMoveOnly(int i)
+{
+  return MoveOnly(i);
+}
+
+optional makeOptMoveOnly(int i)
+{
+  return optional(MoveOnly(i));
+}
+
+optional get_val(MoveOnly m)
+{
+  return optional(m.value != 0, m.value);
+}
+
+void test_flat_map_move_only()
+{
+  {
+    optional om (makeMoveOnly(1)), om2 (makeMoveOnly(2));
+    verify_type >(boost::move(om).flat_map(get_val));
+    optional oi = boost::move(om2).flat_map(get_val);
+    BOOST_TEST(bool(oi));
+    BOOST_TEST_EQ(2, *oi);
+  }
+  {
+    optional oj = makeOptMoveOnly(4).flat_map(get_val);
+    BOOST_TEST(bool(oj));
+    BOOST_TEST_EQ(4, *oj);
+  }
+  {
+    optional oj = optional().flat_map(get_val);
+    BOOST_TEST(!oj);
+  }
+}
+
+#endif // no rvalue refs
+
+int main()
+{
+  test_flat_map_on_mutable_optional_with_function_object();
+  test_flat_map_on_const_optional_with_function_object();
+  test_flat_map_with_lambda();
+  test_flat_map_obj_to_ref();
+  test_flat_map_ref_to_ref();
+  test_flat_map_opt_opt();
+
+#if (!defined BOOST_NO_CXX11_REF_QUALIFIERS) && (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES)
+  test_flat_map_move_only();
+#endif
+
+  return boost::report_errors();
+}

From d0b87d2f359f8fa4fa31c84ca03e0e18576a7c11 Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski 
Date: Mon, 2 Jul 2018 23:07:47 +0200
Subject: [PATCH 13/13] documented flat_map

---
 doc/27_ref_optional_synopsis.qbk              |  89 ++++++++--------
 doc/28_ref_optional_semantics.qbk             | 100 +++++++++++++-----
 doc/91_relnotes.qbk                           |   7 +-
 ...ailed_semantics___optional_references.html |  24 +++++
 .../detailed_semantics___optional_values.html |  76 +++++++++++++
 .../header_optional_optional_refs.html        |   3 +-
 .../header_optional_optional_values.html      |   4 +
 doc/html/boost_optional/relnotes.html         |   5 +-
 doc/html/index.html                           |   2 +-
 9 files changed, 236 insertions(+), 74 deletions(-)

diff --git a/doc/27_ref_optional_synopsis.qbk b/doc/27_ref_optional_synopsis.qbk
index 5d4c2e4..7114b43 100644
--- a/doc/27_ref_optional_synopsis.qbk
+++ b/doc/27_ref_optional_synopsis.qbk
@@ -17,16 +17,16 @@
 
     class in_place_init_t { /* see below */ } ; ``[link reference_in_place_init __GO_TO__]``
     const in_place_init_t in_place_init ( /* see below */ ) ;
-    
+
     class in_place_init_if_t { /*see below*/ } ; ``[link reference_in_place_init_if __GO_TO__]``
     const in_place_init_if_t in_place_init_if ( /*see below*/ ) ;
-    
+
     template 
     class optional ; ``[link reference_operator_template __GO_TO__]``
-    
+
     template 
     class optional ; ``[link reference_operator_template_spec __GO_TO__]``
-    
+
     template inline bool operator == ( optional const& x, optional const& y ) ; ``[link reference_operator_compare_equal_optional_optional __GO_TO__]``
 
     template inline bool operator != ( optional const& x, optional const& y ) ; ``[link reference_operator_compare_not_equal_optional_optional __GO_TO__]``
@@ -38,21 +38,21 @@
     template inline bool operator <= ( optional const& x, optional const& y ) ; ``[link reference_operator_compare_less_or_equal_optional_optional __GO_TO__]``
 
     template inline bool operator >= ( optional const& x, optional const& y ) ; ``[link reference_operator_compare_greater_or_equal_optional_optional __GO_TO__]``
-    
+
     template inline bool operator == ( optional const& x, none_t ) noexcept ; ``[link reference_operator_compare_equal_optional_none __GO_TO__]``
 
     template inline bool operator != ( optional const& x, none_t ) noexcept ; ``[link reference_operator_compare_not_equal_optional_none __GO_TO__]``
 
     template inline optional make_optional ( T const& v ) ; ``[link reference_make_optional_value __GO_TO__]``
-    
+
     template inline optional> make_optional ( T && v ) ; ``[link reference_make_optional_rvalue __GO_TO__]``
 
     template inline optional make_optional ( bool condition, T const& v ) ; ``[link reference_make_optional_bool_value __GO_TO__]``
-    
+
     template inline optional> make_optional ( bool condition, T && v ) ; ``[link reference_make_optional_bool_rvalue __GO_TO__]``
 
