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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/. */
/**
* A header for declaring various things that binding implementation headers
* might need. The idea is to make binding implementation headers safe to
* include anywhere without running into include hell like we do with
* BindingUtils.h
*/
#ifndef mozilla_dom_BindingDeclarations_h__
#define mozilla_dom_BindingDeclarations_h__
#include "js/RootingAPI.h"
#include "js/TypeDecls.h"
#include "mozilla/Maybe.h"
#include "mozilla/dom/DOMString.h"
#include "nsCOMPtr.h"
#include "nsString.h"
#include "nsTArray.h"
#include <type_traits>
#include "js/Value.h"
#include "mozilla/RootedOwningNonNull.h"
#include "mozilla/RootedRefPtr.h"
class nsIPrincipal;
class nsWrapperCache;
namespace mozilla {
class ErrorResult;
class OOMReporter;
class CopyableErrorResult;
namespace dom {
class BindingCallContext;
// Struct that serves as a base class for all dictionaries. Particularly useful
// so we can use std::is_base_of to detect dictionary template arguments.
struct DictionaryBase {
protected:
bool ParseJSON(JSContext* aCx, const nsAString& aJSON,
JS::MutableHandle<JS::Value> aVal);
bool StringifyToJSON(JSContext* aCx, JS::Handle<JSObject*> aObj,
nsAString& aJSON) const;
// Struct used as a way to force a dictionary constructor to not init the
// dictionary (via constructing from a pointer to this class). We're putting
// it here so that all the dictionaries will have access to it, but outside
// code will not.
struct FastDictionaryInitializer {};
bool mIsAnyMemberPresent = false;
private:
// aString is expected to actually be an nsAString*. Should only be
// called from StringifyToJSON.
static bool AppendJSONToString(const char16_t* aJSONData,
uint32_t aDataLength, void* aString);
public:
bool IsAnyMemberPresent() const { return mIsAnyMemberPresent; }
};
template <typename T>
inline std::enable_if_t<std::is_base_of<DictionaryBase, T>::value, void>
ImplCycleCollectionUnlink(T& aDictionary) {
aDictionary.UnlinkForCC();
}
template <typename T>
inline std::enable_if_t<std::is_base_of<DictionaryBase, T>::value, void>
ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
T& aDictionary, const char* aName,
uint32_t aFlags = 0) {
aDictionary.TraverseForCC(aCallback, aFlags);
}
// Struct that serves as a base class for all typed arrays and array buffers and
// array buffer views. Particularly useful so we can use std::is_base_of to
// detect typed array/buffer/view template arguments.
struct AllTypedArraysBase {};
// Struct that serves as a base class for all owning unions.
// Particularly useful so we can use std::is_base_of to detect owning union
// template arguments.
struct AllOwningUnionBase {};
struct EnumEntry {
const char* value;
size_t length;
};
enum class CallerType : uint32_t;
class MOZ_STACK_CLASS GlobalObject {
public:
GlobalObject(JSContext* aCx, JSObject* aObject);
JSObject* Get() const { return mGlobalJSObject; }
nsISupports* GetAsSupports() const;
// The context that this returns is not guaranteed to be in the compartment of
// the object returned from Get(), in fact it's generally in the caller's
// compartment.
JSContext* Context() const { return mCx; }
bool Failed() const { return !Get(); }
// It returns the subjectPrincipal if called on the main-thread, otherwise
// a nullptr is returned.
nsIPrincipal* GetSubjectPrincipal() const;
// Get the caller type. Note that this needs to be called before anyone has
// had a chance to mess with the JSContext.
dom::CallerType CallerType() const;
protected:
JS::Rooted<JSObject*> mGlobalJSObject;
JSContext* mCx;
mutable nsISupports* MOZ_UNSAFE_REF(
"Valid because GlobalObject is a stack "
"class, and mGlobalObject points to the "
"global, so it won't be destroyed as long "
"as GlobalObject lives on the stack") mGlobalObject;
};
// Class for representing optional arguments.
