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ladybird/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.cpp

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LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
/*
LibJS: Rename Environment Records so they match the spec :^) This patch makes the following name changes: - ScopeObject => EnvironmentRecord - LexicalEnvironment => DeclarativeEnvironmentRecord - WithScope => ObjectEnvironmentRecord
2021-06-21 23:17:24 +02:00
* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
*
Everything: Move to SPDX license identifiers in all files. SPDX License Identifiers are a more compact / standardized way of representing file license information. See: https://spdx.dev/resources/use/#identifiers This was done with the `ambr` search and replace tool. ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
2021-04-22 01:24:48 -07:00
* SPDX-License-Identifier: BSD-2-Clause
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
*/
LibJS: Initial class implementation; allow super expressions in object literal methods; add EnvrionmentRecord fields and methods to LexicalEnvironment Adding EnvrionmentRecord's fields and methods lets us throw an exception when |this| is not initialized, which occurs when the super constructor in a derived class has not yet been called, or when |this| has already been initialized (the super constructor was already called).
2020-06-08 13:31:21 -05:00
#include <LibJS/Interpreter.h>
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
#include <LibJS/Runtime/DeclarativeEnvironment.h>
LibJS: Initial class implementation; allow super expressions in object literal methods; add EnvrionmentRecord fields and methods to LexicalEnvironment Adding EnvrionmentRecord's fields and methods lets us throw an exception when |this| is not initialized, which occurs when the super constructor in a derived class has not yet been called, or when |this| has already been initialized (the super constructor was already called).
2020-06-08 13:31:21 -05:00
#include <LibJS/Runtime/Error.h>
LibJS: Rename Function => FunctionObject
2021-06-27 21:48:34 +02:00
#include <LibJS/Runtime/FunctionObject.h>
LibJS: Move most of Interpreter into VM This patch moves the exception state, call stack and scope stack from Interpreter to VM. I'm doing this to help myself discover what the split between Interpreter and VM should be, by shuffling things around and seeing what falls where. With these changes, we no longer have a persistent lexical environment for the current global object on the Interpreter's call stack. Instead, we push/pop that environment on Interpreter::run() enter/exit. Since it should only be used to find the global "this", and not for variable storage (that goes directly into the global object instead!), I had to insert some short-circuiting when walking the environment parent chain during variable lookup. Note that this is a "stepping stone" commit, not a final design.
2020-09-27 15:18:55 +02:00
#include <LibJS/Runtime/GlobalObject.h>
LibJS: Initial class implementation; allow super expressions in object literal methods; add EnvrionmentRecord fields and methods to LexicalEnvironment Adding EnvrionmentRecord's fields and methods lets us throw an exception when |this| is not initialized, which occurs when the super constructor in a derived class has not yet been called, or when |this| has already been initialized (the super constructor was already called).
2020-06-08 13:31:21 -05:00
#include <LibJS/Runtime/Value.h>
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
namespace JS {
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
DeclarativeEnvironment::DeclarativeEnvironment()
: Environment(nullptr)
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
{
}
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
DeclarativeEnvironment::DeclarativeEnvironment(Environment* parent_scope)
: Environment(parent_scope)
LibJS: Implement the NewDeclarativeEnvironment() abstract operation
2021-06-22 00:56:14 +02:00
{
}
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
DeclarativeEnvironment::DeclarativeEnvironment(HashMap<FlyString, Variable> variables, Environment* parent_scope)
: Environment(parent_scope)
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
, m_variables(move(variables))
{
}
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
DeclarativeEnvironment::~DeclarativeEnvironment()
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
{
}
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
void DeclarativeEnvironment::visit_edges(Visitor& visitor)
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
{
LibJS: Call the correct base class in LexicalEnvironment::visit_edges() We were calling directly up to Cell, skipping over ScopeObject. This made us not mark the scope chain parent for lexical environments, sometimes causing them to get GC'd and use-after-free'd. Found by Fuzzilli. Fixes #5140.
2021-01-28 10:13:47 +01:00
Base::visit_edges(visitor);
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
for (auto& it : m_variables)
visitor.visit(it.value.value);
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
for (auto& it : m_bindings)
visitor.visit(it.value.value);
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
}
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
Optional<Variable> DeclarativeEnvironment::get_from_environment(FlyString const& name) const
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
{
return m_variables.get(name);
}
LibJS: Make Environment::put_into_environment() return a success bool This code is non-conforming and will eventually get cleaned out once we implement proper variable bindings. However, this will aid us in improving other parts of the code right now.
2021-07-02 00:14:38 +02:00
bool DeclarativeEnvironment::put_into_environment(FlyString const& name, Variable variable)
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
{
LibJS: Add a scope object abstraction Both GlobalObject and LexicalEnvironment now inherit from ScopeObject, and the VM's call frames point to a ScopeObject chain rather than just a LexicalEnvironment chain. This gives us much more flexibility to implement things like "with", and also unifies some of the code paths that previously required special handling of the global object. There's a bunch of more cleanup that can be done in the wake of this change, and there might be some oversights in the handling of the "super" keyword, but this generally seems like a good architectural improvement. :^)
2020-11-28 16:02:27 +01:00
m_variables.set(name, variable);
LibJS: Make Environment::put_into_environment() return a success bool This code is non-conforming and will eventually get cleaned out once we implement proper variable bindings. However, this will aid us in improving other parts of the code right now.
