Avoid 'reference to reference' error with strict C++03 compiler.
While I can't reproduce the error you describe, the patch looks good and it tested okay with Clang 6.0 on Mac and gcc-4.9.1 on Linux. Thanks for the patch.
Some (strict) C++03 compilers (e.g. `gcc -std=c++03`) reject
'reference-to-reference' in the template and typedef which described
in CWG DR106 [1].
In such situations, iterator_facade rejects reference type as a value
type and some special iterators will become ill-formed:
the test libs/range/test/join.hpp might be descriptive.
[1] http://www.open-std.org/Jtc1/sc22/wg21/docs/cwg_defects.html#106
Signed-off-by: Kohei Takahashi <flast@flast.jp>
Also added an import into the boost::detail namespace for backward compatibility with Boost.Range. Added a pure_iterator_traversal metafunction that automatically converts iterator category as well.
This change excludes boost:: and boost::detail:: namespaces from ADL for unqualified function calls (e.g. algorithms). This reduces the possibility of name clashes with other libraries and user's code. One of the effects should be fixing test failures on gcc 4.2 and 4.4 due to clashed with Boost.TypeTraits.
Also some of the functions marked with inline keyword.
This makes iterators defined using iterator_facade more friendly to type inspection and fixes its use with next()/prior() since commit 651a869d4f.
The arithmetic, indexing and relational operators are only defined if the iterator category or traversal permits that. Note that the implementation requires partial template specialization support now.
Reverted: 2e099caceb9..21102938e8ccb
I'm going to reapply some of them soon, but it's easier to revert them
all first, as there are conflicts. Also the number of changes that were
inserted since then, mean that there would be a huge gap between related
changes.
