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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* The IterableIterator class is used for WebIDL interfaces that have a
* iterable<> member defined with two types (so a pair iterator). It handles
* the ES6 Iterator-like functions that are generated for the iterable
* interface.
*
* For iterable interfaces with a pair iterator, the implementation class will
* need to implement these two functions:
*
* - size_t GetIterableLength()
* - Returns the number of elements available to iterate over
* - [type] GetValueAtIndex(size_t index)
* - Returns the value at the requested index.
* - [type] GetKeyAtIndex(size_t index)
* - Returns the key at the requested index
*
* Examples of iterable interface implementations can be found in the bindings
* test directory.
*/
#ifndef mozilla_dom_IterableIterator_h
#define mozilla_dom_IterableIterator_h
#include "js/TypeDecls.h"
#include "js/Value.h"
#include "nsISupports.h"
#include "mozilla/dom/IterableIteratorBinding.h"
#include "mozilla/dom/RootedDictionary.h"
#include "mozilla/dom/ToJSValue.h"
namespace mozilla {
namespace dom {
class IterableIteratorBase : public nsISupports {
public:
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_CLASS(IterableIteratorBase)
typedef enum { Keys = 0, Values, Entries } IterableIteratorType;
IterableIteratorBase() = default;
protected:
virtual ~IterableIteratorBase() = default;
virtual void UnlinkHelper() = 0;
virtual void TraverseHelper(nsCycleCollectionTraversalCallback& cb) = 0;
};
// Helpers to call iterator getter methods with the correct arguments, depending
// on the types they return, and convert the result to JS::Values.
// Helper for Get[Key,Value]AtIndex(uint32_t) methods, which accept an index and
// return a type supported by ToJSValue.
template <typename T, typename U>
bool CallIterableGetter(JSContext* aCx, U (T::*aMethod)(uint32_t), T* aInst,
uint32_t aIndex, JS::MutableHandle<JS::Value> aResult) {
return ToJSValue(aCx, (aInst->*aMethod)(aIndex), aResult);
}
template <typename T, typename U>
bool CallIterableGetter(JSContext* aCx, U (T::*aMethod)(uint32_t) const,
const T* aInst, uint32_t aIndex,
JS::MutableHandle<JS::Value> aResult) {
return ToJSValue(aCx, (aInst->*aMethod)(aIndex), aResult);
}
// Helper for Get[Key,Value]AtIndex(JSContext*, uint32_t, MutableHandleValue)
// methods, which accept a JS context, index, and mutable result value handle,
// and return true on success or false on failure.
template <typename T>
bool CallIterableGetter(JSContext* aCx,
bool (T::*aMethod)(JSContext*, uint32_t,
JS::MutableHandle<JS::Value>),
T* aInst, uint32_t aIndex,
JS::MutableHandle<JS::Value> aResult) {
return (aInst->*aMethod)(aCx, aIndex, aResult);
}
template <typename T>
bool CallIterableGetter(JSContext* aCx,
bool (T::*aMethod)(JSContext*, uint32_t,
JS::MutableHandle<JS::Value>) const,
const T* aInst, uint32_t aIndex,
JS::MutableHandle<JS::Value> aResult) {
return (aInst->*aMethod)(aCx, aIndex, aResult);
}
template <typename T>
class IterableIterator final : public IterableIteratorBase {
public:
typedef bool (*WrapFunc)(JSContext* aCx, IterableIterator<T>* aObject,
JS::Handle<JSObject*> aGivenProto,
JS::MutableHandle<JSObject*> aReflector);
explicit IterableIterator(T* aIterableObj, IterableIteratorType aIteratorType,
WrapFunc aWrapFunc)
: mIterableObj(aIterableObj),
mIteratorType(aIteratorType),
mWrapFunc(aWrapFunc),
mIndex(0) {
MOZ_ASSERT(mIterableObj);
MOZ_ASSERT(mWrapFunc);
}
