Move the exception logic to the AudioNode creator

third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp

Index: third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp b/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp
index 6f26b7d3d951a565623fab7b6ed7e101915fbb99..9ad4e6e31490a8fd3238a222dc03189ad1332f4f 100644
--- a/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp
@@ -259,8 +259,75 @@ static size_t chooseBufferSize()
     return bufferSize;
 }
 
-ScriptProcessorNode* ScriptProcessorNode::create(AbstractAudioContext& context, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels)
+ScriptProcessorNode* ScriptProcessorNode::create(
+    AbstractAudioContext& context,
+    ExceptionState& exceptionState)
 {
+    ASSERT(isMainThread());

[hongchan, 2016/05/13 01:20:13]

DCHECK.

[Raymond Toy, 2016/05/20 23:12:01]

Done.

+
+    return create(context, 0, 2, 2, exceptionState);
+}
+
+ScriptProcessorNode* ScriptProcessorNode::create(
+    AbstractAudioContext& context,
+    size_t bufferSize,
+    ExceptionState& exceptionState)
+{
+    ASSERT(isMainThread());

[hongchan, 2016/05/13 01:20:13]

Ditto.

[Raymond Toy, 2016/05/20 23:12:01]

Done.

+
+    return create(context, bufferSize, 2, 2, exceptionState);
+}
+
+ScriptProcessorNode* ScriptProcessorNode::create(
+    AbstractAudioContext& context,
+    size_t bufferSize,
+    unsigned numberOfInputChannels,
+    ExceptionState& exceptionState)
+{
+    ASSERT(isMainThread());

[hongchan, 2016/05/13 01:20:13]

Ditto.

[Raymond Toy, 2016/05/20 23:12:01]

Done.

+
+    return create(context, bufferSize, numberOfInputChannels, 2, exceptionState);
+}
+
+ScriptProcessorNode* ScriptProcessorNode::create(
+    AbstractAudioContext& context,
+    size_t bufferSize,
+    unsigned numberOfInputChannels,
+    unsigned numberOfOutputChannels,
+    ExceptionState& exceptionState)
+{
+    ASSERT(isMainThread());
+
+    if (context.isContextClosed()) {
+        context.throwExceptionForClosedState(exceptionState);
+        return nullptr;
+    }
+
+    if (numberOfInputChannels == 0 && numberOfOutputChannels == 0) {
+        exceptionState.throwDOMException(
+            IndexSizeError,
+            "number of input channels and output channels cannot both be zero.");

[hongchan, 2016/05/13 01:20:13]

input channels and output channels => input and output channels

Then we can contain this within 80 cols.

[Raymond Toy, 2016/05/13 16:36:01]

I chose this originally to kind of match the text in the other exceptions below.

Plus, we shouldn't shorten a user message just to make source code fit in 80
cols.  That's the wrong approach.

+        return nullptr;
+    }
+
+    if (numberOfInputChannels > AbstractAudioContext::maxNumberOfChannels()) {
+        exceptionState.throwDOMException(
+            IndexSizeError,
+            "number of input channels (" + String::number(numberOfInputChannels)
+            + ") exceeds maximum ("
+            + String::number(AbstractAudioContext::maxNumberOfChannels()) + ").");
+        return nullptr;
+    }
+
+    if (numberOfOutputChannels > AbstractAudioContext::maxNumberOfChannels()) {
+        exceptionState.throwDOMException(
+            IndexSizeError,
+            "number of output channels (" + String::number(numberOfInputChannels)
+            + ") exceeds maximum ("
+            + String::number(AbstractAudioContext::maxNumberOfChannels()) + ").");
+        return nullptr;
+    }
+

[hongchan, 2016/05/13 01:20:13]

In the change above, we have few "80-col" issues. Perhaps we should discuss this
in person.

     // Check for valid buffer size.
     switch (bufferSize) {
     case 0:
@@ -275,19 +342,21 @@ ScriptProcessorNode* ScriptProcessorNode::create(AbstractAudioContext& context,
     case 16384:
         break;
     default:
+        exceptionState.throwDOMException(
+            IndexSizeError,
+            "buffer size (" + String::number(bufferSize)
+            + ") must be 0 or a power of two between 256 and 16384.");
         return nullptr;
     }
 
-    if (!numberOfInputChannels && !numberOfOutputChannels)
-        return nullptr;
+    ScriptProcessorNode* node =  new ScriptProcessorNode(context, context.sampleRate(), bufferSize, numberOfInputChannels, numberOfOutputChannels);

[hongchan, 2016/05/13 01:20:13]

Let's wrap arguments.

 
-    if (numberOfInputChannels > AbstractAudioContext::maxNumberOfChannels())
-        return nullptr;
-
-    if (numberOfOutputChannels > AbstractAudioContext::maxNumberOfChannels())
-        return nullptr;
+    if (node) {
+        // context keeps reference until we stop making javascript rendering callbacks

[hongchan, 2016/05/13 01:20:13]

If we move this comment above |if (node)| Then we can remove curly braces.

[hongchan, 2016/05/20 21:28:32]

Perhaps it needs one more look here?

[Raymond Toy, 2016/05/20 21:46:09]

I like the braces; moving the comment out just so I can remove braces seems
unnecessary.

(FWIW, I hate the rule that braces are not needed.  It's a needless extra rule
and it's a great source of silly bugs when modifying code.)

[hongchan, 2016/05/20 22:57:48]

It goes both ways. Without braces, we can easily tell this is a single action
based on the condition. Also the condition is the part of 'comment' here. Isn't
it?

Anyhow, I will leave this up to you.

+        context.notifySourceNodeStartedProcessing(node);
+    }
 
-    return new ScriptProcessorNode(context, sampleRate, bufferSize, numberOfInputChannels, numberOfOutputChannels);
+    return node;

[hongchan, 2016/05/13 01:20:13]

The same issue before - we should return node when it is valid. Otherwise we
should return nullptr.

[hongchan, 2016/05/20 21:28:32]

Is this addressed somewhere?

[Raymond Toy, 2016/05/20 21:46:09]

If line 352 fails to create a ScriptProcessor, node is null, and we'll return a
null here.

[hongchan, 2016/05/20 22:57:48]

But can we be explicit about that? We can easily return null in the if clause
above.

 }
 
 size_t ScriptProcessorNode::bufferSize() const