Refactor treatment of request-method (API Change):

fix #397

method enum class is added to represent all known request methods.
Functions are provided to convert from strings to and from the method
enumeration.

The fields container is modified to also work with the enum.

include/beast/http/impl/fields.ipp

@@ -100,6 +100,7 @@ basic_fields(basic_fields&& other)
         std::move(other.member()))
     , detail::basic_fields_base(
         std::move(other.set_), std::move(other.list_))
+    , verb_(other.verb_)
 {
 }
 
@@ -114,6 +115,7 @@ operator=(basic_fields&& other) ->
     clear();
     move_assign(other, std::integral_constant<bool,
         alloc_traits::propagate_on_container_move_assignment::value>{});
+    verb_ = other.verb_;
     return *this;
 }
 
@@ -124,6 +126,7 @@ basic_fields(basic_fields const& other)
         select_on_container_copy_construction(other.member()))
 {
     copy_from(other);
+    verb_ = other.verb_;
 }
 
 template<class Allocator>
@@ -135,6 +138,7 @@ operator=(basic_fields const& other) ->
     clear();
     copy_assign(other, std::integral_constant<bool,
         alloc_traits::propagate_on_container_copy_assignment::value>{});
+    verb_ = other.verb_;
     return *this;
 }
 
@@ -144,6 +148,7 @@ basic_fields<Allocator>::
 basic_fields(basic_fields<OtherAlloc> const& other)
 {
     copy_from(other);
+    verb_ = other.verb_;
 }
 
 template<class Allocator>
@@ -155,18 +160,10 @@ operator=(basic_fields<OtherAlloc> const& other) ->
 {
     clear();
     copy_from(other);
+    verb_ = other.verb_;
     return *this;
 }
 
-template<class Allocator>
-template<class FwdIt>
-basic_fields<Allocator>::
-basic_fields(FwdIt first, FwdIt last)
-{
-    for(;first != last; ++first)
-        insert(first->name(), first->value());
-}
-
 template<class Allocator>
 std::size_t
 basic_fields<Allocator>::
@@ -260,6 +257,37 @@ replace(string_view const& name,
     insert(name, value);
 }
 
+template<class Allocator>
+string_view
+basic_fields<Allocator>::
+method() const
+{
+    if(verb_)
+        return to_string(*verb_);
+    return (*this)[":method"];
+}
+
+template<class Allocator>
+void
+basic_fields<Allocator>::
+method(verb v)
+{
+    verb_ = v;
+    this->erase(":method");
+}
+
+template<class Allocator>
+void
+basic_fields<Allocator>::
+method(string_view const& s)
+{
+    verb_ = string_to_verb(s);
+    if(verb_)
+        this->erase(":method");
+    else
+        this->replace(":method", s);
+}
+
 } // http
 } // beast