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3cf50539ec
The special empty value (that we use for array holes, Optional<Value> when empty and a few other other placeholder/sentinel tasks) still exists, but you now create one via JS::js_special_empty_value() and check for it with Value::is_special_empty_value(). The main idea here is to make it very unlikely to accidentally create an unexpected special empty value.
101 lines
3.2 KiB
C++
101 lines
3.2 KiB
C++
/*
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* Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibJS/Runtime/Completion.h>
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#include <LibJS/Runtime/ECMAScriptFunctionObject.h>
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#include <LibJS/Runtime/FunctionEnvironment.h>
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#include <LibJS/Runtime/GlobalObject.h>
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namespace JS {
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GC_DEFINE_ALLOCATOR(FunctionEnvironment);
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FunctionEnvironment::FunctionEnvironment(Environment* parent_environment)
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: DeclarativeEnvironment(parent_environment)
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{
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}
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void FunctionEnvironment::visit_edges(Visitor& visitor)
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{
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Base::visit_edges(visitor);
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visitor.visit(m_this_value);
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visitor.visit(m_new_target);
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visitor.visit(m_function_object);
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}
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// 9.1.1.3.5 GetSuperBase ( ), https://tc39.es/ecma262/#sec-getsuperbase
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ThrowCompletionOr<Value> FunctionEnvironment::get_super_base() const
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{
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VERIFY(m_function_object);
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// 1. Let home be envRec.[[FunctionObject]].[[HomeObject]].
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auto home_object = m_function_object->home_object();
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// 2. If home is undefined, return undefined.
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if (!home_object)
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return js_undefined();
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// 3. Assert: Type(home) is Object.
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// 4. Return ? home.[[GetPrototypeOf]]().
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return TRY(home_object->internal_get_prototype_of());
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}
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// 9.1.1.3.2 HasThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hasthisbinding
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bool FunctionEnvironment::has_this_binding() const
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{
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if (this_binding_status() == ThisBindingStatus::Lexical)
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return false;
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return true;
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}
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// 9.1.1.3.3 HasSuperBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hassuperbinding
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bool FunctionEnvironment::has_super_binding() const
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{
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if (this_binding_status() == ThisBindingStatus::Lexical)
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return false;
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if (!function_object().home_object())
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return false;
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return true;
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}
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// 9.1.1.3.4 GetThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-getthisbinding
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ThrowCompletionOr<Value> FunctionEnvironment::get_this_binding(VM& vm) const
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{
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// 1. Assert: envRec.[[ThisBindingStatus]] is not lexical.
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VERIFY(m_this_binding_status != ThisBindingStatus::Lexical);
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// 2. If envRec.[[ThisBindingStatus]] is uninitialized, throw a ReferenceError exception.
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if (m_this_binding_status == ThisBindingStatus::Uninitialized)
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return vm.throw_completion<ReferenceError>(ErrorType::ThisHasNotBeenInitialized);
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// 3. Return envRec.[[ThisValue]].
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return m_this_value;
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}
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// 9.1.1.3.1 BindThisValue ( V ), https://tc39.es/ecma262/#sec-bindthisvalue
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ThrowCompletionOr<Value> FunctionEnvironment::bind_this_value(VM& vm, Value this_value)
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{
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VERIFY(!this_value.is_special_empty_value());
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// 1. Assert: envRec.[[ThisBindingStatus]] is not lexical.
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VERIFY(m_this_binding_status != ThisBindingStatus::Lexical);
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// 2. If envRec.[[ThisBindingStatus]] is initialized, throw a ReferenceError exception.
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if (m_this_binding_status == ThisBindingStatus::Initialized)
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return vm.throw_completion<ReferenceError>(ErrorType::ThisIsAlreadyInitialized);
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// 3. Set envRec.[[ThisValue]] to V.
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m_this_value = this_value;
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// 4. Set envRec.[[ThisBindingStatus]] to initialized.
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m_this_binding_status = ThisBindingStatus::Initialized;
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// 5. Return V.
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return this_value;
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}
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}
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