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Add parsing for conditionals

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Vili Sinervä 2025-01-28 19:33:15 +02:00
parent f3a252b510
commit 8d4f452f34
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GPG key ID: DF8FEAF54EFAC996
1 changed files with 42 additions and 10 deletions
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52
src/compiler/parser.rs
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@ -95,6 +95,16 @@ fn parse_int_literal<'source>(pos: &mut usize, tokens: &[Token]) -> Expression<'
)
}
fn parse_bool_literal<'source>(pos: &mut usize, tokens: &[Token]) -> Expression<'source> {
let token = next_expect_type(pos, tokens, TokenType::Identifier);
match token.text {
"true" => BoolLiteral(true),
"false" => BoolLiteral(false),
_ => panic!("Fatal parser error! Expected bool literal but found {token}"),
}
}
fn parse_identifier<'source>(pos: &mut usize, tokens: &[Token<'source>]) -> Expression<'source> {
let token = next_expect_type(pos, tokens, TokenType::Identifier);
Identifier(token.text)
@ -115,22 +125,45 @@ fn parse_factor<'source>(pos: &mut usize, tokens: &[Token<'source>]) -> Expressi
}
match token.token_type {
TokenType::Integer => parse_int_literal(pos, tokens),
TokenType::Identifier => parse_identifier(pos, tokens),
TokenType::Identifier => match token.text {
"true" | "false" => parse_bool_literal(pos, tokens),
_ => parse_identifier(pos, tokens),
},
_ => panic!("Unexpected {}", peek(pos, tokens)),
}
}
fn parse_conditional<'source>(pos: &mut usize, tokens: &[Token<'source>]) -> Expression<'source> {
next_expect_string(pos, tokens, "if");
let condition = Box::new(parse_expression(pos, tokens));
next_expect_string(pos, tokens, "then");
let then_expr = Box::new(parse_expression(pos, tokens));
let else_expr = match peek(pos, tokens).text {
"else" => {
next_expect_string(pos, tokens, "else");
Some(Box::new(parse_expression(pos, tokens)))
}
_ => None,
};
Conditional(condition, then_expr, else_expr)
}
fn parse_term<'source>(pos: &mut usize, tokens: &[Token<'source>]) -> Expression<'source> {
let mut left = parse_factor(pos, tokens);
match peek(pos, tokens).text {
"if" => parse_conditional(pos, tokens),
_ => {
let mut left = parse_factor(pos, tokens);
while ["*", "/"].contains(&peek(pos, tokens).text) {
let operator_token = next_expect_strings(pos, tokens, &vec!["*", "/"]);
let right = parse_factor(pos, tokens);
while ["*", "/"].contains(&peek(pos, tokens).text) {
let operator_token = next_expect_strings(pos, tokens, &vec!["*", "/"]);
let right = parse_factor(pos, tokens);
left = BinaryOp(Box::new(left), operator_token.text, Box::new(right));
left = BinaryOp(Box::new(left), operator_token.text, Box::new(right));
}
left
}
}
left
}
fn parse_expression<'source>(pos: &mut usize, tokens: &[Token<'source>]) -> Expression<'source> {
@ -408,7 +441,6 @@ mod tests {
#[test]
fn test_nested_if_then_else() {
// if true then if false then 1 else 2 else 3
let result = parse(&vec![
new_id("if"),
new_id("true"),