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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
//! `mbe` (short for Macro By Example) crate contains code for handling
//! `macro_rules` macros. It uses `TokenTree` (from `ra_tt` package) as the
//! interface, although it contains some code to bridge `SyntaxNode`s and
//! `TokenTree`s as well!
mod parser;
mod mbe_expander;
mod syntax_bridge;
mod tt_iter;
mod subtree_source;
pub use tt::{Delimiter, Punct};
use crate::{
parser::{parse_pattern, Op},
tt_iter::TtIter,
};
#[derive(Debug, PartialEq, Eq)]
pub enum ParseError {
Expected(String),
}
#[derive(Debug, PartialEq, Eq)]
pub enum ExpandError {
NoMatchingRule,
UnexpectedToken,
BindingError(String),
ConversionError,
InvalidRepeat,
}
pub use crate::syntax_bridge::{
ast_to_token_tree, syntax_node_to_token_tree, token_tree_to_expr, token_tree_to_items,
token_tree_to_macro_stmts, token_tree_to_pat, token_tree_to_ty, TokenMap,
};
/// This struct contains AST for a single `macro_rules` definition. What might
/// be very confusing is that AST has almost exactly the same shape as
/// `tt::TokenTree`, but there's a crucial difference: in macro rules, `$ident`
/// and `$()*` have special meaning (see `Var` and `Repeat` data structures)
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct MacroRules {
pub(crate) rules: Vec<Rule>,
/// Highest id of the token we have in TokenMap
pub(crate) shift: u32,
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) struct Rule {
pub(crate) lhs: tt::Subtree,
pub(crate) rhs: tt::Subtree,
}
// Find the max token id inside a subtree
fn max_id(subtree: &tt::Subtree) -> Option<u32> {
subtree
.token_trees
.iter()
.filter_map(|tt| match tt {
tt::TokenTree::Subtree(subtree) => max_id(subtree),
tt::TokenTree::Leaf(tt::Leaf::Ident(ident))
if ident.id != tt::TokenId::unspecified() =>
{
Some(ident.id.0)
}
_ => None,
})
.max()
}
/// Shift given TokenTree token id
fn shift_subtree(tt: &mut tt::Subtree, shift: u32) {
for t in tt.token_trees.iter_mut() {
match t {
tt::TokenTree::Leaf(leaf) => match leaf {
tt::Leaf::Ident(ident) if ident.id != tt::TokenId::unspecified() => {
ident.id.0 += shift;
}
_ => (),
},
tt::TokenTree::Subtree(tt) => shift_subtree(tt, shift),
}
}
}
impl MacroRules {
pub fn parse(tt: &tt::Subtree) -> Result<MacroRules, ParseError> {
// Note: this parsing can be implemented using mbe machinery itself, by
// matching against `$($lhs:tt => $rhs:tt);*` pattern, but implementing
// manually seems easier.
let mut src = TtIter::new(tt);
let mut rules = Vec::new();
while src.len() > 0 {
let rule = Rule::parse(&mut src)?;
rules.push(rule);
if let Err(()) = src.expect_char(';') {
if src.len() > 0 {
return Err(ParseError::Expected("expected `:`".to_string()));
}
break;
}
}
for rule in rules.iter() {
validate(&rule.lhs)?;
}
// Note that TokenId is started from zero,
// We have to add 1 to prevent duplication.
let shift = max_id(tt).map_or(0, |it| it + 1);
Ok(MacroRules { rules, shift })
}
pub fn expand(&self, tt: &tt::Subtree) -> Result<tt::Subtree, ExpandError> {
// apply shift
let mut tt = tt.clone();
shift_subtree(&mut tt, self.shift);
mbe_expander::expand(self, &tt)
}
}
impl Rule {
fn parse(src: &mut TtIter) -> Result<Rule, ParseError> {
let mut lhs = src
.expect_subtree()
.map_err(|()| ParseError::Expected("expected subtree".to_string()))?
.clone();
lhs.delimiter = tt::Delimiter::None;
src.expect_char('=').map_err(|()| ParseError::Expected("expected `=`".to_string()))?;
src.expect_char('>').map_err(|()| ParseError::Expected("expected `>`".to_string()))?;
let mut rhs = src
.expect_subtree()
.map_err(|()| ParseError::Expected("expected subtree".to_string()))?
.clone();
rhs.delimiter = tt::Delimiter::None;
Ok(crate::Rule { lhs, rhs })
}
}
fn validate(pattern: &tt::Subtree) -> Result<(), ParseError> {
for op in parse_pattern(pattern) {
let op = match op {
Ok(it) => it,
Err(e) => {
let msg = match e {
ExpandError::InvalidRepeat => "invalid repeat".to_string(),
_ => "invalid macro definition".to_string(),
};
return Err(ParseError::Expected(msg));
}
};
match op {
Op::TokenTree(tt::TokenTree::Subtree(subtree)) | Op::Repeat { subtree, .. } => {
validate(subtree)?
}
_ => (),
}
}
Ok(())
}
#[cfg(test)]
mod tests;
|
