Improve TypeError messages from failed array conversions.

Source/bindings/v8/V8Binding.h

 /*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 * Copyright (C) 2012 Ericsson AB. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
@@ skipping 15 matching lines @@
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
 #ifndef V8Binding_h
 #define V8Binding_h
 
 #include "bindings/v8/DOMWrapperWorld.h"
+#include "bindings/v8/ExceptionMessages.h"
 #include "bindings/v8/V8BindingMacros.h"
 #include "bindings/v8/V8PerIsolateData.h"
 #include "bindings/v8/V8StringResource.h"
 #include "bindings/v8/V8ThrowException.h"
 #include "bindings/v8/V8ValueCache.h"
 #include "wtf/MathExtras.h"
 #include "wtf/text/AtomicString.h"
 #include <v8.h>
 
 namespace WebCore {
@@ skipping 21 matching lines @@
     v8::Handle<v8::Value> throwError(v8::Handle<v8::Value>, v8::Isolate*);
 
     // A helper for throwing JavaScript TypeError.
     v8::Handle<v8::Value> throwTypeError(const String&, v8::Isolate*);
 
     // FIXME: Remove this once we kill its callers.
     v8::Handle<v8::Value> throwUninformativeAndGenericTypeError(v8::Isolate*);
 
     v8::ArrayBuffer::Allocator* v8ArrayBufferAllocator();
 
-    v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value>, uint32_t& length, bool* notASequence, v8::Isolate*);
+    v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value>, uint32_t& length, bool& notASequence, v8::Isolate*);
 
     inline v8::Handle<v8::Value> argumentOrNull(const v8::FunctionCallbackInfo<v8::Value>& args, int index)
     {
         return index >= args.Length() ? v8::Local<v8::Value>() : args[index];
     }
 
     // Since v8::Null(isolate) crashes if we pass a null isolate,
     // we need to use v8NullWithCheck(isolate) if an isolate can be null.
     //
     // FIXME: Remove all null isolates from V8 bindings, and remove v8NullWithCheck(isolate).
@@ skipping 344 matching lines @@
     template<>
     struct NativeValueTraits<double> {
         static inline double nativeValue(const v8::Handle<v8::Value>& value)
         {
             return static_cast<double>(value->NumberValue());
         }
     };
 
     // Converts a JavaScript value to an array as per the Web IDL specification:
     // http://www.w3.org/TR/2012/CR-WebIDL-20120419/#es-array
+    // To improve error message reporting, separate the conversion of the array
+    // elements from the sequence/array type checking.

[Mike West, 2013/10/24 07:08:54]

I don't think we need this comment in the code. I do think it should be in the
change description, however.

     template <class T, class V8T>
-    Vector<RefPtr<T> > toRefPtrNativeArray(v8::Handle<v8::Value> value, v8::Isolate* isolate, bool* success = 0)
+    Vector<RefPtr<T> > toRefPtrNativeArrayUnchecked(v8::Local<v8::Value> v8Value, uint32_t length, v8::Isolate* isolate, bool* success = 0)
     {
-        if (success)
-            *success = true;
-
-        v8::Local<v8::Value> v8Value(v8::Local<v8::Value>::New(isolate, value));
-        uint32_t length = 0;
-        if (value->IsArray())
-            length = v8::Local<v8::Array>::Cast(v8Value)->Length();
-        else if (toV8Sequence(value, length, 0, isolate).IsEmpty())
-            return Vector<RefPtr<T> >();
-
         Vector<RefPtr<T> > result;
         result.reserveInitialCapacity(length);
         v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(v8Value);
         for (uint32_t i = 0; i < length; ++i) {
             v8::Handle<v8::Value> element = object->Get(i);
 
             if (V8T::HasInstance(element, isolate, worldType(isolate))) {
                 v8::Handle<v8::Object> elementObject = v8::Handle<v8::Object>::Cast(element);
                 result.uncheckedAppend(V8T::toNative(elementObject));
             } else {
                 if (success)
                     *success = false;
                 throwTypeError("Invalid Array element type", isolate);
                 return Vector<RefPtr<T> >();
             }
         }
         return result;
     }
 
