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ladybird/Userland/Libraries/LibJS/Interpreter.cpp

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LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
2020-03-07 19:42:11 +01:00
/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
LibJS: Ensure function declarations don't leak outside function scopes When using VM::set_variable() to put the created ScriptFunction onto a ScopeObject, we would previously unexpectedly reach the global object as set_variable() checks each traversed scope for an existing Variable with the given name - which would cause a leak of the inner function past the outer function (we even had a test expecting that behaviour!). Now we first declare functions (as DeclarationKind::Var) before setting them. This will need some more work to make hoisting across non-lexical scopes work, but it fixes this specific issue for now. Fixes #6766.
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* Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
2020-03-07 19:42:11 +01:00
*
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 *
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* SPDX-License-Identifier: BSD-2-Clause
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
2020-03-07 19:42:11 +01:00
*/
LibJS: Ensure function declarations don't leak outside function scopes When using VM::set_variable() to put the created ScriptFunction onto a ScopeObject, we would previously unexpectedly reach the global object as set_variable() checks each traversed scope for an existing Variable with the given name - which would cause a leak of the inner function past the outer function (we even had a test expecting that behaviour!). Now we first declare functions (as DeclarationKind::Var) before setting them. This will need some more work to make hoisting across non-lexical scopes work, but it fixes this specific issue for now. Fixes #6766.
2021-05-13 23:58:45 +01:00
#include <AK/ScopeGuard.h>
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
2020-03-07 19:42:11 +01:00
#include <LibJS/AST.h>
#include <LibJS/Interpreter.h>
LibJS: Make scoping follow the spec Before this we used an ad-hoc combination of references and 'variables' stored in a hashmap. This worked in most cases but is not spec like. Additionally hoisting, dynamically naming functions and scope analysis was not done properly. This patch fixes all of that by: - Implement BindingInitialization for destructuring assignment. - Implementing a new ScopePusher which tracks the lexical and var scoped declarations. This hoists functions to the top level if no lexical declaration name overlaps. Furthermore we do checking of redeclarations in the ScopePusher now requiring less checks all over the place. - Add methods for parsing the directives and statement lists instead of having that code duplicated in multiple places. This allows declarations to pushed to the appropriate scope more easily. - Remove the non spec way of storing 'variables' in DeclarativeEnvironment and make Reference follow the spec instead of checking both the bindings and 'variables'. - Remove all scoping related things from the Interpreter. And instead use environments as specified by the spec. This also includes fixing that NativeFunctions did not produce a valid FunctionEnvironment which could cause issues with callbacks and eval. All FunctionObjects now have a valid NewFunctionEnvironment implementation. - Remove execute_statements from Interpreter and instead use ASTNode::execute everywhere this simplifies AST.cpp as you no longer need to worry about which method to call. - Make ScopeNodes setup their own environment. This uses four different methods specified by the spec {Block, Function, Eval, Global}DeclarationInstantiation with the annexB extensions. - Implement and use NamedEvaluation where specified. Additionally there are fixes to things exposed by these changes to eval, {for, for-in, for-of} loops and assignment. Finally it also fixes some tests in test-js which where passing before but not now that we have correct behavior :^).
2021-09-22 12:44:56 +02:00
#include <LibJS/Runtime/AbstractOperations.h>
LibJS: Rename OrdinaryFunctionObject to ECMAScriptFunctionObject The old name is the result of the perhaps somewhat confusingly named abstract operation OrdinaryFunctionCreate(), which creates an "ordinary object" (https://tc39.es/ecma262/#ordinary-object) in contrast to an "exotic object" (https://tc39.es/ecma262/#exotic-object). However, the term "Ordinary Function" is not used anywhere in the spec, instead the created object is referred to as an "ECMAScript Function Object" (https://tc39.es/ecma262/#sec-ecmascript-function-objects), so let's call it that. The "ordinary" vs. "exotic" distinction is important because there are also "Built-in Function Objects", which can be either implemented as ordinary ECMAScript function objects, or as exotic objects (our NativeFunction). More work needs to be done to move a lot of infrastructure to ECMAScriptFunctionObject in order to make FunctionObject nothing more than an interface for objects that implement [[Call]] and optionally [[Construct]].
