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LibJS: Implement parsing and evaluation for AssignmentPatterns

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e.g. `[...foo] = bar` can now be evaluated :^)
This commit is contained in:
Ali Mohammad Pur 2021-07-11 01:16:17 +04:30 • committed by Linus Groh
parent 7fc6cd6b20
commit 1a9518ebe3
7 changed files with 104 additions and 40 deletions
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33
Userland/Libraries/LibJS/Parser.cpp
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@ -1305,6 +1305,36 @@ NonnullRefPtr<AssignmentExpression> Parser::parse_assignment_expression(Assignme
|| match(TokenType::DoublePipeEquals)
|| match(TokenType::DoubleQuestionMarkEquals));
consume();
if (assignment_op == AssignmentOp::Assignment) {
auto synthesize_binding_pattern = [this](Expression const& expression) -> RefPtr<BindingPattern> {
// Clear any syntax error that has occurred in the range that 'expression' spans.
m_state.errors.remove_all_matching([range = expression.source_range()](auto const& error) {
return error.position.has_value() && range.contains(*error.position);
});
// Make a parser and parse the source for this expression as a binding pattern.
auto source = m_state.lexer.source().substring_view(expression.source_range().start.offset - 2, expression.source_range().end.offset - expression.source_range().start.offset);
Lexer lexer { source, m_state.lexer.filename(), expression.source_range().start.line, expression.source_range().start.column };
Parser parser { lexer };
auto result = parser.parse_binding_pattern();
if (parser.has_errors()) {
for (auto& error : parser.errors())
syntax_error(move(error.message), move(error.position));
}
return result;
};
if (is<ArrayExpression>(*lhs) || is<ObjectExpression>(*lhs)) {
auto binding_pattern = synthesize_binding_pattern(*lhs);
if (binding_pattern) {
auto rhs = parse_expression(min_precedence, associativity);
return create_ast_node<AssignmentExpression>(
{ m_state.current_token.filename(), rule_start.position(), position() },
assignment_op,
binding_pattern.release_nonnull(),
move(rhs));
}
}
}
if (!is<Identifier>(*lhs) && !is<MemberExpression>(*lhs) && !is<CallExpression>(*lhs)) {
syntax_error("Invalid left-hand side in assignment");
} else if (m_state.strict_mode && is<Identifier>(*lhs)) {
@ -2398,7 +2428,8 @@ Position Parser::position() const
{
return {
m_state.current_token.line_number(),
m_state.current_token.line_column()
m_state.current_token.line_column(),
m_state.current_token.offset(),
};
}