-    template inline auto get_optional_value_or ( optional const& opt, typename optional::reference_const_type def ) -> typename optional::reference_const_type; ``[link reference_free_get_value_or __GO_TO__]`` 
-    
+    template inline auto get_optional_value_or ( optional const& opt, typename optional::reference_const_type def ) -> typename optional::reference_const_type; ``[link reference_free_get_value_or __GO_TO__]``
+
     template inline auto get_optional_value_or ( optional const& opt, typename optional::reference_type def ) -> typename optional::reference_type ; ``[link reference_free_get_value_or __GO_TO__]``
 
     template inline T const& get ( optional const& opt ) ; ``[link reference_optional_get __GO_TO__]``
@@ -68,7 +68,7 @@
     template inline auto get_pointer ( optional & opt ) -> ``['see below]``; ``[link reference_free_get_pointer __GO_TO__]``
 
     template inline void swap( optional& x, optional& y ) ; ``[link reference_swap_optional_optional __GO_TO__]``
-    
+
     template inline void swap( optional& x, optional& y ) ; ``[link reference_swap_optional_reference __GO_TO__]``
 
     } // namespace boost
@@ -86,21 +86,21 @@
 
     class in_place_init_t { /* see below */ } ;
     const in_place_init_t in_place_init ( /* see below */ ) ;
-    
+
     class in_place_init_if_t { /*see below*/ } ;
     const in_place_init_if_t in_place_init_if ( /*see below*/ ) ;
-    
+
     }
 
-Classes `in_place_init_t` and `in_place_init_if_t` are empty clsses. Their purpose is to control overload resolution in the initialization of optional objects. 
-They are empty, trivially copyable classes with disabled default constructor.  
+Classes `in_place_init_t` and `in_place_init_if_t` are empty clsses. Their purpose is to control overload resolution in the initialization of optional objects.
+They are empty, trivially copyable classes with disabled default constructor.
 
 [endsect]
 
 [section:header_optional_optional_values Optional Values]
 
 [#reference_operator_template]
-    
+
     template 
     class optional
     {
@@ -112,27 +112,27 @@ They are empty, trivially copyable classes with disabled default constructor.
         typedef T &&      rval_reference_type ;
         typedef T *       pointer_type ;
         typedef T const*  pointer_const_type ;
-        
+
         optional () noexcept ; ``[link reference_optional_constructor __GO_TO__]``
 
         optional ( none_t ) noexcept ; ``[link reference_optional_constructor_none_t __GO_TO__]``
 
         optional ( T const& v ) ; ``[link reference_optional_constructor_value __GO_TO__]``
-        
+
         optional ( T&& v ) ; ``[link reference_optional_constructor_move_value __GO_TO__]``
 
-        optional ( bool condition, T const& v ) ; ``[link reference_optional_constructor_bool_value __GO_TO__]`` 
+        optional ( bool condition, T const& v ) ; ``[link reference_optional_constructor_bool_value __GO_TO__]``
 
         optional ( optional const& rhs ) ; ``[link reference_optional_constructor_optional __GO_TO__]``
-        
+
         optional ( optional&& rhs ) noexcept(``['see below]``) ; ``[link reference_optional_move_constructor_optional __GO_TO__]``
 
         template explicit optional ( optional const& rhs ) ; ``[link reference_optional_constructor_other_optional __GO_TO__]``
-        
+
         template explicit optional ( optional&& rhs ) ; ``[link reference_optional_move_constructor_other_optional __GO_TO__]``
-        
+
         template explicit optional ( in_place_init_t, Args&&... args ) ; ``[link reference_optional_in_place_init __GO_TO__]``
-        
+
         template explicit optional ( in_place_init_if_t, bool condition, Args&&... args ) ; ``[link reference_optional_in_place_init_if __GO_TO__]``
 
         template explicit optional ( InPlaceFactory const& f ) ; ``[link reference_optional_constructor_factory __GO_TO__]``
@@ -142,17 +142,17 @@ They are empty, trivially copyable classes with disabled default constructor.
         optional& operator = ( none_t ) noexcept ; ``[link reference_optional_operator_equal_none_t __GO_TO__]``
 
         optional& operator = ( T const& v ) ; ``[link reference_optional_operator_equal_value __GO_TO__]``
-        
+
         optional& operator = ( T&& v ) ; ``[link reference_optional_operator_move_equal_value __GO_TO__]``
 
         optional& operator = ( optional const& rhs ) ; ``[link reference_optional_operator_equal_optional __GO_TO__]``
-        
+
         optional& operator = ( optional&& rhs ) noexcept(``['see below]``) ; ``[link reference_optional_operator_move_equal_optional __GO_TO__]``
 
         template optional& operator = ( optional const& rhs ) ; ``[link reference_optional_operator_equal_other_optional __GO_TO__]``
-        
+
         template optional& operator = ( optional&& rhs ) ; ``[link reference_optional_operator_move_equal_other_optional __GO_TO__]``
-        
+
         template void emplace ( Args&&... args ) ; ``[link reference_optional_emplace __GO_TO__]``
 
