basic_string.h (front, back): Add.

2010-05-31  Paolo Carlini  <paolo.carlini@oracle.com>

	* include/bits/basic_string.h (front, back): Add.
	* include/debug/string: Adjust.
	* include/ext/vstring.h (front, back): Tweak the implementation
	to follow more closely the letter of the specs.
	* testsuite/21_strings/basic_string/element_access/char/
	front_back.cc: New.
	* testsuite/21_strings/basic_string/element_access/wchar_t/
	front_back.cc: Likewise.
	* config/abi/pre/gnu.ver: Export new symbols.
	* testsuite/util/testsuite_abi.cc: Adjust.
	* configure.ac: Bump minor version to 6:15:0.
	* configure: Regenerate.

From-SVN: r160071

3 files changed, 45 insertions, 6 deletions

diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index d6d9989..fe9e1a3 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -851,6 +851,40 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
 	return _M_data()[__n];
       }
 
+#ifdef __GXX_EXPERIMENTAL_CXX0X__
+      /**
+       *  Returns a read/write reference to the data at the first
+       *  element of the %string.
+       */
+      reference
+      front()
+      { return operator[](0); }
+
+      /**
+       *  Returns a read-only (constant) reference to the data at the first
+       *  element of the %string.
+       */
+      const_reference
+      front() const
+      { return operator[](0); }
+
+      /**
+       *  Returns a read/write reference to the data at the last
+       *  element of the %string.
+       */
+      reference
+      back()
+      { return operator[](this->size() - 1); }
+
+      /**
+       *  Returns a read-only (constant) reference to the data at the
+       *  last element of the %string.
+       */
+      const_reference
+      back() const
+      { return operator[](this->size() - 1); }
+#endif
+
       /**
        *  @brief  Provides access to the data contained in the %string.
        *  @param n The index of the character to access.
diff --git a/libstdc++-v3/include/debug/string b/libstdc++-v3/include/debug/string
index 160488e..fe31ffb 100644
--- a/libstdc++-v3/include/debug/string
+++ b/libstdc++-v3/include/debug/string
@@ -262,6 +262,11 @@ namespace __gnu_debug
 
     using _Base::at;
 
+#ifdef __GXX_EXPERIMENTAL_CXX0X__
+    using _Base::front;
+    using _Base::back;
+#endif
+
     // 21.3.5 modifiers:
     basic_string&
     operator+=(const basic_string& __str)
diff --git a/libstdc++-v3/include/ext/vstring.h b/libstdc++-v3/include/ext/vstring.h
index fc469cb..dffd35a 100644
--- a/libstdc++-v3/include/ext/vstring.h
+++ b/libstdc++-v3/include/ext/vstring.h
@@ -62,8 +62,8 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
       typedef _Alloc					    allocator_type;
       typedef typename _CharT_alloc_type::size_type	    size_type;
       typedef typename _CharT_alloc_type::difference_type   difference_type;
-      typedef typename _CharT_alloc_type::reference	    reference;
-      typedef typename _CharT_alloc_type::const_reference   const_reference;
+      typedef value_type&               	            reference;
+      typedef const value_type&                             const_reference;
       typedef typename _CharT_alloc_type::pointer	    pointer;
       typedef typename _CharT_alloc_type::const_pointer	    const_pointer;
       typedef __gnu_cxx::__normal_iterator<pointer, __versa_string>  iterator;
@@ -598,7 +598,7 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
        */
       reference
       front()
-      { return *begin(); }
+      { return operator[](0); }
 
       /**
        *  Returns a read-only (constant) reference to the data at the first
@@ -606,7 +606,7 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
        */
       const_reference
       front() const
-      { return *begin(); }
+      { return operator[](0); }
 
       /**
        *  Returns a read/write reference to the data at the last
@@ -614,7 +614,7 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
        */
       reference
       back()
-      { return *(end() - 1); }
+      { return operator[](this->size() - 1); }
 
       /**
        *  Returns a read-only (constant) reference to the data at the
@@ -622,7 +622,7 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
        */
       const_reference
       back() const
-      { return *(end() - 1); }
+      { return operator[](this->size() - 1); }
 #endif
 
       // Modifiers: