2001-12-15 Paolo Carlini <pcarlini@unitus.it>

            Nathan Myers  <ncm@cantrip.org>

        * include/bits/basic_string.h
	(assign(__str, __pos, __n), assign(__s, __n)):  Optimize
	by avoiding unnecessary temporaries.
	(assign(__s)): Call assign(__s, __n).
	* include/bits/basic_string.tcc (_M_replace_safe): Adjust comment.
	* include/bits/std_string.h: include stl_function.h.
        * testsuite/21_strings/assign.cc (test02, test03): New tests.

Co-Authored-By: Nathan Myers <ncm@cantrip.org>

From-SVN: r48053

libstdc++-v3/ChangeLog

+2001-12-15  Paolo Carlini  <pcarlini@unitus.it>
+            Nathan Myers  <ncm@cantrip.org>
+
+	* include/bits/basic_string.h
+	(assign(__str, __pos, __n), assign(__s, __n)):  Optimize
+	by avoiding unnecessary temporaries.
+	(assign(__s)): Call assign(__s, __n).
+	* include/bits/basic_string.tcc (_M_replace_safe): Adjust comment.
+	* include/bits/std_string.h: include stl_function.h.
+	* testsuite/21_strings/assign.cc (test02, test03): New tests.
+
 2001-12-15  Benjamin Kosnik  <bkoz@redhat.com>
 
 	* acinclude.m4 (GLIBCPP_ENABLE_CLOCALE): Enable gnu locale model

libstdc++-v3/include/bits/basic_string.h

@@ -478,16 +478,52 @@ namespace std
       basic_string& 
       assign(const basic_string& __str, size_type __pos, size_type __n)
       {
-	return this->assign(__str._M_check(__pos), __str._M_fold(__pos, __n)); 
+	if (__pos > __str.size())
+	  __throw_out_of_range("basic_string::assign");
+	if (_M_rep()->_M_is_shared() || _M_rep() != __str._M_rep())
+	  return _M_replace_safe(_M_ibegin(), _M_iend(), 
+				 __str._M_check(__pos),
+				 __str._M_fold(__pos, __n));
+	else
+	  {
+	    // Work in-place.
+	    bool __testn = __n < __str.size() - __pos;
+	    const size_type __newsize = __testn ? __n : __str.size() - __pos;
+	    // Avoid move, if possible.
+	    if (__pos >= __newsize)
+	      traits_type::copy(_M_data(), __str._M_data() + __pos, __newsize);
+	    else if (__pos)	      
+	      traits_type::move(_M_data(), __str._M_data() + __pos, __newsize);
+	    // else nothing (avoid calling move unnecessarily)
+	    _M_rep()->_M_length = __newsize;
+	    return *this;
+	  }
       }
 
       basic_string& 
       assign(const _CharT* __s, size_type __n)
-      { return this->assign(__s, __s + __n); }
+      {
+	if (__n > this->max_size())
+	  __throw_length_error("basic_string::assign");
+	if (_M_rep()->_M_is_shared() || less<const _CharT*>()(__s, _M_data())
+	    || less<const _CharT*>()(_M_data() + this->size(), __s))
+	  return _M_replace_safe(_M_ibegin(), _M_iend(), __s, __s + __n);
+	else
+	  {
+	    // Work in-place
+	    const size_type __pos = __s - _M_data();
+	    if (__pos >= __n)
+	      traits_type::copy(_M_data(), __s, __n);
+	    else if (__pos)
+	      traits_type::move(_M_data(), __s, __n);
+	    _M_rep()->_M_length = __n;
+	    return *this;
+	  }
+      }
 
       basic_string& 
       assign(const _CharT* __s)
-      { return this->assign(__s, __s + traits_type::length(__s)); }
+      { return this->assign(__s, traits_type::length(__s)); }
 
       basic_string& 
       assign(size_type __n, _CharT __c)

libstdc++-v3/include/bits/basic_string.tcc

@@ -512,7 +512,8 @@ namespace std
   // This is a special replace helper, which does not buffer internally
   // and can be used in the "safe" situations involving forward-iterators,
   // i.e., when source and destination ranges are known to not overlap.
-  // Presently, is called by _M_replace and by the various append.
+  // Presently, is called by _M_replace, by the various append and by
+  // the assigns.
   template<typename _CharT, typename _Traits, typename _Alloc>
     template<typename _ForwardIter>
       basic_string<_CharT, _Traits, _Alloc>&

libstdc++-v3/include/bits/std_string.h

@@ -48,6 +48,7 @@
 #include <bits/type_traits.h>
 #include <bits/std_iosfwd.h> 	// For operators >>, <<, and getline decls.
 #include <bits/stl_iterator.h>
+#include <bits/stl_function.h>  // For less
 #include <bits/basic_string.h>
 
 #ifdef _GLIBCPP_NO_TEMPLATE_EXPORT

libstdc++-v3/testsuite/21_strings/assign.cc

@@ -39,8 +39,71 @@ test01()
   VERIFY(aux == "Hawaii");
 }
 
+// assign(const basic_string& __str, size_type __pos, size_type __n)
+void
+test02()
+{
+  bool test = true;
+
+  using namespace std;
+  
+  string one = "Selling England by the pound";
+  string two = one;
+  string three = "Brilliant trees";
+
+  one.assign(one, 8, 100);
+  VERIFY( one == "England by the pound" );
+
+  one.assign(one, 8, 0);
+  VERIFY( one == "" );
+ 
+  one.assign(two, 8, 7);
+  VERIFY( one == "England" );
+
+  one.assign(three, 10, 100);
+  VERIFY( one == "trees" );
+
+  three.assign(one, 0, 3);
+  VERIFY( three == "tre" );
+}
+
+// assign(const _CharT* __s, size_type __n)
+// assign(const _CharT* __s)
+void
+test03()
+{
+  bool test = true;
+
+  using namespace std;
+ 
+  string one; 
+  string two;
+  string three = two;
+  const char * source = "Selling England by the pound";
+
+  one.assign(source);
+  VERIFY( one == "Selling England by the pound" );
+
+  one.assign(source, 28);
+  VERIFY( one == "Selling England by the pound" );
+
+  two.assign(source, 7);
+  VERIFY( two == "Selling" );
+  
+  one.assign(one.c_str() + 8, 20);
+  VERIFY( one == "England by the pound" );
+
+  one.assign(one.c_str() + 8, 6);
+  VERIFY( one == "by the" );
+}
+
+
+
 int main()
 { 
   test01();
+  test02();
+  test03();
+
   return 0;
 }