Re: [Boost-bugs] [Boost C++ Libraries] #5475: [Foreach] rvalue reference binding of temporary ranges

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #5475: [Foreach] rvalue reference binding of temporary ranges
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-04-15 06:11:06

#5475: [Foreach] rvalue reference binding of temporary ranges
--------------------------------------+-------------------------------------
  Reporter:  mimomorin@…              |       Owner:  eric_niebler  
      Type:  Patches                  |      Status:  new           
 Milestone:  To Be Determined         |   Component:  foreach       
   Version:  Boost Development Trunk  |    Severity:  Problem       
Resolution:                           |    Keywords:  foreach, C++0x
--------------------------------------+-------------------------------------

Comment (by mimomorin@…):

 Hmm, I cannot attach a patch for `foreach.hpp`...

 The patch I made does the following:

 (Note: contrary to C++0x range-based for,
 this does not allow mutable iteration over rvalue ranges;
 Non-const rvalue ranges are bounded to **const** rvalue references.)

 1. Adding a configuration macro
 * BOOST_FOREACH_USE_RVALUE_REFERENCE_BINDING
   * When a compiler supports rvalue references and `decltype`,
     this macro is defined and rvalue reference binding is used.

 2. Adding macros for auto declarations
 * BOOST_FOREACH_AUTO_OBJECT(NAME, EXPR)
   * Equivalent to `auto NAME = EXPR;`.
 * BOOST_FOREACH_AUTO_REF_REF(NAME, EXPR)
   * Equivalent to `auto && NAME = EXPR;`if EXPR is an lvalue.
   * Equivalent to `auto const && NAME = EXPR;`if EXPR is an rvalue.

 3. Adding overloaded functions
 * `begin`
 * `end`
   * For C-strings, this function returns `cstr_end_iterator`, which is
 defined as an empty struct.
     I also overloaded `operator !=`  to support C-strings:
     {{{
     template <typename Iterator>
     inline bool operator !=(Iterator cur, cstr_end_iterator)
     {
         return *cur != 0;
     }
     }}}
 * `rbegin`
 * `rend`


 All the regression tests ran successfully with the following compilers
 (both in C++03 and C++0x modes):
 gcc-4.3.5, gcc-4.4.5, gcc-4.5.2, gcc-4.6.0, clang (TOT).

 Newly added tests (in `test_noncopyable_rvalue.patch`) ran successfully in
 a C++0x mode.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/5475#comment:2>
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