template <typename T, typename InternalType>
class Optional_base {
public:
Optional_base() = default;
explicit Optional_base(const T& aValue) { mImpl.emplace(aValue); }
bool operator==(const Optional_base<T, InternalType>& aOther) const {
return mImpl == aOther.mImpl;
}
bool operator!=(const Optional_base<T, InternalType>& aOther) const {
return mImpl != aOther.mImpl;
}
template <typename T1, typename T2>
explicit Optional_base(const T1& aValue1, const T2& aValue2) {
mImpl.emplace(aValue1, aValue2);
}
bool WasPassed() const { return mImpl.isSome(); }
// Return InternalType here so we can work with it usefully.
template <typename... Args>
InternalType& Construct(Args&&... aArgs) {
mImpl.emplace(std::forward<Args>(aArgs)...);
return *mImpl;
}
void Reset() { mImpl.reset(); }
const T& Value() const { return *mImpl; }
// Return InternalType here so we can work with it usefully.
InternalType& Value() { return *mImpl; }
// And an explicit way to get the InternalType even if we're const.
const InternalType& InternalValue() const { return *mImpl; }
// If we ever decide to add conversion operators for optional arrays
// like the ones Nullable has, we'll need to ensure that Maybe<> has
// the boolean before the actual data.
private:
// Forbid copy-construction and assignment
Optional_base(const Optional_base& other) = delete;
const Optional_base& operator=(const Optional_base& other) = delete;
protected:
Maybe<InternalType> mImpl;
};
template <typename T>
class Optional : public Optional_base<T, T> {
public:
MOZ_ALLOW_TEMPORARY Optional() : Optional_base<T, T>() {}
explicit Optional(const T& aValue) : Optional_base<T, T>(aValue) {}
};
template <typename T>
class Optional<JS::Handle<T>>
: public Optional_base<JS::Handle<T>, JS::Rooted<T>> {
public:
MOZ_ALLOW_TEMPORARY Optional()
: Optional_base<JS::Handle<T>, JS::Rooted<T>>() {}
explicit Optional(JSContext* cx)
: Optional_base<JS::Handle<T>, JS::Rooted<T>>() {
this->Construct(cx);
}
Optional(JSContext* cx, const T& aValue)
: Optional_base<JS::Handle<T>, JS::Rooted<T>>(cx, aValue) {}
// Override the const Value() to return the right thing so we're not
// returning references to temporaries.
JS::Handle<T> Value() const { return *this->mImpl; }
// And we have to override the non-const one too, since we're
// shadowing the one on the superclass.
JS::Rooted<T>& Value() { return *this->mImpl; }
};
// A specialization of Optional for JSObject* to make sure that when someone
// calls Construct() on it we will pre-initialized the JSObject* to nullptr so
// it can be traced safely.
template <>
class Optional<JSObject*> : public Optional_base<JSObject*, JSObject*> {
public:
Optional() = default;
explicit Optional(JSObject* aValue)
: Optional_base<JSObject*, JSObject*>(aValue) {}
// Don't allow us to have an uninitialized JSObject*
JSObject*& Construct() {
// The Android compiler sucks and thinks we're trying to construct
// a JSObject* from an int if we don't cast here. :(
return Optional_base<JSObject*, JSObject*>::Construct(
static_cast<JSObject*>(nullptr));
}
template <class T1>
JSObject*& Construct(const T1& t1) {
return Optional_base<JSObject*, JSObject*>::Construct(t1);
}
};
// A specialization of Optional for JS::Value to make sure no one ever uses it.
template <>
class Optional<JS::Value> {
private:
Optional() = delete;
explicit Optional(const JS::Value& aValue) = delete;
};
// A specialization of Optional for NonNull that lets us get a T& from Value()
template <typename U>
class NonNull;
template <typename T>
class Optional<NonNull<T>> : public Optional_base<T, NonNull<T>> {
public:
// We want our Value to actually return a non-const reference, even
// if we're const. At least for things that are normally pointer
// types...