2021-09-24 22:40:38 +02:00
#include <LibJS/Runtime/ECMAScriptFunctionObject.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/FunctionEnvironment.h>
#include <LibJS/Runtime/GlobalEnvironment.h>
LibJS: Add "Heap" and "Runtime" subdirectories Let's try to keep LibJS tidy as it expands. :^)
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#include <LibJS/Runtime/GlobalObject.h>
LibJS: Allow "delete someGlobalVariable" This is solved by allowing Identifier nodes to produce a Reference with the global object as base.
2020-04-27 12:37:27 +02:00
#include <LibJS/Runtime/Reference.h>
LibJS: Start implementing object shapes This patch adds JS::Shape, which implements a transition tree for our Object class. Object property keys, prototypes and attributes are now stored in a Shape, and each Object has a Shape. When adding a property to an Object, we make a transition from the old Shape to a new Shape. If we've made the same exact transition in the past (with another Object), we reuse the same transition and both objects may now share a Shape. This will become the foundation of inline caching and other engine optimizations in the future. :^)
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#include <LibJS/Runtime/Shape.h>
LibJS: Add "Heap" and "Runtime" subdirectories Let's try to keep LibJS tidy as it expands. :^)
2020-03-16 14:20:30 +01:00
#include <LibJS/Runtime/Value.h>
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
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namespace JS {
LibJS: Change Interpreter::create_with_existing_{global_object => realm} We need both a GlobalObject and Realm now, but can get the former from the latter (once initialized). This also fixes JS execution in LibWeb, as we failed to set the Realm of the newly created Interpreter in this function.
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NonnullOwnPtr<Interpreter> Interpreter::create_with_existing_realm(Realm& realm)
LibJS: Make Function::call() not require an Interpreter& This makes a difference inside ScriptFunction::call(), which will now instantiate a temporary Interpreter if one is not attached to the VM.
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{
LibJS: Change Interpreter::create_with_existing_{global_object => realm} We need both a GlobalObject and Realm now, but can get the former from the latter (once initialized). This also fixes JS execution in LibWeb, as we failed to set the Realm of the newly created Interpreter in this function.
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auto& global_object = realm.global_object();
LibJS: Make Function::call() not require an Interpreter& This makes a difference inside ScriptFunction::call(), which will now instantiate a temporary Interpreter if one is not attached to the VM.
2020-09-27 17:24:14 +02:00
DeferGC defer_gc(global_object.heap());
auto interpreter = adopt_own(*new Interpreter(global_object.vm()));
LibJS: Allocate a Realm next to GlobalObject in Interpreter::create() Also pass a Realm reference to the Bytecode::Interpreter constructor, just like we pass the GlobalObject.
2021-09-11 19:36:25 +01:00
interpreter->m_global_object = make_handle(&global_object);
LibJS: Change Interpreter::create_with_existing_{global_object => realm} We need both a GlobalObject and Realm now, but can get the former from the latter (once initialized). This also fixes JS execution in LibWeb, as we failed to set the Realm of the newly created Interpreter in this function.
2021-09-12 12:33:54 +01:00
interpreter->m_realm = make_handle(&realm);
LibJS: Make Function::call() not require an Interpreter& This makes a difference inside ScriptFunction::call(), which will now instantiate a temporary Interpreter if one is not attached to the VM.
