IDL: Generate union type containers

Source/bindings/templates/union.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// FIXME: Implement
+// This file has been auto-generated by {{code_generator}}. DO NOT MODIFY!
+
+#include "config.h"
+#include "{{header_filename}}"
+
+{% for filename in cpp_includes %}
+#include "{{filename}}"
+{% endfor %}
+
+namespace blink {
+
+{% for container in containers %}
+{{container.cpp_class}}::{{container.cpp_class}}()
+    : m_type(SpecificTypeNone)
+{
+}
+
+{% for member in container.members %}
+{{member.rvalue_cpp_type}} {{container.cpp_class}}::getAs{{member.type_name}}()
+{
+    ASSERT(is{{member.type_name}}());
+    return m_{{member.cpp_name}};
+}
+
+void {{container.cpp_class}}::set{{member.type_name}}({{member.rvalue_cpp_type}} value)
+{
+    ASSERT(isNull());
+    m_{{member.cpp_name}} = value;
+    m_type = {{member.specific_type_enum}};
+}
+
+{% endfor %}
+void V8{{container.cpp_class}}::toImpl(v8::Isolate* isolate, v8::Handle<v8::Value> v8Value, {{container.cpp_class}}& impl, ExceptionState& exceptionState)
+{
+    {# FIXME: We don't follow the spec on handling null and undefined at this
+       moment. Should be fixed once we implement all necessary conversion steps
+       below. #}
+    if (v8Value.IsEmpty() || isUndefinedOrNull(v8Value))
+        return;
+
+    {# The numbers in the following comments refer the steps described in
+       http://heycam.github.io/webidl/#es-union
+       FIXME: Implement all necessary steps #}
+    {# 3. Platform objects (interfaces) #}
+    {% for interface in container.interface_types %}
+    if (V8{{interface.type_name}}::hasInstance(v8Value, isolate)) {
+        {{interface.cpp_local_type}} cppValue = V8{{interface.type_name}}::toImpl(v8::Handle<v8::Object>::Cast(v8Value));
+        impl.set{{interface.type_name}}(cppValue);
+        return;
+    }
+
+    {% endfor %}
+    {% if container.dictionary_type %}
+    {# 12. Dictionaries #}
+    {# FIXME: This should be "object but not Date or RegExp". Adds checks when
+       we implement conversions for Date and RegExp. #}
+    if (v8Value->IsObject()) {
+        {{container.dictionary_type.cpp_local_type}} cppValue = V8{{container.dictionary_type.type_name}}::toImpl(isolate, v8Value, exceptionState);
+        if (!exceptionState.hadException())
+            impl.set{{container.dictionary_type.type_name}}(cppValue);
+        return;
+    }
+
+    {% endif %}
+    {% if container.boolean_type %}
+    {# 14. Boolean #}
+    if (v8Value->IsBoolean()) {
+        impl.setBoolean(v8Value->ToBoolean()->Value());
+        return;
+    }
+
+    {% endif %}
+    {% if container.numeric_type %}
+    {# 15. Number #}
+    if (v8Value->IsNumber()) {
+        {{container.numeric_type.v8_value_to_local_cpp_value}};
+        impl.set{{container.numeric_type.type_name}}(cppValue);
+        return;
+    }
+
+    {% endif %}
+    {% if container.string_type %}
+    {# 16. String #}
+    {
+        {{container.string_type.v8_value_to_local_cpp_value}};
+        impl.set{{container.string_type.type_name}}(cppValue);
+        return;
+    }
+
+    {# 17. Number (fallback) #}
+    {% elif container.numeric_type %}
+    {
+        {{container.numeric_type.v8_value_to_local_cpp_value}};
+        return;
+    }
+
+    {# 18. Boolean (fallback) #}
+    {% elif container.boolean_type %}
+    {
+        impl.setBoolean(v8Value->ToBoolean()->Value());
+        return;
+    }
+
+    {% endif %}
+    {# 19. TypeError #}
+    exceptionState.throwTypeError("Not a valid union member.");
+}
+
+v8::Handle<v8::Value> toV8({{container.cpp_class}}& impl, v8::Handle<v8::Object> creationContext, v8::Isolate* isolate)
+{
+    if (impl.isNull())
+        return v8::Null(isolate);

[Jens Widell, 2014/10/29 11:40:45]

It's possible we should sometimes convert to undefined here. WebIDL has the
(somewhat unclear, to me) text

  "If the value is an object reference to a special object that represents an
ECMAScript undefined value, then it is converted to the ECMAScript undefined
value."

OTOH, if a member type is nullable and this "union value" was the result of
converting an ECMAScript null value, then surely it should convert back to an
ECMAScript null value, so... either might be right or wrong.  :-)

[bashi, 2014/10/30 01:34:37]

I missed the statement, thank you for pointing this out.

That said, as we don't distinguish undefined/null in dictionary, I'd like to
leave it as is for now. Added a FIXME comment.

+
+    {% for member in container.members %}
+    if (impl.is{{member.type_name}}())
+        return {{member.cpp_value_to_v8_value}};
+
+    {% endfor %}
+    ASSERT_NOT_REACHED();
+    return v8::Handle<v8::Value>();
+}
+
+{% endfor %}
+} // namespace blink