T& Value() const { return *this->mImpl->get(); }
// And we have to override the non-const one too, since we're
// shadowing the one on the superclass.
NonNull<T>& Value() { return *this->mImpl; }
};
// A specialization of Optional for OwningNonNull that lets us get a
// T& from Value()
template <typename T>
class Optional<OwningNonNull<T>> : public Optional_base<T, OwningNonNull<T>> {
public:
// We want our Value to actually return a non-const reference, even
// if we're const. At least for things that are normally pointer
// types...
T& Value() const { return *this->mImpl->get(); }
// And we have to override the non-const one too, since we're
// shadowing the one on the superclass.
OwningNonNull<T>& Value() { return *this->mImpl; }
};
// Specialization for strings.
// XXXbz we can't pull in FakeString here, because it depends on internal
// strings. So we just have to forward-declare it and reimplement its
// ToAStringPtr.
namespace binding_detail {
template <typename CharT>
struct FakeString;
} // namespace binding_detail
template <typename CharT>
class Optional<nsTSubstring<CharT>> {
using AString = nsTSubstring<CharT>;
public:
Optional() : mStr(nullptr) {}
bool WasPassed() const { return !!mStr; }
void operator=(const AString* str) {
MOZ_ASSERT(str);
mStr = str;
}
// If this code ever goes away, remove the comment pointing to it in the
// FakeString class in BindingUtils.h.
void operator=(const binding_detail::FakeString<CharT>* str) {
MOZ_ASSERT(str);
mStr = reinterpret_cast<const nsTString<CharT>*>(str);
}
const AString& Value() const {
MOZ_ASSERT(WasPassed());
return *mStr;
}
private:
// Forbid copy-construction and assignment
Optional(const Optional& other) = delete;
const Optional& operator=(const Optional& other) = delete;
const AString* mStr;
};
template <typename T>
inline void ImplCycleCollectionUnlink(Optional<T>& aField) {
if (aField.WasPassed()) {
ImplCycleCollectionUnlink(aField.Value());
}
}
template <typename T>
inline void ImplCycleCollectionTraverse(
nsCycleCollectionTraversalCallback& aCallback, Optional<T>& aField,
const char* aName, uint32_t aFlags = 0) {
if (aField.WasPassed()) {
ImplCycleCollectionTraverse(aCallback, aField.Value(), aName, aFlags);
}
}
template <class T>
class NonNull {
public:
NonNull()
#ifdef DEBUG
: inited(false)
#endif
{
}
// This is no worse than get() in terms of const handling.
operator T&() const {
MOZ_ASSERT(inited);
MOZ_ASSERT(ptr, "NonNull<T> was set to null");
return *ptr;
}
operator T*() const {
MOZ_ASSERT(inited);
MOZ_ASSERT(ptr, "NonNull<T> was set to null");
return ptr;
}
void operator=(T* t) {
ptr = t;
MOZ_ASSERT(ptr);
#ifdef DEBUG
inited = true;
#endif
}
template <typename U>
void operator=(U* t) {
ptr = t->ToAStringPtr();
MOZ_ASSERT(ptr);
#ifdef DEBUG
inited = true;
#endif
}
T** Slot() {
#ifdef DEBUG
inited = true;
#endif
return &ptr;
}
T* Ptr() {
MOZ_ASSERT(inited);
MOZ_ASSERT(ptr, "NonNull<T> was set to null");
return ptr;
}
// Make us work with smart-ptr helpers that expect a get()
T* get() const {
MOZ_ASSERT(inited);
MOZ_ASSERT(ptr);
return ptr;
}
protected:
// ptr is left uninitialized for optimization purposes.
