/
tokentrees.rs
149 lines (133 loc) · 6.42 KB
/
tokentrees.rs
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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use print::pprust::token_to_string;
use parse::lexer::StringReader;
use parse::{token, PResult};
use tokenstream::{Delimited, TokenStream, TokenTree};
impl<'a> StringReader<'a> {
// Parse a stream of tokens into a list of `TokenTree`s, up to an `Eof`.
crate fn parse_all_token_trees(&mut self) -> PResult<'a, TokenStream> {
let mut tts = Vec::new();
while self.token != token::Eof {
tts.push(self.parse_token_tree()?);
}
Ok(TokenStream::concat(tts))
}
// Parse a stream of tokens into a list of `TokenTree`s, up to a `CloseDelim`.
fn parse_token_trees_until_close_delim(&mut self) -> TokenStream {
let mut tts = vec![];
loop {
if let token::CloseDelim(..) = self.token {
return TokenStream::concat(tts);
}
match self.parse_token_tree() {
Ok(tree) => tts.push(tree),
Err(mut e) => {
e.emit();
return TokenStream::concat(tts);
}
}
}
}
fn parse_token_tree(&mut self) -> PResult<'a, TokenStream> {
match self.token {
token::Eof => {
let msg = "this file contains an un-closed delimiter";
let mut err = self.sess.span_diagnostic.struct_span_err(self.span, msg);
for &(_, sp) in &self.open_braces {
err.span_label(sp, "un-closed delimiter");
}
Err(err)
},
token::OpenDelim(delim) => {
// The span for beginning of the delimited section
let pre_span = self.span;
// Parse the open delimiter.
self.open_braces.push((delim, self.span));
self.real_token();
// Parse the token trees within the delimiters.
// We stop at any delimiter so we can try to recover if the user
// uses an incorrect delimiter.
let tts = self.parse_token_trees_until_close_delim();
// Expand to cover the entire delimited token tree
let span = pre_span.with_hi(self.span.hi());
match self.token {
// Correct delimiter.
token::CloseDelim(d) if d == delim => {
self.open_braces.pop().unwrap();
// Parse the close delimiter.
self.real_token();
}
// Incorrect delimiter.
token::CloseDelim(other) => {
let token_str = token_to_string(&self.token);
if self.last_unclosed_found_span != Some(self.span) {
// do not complain about the same unclosed delimiter multiple times
self.last_unclosed_found_span = Some(self.span);
let msg = format!("incorrect close delimiter: `{}`", token_str);
let mut err = self.sess.span_diagnostic.struct_span_err(
self.span,
&msg,
);
err.span_label(self.span, "incorrect close delimiter");
// This is a conservative error: only report the last unclosed
// delimiter. The previous unclosed delimiters could actually be
// closed! The parser just hasn't gotten to them yet.
if let Some(&(_, sp)) = self.open_braces.last() {
err.span_label(sp, "un-closed delimiter");
};
err.emit();
}
self.open_braces.pop().unwrap();
// If the incorrect delimiter matches an earlier opening
// delimiter, then don't consume it (it can be used to
// close the earlier one). Otherwise, consume it.
// E.g., we try to recover from:
// fn foo() {
// bar(baz(
// } // Incorrect delimiter but matches the earlier `{`
if !self.open_braces.iter().any(|&(b, _)| b == other) {
self.real_token();
}
}
token::Eof => {
// Silently recover, the EOF token will be seen again
// and an error emitted then. Thus we don't pop from
// self.open_braces here.
},
_ => {}
}
Ok(TokenTree::Delimited(span, Delimited {
delim,
tts: tts.into(),
}).into())
},
token::CloseDelim(_) => {
// An unexpected closing delimiter (i.e., there is no
// matching opening delimiter).
let token_str = token_to_string(&self.token);
let msg = format!("unexpected close delimiter: `{}`", token_str);
let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg);
err.span_label(self.span, "unexpected close delimiter");
Err(err)
},
_ => {
let tt = TokenTree::Token(self.span, self.token.clone());
// Note that testing for joint-ness here is done via the raw
// source span as the joint-ness is a property of the raw source
// rather than wanting to take `override_span` into account.
let raw = self.span_src_raw;
self.real_token();
let is_joint = raw.hi() == self.span_src_raw.lo() && token::is_op(&self.token);
Ok(if is_joint { tt.joint() } else { tt.into() })
}
}
}
}