Amneesh Singh
af30410aab
since there is no EOL delimiter like ';', we have to check for newline to avoid something like `a = 4 + 4 b = a` also added tests for expr parsing Signed-off-by: Amneesh Singh <natto@weirdnatto.in>
92 lines
2.4 KiB
Rust
92 lines
2.4 KiB
Rust
use super::Parser;
|
|
use crate::ast::*;
|
|
use crate::lexer::{
|
|
TokenKeyword,
|
|
TokenKind,
|
|
TokenSymbol,
|
|
};
|
|
|
|
impl<'a> Parser<'a> {
|
|
/// statement ::= static | let | expr
|
|
pub(super) fn parse_statement(&mut self) -> Option<Statement> {
|
|
use TokenKeyword::*;
|
|
println!("STMT");
|
|
|
|
Some(match self.peek_token().kind {
|
|
TokenKind::Keyword(Static) => Statement::Static(self.parse_static()?),
|
|
TokenKind::Keyword(Let) => Statement::Let(self.parse_let()?),
|
|
_ => Statement::Expr(self.parse_expr()?),
|
|
})
|
|
}
|
|
|
|
/// static ::="static" let
|
|
pub(super) fn parse_static(&mut self) -> Option<Let> {
|
|
self.next_token();
|
|
|
|
if self.peek_token().kind != TokenKind::Keyword(TokenKeyword::Let) {
|
|
self.error_expected_peek("let");
|
|
return None;
|
|
}
|
|
|
|
self.parse_let()
|
|
}
|
|
|
|
/// let ::= "let" identWithTy "=" expr
|
|
pub(super) fn parse_let(&mut self) -> Option<Let> {
|
|
self.next_token();
|
|
|
|
let (name, ty) = self.parse_ident_with_ty()?;
|
|
|
|
let expr = if self.skip_token(TokenKind::Symbol(TokenSymbol::Eq)) {
|
|
self.parse_expr()
|
|
} else if self.peek_token().kind == TokenKind::Newline {
|
|
None
|
|
} else {
|
|
self.error_expected_peek("= or newline");
|
|
return None;
|
|
};
|
|
|
|
Some(Let { name, ty, expr })
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn test_parse_let() {
|
|
use Literal::*;
|
|
|
|
let mut parser = Parser::new(
|
|
r#"static let test01: int = 4
|
|
let test02: char = '6'
|
|
static let test03: float
|
|
let test04 = 9"#,
|
|
);
|
|
assert_eq!(
|
|
parser.parse_static(),
|
|
Some(Let {
|
|
name: "test01".into(),
|
|
ty: Ty::Int,
|
|
expr: Some(Expr::Literal(Int(4)))
|
|
})
|
|
);
|
|
assert_eq!(parser.skip_token(TokenKind::Newline), true);
|
|
assert_eq!(
|
|
parser.parse_let(),
|
|
Some(Let {
|
|
name: "test02".into(),
|
|
ty: Ty::Char,
|
|
expr: Some(Expr::Literal(Char('6')))
|
|
})
|
|
);
|
|
assert_eq!(parser.skip_token(TokenKind::Newline), true);
|
|
assert_eq!(
|
|
parser.parse_static(),
|
|
Some(Let {
|
|
name: "test03".into(),
|
|
ty: Ty::Float,
|
|
expr: None
|
|
})
|
|
);
|
|
assert_eq!(parser.skip_token(TokenKind::Newline), true);
|
|
assert_eq!(parser.parse_let(), None);
|
|
}
|