1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
use crate::tt;
pub(crate) struct TtCursor<'a> {
subtree: &'a tt::Subtree,
pos: usize,
}
impl<'a> TtCursor<'a> {
pub(crate) fn new(subtree: &'a tt::Subtree) -> TtCursor<'a> {
TtCursor { subtree, pos: 0 }
}
pub(crate) fn is_eof(&self) -> bool {
self.pos == self.subtree.token_trees.len()
}
pub(crate) fn current(&self) -> Option<&'a tt::TokenTree> {
self.subtree.token_trees.get(self.pos)
}
pub(crate) fn at_punct(&self) -> Option<&'a tt::Punct> {
match self.current() {
Some(tt::TokenTree::Leaf(tt::Leaf::Punct(it))) => Some(it),
_ => None,
}
}
pub(crate) fn at_char(&self, char: char) -> bool {
match self.at_punct() {
Some(tt::Punct { char: c }) if *c == char => true,
_ => false,
}
}
pub(crate) fn at_ident(&mut self) -> Option<&'a tt::Ident> {
match self.current() {
Some(tt::TokenTree::Leaf(tt::Leaf::Ident(i))) => Some(i),
_ => None,
}
}
pub(crate) fn bump(&mut self) {
self.pos += 1;
}
pub(crate) fn rev_bump(&mut self) {
self.pos -= 1;
}
pub(crate) fn eat(&mut self) -> Option<&'a tt::TokenTree> {
match self.current() {
Some(it) => {
self.bump();
Some(it)
}
None => None,
}
}
pub(crate) fn eat_subtree(&mut self) -> Option<&'a tt::Subtree> {
match self.current()? {
tt::TokenTree::Subtree(sub) => {
self.bump();
Some(sub)
}
_ => return None,
}
}
pub(crate) fn eat_punct(&mut self) -> Option<&'a tt::Punct> {
if let Some(it) = self.at_punct() {
self.bump();
return Some(it);
}
None
}
pub(crate) fn eat_ident(&mut self) -> Option<&'a tt::Ident> {
if let Some(i) = self.at_ident() {
self.bump();
return Some(i);
}
None
}
pub(crate) fn expect_char(&mut self, char: char) -> Option<()> {
if self.at_char(char) {
self.bump();
return Some(());
}
None
}
}
|