2020-09-27 17:24:14 +02:00
return interpreter;
}
LibJS+Clients: Add JS::VM object, separate Heap from Interpreter Taking a big step towards a world of multiple global object, this patch adds a new JS::VM object that houses the JS::Heap. This means that the Heap moves out of Interpreter, and the same Heap can now be used by multiple Interpreters, and can also outlive them. The VM keeps a stack of Interpreter pointers. We push/pop on this stack when entering/exiting execution with a given Interpreter. This allows us to make this change without disturbing too much of the existing code. There is still a 1-to-1 relationship between Interpreter and the global object. This will change in the future. Ultimately, the goal here is to make Interpreter a transient object that only needs to exist while you execute some code. Getting there will take a lot more work though. :^) Note that in LibWeb, the global JS::VM is called main_thread_vm(), to distinguish it from future worker VM's.
2020-09-20 19:24:44 +02:00
Interpreter::Interpreter(VM& vm)
: m_vm(vm)
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
2020-03-07 19:42:11 +01:00
{
}
Interpreter::~Interpreter()
{
}
LibJS: Convert Interpreter::run() to ThrowCompletionOr<Value> Instead of making it a void function, checking for an exception, and then receiving the relevant result via VM::last_value(), we can consolidate all of this by using completions. This allows us to remove more uses of VM::exception(), and all uses of VM::last_value().
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ThrowCompletionOr<Value> Interpreter::run(GlobalObject& global_object, const Program& program)
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
2020-03-07 19:42:11 +01:00
{
LibJS: Move the GlobalEnvironment from GlobalObject to Realm This is where the spec wants to have it. Requires a couple of hacks as currently everything that needs a Realm actually has a GlobalObject, so we need to go via the Interpreter.
2021-09-11 20:27:36 +01:00
// FIXME: Why does this receive a GlobalObject? Interpreter has one already, and this might not be in sync with the Realm's GlobalObject.
LibJS: Throw RuntimeError when reaching the end of the stack This prevents stack overflows when calling infinite/deep recursive functions, e.g.: const f = () => f(); f(); JSON.stringify({}, () => ({ foo: "bar" })); new Proxy({}, { get: (_, __, p) => p.foo }).foo; The VM caches a StackInfo object to not slow down function calls considerably. VM::push_call_frame() will throw an exception if necessary (plain Error with "RuntimeError" as its .name).
2020-11-08 12:54:52 +00:00
auto& vm = this->vm();
Everywhere: Rename ASSERT => VERIFY (...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED) Since all of these checks are done in release builds as well, let's rename them to VERIFY to prevent confusion, as everyone is used to assertions being compiled out in release. We can introduce a new ASSERT macro that is specifically for debug checks, but I'm doing this wholesale conversion first since we've accumulated thousands of these already, and it's not immediately obvious which ones are suitable for ASSERT.
2021-02-23 20:42:32 +01:00
VERIFY(!vm.exception());
LibJS: Hoist variable declarations to the nearest relevant scope "var" declarations are hoisted to the nearest function scope, while "let" and "const" are hoisted to the nearest block scope. This is done by the parser, which keeps two scope stacks, one stack for the current var scope and one for the current let/const scope. When the interpreter enters a scope, we walk all of the declarations and insert them into the variable environment. We don't support the temporal dead zone for let/const yet.
2020-04-13 16:42:54 +02:00
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
VM::InterpreterExecutionScope scope(*this);
LibJS: Add basic support for (scoped) variables It's now possible to assign expressions to variables. The variables are put into the current scope of the interpreter. Variable lookup follows the scope chain, ending in the global object.