         template optional& operator = ( InPlaceFactory const& f ) ; ``[link reference_optional_operator_equal_factory __GO_TO__]``
@@ -168,14 +168,14 @@ They are empty, trivially copyable classes with disabled default constructor.
         T const& operator *() const& ; ``[link reference_optional_operator_asterisk __GO_TO__]``
         T&       operator *() & ; ``[link reference_optional_operator_asterisk __GO_TO__]``
         T&&      operator *() && ; ``[link reference_optional_operator_asterisk_move __GO_TO__]``
-        
+
         T const& value() const& ; ``[link reference_optional_value __GO_TO__]``
         T&       value() & ; ``[link reference_optional_value __GO_TO__]``
         T&&      value() && ; ``[link reference_optional_value_move __GO_TO__]``
-        
+
         template T value_or( U && v ) const& ; ``[link reference_optional_value_or __GO_TO__]``
         template T value_or( U && v ) && ; ``[link reference_optional_value_or_move __GO_TO__]``
-        
+
         template T value_or_eval( F f ) const& ; ``[link reference_optional_value_or_call __GO_TO__]``
         template T value_or_eval( F f ) && ; ``[link reference_optional_value_or_call_move __GO_TO__]``
 
@@ -183,11 +183,15 @@ They are empty, trivially copyable classes with disabled default constructor.
         template auto map( F f ) & -> ``['see below]``; ``[link reference_optional_map __GO_TO__]``
         template auto map( F f ) && -> ``['see below]``; ``[link reference_optional_map_move __GO_TO__]``
 
+        template auto flat_map( F f ) const& -> ``['see below]``; ``[link reference_optional_flat_map __GO_TO__]``
+        template auto flat_map( F f ) & -> ``['see below]``; ``[link reference_optional_flat_map __GO_TO__]``
+        template auto flat_map( F f ) && -> ``['see below]``; ``[link reference_optional_flat_map_move __GO_TO__]``
+
         T const* get_ptr() const ; ``[link reference_optional_get_ptr __GO_TO__]``
         T*       get_ptr() ; ``[link reference_optional_get_ptr __GO_TO__]``
 
         bool has_value() const noexcept ; ``[link reference_optional_operator_bool __GO_TO__]``
-        
+
         explicit operator bool() const noexcept ; ``[link reference_optional_operator_bool __GO_TO__]``
 
         bool operator!() const noexcept ; ``[link reference_optional_operator_not __GO_TO__]``
@@ -204,7 +208,7 @@ They are empty, trivially copyable classes with disabled default constructor.
         bool is_initialized() const ; ``[link reference_optional_is_initialized __GO_TO__]``
 
         // (deprecated)
-        T const& get_value_or( T const& default ) const ; ``[link reference_optional_get_value_or_value __GO_TO__]`` 
+        T const& get_value_or( T const& default ) const ; ``[link reference_optional_get_value_or_value __GO_TO__]``
     };
 
 
@@ -231,22 +235,21 @@ They are empty, trivially copyable classes with disabled default constructor.
         optional ( none_t ) noexcept ; ``[link reference_optional_ref_default_ctor __GO_TO__]``
 
         template optional(R&& r) noexcept ;  ``[link reference_optional_ref_value_ctor __GO_TO__]``
-        
+
         template  optional(bool cond, R&& r) noexcept ; ``[link reference_optional_ref_cond_value_ctor __GO_TO__]``
-        
+
         optional ( optional const& rhs ) noexcept ; ``[link reference_optional_ref_copy_ctor __GO_TO__]``
 
         template explicit optional ( optional const& rhs ) noexcept ; ``[link reference_optional_ref_ctor_from_opt_U __GO_TO__]``
 
         optional& operator = ( none_t ) noexcept ; ``[link reference_optional_ref_assign_none_t __GO_TO__]``
 
-
         optional& operator = ( optional const& rhs ) noexcept; ``[link reference_optional_ref_copy_assign __GO_TO__]``
 
         template optional& operator = ( optional const& rhs ) noexcept ; ``[link reference_optional_ref_assign_optional_U __GO_TO__]``
-          
-        template optional& operator = (R&& r) noexcept ; ``[link reference_optional_ref_assign_R __GO_TO__]``      
-        
+
+        template optional& operator = (R&& r) noexcept ; ``[link reference_optional_ref_assign_R __GO_TO__]``
+
         template void emplace ( R&& r ) noexcept ; ``[link reference_optional_ref_emplace_R __GO_TO__]``
 
         T& get() const ; ``[link reference_optional_ref_get __GO_TO__]``
@@ -255,17 +258,19 @@ They are empty, trivially copyable classes with disabled default constructor.
         T* operator ->() const ; ``[link reference_optional_ref_arrow __GO_TO__]``
 
