52 lines
1.4 KiB
Rust
52 lines
1.4 KiB
Rust
use num::Num;
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use yap::{IntoTokens, Tokens};
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pub fn space(tokens: &mut impl Tokens<Item = char>) -> bool {
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tokens.token(' ')
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}
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pub fn newline(tokens: &mut impl Tokens<Item = char>) -> bool {
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tokens.tokens("\r\n".into_tokens()) || tokens.token('\n')
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}
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pub fn parse_number<T: Num>(tokens: &mut impl Tokens<Item = char>) -> Option<T> {
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parse_number_with_radix(tokens, 10, None)
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}
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pub fn parse_digit<T: Num>(tokens: &mut impl Tokens<Item = char>) -> Option<T> {
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parse_number_with_radix(tokens, 10, Some(1))
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}
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pub fn parse_number_with_radix<T: Num>(
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tokens: &mut impl Tokens<Item = char>,
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base: u32,
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limit: Option<usize>,
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) -> Option<T> {
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tokens.skip_tokens_while(|t| *t == ' ');
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let mut remaining = limit.map(|x| x as isize).unwrap_or(isize::MAX);
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let digits: String = tokens
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.tokens_while(|c| {
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remaining -= 1;
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c.is_digit(base) && remaining >= 0
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})
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.collect();
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if !digits.is_empty() {
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T::from_str_radix(&digits, base).ok()
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} else {
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None
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}
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}
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#[cfg(test)]
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mod test {
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use yap::IntoTokens;
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#[test]
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fn parse_digit() {
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let mut tokens = "1234".into_tokens();
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assert_eq!(Some(1), super::parse_digit(&mut tokens));
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assert_eq!(Some(2), super::parse_digit(&mut tokens));
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assert_eq!(Some(3), super::parse_digit(&mut tokens));
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assert_eq!(Some(4), super::parse_digit(&mut tokens));
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}
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}
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