[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 <algorithm>
+#include <vector>
+
+#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;
+
+  const std::vector<base::string16>& suggestion_tokens =
+      base::SplitString(suggestion, base::ASCIIToUTF16(kSplitCharacters),
+                        base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
+
+  // Check whether the |field_contents| prefixes any of the |suggestion|'s
+  // tokens.
+  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) {
+  // Loop until we find either the |field_contents| is a prefix of |suggestion|
+  // or character right before the match is one of the splitting characters.
+  for (base::string16::const_iterator it = suggestion.begin();
+       (it = std::search(
+            it, suggestion.end(), field_contents.begin(), field_contents.end(),
+            base::CaseInsensitiveCompare<base::string16::value_type>())) !=
+           suggestion.end();
+       ++it) {
+    if (it == suggestion.begin() ||
+        ContainsOnlyChars(suggestion.substr((it - suggestion.begin() - 1), 1),
+                          base::ASCIIToUTF16(kSplitCharacters))) {

[please use gerrit instead, 2015/06/30 19:06:23]

It should be easier to dereference the pointer (*it) instead of taking a single
character substring.

base::string16 split_chars = base::ASCIIToUTF16(kSplitCharacters);
...
if (it == suggestion.begin() || split_chars.find(*it) != std::string::npos)) {
  ...
}

[Pritam Nikam, 2015/07/01 17:26:00]

Done.

Did you mean?

    base::string16 split_chars = base::ASCIIToUTF16(kSplitCharacters);
    if (it == suggestion.begin() || split_chars.find(*(it-1)) !=
std::string::npos)) {
      ...   
    }

*it -> Character where match found.
*(it-1) -> Character right before the match.

[please use gerrit instead, 2015/07/03 02:05:43]

You're right.

+      // Returns the character position right after the |field_contents| within
+      // |suggestion| text as a caret position for text selection.
+      return it - suggestion.begin() + field_contents.size();
+    }
+  }
+
+  // Unable to find the |field_contents| in |suggestion| text.
+  NOTREACHED();
+  return base::string16::npos;
+}
+
+}  // namespace autofill