basic_string.h (replace(i1, i2, _CharT* k1, _CharT* k2), [...]): New specializations to optimize for the common cases of pointers and iterators.

2002-04-02  Paolo Carlini  <pcarlini@unitus.it>
	    Nathan Myers  <ncm@cantrip.org>
            Philip Martin  <philip@codematters.co.uk>

	* include/bits/basic_string.h
	(replace(i1, i2, _CharT* k1, _CharT* k2),
	replace(i2, i2, const _CharT* k1, const _CharT* k2),
	replace(i1, i2, iterator k1, iterator k2,
	replace(i1, i2, const_iterator k1, const_iterator k2):
	New specializations to optimize for the common cases of
	pointers and iterators.
	(replace(pos, n1, s, n2)): Tweak.
	* include/bits/basic_string.tcc: Tweak comments.
	* testsuite/21_strings/replace.cc (test04): New tests.

Co-Authored-By: Nathan Myers <ncm@cantrip.org>
Co-Authored-By: Philip Martin <philip@codematters.co.uk>

From-SVN: r51746

libstdc++-v3/ChangeLog

@@ -1,3 +1,18 @@
+2002-04-02  Paolo Carlini  <pcarlini@unitus.it>
+            Nathan Myers  <ncm@cantrip.org>
+            Philip Martin  <philip@codematters.co.uk>
+
+	* include/bits/basic_string.h
+	(replace(i1, i2, _CharT* k1, _CharT* k2),
+	replace(i2, i2, const _CharT* k1, const _CharT* k2),
+	replace(i1, i2, iterator k1, iterator k2,
+	replace(i1, i2, const_iterator k1, const_iterator k2):
+	New specializations to optimize for the common cases of
+	pointers and iterators.
+	(replace(pos, n1, s, n2)): Tweak.
+	* include/bits/basic_string.tcc: Tweak comments.
+	* testsuite/21_strings/replace.cc (test04): New tests.
+
 2002-04-01  Benjamin Kosnik  <bkoz@redhat.com>
 
 	libstdc++/5542

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

@@ -649,8 +649,11 @@ namespace std
 	    || less<const _CharT*>()(_M_data() + __size, __s))
 	  return _M_replace_safe(_M_ibegin() + __pos,
 				 _M_ibegin() + __pos + __foldn1, __s, __s + __n2);
-	else return this->replace(_M_check(__pos), _M_fold(__pos, __n1),
-				  __s, __s + __n2); 
+	// Todo: optimized in-place replace.
+	else return
+	       _M_replace(_M_ibegin() + __pos, _M_ibegin() + __pos + __foldn1,
+			  __s, __s + __n2,
+			  typename iterator_traits<const _CharT*>::iterator_category());
       }
 
       basic_string& 
@@ -684,6 +687,30 @@ namespace std
         { return _M_replace(__i1, __i2, __k1, __k2,
 	     typename iterator_traits<_InputIterator>::iterator_category()); }
 
+      // Specializations for the common case of pointer and iterator:
+      // useful to avoid the overhead of temporary buffering in _M_replace.
+      basic_string& 
+      replace(iterator __i1, iterator __i2, _CharT* __k1, _CharT* __k2)
+        { return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
+			       __k1, __k2 - __k1); }
+
+      basic_string& 
+      replace(iterator __i1, iterator __i2, const _CharT* __k1, const _CharT* __k2)
+        { return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
+			       __k1, __k2 - __k1); }
+
+      basic_string& 
+      replace(iterator __i1, iterator __i2, iterator __k1, iterator __k2)
+        { return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
+			       __k1.base(), __k2 - __k1);
+	}
+
+      basic_string& 
+      replace(iterator __i1, iterator __i2, const_iterator __k1, const_iterator __k2)
+        { return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
+			       __k1.base(), __k2 - __k1);
+	}
+
     private:
       template<class _InputIterator>
         basic_string& 

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

@@ -498,13 +498,9 @@ namespace std
       // else nothing (in particular, avoid calling _M_mutate() unnecessarily.)
     }
 
-  // This is the general replace helper, which gets instantiated both
-  // for input-iterators and forward-iterators. It buffers internally and
-  // then calls _M_replace_safe. For input-iterators this is almost the
-  // best we can do, but for forward-iterators many optimizations could be
-  // conceived: f.i., when source and destination ranges do not overlap
-  // buffering is not really needed. In order to easily implement them, it
-  // could become useful to add an _M_replace(forward_iterator_tag)
+  // This is the general replace helper, which currently gets instantiated both
+  // for input iterators and reverse iterators. It buffers internally and then
+  // calls _M_replace_safe.
   template<typename _CharT, typename _Traits, typename _Alloc>
     template<typename _InputIter>
       basic_string<_CharT, _Traits, _Alloc>&
@@ -518,10 +514,8 @@ namespace std
       }
 
   // This is a special replace helper, which does not buffer internally
-  // and can be used in the "safe" situations involving forward-iterators,
+  // and can be used in "safe" situations involving forward iterators,
   // i.e., when source and destination ranges are known to not overlap.
-  // 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/testsuite/21_strings/replace.cc

@@ -139,10 +139,47 @@ test03()
   VERIFY(str01 == "ultra");
 }
 
+// Some more tests for 
+// template<typename InputIter>
+//   string& replace(iterator it1, iterator it2, InputIter j1, InputIter j2)
+void
+test04()
+{
+  std::string str01 = "geogaddi";
+  std::string str02;
+
+  typedef std::string::iterator iterator;
+  typedef std::string::const_iterator const_iterator;
+  
+  iterator it1 = str01.begin();
+  iterator it2 = str01.end();
+  str02.replace(str02.begin(), str02.end(), it1, it2);
+  VERIFY(str02 == "geogaddi");
+
+  str02 = "boards";
+  const_iterator c_it1 = str01.begin();
+  const_iterator c_it2 = str01.end();
+  str02.replace(str02.begin(), str02.end(), c_it1, c_it2);
+  VERIFY(str02 == "geogaddi");
+
+  str02 = "boards";
+  const char* c_ptr1 = str01.c_str();
+  const char* c_ptr2 = str01.c_str() + 8;
+  str02.replace(str02.begin(), str02.end(), c_ptr1, c_ptr2);
+  VERIFY(str02 == "geogaddi");
+
+  str02 = "boards";
+  char* ptr1 = &*str01.begin();
+  char* ptr2 = &*str01.end();
+  str02.replace(str02.begin(), str02.end(), ptr1, ptr2);
+  VERIFY(str02 == "geogaddi");
+}
+
 int main()
 { 
   test01();
   test02();
   test03();
+  test04();
   return 0;
 }