         T& value() const& ; ``[link reference_optional_ref_value __GO_TO__]``
-        
+
         template T& value_or( R && r ) const noexcept ; ``[link reference_optional_ref_value_or __GO_TO__]``
-        
+
         template T& value_or_eval( F f ) const ; ``[link reference_optional_ref_value_or_eval __GO_TO__]``
 
         template auto map( F f ) const -> ``['see below]``; ``[link reference_optional_ref_map __GO_TO__]``
 
+        template auto flat_map( F f ) const -> ``['see below]``; ``[link reference_optional_ref_flat_map __GO_TO__]``
+
         T* get_ptr() const noexcept ; ``[link reference_optional_ref_get_ptr __GO_TO__]``
 
         bool has_value() const noexcept ; ``[link reference_optional_ref_operator_bool __GO_TO__]``
-        
+
         explicit operator bool() const noexcept ; ``[link reference_optional_ref_operator_bool __GO_TO__]``
 
         bool operator!() const noexcept ; ``[link reference_optional_ref_operator_not __GO_TO__]``
@@ -282,8 +287,8 @@ They are empty, trivially copyable classes with disabled default constructor.
         bool is_initialized() const noexcept ; ``[link reference_optional_ref_is_initialized __GO_TO__]``
 
         // (deprecated)
-        template T& get_value_or( R && r ) constnoexcept; ``[link reference_optional_ref_get_value_or_value __GO_TO__]`` 
-        
+        template T& get_value_or( R && r ) constnoexcept; ``[link reference_optional_ref_get_value_or_value __GO_TO__]``
+
     private:
         T* ref; // exposition only
     };
diff --git a/doc/28_ref_optional_semantics.qbk b/doc/28_ref_optional_semantics.qbk
index b615e35..6ce0d2e 100644
--- a/doc/28_ref_optional_semantics.qbk
+++ b/doc/28_ref_optional_semantics.qbk
@@ -233,7 +233,7 @@ __SPACE__
 arguments `std::forward(args)...`.
 * [*Postconditions:] `*this` is initialized.
 * [*Throws:] Any exception thrown by the selected constructor of `T`.
-* [*Notes: ] `T` need not be __MOVE_CONSTRUCTIBLE__. On compilers that do not suppor variadic templates or rvalue references, this constuctor is available in limited functionality. For details [link optional_emplace_workaround see here]. 
+* [*Notes: ] `T` need not be __MOVE_CONSTRUCTIBLE__. On compilers that do not suppor variadic templates or rvalue references, this constuctor is available in limited functionality. For details [link optional_emplace_workaround see here].
 
 * [*Example:]
 ``
@@ -257,7 +257,7 @@ __SPACE__
 * [*Effect:] If `condition` is `true`, initializes the contained value as if direct-non-list-initializing an object of type `T` with the arguments `std::forward(args)...`.
 * [*Postconditions:] `bool(*this) == condition`.
 * [*Throws:] Any exception thrown by the selected constructor of `T`.
-* [*Notes: ] `T` need not be __MOVE_CONSTRUCTIBLE__. On compilers that do not suppor variadic templates or rvalue references, this constuctor is available in limited functionality. For details [link optional_emplace_workaround see here]. 
+* [*Notes: ] `T` need not be __MOVE_CONSTRUCTIBLE__. On compilers that do not suppor variadic templates or rvalue references, this constuctor is available in limited functionality. For details [link optional_emplace_workaround see here].
 
 * [*Example:]
 ``
@@ -376,13 +376,13 @@ __SPACE__
 * [*Requires:] `T` is __COPY_CONSTRUCTIBLE__ and `CopyAssignable`.
 * [*Effects:]
 [table
-  [] 
+  []
   [[][[*`*this` contains a value]][[*`*this` does not contain a value]]]
   [[[*`rhs` contains a value]][assigns `*rhs` to the contained value][initializes the contained value as if direct-initializing an object of type `T` with `*rhs`]]
   [[[*`rhs` does not contain a value]][destroys the contained value by calling `val->T::~T()`][no effect]]
 ]
 * [*Returns:] `*this`;
-* [*Postconditions:] `bool(rhs) == bool(*this)`. 
+* [*Postconditions:] `bool(rhs) == bool(*this)`.
 * [*Exception Safety:] If any exception is thrown, the initialization state of `*this` and `rhs` remains unchanged.
 If an exception is thrown during the call to `T`'s copy constructor, no effect.
 If an exception is thrown during the call to `T`'s copy assignment, the state of its contained value is as defined by the exception safety guarantee of `T`'s copy assignment.
@@ -406,14 +406,14 @@ __SPACE__
 
