[Autofill/Autocomplete Feature] Substring matching instead of prefix matching.

base/strings/string_util.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/strings/string_util.h"
 
 #include <ctype.h>
 #include <errno.h>
 #include <math.h>
 #include <stdarg.h>
@@ skipping 988 matching lines @@
                        pattern.data(), pattern.data() + pattern.size(),
                        0, NextCharUTF8());
 }
 
 bool MatchPattern(const string16& eval, const string16& pattern) {
   return MatchPatternT(eval.c_str(), eval.c_str() + eval.size(),
                        pattern.c_str(), pattern.c_str() + pattern.size(),
                        0, NextCharUTF16());
 }
 
+template <typename STR>
+string16::size_type StartsAtT(const STR& str,
+                              const STR& search,
+                              bool case_sensitive) {
+  typename STR::const_iterator it;
+  if (case_sensitive) {
+    it = std::search(str.begin(), str.end(), search.begin(), search.end());
+  } else {
+    it = std::search(str.begin(), str.end(), search.begin(), search.end(),
+                     base::CaseInsensitiveCompare<typename STR::value_type>());
+  }
+
+  return (it != str.end()) ? std::distance(str.begin(), it) : string16::npos;

[danakj, 2015/04/02 18:31:42]

does (it - str.begin()) not work instead of std::distance? distance() can be
O(n) where as operator- should always be cheap, so if it can work with operator-
that'd be nice to be clear about the cost.

[Pritam Nikam, 2015/04/06 06:13:10]

Done.

+}
+
+string16::size_type StartsAt(const string16& str,
+                             const string16& search,
+                             bool case_sensitive) {
+  return StartsAtT(str, search, case_sensitive);
+}
+
 // The following code is compatible with the OpenBSD lcpy interface.  See:
 //   http://www.gratisoft.us/todd/papers/strlcpy.html
 //   ftp://ftp.openbsd.org/pub/OpenBSD/src/lib/libc/string/{wcs,str}lcpy.c
 
 namespace {
 
 template <typename CHAR>
 size_t lcpyT(CHAR* dst, const CHAR* src, size_t dst_size) {
   for (size_t i = 0; i < dst_size; ++i) {
     if ((dst[i] = src[i]) == 0)  // We hit and copied the terminating NULL.
@@ skipping 10 matching lines @@
 }
 
 }  // namespace
 
 size_t base::strlcpy(char* dst, const char* src, size_t dst_size) {
   return lcpyT<char>(dst, src, dst_size);
 }
 size_t base::wcslcpy(wchar_t* dst, const wchar_t* src, size_t dst_size) {
   return lcpyT<wchar_t>(dst, src, dst_size);
 }