Add Automatic spell correction support in Chrome.

Issue=7624
Review URL: http://codereview.chromium.org/42608

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@15888 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 102 insertions, 0 deletions

diff --git a/chrome/browser/renderer_host/browser_render_process_host.cc b/chrome/browser/renderer_host/browser_render_process_host.cc
index f43e06ba..fce7128 100644
--- a/chrome/browser/renderer_host/browser_render_process_host.cc
+++ b/chrome/browser/renderer_host/browser_render_process_host.cc
@@ -264,6 +264,7 @@ bool BrowserRenderProcessHost::Init() {
     switches::kEnableStatsTable,
     switches::kEnableExtensions,
     switches::kEnableOutOfProcessDevTools,
+    switches::kAutoSpellCorrect,
     switches::kDisableAudio,
     switches::kSimpleDataSource,
   };
diff --git a/chrome/browser/renderer_host/resource_message_filter.cc b/chrome/browser/renderer_host/resource_message_filter.cc
index 0b86265..594163f 100644
--- a/chrome/browser/renderer_host/resource_message_filter.cc
+++ b/chrome/browser/renderer_host/resource_message_filter.cc
@@ -253,6 +253,8 @@ bool ResourceMessageFilter::OnMessageReceived(const IPC::Message& message) {
       IPC_MESSAGE_HANDLER(ViewHostMsg_ForwardToWorker,
                           OnForwardToWorker)
       IPC_MESSAGE_HANDLER_DELAY_REPLY(ViewHostMsg_SpellCheck, OnSpellCheck)
+      IPC_MESSAGE_HANDLER_DELAY_REPLY(ViewHostMsg_GetAutoCorrectWord,
+                                      OnGetAutoCorrectWord)
       IPC_MESSAGE_HANDLER(ViewHostMsg_DnsPrefetch, OnDnsPrefetch)
       IPC_MESSAGE_HANDLER(ViewHostMsg_RendererHistograms,
                           OnRendererHistograms)
@@ -794,6 +796,20 @@ void ResourceMessageFilter::OnSpellCheck(const std::wstring& word,
   return;
 }
 
+
+void ResourceMessageFilter::OnGetAutoCorrectWord(const std::wstring& word,
+                                                 IPC::Message* reply_msg) {
+  std::wstring autocorrect_word;
+  if (spellchecker_ != NULL) {
+    spellchecker_->GetAutoCorrectionWord(word, &autocorrect_word);
+  }
+
+  ViewHostMsg_GetAutoCorrectWord::WriteReplyParams(reply_msg,
+                                                   autocorrect_word);
+  Send(reply_msg);
+  return;
+}
+
 void ResourceMessageFilter::Observe(NotificationType type,
                                     const NotificationSource &source,
                                     const NotificationDetails &details) {
diff --git a/chrome/browser/renderer_host/resource_message_filter.h b/chrome/browser/renderer_host/resource_message_filter.h
index c28618b..8a406f0 100644
--- a/chrome/browser/renderer_host/resource_message_filter.h
+++ b/chrome/browser/renderer_host/resource_message_filter.h
@@ -146,6 +146,8 @@ class ResourceMessageFilter : public IPC::ChannelProxy::MessageFilter,
                      const GURL& referrer);
   void OnSpellCheck(const std::wstring& word,
                     IPC::Message* reply_msg);
+  void OnGetAutoCorrectWord(const std::wstring& word,
+                            IPC::Message* reply_msg);
   void OnDnsPrefetch(const std::vector<std::string>& hostnames);
   void OnRendererHistograms(const std::vector<std::string>& histogram_info);
   void OnReceiveContextMenuMsg(const IPC::Message& msg);
diff --git a/chrome/browser/spellcheck_unittest.cc b/chrome/browser/spellcheck_unittest.cc
index 8a9731f..aa76bf0 100644
--- a/chrome/browser/spellcheck_unittest.cc
+++ b/chrome/browser/spellcheck_unittest.cc
@@ -495,3 +495,36 @@ TEST_F(SpellCheckTest, DISABLED_SpellCheckSuggestionsAddToDictionary_EN_US) {
   // Remove the temp custom dictionary file.
   file_util::Delete(custom_dictionary_file, false);
 }
+
+TEST_F(SpellCheckTest, GetAutoCorrectionWord_EN_US) {
+  static const struct {
+    // A misspelled word.
+    const wchar_t* input;
+
+    // An expected result for this test case.
+    // Should be an empty string if there are no suggestions for auto correct.
+    const wchar_t* expected_result;
+  } kTestCases[] = {
+    {L"teh", L"the"},
+    {L"moer", L"more"},
+    {L"watre", L"water"},
+    {L"noen", L""},
+    {L"what", L""},
+  };
+
+  FilePath hunspell_directory = GetHunspellDirectory();
+  ASSERT_FALSE(hunspell_directory.empty());
+
+  scoped_refptr<SpellChecker> spell_checker(new SpellChecker(
+      hunspell_directory, "en-US", NULL, FilePath()));
+
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(kTestCases); ++i) {
+    std::wstring misspelled_word(kTestCases[i].input);
+    std::wstring expected_autocorrect_word(kTestCases[i].expected_result);
+    std::wstring autocorrect_word;
+    spell_checker->GetAutoCorrectionWord(misspelled_word, &autocorrect_word);
+
+    // Check for spelling.
+    EXPECT_EQ(expected_autocorrect_word, autocorrect_word);
+  }
+}
diff --git a/chrome/browser/spellchecker.cc b/chrome/browser/spellchecker.cc
index 1a28cf1..75ef204 100644
--- a/chrome/browser/spellchecker.cc
+++ b/chrome/browser/spellchecker.cc
@@ -30,6 +30,7 @@ using base::TimeTicks;
 