 * [*Requires:] `T` is __MOVE_CONSTRUCTIBLE__ and `MoveAssignable`.
 * [*Effects:]
-[table 
+[table
   []
   [[][[*`*this` contains a value]][[*`*this` does not contain a value]]]
   [[[*`rhs` contains a value]][assigns `std::move(*rhs)` to the contained value][initializes the contained value as if direct-initializing an object of type `T` with `std::move(*rhs)`]]
   [[[*`rhs` does not contain a value]][destroys the contained value by calling `val->T::~T()`][no effect]]
 ]
 * [*Returns:] `*this`;
-* [*Postconditions:] `bool(rhs) == bool(*this)`. 
+* [*Postconditions:] `bool(rhs) == bool(*this)`.
 * [*Remarks:] The expression inside `noexcept` is equivalent to `is_nothrow_move_constructible::value && is_nothrow_move_assignable::value`.
 * [*Exception Safety:] If any exception is thrown, the initialization state of `*this` and `rhs` remains unchanged. If an exception is
 thrown during the call to `T`'s move constructor, the state of `*rhs` is determined by the exception safety guarantee
@@ -437,15 +437,15 @@ __SPACE__
 
 [: `template optional& optional::operator= ( optional const& rhs ) ;`]
 
-* [*Effect:] 
-[table 
+* [*Effect:]
+[table
   []
   [[][[*`*this` contains a value]][[*`*this` does not contain a value]]]
   [[[*`rhs` contains a value]][assigns `*rhs` to the contained value][initializes the contained value as if direct-initializing an object of type `T` with `*rhs`]]
   [[[*`rhs` does not contain a value]][destroys the contained value by calling `val->T::~T()`][no effect]]
 ]
 * [*Returns:] `*this`.
-* [*Postconditions:] `bool(rhs) == bool(*this)`. 
+* [*Postconditions:] `bool(rhs) == bool(*this)`.
 * [*Exception Safety:] If any exception is thrown, the result of the expression `bool(*this)` remains unchanged.
 If an exception is thrown during the call to `T`'s constructor, no effect.
 If an exception is thrown during the call to `T`'s assignment, the state of its contained value is as defined by the exception safety guarantee of `T`'s copy assignment.
@@ -467,13 +467,13 @@ __SPACE__
 
 * [*Effect:]
 [table
-  [] 
+  []
   [[][[*`*this` contains a value]][[*`*this` does not contain a value]]]
   [[[*`rhs` contains a value]][assigns `std::move(*rhs)` to the contained value][initializes the contained value as if direct-initializing an object of type `T` with `std::move(*rhs)`]]
   [[[*`rhs` does not contain a value]][destroys the contained value by calling `val->T::~T()`][no effect]]
 ]
 * [*Returns:] `*this`.
-* [*Postconditions:] `bool(rhs) == bool(*this)`. 
+* [*Postconditions:] `bool(rhs) == bool(*this)`.
 * [*Exception Safety:] If any exception is thrown, the result of the expression `bool(*this)` remains unchanged.
 If an exception is thrown during the call to `T`'s constructor, no effect.
 If an exception is thrown during the call to `T`'s assignment, the state of its contained value is as defined by the exception safety guarantee of `T`'s copy assignment.
@@ -485,7 +485,7 @@ optional opt1;
 
 opt1 = std::move(opt0) ;
 assert ( opt0 );
-assert ( opt1 ) 
+assert ( opt1 )
 assert ( *opt1 == static_cast(v) ) ;
 ``
 
@@ -498,11 +498,11 @@ __SPACE__
 * [*Requires:] The compiler supports rvalue references and variadic templates.
 * [*Effect:] If `*this` is initialized calls `*this = none`.
  Then initializes in-place the contained value as if direct-initializing an object
- of type `T` with `std::forward(args)...`. 
+ of type `T` with `std::forward(args)...`.
 * [*Postconditions: ] `*this` is [_initialized].
 * [*Throws:] Whatever the selected `T`'s  constructor throws.
 * [*Exception Safety:] If an exception is thrown during the initialization of `T`, `*this` is ['uninitialized].
-* [*Notes:] `T` need not be __MOVE_CONSTRUCTIBLE__ or `MoveAssignable`. On compilers that do not suppor variadic templates or rvalue references, this function is available in limited functionality. For details [link optional_emplace_workaround see here].  
+* [*Notes:] `T` need not be __MOVE_CONSTRUCTIBLE__ or `MoveAssignable`. On compilers that do not suppor variadic templates or rvalue references, this function is available in limited functionality. For details [link optional_emplace_workaround see here].
 * [*Example:]
 ``
 T v;
@@ -691,7 +691,16 @@ __SPACE__
 [: `template auto optional::map(F f) & -> `['see below]` ;`]
 
