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a63b0cfaba
This hosts the ability to compile and run JavaScript to implement native functions. This is particularly useful for any native function that is not a normal function, for example async functions such as Array.fromAsync, which require yielding. These functions are not allowed to observe anything from outside their environment. Any global identifiers will instead be assumed to be a reference to an abstract operation or a constant. The generator will inject the appropriate bytecode if the name of the global identifier matches a known name. Anything else will cause a code generation error.
108 lines
3.5 KiB
C++
108 lines
3.5 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* ecmascript_function_object = as_if<ECMAScriptFunctionObject>(*m_function_object);
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if (!ecmascript_function_object)
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return js_undefined();
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auto home_object = ecmascript_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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auto* ecmascript_function_object = as_if<ECMAScriptFunctionObject>(*m_function_object);
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if (!ecmascript_function_object)
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return false;
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if (!ecmascript_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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