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

components/autofill/core/common/autofill_util.h

+// 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.
+
+#ifndef COMPONENTS_AUTOFILL_CORE_COMMON_AUTOFILL_UTIL_H_
+#define COMPONENTS_AUTOFILL_CORE_COMMON_AUTOFILL_UTIL_H_
+
+#include "base/strings/string16.h"
+
+namespace autofill {
+
+// Returns |true| when command line switch
+// |kEnableSuggestionsWithSubstringMatch| is on; otherwise |false|.
+bool IsFeatureSubstringMatchEnabled();
+
+// Returns |true| if a substring token within |field_suggestion| begins with

[vabr (Chromium), 2015/03/24 13:32:28]

Not clear what a "substring token" is. What about rewriting the whole comment
to:

// Splits |field_suggestion| into tokens, separated by characters from " .,-_@".
Returns true if |field_content| is a prefix of some token.

[Pritam Nikam, 2015/03/25 14:25:26]

Done.

+// |field_contents|; otherwise |false|. The set of delimiters (the characters
+// that separate tokens) are ' ', '.', ',', '-', '_' and '@'. By default it
+// performs case insensitive search. Caller can perform case sensitive search by
+// explicitly passing |true| as |case_sensitive| parameter to this API.
+bool HasTokenStartsWith(const base::string16& field_suggestion,

[vabr (Chromium), 2015/03/24 13:32:28]

The name still sounds hard to understand. What about
IsContentsPrefixOfSuggestionToken
?

[Pritam Nikam, 2015/03/25 14:25:26]

Done.

+                        const base::string16& field_contents,
+                        bool case_sensitive = false);

[vabr (Chromium), 2015/03/24 13:32:28]

optional: By changing the bool to an enum with well described type name and
values, you can make the callsites much easier to understand, and spare the last
2 sentences of the comment above.

[vabr (Chromium), 2015/03/24 13:32:28]

The style guide forbids default arguments in this case.
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Default_Argum...

[Pritam Nikam, 2015/03/25 14:25:26]

Done.

Added enum instead.

enum CaseSensitivity {
  CASE_SENSITIVE,  // for case sensitive match;
  CASE_IGNORE      // for case insensitive match;
};

[Pritam Nikam, 2015/03/25 14:25:26]

Done.

+
+// Returns |field_contents|'s offset within the |field_suggestion| on successful
+// match and compute the selection range's |start| and |end| indices; otherwise
+// returns |base::string16::npos|.
+base::string16::size_type ComputeRange(const base::string16& field_suggestion,
+                                       const base::string16& field_contents,
+                                       size_t* start,
+                                       size_t* end);
+
+}  // namespace autofill
+
+#endif  // COMPONENTS_AUTOFILL_CORE_COMMON_AUTOFILL_UTIL_H_