 * [*Effects:] `if (*this) return f(**this); else return none;`
-* [*Notes:] The return type of these overloads is `optional`. On compilers that do not support ref-qualifiers on member functions, these two (as well as the next one) overloads are replaced with good old const and non-const overloads. 
+* [*Notes:] The return type of these overloads is `optional`. On compilers that do not support ref-qualifiers on member functions, these two (as well as the next one) overloads are replaced with good old const and non-const overloads.
+* [*Example:]
+``
+auto length = [](const string& s){ return s.size(); };
+optional o1 {}, o2 {"cat"};
+optional os1 = o1.map(length), os2 = o2.map(length);
+assert ( !os1 ) ;
+assert ( os2 ) ;
+assert ( *os2 == 3 ) ;
+``
 
 __SPACE__
 
@@ -704,6 +713,37 @@ __SPACE__
 
 __SPACE__
 
+[#reference_optional_flat_map]
+
+[: `template auto optional::flat_map(F f) const& -> `['see below]` ;`]
+[: `template auto optional::flat_map(F f) & -> `['see below]` ;`]
+
+* [*Requires:] The return type of expression `f(**this)` is `optional` for some object or reference type `U`.
+* [*Effects:] `if (*this) return f(**this); else return none;`
+* [*Notes:] The return type of these overloads is `optional`. On compilers that do not support ref-qualifiers on member functions, these two (as well as the next one) overloads are replaced with good old const and non-const overloads.
+* [*Example:]
+``
+optional first_char(const string& s) {
+  return s.empty() ? none : optional(s[0]);
+};
+optional o1 {}, o2 {"cat"};
+optional os1 = o1.flat_map(first_char), os2 = o2.flat_map(first_char);
+assert ( !os1 ) ;
+assert ( os2 ) ;
+assert ( *os2 == 'c' ) ;
+``
+__SPACE__
+
+[#reference_optional_flat_map_move]
+
+[: `template auto optional::flat_map(F f) && -> `['see below]` ;`]
+
+* [*Requires:] The return type of expression `f(std::move(**this))` is `optional` for some object or reference type `U`.
+* [*Effects:] `if (*this) return f(std::move(**this)); else return none;`
+* [*Notes:] The return type of this overload is `optional`.
+
+__SPACE__
+
 [#reference_optional_get_value_or_value]
 
 [: `T const& optional::get_value_or( T const& default) const ;`]
@@ -835,7 +875,7 @@ __SPACE__
 [: `template optional::optional(R&& r) noexcept;`]
 * [*Postconditions:] `bool(*this) == true`; `addressof(**this) == addressof(r)`.
 * [*Remarks:] Unless `R` is an lvalue reference, the program is ill-formed. This constructor does not participate in overload resolution if `decay` is an instance of `boost::optional`.
-* [*Notes:] This constructor is declared `explicit` on compilers that do not correctly suport binding to const lvalues of integral types. For more details [link optional_reference_binding see here]. 
+* [*Notes:] This constructor is declared `explicit` on compilers that do not correctly suport binding to const lvalues of integral types. For more details [link optional_reference_binding see here].
 * [*Example:]
 ``
 T v;
@@ -862,7 +902,7 @@ __SPACE__
 [: `optional::optional ( optional const& rhs ) noexcept ;`]
 
 * [*Effects: ] Initializes `ref` with expression `rhs.ref`.
- 
+
 * [*Postconditions:] `bool(*this) == bool(rhs)`.
 
 * [*Example:]
@@ -895,7 +935,7 @@ __SPACE__
 * [*Requires:] `is_convertible::value` is `true`.
 
 * [*Effects: ] Initializes `ref` with expression `rhs.ref`.
- 
+
 * [*Postconditions:] `bool(*this) == bool(rhs)`.
 
 
@@ -911,7 +951,7 @@ __SPACE__
 
 * [*Postconditions:] `bool(*this) == false`.
 
- 
+
 
 [#reference_optional_ref_copy_assign]
 
@@ -959,7 +999,7 @@ assert ( *ora == 4 ) ;
 * [*returns:] `*this`.
 
 * [*Postconditions:] `bool(*this) == bool(rhs)`.
-   
+
 
 __SPACE__
 
@@ -970,7 +1010,7 @@ __SPACE__
 * [*Effects: ] Assigns `ref` with expression `r`.
 
 * [*returns:] `*this`.
- 
+
 * [*Postconditions:] `bool(*this) == true`.
 
 * [*Remarks:] Unless `R` is an lvalue reference, the program is ill-formed. This function does not participate in overload resolution if `decay` is an instance of `boost::optional`.
@@ -1035,13 +1075,13 @@ __SPACE__
 
 [#reference_optional_ref_value]
 [: `T& optional::value() const ;`]
-* [*Effects:] Equivalent to `return bool(*this) ? *val : throw bad_optional_access();`. 
+* [*Effects:] Equivalent to `return bool(*this) ? *val : throw bad_optional_access();`.
 
