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

components/autofill/core/browser/autocomplete_history_manager.cc

 // Copyright 2013 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/browser/autocomplete_history_manager.h"
 
 #include <vector>
 
 #include "base/prefs/pref_service.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/strings/string16.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/autofill/core/browser/autofill_client.h"
 #include "components/autofill/core/browser/autofill_driver.h"
 #include "components/autofill/core/browser/autofill_experiments.h"
 #include "components/autofill/core/browser/autofill_external_delegate.h"
 #include "components/autofill/core/browser/validation.h"
 #include "components/autofill/core/common/autofill_pref_names.h"
+#include "components/autofill/core/common/autofill_util.h"
 #include "components/autofill/core/common/form_data.h"
 
 namespace autofill {
 namespace {
 
 // Limit on the number of suggestions to appear in the pop-up menu under an
 // text input element in a form.
 const int kMaxAutocompleteMenuItems = 6;
 
 bool IsTextField(const FormFieldData& field) {
@@ skipping 46 matching lines @@
   // See http://crbug.com/68783.
   if (!result) {
     SendSuggestions(NULL);
     return;
   }
 
   DCHECK_EQ(AUTOFILL_VALUE_RESULT, result->GetType());
   const WDResult<std::vector<base::string16> >* autofill_result =
       static_cast<const WDResult<std::vector<base::string16> >*>(result);
   std::vector<base::string16> suggestions = autofill_result->GetValue();
-  SendSuggestions(&suggestions);
+
+  if (!IsFeatureSubstringMatchEnabled() || pending_query_prefix_.empty()) {
+    SendSuggestions(&suggestions);
+  } else {
+    std::vector<base::string16> preferred_suggestions;
+    std::vector<base::string16> substring_matched_suggestions;
+    for (base::string16 suggestion : suggestions) {

[please use gerrit instead, 2015/06/29 22:06:28]

const base::string16&

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

Done.

+      if (StartsWith(suggestion, pending_query_prefix_, false)) {
+        preferred_suggestions.push_back(suggestion);
+      } else if (ContainsTokenThatStartsWith(suggestion, pending_query_prefix_,
+                                             false)) {
+        substring_matched_suggestions.push_back(suggestion);
+      }
+    }
+
+    // Prefix matches should precede other token matches.
+    if (IsFeatureSubstringMatchEnabled()) {
+      preferred_suggestions.insert(preferred_suggestions.end(),
+                                   substring_matched_suggestions.begin(),
+                                   substring_matched_suggestions.end());
+    }
+
+    SendSuggestions(&preferred_suggestions);
+  }
 }
 
 void AutocompleteHistoryManager::OnGetAutocompleteSuggestions(
     int query_id,
     const base::string16& name,
     const base::string16& prefix,
     const std::string& form_control_type,
     const std::vector<Suggestion>& suggestions) {
   CancelPendingQuery();
 
   query_id_ = query_id;
   autofill_suggestions_ = suggestions;
   if (!autofill_client_->IsAutocompleteEnabled() ||
       form_control_type == "textarea" ||
       IsInAutofillSuggestionsDisabledExperiment()) {
     SendSuggestions(NULL);
     return;
   }
 
   if (database_.get()) {
+    // TODO(pritam.nikam): Prensently there is unavailability of SQL solutions
+    // to handle '_' along LIKE operator on Chromium Linux bot. Patterns like
+    // '%s\_foo%' and '%[_]foo%' are not working. Revisit below code snippet in
+    // future so that logic can be handled in SQL query instead.

[please use gerrit instead, 2015/06/29 22:06:28]

No need for "Revisit.." sentence and TODO marker. Instead, please find the
sqlite documentation that explains why sqlite filtering will not work for our
case and paste the link in the comment.

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

With ESCAPE clause its working. I've modified
|AutofillTable::GetFormValuesForElementName()|.

SELECT value FROM table
  WHERE value LIKE '%!_foo%' ESCAPE '!'

+    pending_query_prefix_ = prefix;
     pending_query_handle_ = database_->GetFormValuesForElementName(
-        name, prefix, kMaxAutocompleteMenuItems, this);
+        name, IsFeatureSubstringMatchEnabled() ? base::string16() : prefix,
+        kMaxAutocompleteMenuItems, this);
   }
 }
 
 void AutocompleteHistoryManager::OnFormSubmitted(const FormData& form) {
   if (!autofill_client_->IsAutocompleteEnabled())
     return;
 
   if (driver_->IsOffTheRecord())
     return;
 
@@ skipping 62 matching lines @@
     }
   }
 
   external_delegate_->OnSuggestionsReturned(query_id_, autofill_suggestions_);
 
   query_id_ = 0;
   autofill_suggestions_.clear();
 }
 
 }  // namespace autofill