 static const int kMaxSuggestions = 5;  // Max number of dictionary suggestions.
 
+static const int kMaxAutoCorrectWordSize = 8;
 
 namespace {
 
@@ -475,6 +476,49 @@ bool SpellChecker::Initialize() {
   return false;
 }
 
+void SpellChecker::GetAutoCorrectionWord(const std::wstring& word,
+                                         std::wstring* autocorrect_word) {
+  autocorrect_word->clear();
+  int word_length = static_cast<int>(word.size());
+  if (word_length < 2 || word_length > kMaxAutoCorrectWordSize)
+    return;
+
+  wchar_t misspelled_word[kMaxAutoCorrectWordSize + 1];
+  const wchar_t* word_char = word.c_str();
+  for (int i = 0; i <= kMaxAutoCorrectWordSize; i++) {
+    if (i >= word_length)
+      misspelled_word[i] = NULL;
+    else
+      misspelled_word[i] = word_char[i];
+  }
+
+  // Swap adjacent characters and spellcheck.
+  int misspelling_start, misspelling_len;
+  for (int i = 0; i < word_length - 1; i++) {
+    // Swap.
+    std::swap(misspelled_word[i], misspelled_word[i + 1]);
+
+    // Check spelling.
+    misspelling_start = misspelling_len = 0;
+    SpellCheckWord(misspelled_word, word_length, &misspelling_start,
+        &misspelling_len, NULL);
+
+    // Make decision: if only one swap produced a valid word, then we want to
+    // return it. If we found two or more, we don't do autocorrection.
+    if (misspelling_len == 0) {
+      if (autocorrect_word->empty()) {
+        autocorrect_word->assign(misspelled_word);
+      } else {
+        autocorrect_word->clear();
+        return;
+      }
+    }
+
+    // Restore the swapped characters.
+    std::swap(misspelled_word[i], misspelled_word[i + 1]);
+  }
+}
+
 void SpellChecker::AddCustomWordsToHunspell() {
   // Add custom words to Hunspell.
   // This should be done in File Loop, but since Hunspell is in this IO Loop,
diff --git a/chrome/browser/spellchecker.h b/chrome/browser/spellchecker.h
index 2827991..0c0b535 100644
--- a/chrome/browser/spellchecker.h
+++ b/chrome/browser/spellchecker.h
@@ -75,6 +75,12 @@ class SpellChecker : public base::RefCountedThreadSafe<SpellChecker> {
                       int* misspelling_len,
                       std::vector<std::wstring>* optional_suggestions);
 
+  // Find a possible correctly spelled word for a misspelled word. Computes an
+  // empty string if input misspelled word is too long, there is ambiguity, or
+  // the correct spelling cannot be determined.
+  void GetAutoCorrectionWord(const std::wstring& word,
+      std::wstring* autocorrect_word);
+
   // Add custom word to the dictionary, which means:
   //    a) Add it to the current hunspell object for immediate use,
   //    b) Add the word to a file in disk for custom dictionary.