1// SPDX-License-Identifier: GPL-2.0
 2
 3use proc_macro::{token_stream, TokenTree};
 4
 5pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option<String> {
 6    if let Some(TokenTree::Ident(ident)) = it.next() {
 7        Some(ident.to_string())
 8    } else {
 9        None
10    }
11}
12
13pub(crate) fn try_literal(it: &mut token_stream::IntoIter) -> Option<String> {
14    if let Some(TokenTree::Literal(literal)) = it.next() {
15        Some(literal.to_string())
16    } else {
17        None
18    }
19}
20
21pub(crate) fn try_string(it: &mut token_stream::IntoIter) -> Option<String> {
22    try_literal(it).and_then(|string| {
23        if string.starts_with('\"') && string.ends_with('\"') {
24            let content = &string[1..string.len() - 1];
25            if content.contains('\\') {
26                panic!("Escape sequences in string literals not yet handled");
27            }
28            Some(content.to_string())
29        } else if string.starts_with("r\"") {
30            panic!("Raw string literals are not yet handled");
31        } else {
32            None
33        }
34    })
35}
36
37pub(crate) fn expect_ident(it: &mut token_stream::IntoIter) -> String {
38    try_ident(it).expect("Expected Ident")
39}
40
41pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char {
42    if let TokenTree::Punct(punct) = it.next().expect("Reached end of token stream for Punct") {
43        punct.as_char()
44    } else {
45        panic!("Expected Punct");
46    }
47}
48
49pub(crate) fn expect_string(it: &mut token_stream::IntoIter) -> String {
50    try_string(it).expect("Expected string")
51}
52
53pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String {
54    let string = try_string(it).expect("Expected string");
55    assert!(string.is_ascii(), "Expected ASCII string");
56    string
57}
58
59pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {
60    if it.next().is_some() {
61        panic!("Expected end");
62    }
63}