2020-03-09 21:13:55 +01:00
LibJS: Change ExecutionContext's arguments list to a MarkedValueList The test262 tests under RegExp/property-escapes/generated will invoke Reflect.apply with up to 10,000 arguments at a time. In LibJS, when the call stack reached VM::call_internal, we transfer those arguments from a MarkedValueList to the execution context's arguments Vector. Because these types differ (MarkedValueList is a Vector<Value, 32>), the arguments are copied rather than moved. By changing the arguments vector to a MarkedValueList, we can properly move the passed arguments over. This shaves about 2 seconds off the following test262 test (from 15sec): RegExp/property-escapes/generated/General_Category_-_Decimal_Number.js
2021-08-09 17:09:48 -04:00
ExecutionContext execution_context(heap());
LibJS: Rename CallFrame => ExecutionContext This struct represents what the ECMAScript specification calls an "execution context" so let's use the same terminology. :^)
2021-06-24 19:17:45 +02:00
execution_context.current_node = &program;
execution_context.this_value = &global_object;
LibJS: Cache commonly used FlyStrings in the VM Roughly 7% of test-js runtime was spent creating FlyStrings from string literals. This patch frontloads that work and caches all the commonly used names in LibJS on a CommonPropertyNames struct that hangs off VM.
2020-10-13 23:49:19 +02:00
static FlyString global_execution_context_name = "(global execution context)";
LibJS: Rename CallFrame => ExecutionContext This struct represents what the ECMAScript specification calls an "execution context" so let's use the same terminology. :^)
2021-06-24 19:17:45 +02:00
execution_context.function_name = global_execution_context_name;
LibJS: Move the GlobalEnvironment from GlobalObject to Realm This is where the spec wants to have it. Requires a couple of hacks as currently everything that needs a Realm actually has a GlobalObject, so we need to go via the Interpreter.
2021-09-11 20:27:36 +01:00
execution_context.lexical_environment = &realm().global_environment();
execution_context.variable_environment = &realm().global_environment();
LibJS: Set the callee context's realm in prepare_for_ordinary_call() This includes making FunctionObject::realm() actually return a Realm, instead of a GlobalObject.
2021-09-11 21:42:01 +01:00
execution_context.realm = &realm();
LibJS: Rename CallFrame => ExecutionContext This struct represents what the ECMAScript specification calls an "execution context" so let's use the same terminology. :^)
2021-06-24 19:17:45 +02:00
execution_context.is_strict_mode = program.is_strict_mode();
LibJS: Convert push_execution_context() to ThrowCompletionOr
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MUST(vm.push_execution_context(execution_context, global_object));
LibJS: Update AST to use completions :^) This is another major milestone on our journey towards removing global VM exception state :^) Does pretty much exactly what it says on the tin: updating ASTNode::execute() to return a Completion instead of a plain value. This will *also* allow us to eventually remove the non-standard unwinding mechanism and purely rely on the various completion types.
2022-01-02 21:37:50 +01:00
auto completion = program.execute(*this, global_object);
LibJS: Add VM::on_call_stack_emptied callback Instead of having to run queued promise jobs in LibWeb in various places, this allows us to consolidate that into one function - this is very close to how the spec describes it as well ("at some future point in time, when there is no running execution context and the execution context stack is empty, the implementation must [...]"). Eventually this will also be used to log unhandled exceptions, and possibly other actions that require JS execution to have ended.
2021-04-24 18:21:02 +02:00
// At this point we may have already run any queued promise jobs via on_call_stack_emptied,
// in which case this is a no-op.
LibJS: Add initial support for Promises Almost a year after first working on this, it's finally done: an implementation of Promises for LibJS! :^) The core functionality is working and closely following the spec [1]. I mostly took the pseudo code and transformed it into C++ - if you read and understand it, you will know how the spec implements Promises; and if you read the spec first, the code will look very familiar. Implemented functions are: - Promise() constructor - Promise.prototype.then() - Promise.prototype.catch() - Promise.prototype.finally() - Promise.resolve() - Promise.reject() For the tests I added a new function to test-js's global object, runQueuedPromiseJobs(), which calls vm.run_queued_promise_jobs(). By design, queued jobs normally only run after the script was fully executed, making it improssible to test handlers in individual test() calls by default [2]. Subsequent commits include integrations into LibWeb and js(1) - pretty-printing, running queued promise jobs when necessary. This has an unusual amount of dbgln() statements, all hidden behind the PROMISE_DEBUG flag - I'm leaving them in for now as they've been very useful while debugging this, things can get quite complex with so many asynchronously executed functions. I've not extensively explored use of these APIs for promise-based functionality in LibWeb (fetch(), Notification.requestPermission() etc.), but we'll get there in due time. [1]: https://tc39.es/ecma262/#sec-promise-objects [2]: https://tc39.es/ecma262/#sec-jobs-and-job-queues
2021-04-01 22:13:29 +02:00
vm.run_queued_promise_jobs();
LibJS: Store and maintain an "execution generation" counter This counter is increased each time a synchronous execution sequence completes, and will allow us to emulate the abstract operations AddToKeptObjects & ClearKeptObjects efficiently.
