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
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
use crate::ParseError;
use crate::subtree_parser::Parser;
#[derive(Clone)]
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> {
self.current().map(|it| {
self.bump();
it
})
}
pub(crate) fn eat_subtree(&mut self) -> Result<&'a tt::Subtree, ParseError> {
match self.current() {
Some(tt::TokenTree::Subtree(sub)) => {
self.bump();
Ok(sub)
}
_ => Err(ParseError::Expected(String::from("subtree"))),
}
}
pub(crate) fn eat_punct(&mut self) -> Option<&'a tt::Punct> {
self.at_punct().map(|it| {
self.bump();
it
})
}
pub(crate) fn eat_ident(&mut self) -> Option<&'a tt::Ident> {
self.at_ident().map(|i| {
self.bump();
i
})
}
pub(crate) fn eat_path(&mut self) -> Option<tt::TokenTree> {
let parser = Parser::new(&mut self.pos, self.subtree);
parser.parse_path()
}
pub(crate) fn eat_expr(&mut self) -> Option<tt::TokenTree> {
let parser = Parser::new(&mut self.pos, self.subtree);
parser.parse_expr()
}
pub(crate) fn eat_ty(&mut self) -> Option<tt::TokenTree> {
let parser = Parser::new(&mut self.pos, self.subtree);
parser.parse_ty()
}
pub(crate) fn eat_pat(&mut self) -> Option<tt::TokenTree> {
let parser = Parser::new(&mut self.pos, self.subtree);
parser.parse_pat()
}
pub(crate) fn eat_stmt(&mut self) -> Option<tt::TokenTree> {
let parser = Parser::new(&mut self.pos, self.subtree);
parser.parse_stmt()
}
pub(crate) fn eat_block(&mut self) -> Option<tt::TokenTree> {
let parser = Parser::new(&mut self.pos, self.subtree);
parser.parse_block()
}
pub(crate) fn eat_meta(&mut self) -> Option<tt::TokenTree> {
let parser = Parser::new(&mut self.pos, self.subtree);
parser.parse_meta()
}
pub(crate) fn eat_item(&mut self) -> Option<tt::TokenTree> {
let parser = Parser::new(&mut self.pos, self.subtree);
parser.parse_item()
}
pub(crate) fn expect_char(&mut self, char: char) -> Result<(), ParseError> {
if self.at_char(char) {
self.bump();
Ok(())
} else {
Err(ParseError::Expected(format!("`{}`", char)))
}
}
}
|
