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

components/autofill/core/common/autofill_util.cc

+// Copyright 2015 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 "components/autofill/core/common/autofill_util.h"
+
+#include <vector>

[please use gerrit instead, 2015/06/29 22:06:29]

Also <algorithm> for std::search.

[Pritam Nikam, 2015/06/30 15:05:50]

Done.

+
+#include "base/command_line.h"
+#include "base/i18n/case_conversion.h"
+#include "base/strings/string_piece.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "components/autofill/core/common/autofill_switches.h"
+
+namespace autofill {
+
+static const char kSplitCharacters[] = " .,-_@";
+
+bool IsFeatureSubstringMatchEnabled() {
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableSuggestionsWithSubstringMatch);
+}
+
+bool ContainsTokenThatStartsWith(const base::string16& suggestion,
+                                 const base::string16& field_contents,
+                                 bool case_sensitive) {
+  if (!IsFeatureSubstringMatchEnabled())
+    return false;
+
+  std::vector<base::string16> suggestion_tokens =

[please use gerrit instead, 2015/06/29 22:06:29]

You can probably save one copy operation by using "const
std::vector<base::string16>&" here.

[Pritam Nikam, 2015/06/30 15:05:51]

Done.

+      base::SplitString(suggestion, base::ASCIIToUTF16(kSplitCharacters),
+                        base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
+
+  // Check whether the |field_contents| prefixes any of the |suggestion|'s
+  // token.

[please use gerrit instead, 2015/06/29 22:06:29]

s/token/tokens

[Pritam Nikam, 2015/06/30 15:05:51]

Done.

+  for (const base::string16& token : suggestion_tokens) {
+    if (StartsWith(token, field_contents, case_sensitive))
+      return true;
+  }
+
+  return false;
+}
+
+size_t GetTextSelectionStart(const base::string16& suggestion,
+                             const base::string16& field_contents) {
+  size_t offset = 0;

[please use gerrit instead, 2015/06/29 22:06:29]

You don't need |offset| variable. You can use "std::search(it, suggestion.end(),
...)". Then you can return "it - suggestion.begin() + field_contents.size()".
Instead of "++offset", you can put "++it" in the third part of
"for(<1>;<2>;<3>)".

[Pritam Nikam, 2015/06/30 15:05:50]

Done.

+  // Loop until we find either the |field_contents| begins with the |suggestion|

[please use gerrit instead, 2015/06/29 22:06:29]

s/begins with/is a prefix of

Right?

[Pritam Nikam, 2015/06/30 15:05:50]

Done.

+  // or character right before |offset| is one of the splitting characters.
+  for (base::string16::const_iterator it = suggestion.begin();
+       (it = std::search(
+            offset + suggestion.begin(), suggestion.end(),
+            field_contents.begin(), field_contents.end(),
+            base::CaseInsensitiveCompare<base::string16::value_type>())) !=
+           suggestion.end();) {
+    offset = it - suggestion.begin();
+    if (offset == 0 ||
+        ContainsOnlyChars(suggestion.substr(offset - 1, 1),
+                          base::ASCIIToUTF16(kSplitCharacters))) {
+      // Set caret position to the end of the |field_contents|.
+      offset += field_contents.size();
+      return offset;
+    }
+
+    // Search didn't meet the criteria, advance the suggestion range.
+    ++offset;
+  }
+
+  // Unable to find the |field_contents| in |suggestion| text.
+  NOTREACHED();
+  return base::string16::npos;
+}
+
+}  // namespace autofill