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LibJS: Implement const variable declarations

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This also tightens the means of redeclaration of a variable by proxy,
since we now have a way of knowing how a variable was initially
declared, we can check if it was declared using `let` or `const` and
not tolerate redeclaration like we did previously.
This commit is contained in:
0xtechnobabble 2020-03-12 14:24:34 +02:00 • committed by Andreas Kling
parent 8557bc56f7
commit ee5a49e2fe
5 changed files with 46 additions and 13 deletions
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33
Libraries/LibJS/Interpreter.cpp
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@ -57,7 +57,12 @@ Value Interpreter::run(const ScopeNode& scope_node, HashMap<String, Value> scope
void Interpreter::enter_scope(const ScopeNode& scope_node, HashMap<String, Value> scope_variables, ScopeType scope_type)
{
m_scope_stack.append({ scope_type, scope_node, move(scope_variables) });
HashMap<String, Variable> scope_variables_with_declaration_type;
for (String name : scope_variables.keys()) {
scope_variables_with_declaration_type.set(name, { scope_variables.get(name).value(), DeclarationType::Var });
}
m_scope_stack.append({ scope_type, scope_node, move(scope_variables_with_declaration_type) });
}
void Interpreter::exit_scope(const ScopeNode& scope_node)
@ -78,7 +83,10 @@ void Interpreter::declare_variable(String name, DeclarationType declaration_type
for (ssize_t i = m_scope_stack.size() - 1; i >= 0; --i) {
auto& scope = m_scope_stack.at(i);
if (scope.type == ScopeType::Function) {
scope.variables.set(move(name), js_undefined());
if (scope.variables.get(name).has_value() && scope.variables.get(name).value().declaration_type != DeclarationType::Var)
ASSERT_NOT_REACHED();
scope.variables.set(move(name), { js_undefined(), declaration_type });
return;
}
}
@ -86,7 +94,11 @@ void Interpreter::declare_variable(String name, DeclarationType declaration_type
global_object().put(move(name), js_undefined());
break;
case DeclarationType::Let:
m_scope_stack.last().variables.set(move(name), js_undefined());
case DeclarationType::Const:
if (m_scope_stack.last().variables.get(name).has_value() && m_scope_stack.last().variables.get(name).value().declaration_type != DeclarationType::Var)
ASSERT_NOT_REACHED();
m_scope_stack.last().variables.set(move(name), { js_undefined(), declaration_type });
break;
}
}
@ -95,8 +107,13 @@ void Interpreter::set_variable(String name, Value value)
{
for (ssize_t i = m_scope_stack.size() - 1; i >= 0; --i) {
auto& scope = m_scope_stack.at(i);
if (scope.variables.contains(name)) {
scope.variables.set(move(name), move(value));
auto possible_match = scope.variables.get(name);
if (possible_match.has_value()) {
if (possible_match.value().declaration_type == DeclarationType::Const)
ASSERT_NOT_REACHED();
scope.variables.set(move(name), { move(value), possible_match.value().declaration_type });
return;
}
}
@ -110,7 +127,7 @@ Value Interpreter::get_variable(const String& name)
auto& scope = m_scope_stack.at(i);
auto value = scope.variables.get(name);
if (value.has_value())
return value.value();
return value.value().value;
}
return global_object().get(name);
@ -122,8 +139,8 @@ void Interpreter::collect_roots(Badge<Heap>, HashTable<Cell*>& roots)
for (auto& scope : m_scope_stack) {
for (auto& it : scope.variables) {
if (it.value.is_cell())
roots.set(it.value.as_cell());
if (it.value.value.is_cell())
roots.set(it.value.value.as_cell());
}
}
}