 __SPACE__
 
 [#reference_optional_ref_value_or]
 [: `template T& optional::value_or( R&& r ) const noexcept;`]
-* [*Effects:] Equivalent to `if (*this) return **this; else return r;`. 
+* [*Effects:] Equivalent to `if (*this) return **this; else return r;`.
 * [*Remarks:] Unless `R` is an lvalue reference, the program is ill-formed.
 
 __SPACE__
@@ -1060,6 +1100,14 @@ __SPACE__
 
 __SPACE__
 
+[#reference_optional_ref_flat_map]
+[: `template auto optional::flat_map( F f ) const -> `['see below]`;`]
+* [*Requires:] The return type of expression `f(**this)` is `optional` for some object or reference type `U`.
+* [*Effects:] Equivalent to `if (*this) return f(**this); else return none;`.
+* [*Remarks:] The return type of this function is `optional`.
+
+__SPACE__
+
 [#reference_optional_ref_get_ptr]
 [: `T* optional::get_ptr () const noexcept;`]
 * [*Returns:] `ref`.
@@ -1102,9 +1150,9 @@ __SPACE__
 
 [#reference_optional_ref_get_value_or_value]
 [: `template T& optional::get_value_or( R&& r ) const noexcept;`]
-* [*Effects:] Equivalent to `return value_or(std::forward(r);`. 
+* [*Effects:] Equivalent to `return value_or(std::forward(r);`.
 * [*Remarks:] This function is depprecated.
-  
+
 [endsect]
 
 
@@ -1303,7 +1351,7 @@ __SPACE__
 
 * [*Requires:] Lvalues of type `T` shall be swappable and `T` shall be __MOVE_CONSTRUCTIBLE__.
 * [*Effects:]
-[table 
+[table
   []
   [[][[*`*this` contains a value]][[*`*this` does not contain a value]]]
   [[[*`rhs` contains a value]][calls `swap(*(*this), *rhs)`][initializes the contained value of `*this` as if direct-initializing an object of type `T` with the expression `std::move(*rhs)`, followed by `rhs.val->T::~T()`, `*this` contains a value and `rhs` does not contain a value]]
diff --git a/doc/91_relnotes.qbk b/doc/91_relnotes.qbk
index 79bb200..b7d410f 100644
--- a/doc/91_relnotes.qbk
+++ b/doc/91_relnotes.qbk
@@ -14,7 +14,8 @@
 [heading Boost Release 1.68]
 
 * Added member function `has_value()` for compatibility with `std::optional` ([@https://github.com/boostorg/optional/issues/52 issue #52]).
-* Added member function `map()` for transforming `optional` into `optional` using a function of type `U(T)`.
+* Added member function `map()` for transforming `optional` into `optional` using a function of type `T -> U`.
+* Added member function `flat_map()` for transforming `optional` into `optional` using a function of type `T -> optonal`.
 
 
 [heading Boost Release 1.67]
@@ -26,7 +27,7 @@
 [heading Boost Release 1.66]
 
 * On newer compilers `optional` is now trivially-copyable for scalar `T`s. This uses a different storage (just `T` rather than `aligned_storage`). We require the compiler to support defaulted functions.
-* Changed the implementation of `operator==` to get rid of the `-Wmaybe-uninitialized` false-positive warning from GCC. 
+* Changed the implementation of `operator==` to get rid of the `-Wmaybe-uninitialized` false-positive warning from GCC.
 
 [heading Boost Release 1.63]
 * Added two new in-place constructors. They work similarly to `emplace()` functions: they initialize the contained value by perfect-forwarding the obtained arguments. One constructor always initializes the contained value, the other based on a boolean condition.
@@ -70,7 +71,7 @@
 * IOStream operators are now mentioned in documentation.
 * Added a way to manually disable move semantics: just define macro `BOOST_OPTIONAL_CONFIG_NO_RVALUE_REFERENCES`. This can be used to work around [@https://svn.boost.org/trac/boost/ticket/10399 Trac #10399].
 * It is no longer possible to assign `optional` to `optional` when `U` is not assignable or convertible to `T` ([@https://svn.boost.org/trac/boost/ticket/11087 Trac #11087]).
-* Value accessors now work correctly on rvalues of `optional` ([@https://svn.boost.org/trac/boost/ticket/10839 Trac #10839]).  
+* Value accessors now work correctly on rvalues of `optional` ([@https://svn.boost.org/trac/boost/ticket/10839 Trac #10839]).
 
 
 [heading Boost Release 1.57]
diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
index acb6775..99b8cb8 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_references.html
@@ -422,6 +422,30 @@
               is optional<decltype(f(**this))>.
             
