C++ MutableHandle::isUndefined方法代码示例

bool
ChromeObjectWrapper::get(JSContext *cx, JS::Handle<JSObject*> wrapper,
                         JS::Handle<JSObject*> receiver, JS::Handle<jsid> id,
                         JS::MutableHandle<JS::Value> vp)
{
    assertEnteredPolicy(cx, wrapper, id);
    vp.setUndefined();
    JSPropertyDescriptor desc;
    // Only call through to the get trap on the underlying object if we're
    // allowed to see the property, and if what we'll find is not on a standard
    // prototype.
    if (AllowedByBase(cx, wrapper, id, js::Wrapper::GET) &&
        !PropIsFromStandardPrototype(cx, wrapper, id))
    {
        // Call the get trap.
        if (!ChromeObjectWrapperBase::get(cx, wrapper, receiver, id, vp))
            return false;
        // If we found something, we're done.
        if (!vp.isUndefined())
            return true;
    }

    // If we have no proto, we're done.
    JSObject *wrapperProto;
    if (!JS_GetPrototype(cx, wrapper, &wrapperProto))
        return false;
    if (!wrapperProto)
        return true;

    // Try the prototype.
    MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx));
    return js::GetGeneric(cx, wrapperProto, receiver, id, vp.address());
}

nsresult
nsJSUtils::EvaluateString(JSContext* aCx,
                          JS::SourceBufferHolder& aSrcBuf,
                          JS::Handle<JSObject*> aScopeObject,
                          JS::CompileOptions& aCompileOptions,
                          const EvaluateOptions& aEvaluateOptions,
                          JS::MutableHandle<JS::Value> aRetValue,
                          void **aOffThreadToken)
{
  PROFILER_LABEL("nsJSUtils", "EvaluateString",
    js::ProfileEntry::Category::JS);

  MOZ_ASSERT_IF(aCompileOptions.versionSet,
                aCompileOptions.version != JSVERSION_UNKNOWN);
  MOZ_ASSERT_IF(aEvaluateOptions.coerceToString, aEvaluateOptions.needResult);
  MOZ_ASSERT_IF(!aEvaluateOptions.reportUncaught, aEvaluateOptions.needResult);
  MOZ_ASSERT(aCx == nsContentUtils::GetCurrentJSContext());
  MOZ_ASSERT(aSrcBuf.get());

  // Unfortunately, the JS engine actually compiles scripts with a return value
  // in a different, less efficient way.  Furthermore, it can't JIT them in many
  // cases.  So we need to be explicitly told whether the caller cares about the
  // return value.  Callers can do this by calling the other overload of
  // EvaluateString() which calls this function with aEvaluateOptions.needResult
  // set to false.
  aRetValue.setUndefined();

  JS::ExposeObjectToActiveJS(aScopeObject);
  nsAutoMicroTask mt;
  nsresult rv = NS_OK;

  bool ok = false;
  nsIScriptSecurityManager* ssm = nsContentUtils::GetSecurityManager();
  NS_ENSURE_TRUE(ssm->ScriptAllowed(js::GetGlobalForObjectCrossCompartment(aScopeObject)), NS_OK);

  mozilla::Maybe<AutoDontReportUncaught> dontReport;
  if (!aEvaluateOptions.reportUncaught) {
    // We need to prevent AutoLastFrameCheck from reporting and clearing
    // any pending exceptions.
    dontReport.emplace(aCx);
  }

  // Scope the JSAutoCompartment so that we can later wrap the return value
  // into the caller's cx.
  {
    JSAutoCompartment ac(aCx, aScopeObject);

    JS::Rooted<JSObject*> rootedScope(aCx, aScopeObject);
    if (aOffThreadToken) {
      JS::Rooted<JSScript*>
        script(aCx, JS::FinishOffThreadScript(aCx, JS_GetRuntime(aCx), *aOffThreadToken));
      *aOffThreadToken = nullptr; // Mark the token as having been finished.
      if (script) {
        if (aEvaluateOptions.needResult) {
          ok = JS_ExecuteScript(aCx, rootedScope, script, aRetValue);
        } else {
          ok = JS_ExecuteScript(aCx, rootedScope, script);
        }
      } else {
        ok = false;
      }
    } else {
      if (aEvaluateOptions.needResult) {
        ok = JS::Evaluate(aCx, rootedScope, aCompileOptions,
                          aSrcBuf, aRetValue);
      } else {
        ok = JS::Evaluate(aCx, rootedScope, aCompileOptions,
                          aSrcBuf);
      }
    }

    if (ok && aEvaluateOptions.coerceToString && !aRetValue.isUndefined()) {
      JS::Rooted<JS::Value> value(aCx, aRetValue);
      JSString* str = JS::ToString(aCx, value);
      ok = !!str;
      aRetValue.set(ok ? JS::StringValue(str) : JS::UndefinedValue());
    }
  }

  if (!ok) {
    if (aEvaluateOptions.reportUncaught) {
      ReportPendingException(aCx);
      if (aEvaluateOptions.needResult) {
        aRetValue.setUndefined();
      }
    } else {
      rv = JS_IsExceptionPending(aCx) ? NS_ERROR_FAILURE
                                      : NS_ERROR_OUT_OF_MEMORY;
      JS::Rooted<JS::Value> exn(aCx);
      JS_GetPendingException(aCx, &exn);
      if (aEvaluateOptions.needResult) {
        aRetValue.set(exn);
      }
      JS_ClearPendingException(aCx);
    }
  }