bool GetKeyAtIndex(JSContext* aCx, uint32_t aIndex,
JS::MutableHandle<JS::Value> aResult) {
return CallIterableGetter(aCx, &T::GetKeyAtIndex, mIterableObj.get(),
aIndex, aResult);
}
bool GetValueAtIndex(JSContext* aCx, uint32_t aIndex,
JS::MutableHandle<JS::Value> aResult) {
return CallIterableGetter(aCx, &T::GetValueAtIndex, mIterableObj.get(),
aIndex, aResult);
}
void Next(JSContext* aCx, JS::MutableHandle<JSObject*> aResult,
ErrorResult& aRv) {
JS::Rooted<JS::Value> value(aCx, JS::UndefinedValue());
if (mIndex >= this->mIterableObj->GetIterableLength()) {
DictReturn(aCx, aResult, true, value, aRv);
return;
}
switch (mIteratorType) {
case IterableIteratorType::Keys: {
if (!GetKeyAtIndex(aCx, mIndex, &value)) {
aRv.Throw(NS_ERROR_FAILURE);
return;
}
DictReturn(aCx, aResult, false, value, aRv);
break;
}
case IterableIteratorType::Values: {
if (!GetValueAtIndex(aCx, mIndex, &value)) {
aRv.Throw(NS_ERROR_FAILURE);
return;
}
DictReturn(aCx, aResult, false, value, aRv);
break;
}
case IterableIteratorType::Entries: {
JS::Rooted<JS::Value> key(aCx);
if (!GetKeyAtIndex(aCx, mIndex, &key)) {
aRv.Throw(NS_ERROR_FAILURE);
return;
}
if (!GetValueAtIndex(aCx, mIndex, &value)) {
aRv.Throw(NS_ERROR_FAILURE);
return;
}
KeyAndValueReturn(aCx, key, value, aResult, aRv);
break;
}
default:
MOZ_CRASH("Invalid iterator type!");
}
++mIndex;
}
bool WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto,
JS::MutableHandle<JSObject*> aObj) {
return (*mWrapFunc)(aCx, this, aGivenProto, aObj);
}
protected:
static void DictReturn(JSContext* aCx, JS::MutableHandle<JSObject*> aResult,
bool aDone, JS::Handle<JS::Value> aValue,
ErrorResult& aRv) {
RootedDictionary<IterableKeyOrValueResult> dict(aCx);
dict.mDone = aDone;
dict.mValue = aValue;
JS::Rooted<JS::Value> dictValue(aCx);
if (!ToJSValue(aCx, dict, &dictValue)) {
aRv.Throw(NS_ERROR_FAILURE);
return;
}
aResult.set(&dictValue.toObject());
}
static void KeyAndValueReturn(JSContext* aCx, JS::Handle<JS::Value> aKey,
JS::Handle<JS::Value> aValue,
JS::MutableHandle<JSObject*> aResult,
ErrorResult& aRv) {
RootedDictionary<IterableKeyAndValueResult> dict(aCx);
dict.mDone = false;
// Dictionary values are a Sequence, which is a FallibleTArray, so we need
// to check returns when appending.
if (!dict.mValue.AppendElement(aKey, mozilla::fallible)) {
aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
return;
}
if (!dict.mValue.AppendElement(aValue, mozilla::fallible)) {
aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
return;
}
JS::Rooted<JS::Value> dictValue(aCx);
if (!ToJSValue(aCx, dict, &dictValue)) {
aRv.Throw(NS_ERROR_FAILURE);
return;
}
aResult.set(&dictValue.toObject());
}
protected:
virtual ~IterableIterator() = default;
// Since we're templated on a binding, we need to possibly CC it, but can't do
// that through macros. So it happens here.
void UnlinkHelper() final { mIterableObj = nullptr; }
virtual void TraverseHelper(nsCycleCollectionTraversalCallback& cb) override {
IterableIterator<T>* tmp = this;
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mIterableObj);
}
// Binding Implementation object that we're iterating over.
RefPtr<T> mIterableObj;
// Tells whether this is a key, value, or entries iterator.
IterableIteratorType mIteratorType;
// Function pointer to binding-type-specific Wrap() call for this iterator.
WrapFunc mWrapFunc;
// Current index of iteration.
uint32_t mIndex;
};
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_IterableIterator_h
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