1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
|
/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibJS/Interpreter.h>
#include <LibJS/Runtime/FunctionEnvironment.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/NativeFunction.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
NativeFunction* NativeFunction::create(GlobalObject& global_object, const FlyString& name, Function<ThrowCompletionOr<Value>(VM&, GlobalObject&)> function)
{
return global_object.heap().allocate<NativeFunction>(global_object, name, move(function), *global_object.function_prototype());
}
// FIXME: m_realm is supposed to be the realm argument of CreateBuiltinFunction, or the current
// Realm Record. The former is not something that's commonly used or we support, the
// latter is impossible as no ExecutionContext exists when most NativeFunctions are created...
NativeFunction::NativeFunction(Object& prototype)
: FunctionObject(prototype)
, m_realm(global_object().associated_realm())
{
}
NativeFunction::NativeFunction(FlyString name, Function<ThrowCompletionOr<Value>(VM&, GlobalObject&)> native_function, Object& prototype)
: FunctionObject(prototype)
, m_name(move(name))
, m_native_function(move(native_function))
, m_realm(global_object().associated_realm())
{
}
NativeFunction::NativeFunction(FlyString name, Object& prototype)
: FunctionObject(prototype)
, m_name(move(name))
, m_realm(global_object().associated_realm())
{
}
NativeFunction::~NativeFunction()
{
}
// NOTE: Do not attempt to DRY these, it's not worth it. The difference in return types (Value vs Object*),
// called functions (call() vs construct(FunctionObject&)), and this value (passed vs uninitialized) make
// these good candidates for a bit of code duplication :^)
// 10.3.1 [[Call]] ( thisArgument, argumentsList ), https://tc39.es/ecma262/#sec-built-in-function-objects-call-thisargument-argumentslist
ThrowCompletionOr<Value> NativeFunction::internal_call(Value this_argument, MarkedValueList arguments_list)
{
auto& vm = this->vm();
auto& global_object = this->global_object();
// 1. Let callerContext be the running execution context.
auto& caller_context = vm.running_execution_context();
// 2. If callerContext is not already suspended, suspend callerContext.
// NOTE: We don't support this concept yet.
// 3. Let calleeContext be a new execution context.
ExecutionContext callee_context(heap());
// 4. Set the Function of calleeContext to F.
callee_context.function = this;
callee_context.function_name = m_name;
// 5. Let calleeRealm be F.[[Realm]].
auto* callee_realm = m_realm;
// NOTE: This non-standard fallback is needed until we can guarantee that literally
// every function has a realm - especially in LibWeb that's sometimes not the case
// when a function is created while no JS is running, as we currently need to rely on
// that (:acid2:, I know - see set_event_handler_attribute() for an example).
// If there's no 'current realm' either, we can't continue and crash.
if (!callee_realm)
callee_realm = vm.current_realm();
VERIFY(callee_realm);
// 6. Set the Realm of calleeContext to calleeRealm.
callee_context.realm = callee_realm;
// 7. Set the ScriptOrModule of calleeContext to null.
// FIXME: Our execution context struct currently does not track this item.
// 8. Perform any necessary implementation-defined initialization of calleeContext.
callee_context.this_value = this_argument;
callee_context.arguments.extend(move(arguments_list));
callee_context.lexical_environment = caller_context.lexical_environment;
callee_context.variable_environment = caller_context.variable_environment;
// NOTE: This is a LibJS specific hack for NativeFunction to inherit the strictness of its caller.
callee_context.is_strict_mode = vm.in_strict_mode();
if (auto* interpreter = vm.interpreter_if_exists())
callee_context.current_node = interpreter->current_node();
// </8.> --------------------------------------------------------------------------
// 9. Push calleeContext onto the execution context stack; calleeContext is now the running execution context.
vm.push_execution_context(callee_context, global_object);
// 10. Let result be the Completion Record that is the result of evaluating F in a manner that conforms to the specification of F. thisArgument is the this value, argumentsList provides the named parameters, and the NewTarget value is undefined.
auto result = call();
// 11. Remove calleeContext from the execution context stack and restore callerContext as the running execution context.
vm.pop_execution_context();
// 12. Return result.
if (auto* exception = vm.exception())
return throw_completion(exception->value());
return result;
}
// 10.3.2 [[Construct]] ( argumentsList, newTarget ), https://tc39.es/ecma262/#sec-built-in-function-objects-construct-argumentslist-newtarget
ThrowCompletionOr<Object*> NativeFunction::internal_construct(MarkedValueList arguments_list, FunctionObject& new_target)
{
auto& vm = this->vm();
auto& global_object = this->global_object();
// 1. Let callerContext be the running execution context.
auto& caller_context = vm.running_execution_context();
// 2. If callerContext is not already suspended, suspend callerContext.
// NOTE: We don't support this concept yet.
// 3. Let calleeContext be a new execution context.
ExecutionContext callee_context(heap());
// 4. Set the Function of calleeContext to F.
callee_context.function = this;
callee_context.function_name = m_name;
// 5. Let calleeRealm be F.[[Realm]].
auto* callee_realm = m_realm;
// NOTE: This non-standard fallback is needed until we can guarantee that literally
// every function has a realm - especially in LibWeb that's sometimes not the case
// when a function is created while no JS is running, as we currently need to rely on
// that (:acid2:, I know - see set_event_handler_attribute() for an example).
// If there's no 'current realm' either, we can't continue and crash.
if (!callee_realm)
callee_realm = vm.current_realm();
VERIFY(callee_realm);
// 6. Set the Realm of calleeContext to calleeRealm.
callee_context.realm = callee_realm;
// 7. Set the ScriptOrModule of calleeContext to null.
// FIXME: Our execution context struct currently does not track this item.
// 8. Perform any necessary implementation-defined initialization of calleeContext.
callee_context.arguments.extend(move(arguments_list));
callee_context.lexical_environment = caller_context.lexical_environment;
callee_context.variable_environment = caller_context.variable_environment;
// NOTE: This is a LibJS specific hack for NativeFunction to inherit the strictness of its caller.
callee_context.is_strict_mode = vm.in_strict_mode();
if (auto* interpreter = vm.interpreter_if_exists())
callee_context.current_node = interpreter->current_node();
// </8.> --------------------------------------------------------------------------
// 9. Push calleeContext onto the execution context stack; calleeContext is now the running execution context.
vm.push_execution_context(callee_context, global_object);
// 10. Let result be the Completion Record that is the result of evaluating F in a manner that conforms to the specification of F. The this value is uninitialized, argumentsList provides the named parameters, and newTarget provides the NewTarget value.
auto result = construct(new_target);
// 11. Remove calleeContext from the execution context stack and restore callerContext as the running execution context.
vm.pop_execution_context();
// 12. Return result.
if (auto* exception = vm.exception())
return throw_completion(exception->value());
return &result.as_object();
}
Value NativeFunction::call()
{
return TRY_OR_DISCARD(m_native_function(vm(), global_object()));
}
Value NativeFunction::construct(FunctionObject&)
{
// Needs to be overridden if [[Construct]] is needed.
VERIFY_NOT_REACHED();
}
bool NativeFunction::is_strict_mode() const
{
return true;
}
}
|