2021-06-12 17:32:54 +03:00
LibJS: Add the FinalizationRegistry built-in object As well as the needed functionality in VM to enqueue and run cleanup jobs for the FinalizationRegistry instances.
2021-06-15 22:16:17 +03:00
vm.run_queued_finalization_registry_cleanup_jobs();
LibJS: Pop execution context after running queued jobs in run() These would crash starting with the next commit otherwise, calling a function always requires the running execution context to exist.
2021-10-08 23:22:50 +01:00
vm.pop_execution_context();
LibJS: Store and maintain an "execution generation" counter This counter is increased each time a synchronous execution sequence completes, and will allow us to emulate the abstract operations AddToKeptObjects & ClearKeptObjects efficiently.
2021-06-12 17:32:54 +03:00
vm.finish_execution_generation();
LibJS: Convert Interpreter::run() to ThrowCompletionOr<Value> Instead of making it a void function, checking for an exception, and then receiving the relevant result via VM::last_value(), we can consolidate all of this by using completions. This allows us to remove more uses of VM::exception(), and all uses of VM::last_value().
2022-01-08 21:28:27 +01:00
if (completion.is_abrupt()) {
VERIFY(completion.type() == Completion::Type::Throw);
return completion.release_error();
}
return completion.value().value_or(js_undefined());
LibJS: Add basic support for (scoped) variables It's now possible to assign expressions to variables. The variables are put into the current scope of the interpreter. Variable lookup follows the scope chain, ending in the global object.
2020-03-09 21:13:55 +01:00
}
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
GlobalObject& Interpreter::global_object()
LibJS: Allow "delete someGlobalVariable" This is solved by allowing Identifier nodes to produce a Reference with the global object as base.
2020-04-27 12:37:27 +02:00
{
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
return static_cast<GlobalObject&>(*m_global_object.cell());
LibJS: Allow "delete someGlobalVariable" This is solved by allowing Identifier nodes to produce a Reference with the global object as base.
2020-04-27 12:37:27 +02:00
}
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
const GlobalObject& Interpreter::global_object() const
LibJS: Make sure we mark everything reachable from the scope stack This ensures that local variables survive GC.
2020-03-09 21:29:22 +01:00
{
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
return static_cast<const GlobalObject&>(*m_global_object.cell());
LibJS: Make sure we mark everything reachable from the scope stack This ensures that local variables survive GC.
2020-03-09 21:29:22 +01:00
}
LibJS: Allocate a Realm next to GlobalObject in Interpreter::create() Also pass a Realm reference to the Bytecode::Interpreter constructor, just like we pass the GlobalObject.
2021-09-11 19:36:25 +01:00
Realm& Interpreter::realm()
{
return static_cast<Realm&>(*m_realm.cell());
}
const Realm& Interpreter::realm() const
{
return static_cast<const Realm&>(*m_realm.cell());
}
LibJS: Start building a JavaScript engine for SerenityOS :^) I always tell people to start building things by working on the thing that seems the most interesting right now. The most interesting thing here was an AST + simple interpreter, so that's where we start! There is no lexer or parser yet, we build an AST directly and then execute it in the interpreter, producing a return value. This seems like the start of something interesting. :^)
2020-03-07 19:42:11 +01:00
}
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