[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 {
+
+enum CaseSensitivity {

[Evan Stade, 2015/03/26 18:54:38]

use a bool imo. base::strings just uses bools for this.

[vabr (Chromium), 2015/03/27 10:13:35]

I actually suggested using enum here in
https://codereview.chromium.org/962673004/diff/200001/components/autofill/cor....
base::strings context might make it more clear that a true/false argument is
about case sensitivity, than it is clear for IsContentsPrefixOfSuggestionToken.

But Evan is the OWNER of this file, so I defer to his decision.

[Pritam Nikam, 2015/03/27 14:57:42]

In that case I'll restore it back to bool, and just remove the default argument
that I've used in API prototype.

+  CASE_SENSITIVE,  // for case sensitive match;
+  CASE_IGNORE      // for case insensitive match;
+};
+
+// Returns |true| when command line switch
+// |kEnableSuggestionsWithSubstringMatch| is on; otherwise |false|.
+bool IsFeatureSubstringMatchEnabled();
+
+// Splits |field_suggestion| into tokens, separated by characters from " .,-_@".
+// Returns true if |field_content| is a prefix of some token; otherwise false.
+bool IsContentsPrefixOfSuggestionToken(const base::string16& field_suggestion,
+                                       const base::string16& field_contents,
+                                       CaseSensitivity case_sensitivity);
+
+// 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,

[Evan Stade, 2015/03/26 18:54:38]

seems like this belongs next to base::StartsWith/EndsWith (base::Contains or
something)

[Pritam Nikam, 2015/03/27 14:57:42]

Sorry, I didn't get this input. Did you mean I shall move this to
string_util.h/.cc instead?

[Evan Stade, 2015/03/30 17:44:58]

yes

[Pritam Nikam, 2015/03/31 14:26:11]

Done.

Added a utility API to string_util.h/cc to get the offset of search string.

// Returns offset to the beginning of first occurence of |search| in the |str|.
// If no such subsequence is found, |base::string16::npos| is returned.
BASE_EXPORT base::string16::size_type StartsAt(const base::string16& str,
                                               const base::string16& search,
                                               bool case_sensitive);

ComputeRange() wraps it for autocomplete/autofill need to calculate the
selection range indices.

+                                       const base::string16& field_contents,
+                                       size_t* start,
+                                       size_t* end);
+
+}  // namespace autofill
+
+#endif  // COMPONENTS_AUTOFILL_CORE_COMMON_AUTOFILL_UTIL_H_