  // Wrap the return value into whatever compartment aCx was in.
  if (aEvaluateOptions.needResult) {
    JS::Rooted<JS::Value> v(aCx, aRetValue);
//.........这里部分代码省略.........

nsresult
nsJSUtils::EvaluateString(JSContext* aCx,
                          JS::SourceBufferHolder& aSrcBuf,
                          JS::Handle<JSObject*> aEvaluationGlobal,
                          JS::CompileOptions& aCompileOptions,
                          const EvaluateOptions& aEvaluateOptions,
                          JS::MutableHandle<JS::Value> aRetValue,
                          void **aOffThreadToken)
{
  PROFILER_LABEL("nsJSUtils", "EvaluateString",
    js::ProfileEntry::Category::JS);

  MOZ_ASSERT(JS::ContextOptionsRef(aCx).autoJSAPIOwnsErrorReporting(),
             "Caller must own error reporting");
  MOZ_ASSERT_IF(aCompileOptions.versionSet,
                aCompileOptions.version != JSVERSION_UNKNOWN);
  MOZ_ASSERT_IF(aEvaluateOptions.coerceToString, !aCompileOptions.noScriptRval);
  MOZ_ASSERT(aCx == nsContentUtils::GetCurrentJSContext());
  MOZ_ASSERT(aSrcBuf.get());
  MOZ_ASSERT(js::GetGlobalForObjectCrossCompartment(aEvaluationGlobal) ==
             aEvaluationGlobal);
  MOZ_ASSERT_IF(aOffThreadToken, aCompileOptions.noScriptRval);
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(nsContentUtils::IsInMicroTask());

  // Unfortunately, the JS engine actually compiles scripts with a return value
  // in a different, less efficient way.  Furthermore, it can't JIT them in many
  // cases.  So we need to be explicitly told whether the caller cares about the
  // return value.  Callers can do this by calling the other overload of
  // EvaluateString() which calls this function with
  // aCompileOptions.noScriptRval set to true.
  aRetValue.setUndefined();

  nsresult rv = NS_OK;

  nsIScriptSecurityManager* ssm = nsContentUtils::GetSecurityManager();
  NS_ENSURE_TRUE(ssm->ScriptAllowed(aEvaluationGlobal), NS_OK);

  bool ok = true;
  // Scope the JSAutoCompartment so that we can later wrap the return value
  // into the caller's cx.
  {
    JSAutoCompartment ac(aCx, aEvaluationGlobal);

    // Now make sure to wrap the scope chain into the right compartment.
    JS::AutoObjectVector scopeChain(aCx);
    if (!scopeChain.reserve(aEvaluateOptions.scopeChain.length())) {
      return NS_ERROR_OUT_OF_MEMORY;
    }

    for (size_t i = 0; i < aEvaluateOptions.scopeChain.length(); ++i) {
      JS::ExposeObjectToActiveJS(aEvaluateOptions.scopeChain[i]);
      scopeChain.infallibleAppend(aEvaluateOptions.scopeChain[i]);
      if (!JS_WrapObject(aCx, scopeChain[i])) {
        ok = false;
        break;
      }
    }

    if (ok && aOffThreadToken) {
      JS::Rooted<JSScript*>
        script(aCx, JS::FinishOffThreadScript(aCx, JS_GetRuntime(aCx), *aOffThreadToken));
      *aOffThreadToken = nullptr; // Mark the token as having been finished.
      if (script) {
        ok = JS_ExecuteScript(aCx, scopeChain, script);
      } else {
        ok = false;
      }
    } else if (ok) {
      ok = JS::Evaluate(aCx, scopeChain, aCompileOptions, aSrcBuf, aRetValue);
    }

    if (ok && aEvaluateOptions.coerceToString && !aRetValue.isUndefined()) {
      JS::Rooted<JS::Value> value(aCx, aRetValue);
      JSString* str = JS::ToString(aCx, value);
      ok = !!str;
      aRetValue.set(ok ? JS::StringValue(str) : JS::UndefinedValue());
    }
  }

  if (!ok) {
    if (JS_IsExceptionPending(aCx)) {
      rv = NS_SUCCESS_DOM_SCRIPT_EVALUATION_THREW;
    } else {
      rv = NS_SUCCESS_DOM_SCRIPT_EVALUATION_THREW_UNCATCHABLE;
    }

    if (!aCompileOptions.noScriptRval) {
      aRetValue.setUndefined();
    }
  }

  // Wrap the return value into whatever compartment aCx was in.
  if (ok && !aCompileOptions.noScriptRval) {
    if (!JS_WrapValue(aCx, aRetValue)) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
  }
  return rv;
}