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Shell: Add runtime errors and implement break/continue

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Such errors are raised when SyntaxError nodes are executed, and are also
used for internal control flow.
The 'break' and 'continue' commands are currently only allowed inside
for loops, and outside function bodies.

This also adds a 'loop' keyword for infinite loops.
This commit is contained in:
AnotherTest 2020-12-10 18:25:13 +03:30 • committed by Andreas Kling
commit 5e5eb615ec
Notes: sideshowbarker 2024-07-19 00:26:20 +09:00
14 changed files with 384 additions and 62 deletions
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89
Shell/Parser.cpp
View file

@ -362,6 +362,7 @@ RefPtr<AST::Node> Parser::parse_function_decl()
}
}
TemporaryChange controls { m_continuation_controls_allowed, false };
auto body = parse_toplevel();
{
@ -499,9 +500,15 @@ RefPtr<AST::Node> Parser::parse_control_structure()
{
auto rule_start = push_start();
consume_while(is_whitespace);
if (auto control = parse_continuation_control())
return control;
if (auto for_loop = parse_for_loop())
return for_loop;
if (auto loop = parse_loop_loop())
return loop;
if (auto if_expr = parse_if_expr())
return if_expr;
@ -514,6 +521,40 @@ RefPtr<AST::Node> Parser::parse_control_structure()
return nullptr;
}
RefPtr<AST::Node> Parser::parse_continuation_control()
{
if (!m_continuation_controls_allowed)
return nullptr;
auto rule_start = push_start();
if (expect("break")) {
{
auto break_end = push_start();
if (consume_while(is_any_of(" \t\n;")).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
restore_to(*break_end);
}
return create<AST::ContinuationControl>(AST::ContinuationControl::Break);
}
if (expect("continue")) {
{
auto continue_end = push_start();
if (consume_while(is_any_of(" \t\n;")).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
restore_to(*continue_end);
}
return create<AST::ContinuationControl>(AST::ContinuationControl::Continue);
}
return nullptr;
}
RefPtr<AST::Node> Parser::parse_for_loop()
{
auto rule_start = push_start();
@ -544,10 +585,8 @@ RefPtr<AST::Node> Parser::parse_for_loop()
{
auto iter_error_start = push_start();
iterated_expression = parse_expression();
if (!iterated_expression) {
auto syntax_error = create<AST::SyntaxError>("Expected an expression in 'for' loop", true);
return create<AST::ForLoop>(move(variable_name), move(syntax_error), nullptr, move(in_start_position)); // ForLoop Var Iterated Block
}
if (!iterated_expression)
iterated_expression = create<AST::SyntaxError>("Expected an expression in 'for' loop", true);
}
consume_while(is_any_of(" \t\n"));
@ -555,10 +594,11 @@ RefPtr<AST::Node> Parser::parse_for_loop()
auto obrace_error_start = push_start();
if (!expect('{')) {
auto syntax_error = create<AST::SyntaxError>("Expected an open brace '{' to start a 'for' loop body", true);
return create<AST::ForLoop>(move(variable_name), iterated_expression.release_nonnull(), move(syntax_error), move(in_start_position)); // ForLoop Var Iterated Block
return create<AST::ForLoop>(move(variable_name), move(iterated_expression), move(syntax_error), move(in_start_position)); // ForLoop Var Iterated Block
}
}
TemporaryChange controls { m_continuation_controls_allowed, true };
auto body = parse_toplevel();
{
@ -573,7 +613,44 @@ RefPtr<AST::Node> Parser::parse_for_loop()
}
}
return create<AST::ForLoop>(move(variable_name), iterated_expression.release_nonnull(), move(body), move(in_start_position)); // ForLoop Var Iterated Block
return create<AST::ForLoop>(move(variable_name), move(iterated_expression), move(body), move(in_start_position)); // ForLoop Var Iterated Block
}
RefPtr<AST::Node> Parser::parse_loop_loop()
{
auto rule_start = push_start();
if (!expect("loop"))
return nullptr;
if (consume_while(is_any_of(" \t\n")).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
{
auto obrace_error_start = push_start();
if (!expect('{')) {
auto syntax_error = create<AST::SyntaxError>("Expected an open brace '{' to start a 'loop' loop body", true);
return create<AST::ForLoop>(String::empty(), nullptr, move(syntax_error), Optional<AST::Position> {}); // ForLoop null null Block
}
}
TemporaryChange controls { m_continuation_controls_allowed, true };
auto body = parse_toplevel();
{
auto cbrace_error_start = push_start();
if (!expect('}')) {
auto error_start = push_start();
auto syntax_error = create<AST::SyntaxError>("Expected a close brace '}' to end a 'loop' loop body", true);
if (body)
body->set_is_syntax_error(*syntax_error);
else
body = syntax_error;
}
}
return create<AST::ForLoop>(String::empty(), nullptr, move(body), Optional<AST::Position> {}); // ForLoop null null Block
}
RefPtr<AST::Node> Parser::parse_if_expr()