Support IDL attributes limited to only known values.

Source/bindings/tests/idls/TestObject.idl

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary formstrArg, with or without
  * modification, are permitted provided that the following conditions
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@@ skipping 56 matching lines @@
     [Reflect, TreatNullAs=NullString] attribute DOMString reflectedStringAttr;
     [Reflect] attribute long reflectedIntegralAttr;
     [Reflect] attribute unsigned long reflectedUnsignedIntegralAttr;
     [Reflect] attribute boolean reflectedBooleanAttr;
     [Reflect, TreatNullAs=NullString, URL] attribute DOMString reflectedURLAttr;
     [Reflect=customContentStringAttr, TreatNullAs=NullString] attribute DOMString reflectedStringAttr;
     [Reflect=customContentIntegralAttr] attribute long reflectedCustomIntegralAttr;
     [Reflect=customContentBooleanAttr] attribute boolean reflectedCustomBooleanAttr;
     [Reflect=customContentURLAttr, TreatNullAs=NullString, URL] attribute DOMString reflectedCustomURLAttr;
     [Reflect] attribute SVGAnimatedString animatedReflectedAttribute;
+    [Reflect, ReflectOnly=unique] attribute DOMString limitedToOnlyOneAttribute;
+    [Reflect, ReflectOnly=Per Paal Espen] attribute DOMString limitedToOnlyAttribute;

[haraken, 2014/01/06 06:23:53]

Shall we use ReflectOnly=Per|Paal|Pspen instead of space splitting?

[sof, 2014/01/06 06:40:51]

I thought I could from reading the IDLExtendedAttributes.txt description for
"Attr=*", but "|" with more than 2 values isn't allowed by the parser.

It looks odd to use space, I agree, should we make the parser more lenient?
(assuming that there isn't a way to express this already.)

[Nils Barth (inactive), 2014/01/06 06:42:51]

??
To agree with haraken, we can't use spaces here.
| should work with arbitrarily many values.
Let me check this.

[Nils Barth (inactive), 2014/01/06 07:12:49]

Thanks for catching this; this is a bug, which I've posted a fix for:
Perl IDL parser: allow extended attributes to have more than 2 values
https://codereview.chromium.org/124943002/

In the initial Python rewrite the grammar explicitly limited extended attribute
value lists to length 2, as that was sufficient for actual use, but I removed
the limit later (someone complained, and it's clearer that way anyway). I didn't
update the Perl then though b/c no-one was using it yet.

[sof, 2014/01/06 10:59:19]

Thanks; rebased this CL on top of it + switched to using "|".

+    [Reflect=Other, ReflectOnly=Value1 Value2] attribute DOMString limitedToOnlyOtherAttribute;
 
     // TypedArray attribute
     attribute Float32Array typedArrayAttr;
 
     // Methods
     void    voidMethod();
     void    voidMethodWithArgs(long longArg, DOMString strArg, TestObject objArg);
     long    longMethod();
     long    longMethodWithArgs(long longArg, DOMString strArg, TestObject objArg);
     [MeasureAs=TestFeature] TestObject objMethod();
@@ skipping 217 matching lines @@
     [DeprecateAs=Constant] const unsigned short DEPRECATED_CONSTANT = 1;
 
     // PutForwards
     [PutForwards=href] readonly attribute TestNode location;
     [PutForwards=hrefThrows] readonly attribute TestNode locationWithException;
 };
 
 // The following comment should not generate any code
 // TestObject implements TestImplements;