 
+

+          space
+        

+

+            template<class F> auto optional<T&>::flat_map(
+            F f
+            ) const
+            -> see below;
+          

+
    
+
  • 
+              Requires: The return type of expression
+              f(**this)
+              is optional<U>
+              for some object or reference type U.
+            
    • 
+
  • 
+              Effects: Equivalent to if (*this) return f(**this); else return none;.
+            
    • 
+
  • 
+              Remarks: The return type of this function
+              is optional<U>.
+            
    • 
+

 

           space
         

diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
index 127df4c..42af248 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/detailed_semantics___optional_values.html
@@ -1495,6 +1495,16 @@
               these two (as well as the next one) overloads are replaced with good
               old const and non-const overloads.
             
+
  • 
+              Example:
+
    auto length = [](const string& s){ return s.size(); };
+optional<string> o1 {}, o2 {"cat"};
+optional<size_t> os1 = o1.map(length), os2 = o2.map(length);
+assert ( !os1 ) ;
+assert ( os2 ) ;
+assert ( *os2 == 3 ) ;
+
    
+            
    • 
 
 
    
           space
@@ -1515,6 +1525,72 @@
               is optional<decltype(f(istd::move(**this)))>.
             
 
+
    
+          space
+        
    
+
    
+            template<class F> auto optional<T>::flat_map(F f) const& ->
+            see below ;
+          
    
+
    
+            template<class F> auto optional<T>::flat_map(F f) & -> see below
+            ;
+          
    
+
      
+
    • 
+              Requires: The return type of expression
+              f(**this)
+              is optional<U>
+              for some object or reference type U.
+            
      • 
+
    • 
+              Effects: if
+              (*this) return f(**this); else return
+              none;
+            
      • 
+
    • 
+              Notes: The return type of these overloads
+              is optional<U>.
+              On compilers that do not support ref-qualifiers on member functions,
+              these two (as well as the next one) overloads are replaced with good
+              old const and non-const overloads.
+            
      • 
+
    • 
+              Example:
+
      optional<char> first_char(const string& s) {
+  return s.empty() ? none : optional<char>(s[0]);
+};
+optional<string> o1 {}, o2 {"cat"};
+optional<char> os1 = o1.flat_map(first_char), os2 = o2.flat_map(first_char);
+assert ( !os1 ) ;
+assert ( os2 ) ;
+assert ( *os2 == 'c' ) ;
+
      
+              space
+            
      • 
+
    
+
    
+            template<class F> auto optional<T>::flat_map(F f) &&
+            -> see below
+            ;
+          
    
+
      
+
    • 
+              Requires: The return type of expression
+              f(std::move(**this))
+              is optional<U>
+              for some object or reference type U.
+            
      • 
+
    • 
+              Effects: if
+              (*this) return f(std::move(**this)); else return
+              none;
+            
      • 
+
    • 
+              Notes: The return type of this overload
+              is optional<U>.
+            
      • 
+
    
 
    
           space
         
    
diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
index 77906eb..43b0c0a 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_refs.html
@@ -53,7 +53,6 @@
 
     optional& operator = ( none_t ) noexcept ; R
 
-
     optional& operator = ( optional const& rhs ) noexcept; R
 
     template<class U> optional& operator = ( optional<U&> const& rhs ) noexcept ; R
@@ -75,6 +74,8 @@
 
     template<class F> auto map( F f ) const -> see below; R
 
+    template<class F> auto flat_map( F f ) const -> see below; R
+
     T* get_ptr() const noexcept ; R
 
     bool has_value() const noexcept ; R
diff --git a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html
index 5e960f1..5e1edff 100644
--- a/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html
+++ b/doc/html/boost_optional/reference/header__boost_optional_optional_hpp_/header_optional_optional_values.html
@@ -109,6 +109,10 @@
     template<class F> auto map( F f ) & -> see below; R
     template<class F> auto map( F f ) && -> see below; R
 
+    template<class F> auto flat_map( F f ) const& -> see below; R
+    template<class F> auto flat_map( F f ) & -> see below; R
+    template<class F> auto flat_map( F f ) && -> see below; R
+
     T const* get_ptr() const ; R
     T*       get_ptr() ; R
 
diff --git a/doc/html/boost_optional/relnotes.html b/doc/html/boost_optional/relnotes.html
index b596e38..f074211 100644
--- a/doc/html/boost_optional/relnotes.html
+++ b/doc/html/boost_optional/relnotes.html
@@ -37,7 +37,10 @@
           #52).
         
 
  • 
-          Added member function map() for transforming optional<T> into optional<U> using a function of type U(T).
+          Added member function map() for transforming optional<T> into optional<U> using a function of type T -> U.
+        
    • 
+
  • 
+          Added member function flat_map() for transforming optional<T> into optional<U> using a function of type T -> optonal<U>.
         
    • 
 
 
    
diff --git a/doc/html/index.html b/doc/html/index.html
index 44e9bc0..c563c86 100644
--- a/doc/html/index.html
+++ b/doc/html/index.html
@@ -145,7 +145,7 @@
 
 
 
-
+
    Last revised: June 23, 2018 at 18:49:36 GMT
    Last revised: July 02, 2018 at 21:10:01 GMT