MOZ_INIT_OUTSIDE_CTOR T* ptr;
#ifdef DEBUG
bool inited;
#endif
};
// Class for representing sequences in arguments. We use a non-auto array
// because that allows us to use sequences of sequences and the like. This
// needs to be fallible because web content controls the length of the array,
// and can easily try to create very large lengths.
template <typename T>
class Sequence : public FallibleTArray<T> {
public:
Sequence() : FallibleTArray<T>() {}
MOZ_IMPLICIT Sequence(FallibleTArray<T>&& aArray)
: FallibleTArray<T>(std::move(aArray)) {}
MOZ_IMPLICIT Sequence(nsTArray<T>&& aArray)
: FallibleTArray<T>(std::move(aArray)) {}
Sequence(Sequence&&) = default;
Sequence& operator=(Sequence&&) = default;
// XXX(Bug 1631461) Codegen.py must be adapted to allow making Sequence
// uncopyable.
Sequence(const Sequence& aOther) {
if (!this->AppendElements(aOther, fallible)) {
MOZ_CRASH("Out of memory");
}
}
Sequence& operator=(const Sequence& aOther) {
if (this != &aOther) {
this->Clear();
if (!this->AppendElements(aOther, fallible)) {
MOZ_CRASH("Out of memory");
}
}
return *this;
}
};
inline nsWrapperCache* GetWrapperCache(nsWrapperCache* cache) { return cache; }
inline nsWrapperCache* GetWrapperCache(void* p) { return nullptr; }
// Helper template for smart pointers to resolve ambiguity between
// GetWrappeCache(void*) and GetWrapperCache(const ParentObject&).
template <template <typename> class SmartPtr, typename T>
inline nsWrapperCache* GetWrapperCache(const SmartPtr<T>& aObject) {
return GetWrapperCache(aObject.get());
}
enum class ReflectionScope { Content, NAC, UAWidget };
struct MOZ_STACK_CLASS ParentObject {
template <class T>
MOZ_IMPLICIT ParentObject(T* aObject)
: mObject(ToSupports(aObject)),
mWrapperCache(GetWrapperCache(aObject)),
mReflectionScope(ReflectionScope::Content) {}
template <class T, template <typename> class SmartPtr>
MOZ_IMPLICIT ParentObject(const SmartPtr<T>& aObject)
: mObject(aObject.get()),
mWrapperCache(GetWrapperCache(aObject.get())),
mReflectionScope(ReflectionScope::Content) {}
ParentObject(nsISupports* aObject, nsWrapperCache* aCache)
: mObject(aObject),
mWrapperCache(aCache),
mReflectionScope(ReflectionScope::Content) {}
// We don't want to make this an nsCOMPtr because of performance reasons, but
// it's safe because ParentObject is a stack class.
nsISupports* const MOZ_NON_OWNING_REF mObject;
nsWrapperCache* const mWrapperCache;
ReflectionScope mReflectionScope;
};
namespace binding_detail {
// Class for simple sequence arguments, only used internally by codegen.
template <typename T>
class AutoSequence : public AutoTArray<T, 16> {
public:
AutoSequence() : AutoTArray<T, 16>() {}
// Allow converting to const sequences as needed
operator const Sequence<T>&() const {
return *reinterpret_cast<const Sequence<T>*>(this);
}
};
} // namespace binding_detail
// Enum to represent a system or non-system caller type.
enum class CallerType : uint32_t { System, NonSystem };
// A class that can be passed (by value or const reference) to indicate that the
// caller is always a system caller. This can be used as the type of an
// argument to force only system callers to call a function.
class SystemCallerGuarantee {
public:
operator CallerType() const { return CallerType::System; }
};
class ProtoAndIfaceCache;
typedef void (*CreateInterfaceObjectsMethod)(JSContext* aCx,
JS::Handle<JSObject*> aGlobal,
ProtoAndIfaceCache& aCache,
bool aDefineOnGlobal);
JS::Handle<JSObject*> GetPerInterfaceObjectHandle(
JSContext* aCx, size_t aSlotId, CreateInterfaceObjectsMethod aCreator,
bool aDefineOnGlobal);
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_BindingDeclarations_h__