+    template <class T, class V8T>
+    Vector<RefPtr<T> > toRefPtrNativeArray(v8::Handle<v8::Value> value, int argumentIndex, v8::Isolate* isolate, bool* success = 0)
+    {
+        if (success)
+            *success = true;
+
+        v8::Local<v8::Value> v8Value(v8::Local<v8::Value>::New(isolate, value));
+        uint32_t length = 0;
+        bool notASequence = false;
+        if (value->IsArray()) {
+            length = v8::Local<v8::Array>::Cast(v8Value)->Length();
+        } else if (toV8Sequence(value, length, notASequence, isolate).IsEmpty()) {
+            if (notASequence)
+                throwTypeError(ExceptionMessages::notASequenceType(argumentIndex), isolate);
+            return Vector<RefPtr<T> >();
+        }
+
+        return toRefPtrNativeArrayUnchecked<T, V8T>(v8Value, length, isolate, success);
+    }
+
+    template <class T, class V8T>
+    Vector<RefPtr<T> > toRefPtrNativeArray(v8::Handle<v8::Value> value, const String& argumentName, const String& argumentKind, v8::Isolate* isolate, bool* success = 0)
+    {
+        if (success)
+            *success = true;
+
+        v8::Local<v8::Value> v8Value(v8::Local<v8::Value>::New(isolate, value));
+        uint32_t length = 0;
+        bool notASequence = false;
+        if (value->IsArray()) {
+            length = v8::Local<v8::Array>::Cast(v8Value)->Length();
+        } else if (toV8Sequence(value, length, notASequence, isolate).IsEmpty()) {
+            if (notASequence)
+                throwTypeError(ExceptionMessages::notASequenceType(argumentName, argumentKind), isolate);
+            return Vector<RefPtr<T> >();
+        }
+
+        return toRefPtrNativeArrayUnchecked<T, V8T>(v8Value, length, isolate, success);
+    }
+
     // Converts a JavaScript value to an array as per the Web IDL specification:
     // http://www.w3.org/TR/2012/CR-WebIDL-20120419/#es-array
     template <class T>
-    Vector<T> toNativeArray(v8::Handle<v8::Value> value, v8::Isolate* isolate)
+    Vector<T> toNativeArray(v8::Handle<v8::Value> value, int argumentIndex, v8::Isolate* isolate)
     {
         v8::Local<v8::Value> v8Value(v8::Local<v8::Value>::New(isolate, value));
         uint32_t length = 0;
-        if (value->IsArray())
+        bool notASequence = false;
+        if (value->IsArray()) {
             length = v8::Local<v8::Array>::Cast(v8Value)->Length();
-        else if (toV8Sequence(value, length, 0, isolate).IsEmpty())
+        } else if (toV8Sequence(value, length, notASequence, isolate).IsEmpty()) {
+            if (notASequence)
+                throwTypeError(ExceptionMessages::notASequenceType(argumentIndex), isolate);
             return Vector<T>();
+        }
 
         Vector<T> result;
         result.reserveInitialCapacity(length);
         typedef NativeValueTraits<T> TraitsType;
         v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(v8Value);
         for (uint32_t i = 0; i < length; ++i)
             result.uncheckedAppend(TraitsType::nativeValue(object->Get(i)));
         return result;
     }
 
     template <class T>
     Vector<T> toNativeArguments(const v8::FunctionCallbackInfo<v8::Value>& args, int startIndex)
     {
         ASSERT(startIndex <= args.Length());
         Vector<T> result;
         typedef NativeValueTraits<T> TraitsType;
         int length = args.Length();
         result.reserveInitialCapacity(length);
         for (int i = startIndex; i < length; ++i)
             result.uncheckedAppend(TraitsType::nativeValue(args[i]));
         return result;
     }
 
     Vector<v8::Handle<v8::Value> > toVectorOfArguments(const v8::FunctionCallbackInfo<v8::Value>& args);
 
     // Validates that the passed object is a sequence type per WebIDL spec
     // http://www.w3.org/TR/2012/CR-WebIDL-20120419/#es-sequence
-    inline v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value> value, uint32_t& length, bool* notASequence, v8::Isolate* isolate)
+    inline v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value> value, uint32_t& length, bool& notASequence, v8::Isolate* isolate)
     {
         // Attempt converting to a sequence if the value is not already an array but is
         // any kind of object except for a native Date object or a native RegExp object.
         ASSERT(!value->IsArray());
         // FIXME: Do we really need to special case Date and RegExp object?
         // https://www.w3.org/Bugs/Public/show_bug.cgi?id=22806
         if (!value->IsObject() || value->IsDate() || value->IsRegExp()) {
             // Signal that the caller must handle the type error.
-            if (notASequence)
-                *notASequence = true;
-            else
-                throwUninformativeAndGenericTypeError(isolate);
+            notASequence = true;
             return v8Undefined();
         }
 
         v8::Local<v8::Value> v8Value(v8::Local<v8::Value>::New(isolate, value));
         v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(v8Value);
 
         // FIXME: The specification states that the length property should be used as fallback, if value
         // is not a platform object that supports indexed properties. If it supports indexed properties,
         // length should actually be one greater than value’s maximum indexed property index.
         V8TRYCATCH(v8::Local<v8::Value>, lengthValue, object->Get(v8::String::NewSymbol("length")));
 
         if (lengthValue->IsUndefined() || lengthValue->IsNull()) {
-            // Signal that the caller must handle the type error.
-            if (notASequence)
-                *notASequence = true;
-            else
-                throwUninformativeAndGenericTypeError(isolate);
+            notASequence = true;
             return v8Undefined();
         }
 
         V8TRYCATCH(uint32_t, sequenceLength, lengthValue->Int32Value());
         length = sequenceLength;
 
         return v8Value;
     }
 
     PassRefPtr<NodeFilter> toNodeFilter(v8::Handle<v8::Value>, v8::Isolate*);
@@ skipping 111 matching lines @@
 
     v8::Isolate* mainThreadIsolate();
     v8::Isolate* toIsolate(ExecutionContext*);
     v8::Isolate* toIsolate(Frame*);
 
     // Can only be called by WebKit::initialize
     void setMainThreadIsolate(v8::Isolate*);
 } // namespace WebCore
 
 #endif // V8Binding_h