2021-07-02 00:14:38 +02:00
return true;
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
}
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
bool DeclarativeEnvironment::delete_from_environment(FlyString const& name)
LibJS: Support deleting local variables with operator delete To make this cleaner i also moved the logic into Reference::delete_.
2021-06-08 04:00:53 +03:00
{
return m_variables.remove(name);
}
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
// 9.1.1.1.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-declarative-environment-records-hasbinding-n
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
bool DeclarativeEnvironment::has_binding(FlyString const& name) const
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
{
return m_bindings.contains(name);
}
LibJS: Add spec links to a bunch of the environment record methods
2021-06-23 13:25:57 +02:00
// 9.1.1.1.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-declarative-environment-records-createmutablebinding-n-d
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
void DeclarativeEnvironment::create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted)
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
{
auto result = m_bindings.set(name,
Binding {
.value = {},
.strict = false,
.mutable_ = true,
.can_be_deleted = can_be_deleted,
.initialized = false,
});
VERIFY(result == AK::HashSetResult::InsertedNewEntry);
}
LibJS: Add spec links to a bunch of the environment record methods
2021-06-23 13:25:57 +02:00
// 9.1.1.1.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-createimmutablebinding-n-s
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
void DeclarativeEnvironment::create_immutable_binding(GlobalObject&, FlyString const& name, bool strict)
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
{
auto result = m_bindings.set(name,
Binding {
.value = {},
.strict = strict,
.mutable_ = false,
.can_be_deleted = false,
.initialized = false,
});
VERIFY(result == AK::HashSetResult::InsertedNewEntry);
}
LibJS: Add spec links to a bunch of the environment record methods
2021-06-23 13:25:57 +02:00
// 9.1.1.1.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-declarative-environment-records-initializebinding-n-v
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
void DeclarativeEnvironment::initialize_binding(GlobalObject&, FlyString const& name, Value value)
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
{
auto it = m_bindings.find(name);
VERIFY(it != m_bindings.end());
VERIFY(it->value.initialized == false);
it->value.value = value;
it->value.initialized = true;
}
LibJS: Add spec links to a bunch of the environment record methods
2021-06-23 13:25:57 +02:00
// 9.1.1.1.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-setmutablebinding-n-v-s
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
void DeclarativeEnvironment::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
{
auto it = m_bindings.find(name);
if (it == m_bindings.end()) {
if (strict) {
global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
return;
}
create_mutable_binding(global_object, name, true);
initialize_binding(global_object, name, value);
return;
}
if (it->value.strict)
strict = true;
if (!it->value.initialized) {
global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::BindingNotInitialized, name);
return;
}
if (it->value.mutable_) {
it->value.value = value;
} else {
if (strict) {
global_object.vm().throw_exception<TypeError>(global_object, ErrorType::InvalidAssignToConst);
}
}
}
LibJS: Add spec links to a bunch of the environment record methods
2021-06-23 13:25:57 +02:00
// 9.1.1.1.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-getbindingvalue-n-s
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
Value DeclarativeEnvironment::get_binding_value(GlobalObject& global_object, FlyString const& name, bool)
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
{
auto it = m_bindings.find(name);
VERIFY(it != m_bindings.end());
if (!it->value.initialized) {
global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::BindingNotInitialized, name);
return {};
}
return it->value.value;
}
LibJS: Add spec links to a bunch of the environment record methods
2021-06-23 13:25:57 +02:00
// 9.1.1.1.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-declarative-environment-records-deletebinding-n
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
bool DeclarativeEnvironment::delete_binding(GlobalObject&, FlyString const& name)
LibJS: Start implementing spec-compliant variable bindings This patch adds the concept of variable bindings to the various environment record classes. The bindings are not yet hooked up to anything, this is just fleshing out all the operations. Most of this is following the spec exactly, but in a few cases we are missing the requisite abstract operations to do the exact right thing. I've added FIXME's in those cases where I noticed it.
2021-06-23 12:26:37 +02:00
{
auto it = m_bindings.find(name);
VERIFY(it != m_bindings.end());
if (!it->value.can_be_deleted)
return false;
m_bindings.remove(it);
return true;
}
LibJS: Introduce LexicalEnvironment This patch replaces the old variable lookup logic with a new one based on lexical environments. This brings us closer to the way JavaScript is actually specced, and also gives us some basic support for closures. The interpreter's call stack frames now have a pointer to the lexical environment for that frame. Each lexical environment can have a chain of parent environments. Before calling a Function, we first ask it to create_environment(). This gives us a new LexicalEnvironment for that function, which has the function's lexical parent's environment as its parent. This allows inner functions to access variables in their outer function: function foo() { <-- LexicalEnvironment A var x = 1; function() { <-- LexicalEnvironment B (parent: A) console.log(x); } } If we return the result of a function expression from a function, that new function object will keep a reference to its parent environment, which is how we get closures. :^) I'm pretty sure I didn't get everything right here, but it's a pretty good start. This is quite a bit slower than before, but also correcter!
2020-04-15 21:58:22 +02:00
}
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