rustversion/
token.rs

1use crate::error::{Error, Result};
2use crate::iter::Iter;
3use proc_macro::{Delimiter, Group, Ident, Literal, Span, TokenTree};
4
5pub fn parse_punct(iter: Iter, ch: char) -> Result<()> {
6    match iter.next() {
7        Some(TokenTree::Punct(ref punct)) if punct.as_char() == ch => Ok(()),
8        unexpected => {
9            let span = unexpected
10                .as_ref()
11                .map_or_else(Span::call_site, TokenTree::span);
12            Err(Error::new(span, format!("expected `{}`", ch)))
13        }
14    }
15}
16
17pub fn parse_optional_punct(iter: Iter, ch: char) -> Option<()> {
18    match iter.peek() {
19        Some(TokenTree::Punct(punct)) if punct.as_char() == ch => iter.next().map(drop),
20        _ => None,
21    }
22}
23
24pub fn parse_optional_keyword(iter: Iter, keyword: &str) -> Option<Span> {
25    match iter.peek() {
26        Some(TokenTree::Ident(ident)) if ident.to_string() == keyword => {
27            Some(iter.next().unwrap().span())
28        }
29        _ => None,
30    }
31}
32
33pub fn parse_literal(iter: Iter) -> Result<Literal> {
34    match iter.next() {
35        Some(TokenTree::Literal(literal)) => Ok(literal),
36        unexpected => {
37            let span = unexpected
38                .as_ref()
39                .map_or_else(Span::call_site, TokenTree::span);
40            Err(Error::new(span, "expected literal"))
41        }
42    }
43}
44
45pub fn parse_paren(introducer: &Ident, iter: Iter) -> Result<Group> {
46    match iter.peek() {
47        Some(TokenTree::Group(group)) if group.delimiter() == Delimiter::Parenthesis => {
48            match iter.next() {
49                Some(TokenTree::Group(group)) => Ok(group),
50                _ => unreachable!(),
51            }
52        }
53        Some(unexpected) => Err(Error::new(unexpected.span(), "expected `(`")),
54        None => Err(Error::new(
55            introducer.span(),
56            format!("expected `(` after `{}`", introducer),
57        )),
58    }
59}
60
61pub fn parse_optional_paren(iter: Iter) -> Option<Group> {
62    match iter.peek() {
63        Some(TokenTree::Group(group)) if group.delimiter() == Delimiter::Parenthesis => {
64            match iter.next() {
65                Some(TokenTree::Group(group)) => Some(group),
66                _ => unreachable!(),
67            }
68        }
69        _ => None,
70    }
71}
72
73pub fn parse_end(iter: Iter) -> Result<()> {
74    match iter.next() {
75        None => Ok(()),
76        Some(unexpected) => Err(Error::new(unexpected.span(), "unexpected token")),
77    }
78}
rustversion/token.rs

rustversion/
token.rs
