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LibJS: Track which Identifier nodes refer to function arguments

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This patch adds an "argument index" field to Identifier AST nodes.
If the Identifier refers to a function parameter in the currently
open function scope, we stash the index of the parameter here.

This will allow us to implement much faster direct access to function
argument variables.
This commit is contained in:
Andreas Kling
2021-06-14 09:30:43 +02:00
parent ae8b55a80a
commit 481cef59b6
4 changed files with 39 additions and 5 deletions
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27
Userland/Libraries/LibJS/Parser.cpp
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@@ -382,6 +382,8 @@ RefPtr<FunctionExpression> Parser::try_parse_arrow_function_expression(bool expe
if (function_length == -1)
function_length = parameters.size();
m_parser_state.function_parameters.append(parameters);
auto old_labels_in_scope = move(m_parser_state.m_labels_in_scope);
ScopeGuard guard([&]() {
m_parser_state.m_labels_in_scope = move(old_labels_in_scope);
@@ -411,6 +413,8 @@ RefPtr<FunctionExpression> Parser::try_parse_arrow_function_expression(bool expe
return nullptr;
}();
m_parser_state.function_parameters.take_last();
if (!function_body_result.is_null()) {
state_rollback_guard.disarm();
discard_saved_state();
@@ -651,7 +655,23 @@ NonnullRefPtr<Expression> Parser::parse_primary_expression()
set_try_parse_arrow_function_expression_failed_at_position(position(), true);
}
return create_ast_node<Identifier>({ m_parser_state.m_current_token.filename(), rule_start.position(), position() }, consume().value());
auto string = consume().value();
Optional<size_t> argument_index;
if (!m_parser_state.function_parameters.is_empty()) {
size_t i = 0;
for (auto& parameter : m_parser_state.function_parameters.last()) {
parameter.binding.visit(
[&](FlyString const& name) {
if (name == string) {
argument_index = i;
}
},
[&](BindingPattern const&) {
});
++i;
}
}
return create_ast_node<Identifier>({ m_parser_state.m_current_token.filename(), rule_start.position(), position() }, string, argument_index);
}
case TokenType::NumericLiteral:
return create_ast_node<NumericLiteral>({ m_parser_state.m_current_token.filename(), rule_start.position(), position() }, consume_and_validate_numeric_literal().double_value());
@@ -1386,8 +1406,13 @@ NonnullRefPtr<FunctionNodeType> Parser::parse_function_node(u8 parse_options)
m_parser_state.m_labels_in_scope = move(old_labels_in_scope);
});
m_parser_state.function_parameters.append(parameters);
bool is_strict = false;
auto body = parse_block_statement(is_strict);
m_parser_state.function_parameters.take_last();
body->add_variables(m_parser_state.m_var_scopes.last());
body->add_functions(m_parser_state.m_function_scopes.last());
return create_ast_node<FunctionNodeType>(