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

base/strings/string_util.cc

Index: base/strings/string_util.cc
diff --git a/base/strings/string_util.cc b/base/strings/string_util.cc
index e084cb5597da6cbdcb50d0c3ce958bbc8dbc220e..77609e787d4d0575cc9ae3ffdd5c52ec1cf1471f 100644
--- a/base/strings/string_util.cc
+++ b/base/strings/string_util.cc
@@ -1006,6 +1006,27 @@ bool MatchPattern(const string16& eval, const string16& pattern) {
                        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