wright/parser/literal/
integer.rs

1//! Integer literal parsing implementation.
2
3use crate::parser::Parser;
4use crate::parser::error::{ParserError, ParserErrorKind};
5use crate::{ast::literal::IntegerLiteral, lexer::token::TokenTy};
6use num::{BigUint, Num};
7
8impl IntegerLiteral {
9    /// Parse an integer literal from the given [Parser].
10    pub fn parse(parser: &mut Parser) -> Result<Self, ParserError> {
11        // Get the token containing the integer literal from the parser.
12        let int_lit_token = parser.next_if_is(TokenTy::IntegerLiteral).ok_or_else(|| {
13            ParserErrorKind::ExpectedIntegerLiteral.at(parser.peek_fragment_or_rest_cloned())
14        })?;
15
16        // Get the string to pass to num for the rest of parsing.
17        let mut parse_str: &str = int_lit_token.fragment.as_str();
18        let mut chars = parse_str.chars();
19
20        // Unwrap: Integer literals must be at minimum 1 character, enforced by the lexer.
21        // use null byte as a sentinel value for the second one, since we're just using the prefix to check for
22        // a radix to pass to num.
23        let prefix: [char; 2] = [chars.next().unwrap(), chars.next().unwrap_or('\0')];
24
25        // Determine the radix and remove any prefix in the process.
26        let radix: u32 = match prefix {
27            // Hexidecimal.
28            ['0', 'x' | 'X'] => {
29                parse_str = &parse_str[2..];
30                16
31            }
32
33            // Binary.
34            ['0', 'b' | 'B'] => {
35                parse_str = &parse_str[2..];
36                2
37            }
38
39            // Octal
40            ['0', 'o'] => {
41                parse_str = &parse_str[2..];
42                8
43            }
44
45            // All other patterns are not radix-prefixes.
46            _ => 10,
47        };
48
49        // Pass the remainder of parsing off to num.
50        let value = BigUint::from_str_radix(parse_str, radix)
51            // We can use expect here for now since we have validated the format of the string
52            // on our own before passing it off.
53            .expect("num should successfully parse");
54
55        Ok(IntegerLiteral {
56            fragment: int_lit_token.fragment,
57            value,
58        })
59    }
60}
61
62#[cfg(test)]
63mod tests {
64    use num::BigUint;
65
66    use crate::{ast::literal::IntegerLiteral, lexer::Lexer, parser::Parser};
67
68    #[test]
69    fn normal() {
70        let mut parser = Parser::new(Lexer::new_test("1000"));
71
72        let int_lit = IntegerLiteral::parse(&mut parser).unwrap();
73
74        assert_eq!(int_lit.value, BigUint::new(vec![1000]));
75        assert_eq!(parser.lexer.remaining.as_str(), "");
76        assert_eq!(int_lit.fragment.as_str(), "1000");
77    }
78
79    // #[test]
80    // fn ingore_underscores
81}
wright/parser/literal/integer.rs

wright/parser/literal/
integer.rs
