Bug 1185235 - Implement SpeechRecognition::maxAlternatives. r=smaug

dom/media/webspeech/recognition/PocketSphinxSpeechRecognitionService.cpp

@@ -54,13 +54,16 @@ public:
     SpeechRecognitionResultList* resultList =
       new SpeechRecognitionResultList(mRecognition);
     SpeechRecognitionResult* result = new SpeechRecognitionResult(mRecognition);
-    SpeechRecognitionAlternative* alternative =
-      new SpeechRecognitionAlternative(mRecognition);
+    ErrorResult rv;
+    if (0 < mRecognition->GetMaxAlternatives(rv)) { // GetMaxAlternatives can't fail
+      SpeechRecognitionAlternative* alternative =
+        new SpeechRecognitionAlternative(mRecognition);
 
-    alternative->mTranscript = mResult;
-    alternative->mConfidence = 100;
+      alternative->mTranscript = mResult;
+      alternative->mConfidence = 100;
 
-    result->mItems.AppendElement(alternative);
+      result->mItems.AppendElement(alternative);
+    }
     resultList->mItems.AppendElement(result);
 
     event->mRecognitionResultList = resultList;
@@ -330,13 +333,16 @@ PocketSphinxSpeechRecognitionService::BuildMockResultList()
   SpeechRecognitionResultList* resultList =
     new SpeechRecognitionResultList(mRecognition);
   SpeechRecognitionResult* result = new SpeechRecognitionResult(mRecognition);
-  SpeechRecognitionAlternative* alternative =
-    new SpeechRecognitionAlternative(mRecognition);
+  ErrorResult rv;
+  if (0 < mRecognition->GetMaxAlternatives(rv)) { // GetMaxAlternatives can't fail
+    SpeechRecognitionAlternative* alternative =
+      new SpeechRecognitionAlternative(mRecognition);
 
-  alternative->mTranscript = NS_LITERAL_STRING("Mock final result");
-  alternative->mConfidence = 0.0f;
+    alternative->mTranscript = NS_LITERAL_STRING("Mock final result");
+    alternative->mConfidence = 0.0f;
 
-  result->mItems.AppendElement(alternative);
+    result->mItems.AppendElement(alternative);
+  }
   resultList->mItems.AppendElement(result);
 
   return resultList;

dom/media/webspeech/recognition/SpeechRecognition.cpp

@@ -117,6 +117,7 @@ SpeechRecognition::SpeechRecognition(nsPIDOMWindow* aOwnerWindow)
   , mSpeechDetectionTimer(do_CreateInstance(NS_TIMER_CONTRACTID))
   , mSpeechGrammarList(new SpeechGrammarList(GetParentObject()))
   , mInterimResults(false)
+  , mMaxAlternatives(1)
 {
   SR_LOG("created SpeechRecognition");
 
@@ -685,14 +686,13 @@ SpeechRecognition::SetInterimResults(bool aArg)
 uint32_t
 SpeechRecognition::GetMaxAlternatives(ErrorResult& aRv) const
 {
-  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
-  return 0;
+  return mMaxAlternatives;
 }
 
 void
 SpeechRecognition::SetMaxAlternatives(uint32_t aArg, ErrorResult& aRv)
 {
-  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
+  mMaxAlternatives = aArg;
   return;
 }
 

dom/media/webspeech/recognition/SpeechRecognition.h

@@ -266,6 +266,17 @@ private:
   // is a conforming implementation.
   bool mInterimResults;
 
+  // WebSpeechAPI (http://bit.ly/1JAiqeo) states:
+  //
+  // 1. Default value is 1
+  // 2. Subsequent value is the "maximum number of SpeechRecognitionAlternatives per result"
+  //
+  // Pocketsphinx can only return at maximum a single SpeechRecognitionAlternative
+  // per SpeechRecognitionResult. So defaulting mMaxAlternatives to 1, for all non
+  // zero values ignoring mMaxAlternatives while for a 0 value returning no
+  // SpeechRecognitionAlternative per result is a conforming implementation.
+  uint32_t mMaxAlternatives;
+
   void ProcessTestEventRequest(nsISupports* aSubject, const nsAString& aEventName);
 
   const char* GetName(FSMState aId);

dom/media/webspeech/recognition/test/FakeSpeechRecognitionService.cpp

@@ -102,12 +102,15 @@ FakeSpeechRecognitionService::BuildMockResultList()
 {
   SpeechRecognitionResultList* resultList = new SpeechRecognitionResultList(mRecognition);
   SpeechRecognitionResult* result = new SpeechRecognitionResult(mRecognition);
-  SpeechRecognitionAlternative* alternative = new SpeechRecognitionAlternative(mRecognition);
+  ErrorResult rv;
+  if (0 < mRecognition->GetMaxAlternatives(rv)) { // GetMaxAlternatives can't fail
+    SpeechRecognitionAlternative* alternative = new SpeechRecognitionAlternative(mRecognition);
 
-  alternative->mTranscript = NS_LITERAL_STRING("Mock final result");
-  alternative->mConfidence = 0.0f;
+    alternative->mTranscript = NS_LITERAL_STRING("Mock final result");
+    alternative->mConfidence = 0.0f;
 
-  result->mItems.AppendElement(alternative);
+    result->mItems.AppendElement(alternative);
+  }
   resultList->mItems.AppendElement(result);
 
   return resultList;