[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;

[please use gerrit instead, 2015/06/28 01:20:07]

Wouldn't it be better to perform this logic in SQL?

https://code.google.com/p/chromium/codesearch#chromium/src/components/autofil...

After performing the first query, if substring match is enabled, then add a
query like this:

sql::Statement s2;
s2.Assign(db_->GetUniqueStatement(
    "SELECT value FROM autofill "
    "WHERE name = ? AND ("
    "    value LIKE ? OR "
    "    value LIKE ? OR "
    "    value LIKE ? OR "
    "    value LIKE ? OR "
    "    value LIKE ? OR "
    "    value LIKE ? ) "
    "ORDER BY count DESC "
    "LIMIT ?");
s2.BindString16(0, name);
s2.BindString16(1, " " + prefix_lower);
s2.BindString16(2, "." + prefix_lower);
s2.BindString16(3, "," + prefix_lower);
s2.BindString16(4, "-" + prefix_lower);
s2.BindString16(5, "_" + prefix_lower);
s2.BindString16(6, "@" + prefix_lower);
s2.BindInt(7, limit);
while (s2.Step())
  values->push_back(s2.ColumnString16(0));

retrun s.Succeeded() && s2.Succeeded();



Since you will perform this query second, the results will be at the end of
|values|, as is desired.

[Pritam Nikam, 2015/06/29 15:38:21]

We need to pass '%<delimiter> + prefix_lower + %'. But there is one problem:

'_' being keyword, suggestions like "test_user" on user input "use" would not
get populated. Moreover, groups i.e. [] does not seems working (tested on my
local linux setup) with chromium.
did you mean "retrun s.Succeeded() || s2.Succeeded();"

[please use gerrit instead, 2015/06/29 17:06:45]

Use '\_' instead?
Why do you need []? Do () work?
I don't have a strong preference, as long as you document the behavior in
function comment.

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

ESCAPE clause worked for (_) case.

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

+    std::vector<base::string16> substring_matched_suggestions;
+    for (base::string16 suggestion : suggestions) {
+      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()) {
+    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