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ladybird/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>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
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
#include <AK/Badge.h>
LibJS: Move join_args() in Interpreter It can be useful outside of Runtime/ConsoleObject.cpp. join_args() => Interpreter::join_arguments()
2020-05-04 12:34:49 +02:00
#include <AK/StringBuilder.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: Implement basic exception throwing You can now throw exceptions by calling Interpreter::throw_exception(). Anyone who calls ASTNode::execute() needs to check afterwards if the Interpreter now has an exception(), and if so, stop what they're doing and simply return. When catching an exception, we'll first execute the CatchClause node if present. After that, we'll execute the finalizer block if present. This is unlikely to be completely correct, but it's a start! :^)
2020-03-24 14:37:39 +01:00
#include <LibJS/Runtime/Error.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/GlobalObject.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
#include <LibJS/Runtime/LexicalEnvironment.h>
LibJS: Add MarkedValueList and use it for argument passing A MarkedValueList is basically a Vector<JS::Value> that registers with the Heap and makes sure that the stored values don't get GC'd. Before this change, we were unsafely keeping Vector<JS::Value> in some places, which is out-of-reach for the live reference finding logic since Vector puts its elements on the heap by default. We now pass all the JavaScript tests even when running with "js -g", which does a GC on every heap allocation.
2020-04-19 17:24:56 +02:00
#include <LibJS/Runtime/MarkedValueList.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/NativeFunction.h>
#include <LibJS/Runtime/Object.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: Hoist function declarations This patch adds function declaration hoisting. The mechanism is similar to var hoisting. Hoisted function declarations are to be put before the hoisted var declarations, hence they have to be treated separately.
2020-06-04 14:48:36 +02:00
#include <LibJS/Runtime/ScriptFunction.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. :^)
2020-04-02 19:32:21 +02:00
#include <LibJS/Runtime/Shape.h>
LibJS: Add symbol objects This commit adds the following classes: SymbolObject, SymbolConstructor, SymbolPrototype, and Symbol. This commit does not introduce any new functionality to the Object class, so they cannot be used as property keys in objects.
2020-04-29 23:25:21 -07:00
#include <LibJS/Runtime/SymbolObject.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. :^)
2020-03-07 19:42:11 +01:00
LibJS: Hide interpreter exception debug output behind a flag
2020-07-02 18:01:09 -07:00
//#define INTERPRETER_DEBUG
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
namespace JS {
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 implementing a Console class for the interpreter The goal is to start factoring out core ConsoleObject functionality and to make ConsoleObject only a JS wrapper around Console.
2020-05-01 14:40:43 +02:00
, m_console(*this)
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: Extract most of Interpreter's run() into execute_statement() Interpreter::run() was so far being used both as the "public API entry point" for running a JS::Program as well as internally to execute JS::Statement|s of all kinds - this is now more distinctly separated. A program as returned by the parser is still going through run(), which is responsible for creating the initial global call frame, but all other statements are executed via execute_statement() directly. Fixes #3437, a regression introduced by adding ASSERT(!exception()) to run() without considering the effects that would have on internal usage.
2020-09-11 22:47:43 +01:00
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 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
ASSERT(!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: 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
CallFrame global_call_frame;
global_call_frame.this_value = &global_object;
global_call_frame.function_name = "(global execution context)";
global_call_frame.environment = heap().allocate<LexicalEnvironment>(global_object, LexicalEnvironment::EnvironmentRecordType::Global);
global_call_frame.environment->bind_this_value(&global_object);
if (vm().exception())
return {};
vm().call_stack().append(move(global_call_frame));
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
auto result = program.execute(*this, global_object);
vm().pop_call_frame();
return result;
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: Add a helper for calling JS::Function's with arguments The fact that a `MarkedValueList` had to be created was just annoying, so here's an alternative. This patchset also removes some (now) unneeded MarkedValueList.h includes.
2020-08-25 22:18:32 +04:30
Value Interpreter::call_internal(Function& function, Value this_value, Optional<MarkedValueList> arguments)
LibJS: Add Interpreter::call(Function*, this_value, arguments) This helper function takes care of pushing/popping a call frame so you don't need to worry about it.
2020-03-18 15:20:49 +01:00
{
LibJS: Assert that there's no exception on entry in Interpreter::call()
2020-08-14 17:30:34 +02:00
ASSERT(!exception());
LibJS: Rename InterpreterScope => InterpreterExecutionScope To make it a little clearer what this is for. (This is an RAII helper class for adding and removing an Interpreter to a VM's list of the currently active (executing code) Interpreters.)
2020-09-21 13:36:32 +02:00
VM::InterpreterExecutionScope scope(*this);
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
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
auto& call_frame = vm().push_call_frame();
LibJS: Pass JS::Function around by reference more
2020-04-29 13:43:57 +02:00
call_frame.function_name = function.name();
LibJS: Use the function's bound |this| and bound arguments in Interpreter::call()
2020-05-30 01:07:02 -05:00
call_frame.this_value = function.bound_this().value_or(this_value);
call_frame.arguments = function.bound_arguments();
LibJS: Add MarkedValueList and use it for argument passing A MarkedValueList is basically a Vector<JS::Value> that registers with the Heap and makes sure that the stored values don't get GC'd. Before this change, we were unsafely keeping Vector<JS::Value> in some places, which is out-of-reach for the live reference finding logic since Vector puts its elements on the heap by default. We now pass all the JavaScript tests even when running with "js -g", which does a GC on every heap allocation.
2020-04-19 17:24:56 +02:00
if (arguments.has_value())
LibJS: Use the function's bound |this| and bound arguments in Interpreter::call()
2020-05-30 01:07:02 -05:00
call_frame.arguments.append(arguments.value().values());
LibJS: Pass JS::Function around by reference more
2020-04-29 13:43:57 +02:00
call_frame.environment = function.create_environment();
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
ASSERT(call_frame.environment->this_binding_status() == LexicalEnvironment::ThisBindingStatus::Uninitialized);
call_frame.environment->bind_this_value(call_frame.this_value);
LibJS: Pass JS::Function around by reference more
2020-04-29 13:43:57 +02:00
auto result = function.call(*this);
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().pop_call_frame();
LibJS: Add Interpreter::call(Function*, this_value, arguments) This helper function takes care of pushing/popping a call frame so you don't need to worry about it.
2020-03-18 15:20:49 +01:00
return result;
}
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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