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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 */
/* JavaScript API. */
#ifndef js_Context_h
#define js_Context_h
#include "jspubtd.h"
// [SMDOC] Nested Thread Data Structures (JSContext, JSRuntime)
// Spidermonkey has two nested data structures for representing threads,
// JSContext and JSRuntime. All JS threads are represented by a context.
// Contexts can contain runtimes. A runtime however is not present for
// all threads. Threads also interact with the GC. See "Nested GC
// DataStructures" for more info.
// Context
// -------
// JSContext represents a thread: there must be exactly one JSContext for each
// thread running JS/Wasm.
// Runtime
// -------
// JSRuntime is very similar to JSContext: each runtime belongs to one context
// (thread), but helper threads don't have their own runtimes (they're shared by
// all runtimes in the process and use the runtime of the task they're
// executing).
// Note:
// Locking, contexts, and memory allocation.
// It is important that SpiderMonkey be initialized, and the first context
// be created, in a single-threaded fashion. Otherwise the behavior of the
// library is undefined.
// See:
// Create a new context (and runtime) for this thread.
extern JS_PUBLIC_API JSContext* JS_NewContext(
uint32_t maxbytes, JSRuntime* parentRuntime = nullptr);
// Destroy a context allocated with JS_NewContext. Must be called on the thread
// that called JS_NewContext.
extern JS_PUBLIC_API void JS_DestroyContext(JSContext* cx);
JS_PUBLIC_API void* JS_GetContextPrivate(JSContext* cx);
JS_PUBLIC_API void JS_SetContextPrivate(JSContext* cx, void* data);
extern JS_PUBLIC_API JSRuntime* JS_GetParentRuntime(JSContext* cx);
extern JS_PUBLIC_API JSRuntime* JS_GetRuntime(JSContext* cx);
extern JS_PUBLIC_API void JS_SetFutexCanWait(JSContext* cx);
namespace js {
void AssertHeapIsIdle();
} /* namespace js */
namespace JS {
* Asserts (in debug and release builds) that `obj` belongs to the current
* thread's context.
JS_PUBLIC_API void AssertObjectBelongsToCurrentThread(JSObject* obj);
* Install a process-wide callback to validate script filenames. The JS engine
* will invoke this callback for each JS script it parses or XDR decodes.
* If the callback returns |false|, an exception is thrown and parsing/decoding
* will be aborted.
* See also CompileOptions::setSkipFilenameValidation to opt-out of the callback
* for specific parse jobs.
using FilenameValidationCallback = bool (*)(JSContext* cx,
const char* filename);
JS_PUBLIC_API void SetFilenameValidationCallback(FilenameValidationCallback cb);
* Install an context wide callback that implements the ECMA262 specification
* host hook `HostEnsureCanAddPrivateElement`.
* This hook, which should only be overriden for Web Browsers, examines the
* provided object to determine if the addition of a private field is allowed,
* throwing an exception and returning false if not.
* The default implementation of this hook, which will be used unless overriden,
* examines only proxy objects, and throws if the proxy handler returns true
* from the handler method `throwOnPrivateField()`.
using EnsureCanAddPrivateElementOp = bool (*)(JSContext* cx, HandleValue val);
JS_PUBLIC_API void SetHostEnsureCanAddPrivateElementHook(
JSContext* cx, EnsureCanAddPrivateElementOp op);
* Transition the cx to a mode where failures that would normally cause a false
* return value will instead crash with a diagnostic assertion.
* Return value: the former brittle mode setting.
JS_PUBLIC_API bool SetBrittleMode(JSContext* cx, bool setting);
class AutoBrittleMode {
bool wasBrittle;
JSContext* cx;
explicit AutoBrittleMode(JSContext* cx) : cx(cx) {
wasBrittle = SetBrittleMode(cx, true);
~AutoBrittleMode() { MOZ_ALWAYS_TRUE(SetBrittleMode(cx, wasBrittle)); }
} /* namespace JS */
#endif // js_Context_h