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
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
#![allow(clippy::implicit_hasher, clippy::or_fun_call)]
//! A tiny crate that helps convert ABNF grammars to [pest][pest].
use abnf::abnf::Rule;
pub use abnf::abnf::{
Alternation, Concatenation, Element, Range, Repeat, Repetition,
};
use itertools::Itertools;
use pretty::{BoxDoc, Doc};
use std::collections::HashMap;
trait Pretty {
fn pretty(&self) -> Doc<'static, BoxDoc<'static, ()>>;
}
impl Pretty for Alternation {
fn pretty(&self) -> Doc<'static, BoxDoc<'static, ()>> {
Doc::intersperse(
self.concatenations
.iter()
.map(|x| x.pretty().nest(2).group()),
Doc::space().append(Doc::text("| ")),
)
}
}
impl Pretty for Concatenation {
fn pretty(&self) -> Doc<'static, BoxDoc<'static, ()>> {
Doc::intersperse(
self.repetitions.iter().map(Repetition::pretty),
Doc::space().append(Doc::text("~ ")),
)
}
}
impl Pretty for Repetition {
fn pretty(&self) -> Doc<'static, BoxDoc<'static, ()>> {
self.element.pretty().append(
self.repeat
.as_ref()
.map(Repeat::pretty)
.unwrap_or(Doc::nil()),
)
}
}
impl Pretty for Repeat {
fn pretty(&self) -> Doc<'static, BoxDoc<'static, ()>> {
Doc::text(match (self.min.unwrap_or(0), self.max) {
(0, None) => "*".into(),
(1, None) => "+".into(),
(0, Some(1)) => "?".into(),
(min, None) => format!("{{{},}}", min),
(min, Some(max)) if min == max => format!("{{{}}}", min),
(min, Some(max)) => format!("{{{},{}}}", min, max),
})
}
}
impl Pretty for Element {
fn pretty(&self) -> Doc<'static, BoxDoc<'static, ()>> {
use abnf::abnf::Element::*;
match self {
Rulename(s) => Doc::text(escape_rulename(s)),
Group(g) => Doc::text("(")
.append((g.alternation).pretty().nest(4).group())
.append(Doc::text(")")),
Option(o) => Doc::text("(")
.append((o.alternation).pretty().nest(4).group())
.append(Doc::text(")?")),
CharVal(s) => Doc::text(format!(
"^\"{}\"",
s.replace("\"", "\\\"").replace("\\", "\\\\")
)),
NumVal(r) => r.pretty(),
ProseVal(_) => unimplemented!(),
}
}
}
impl Pretty for Range {
fn pretty(&self) -> Doc<'static, BoxDoc<'static, ()>> {
use abnf::abnf::Range::*;
Doc::text(match self {
Range(x, y) => {
format!("'{}'..'{}'", format_char(*x), format_char(*y))
}
OneOf(v) => {
format!("\"{}\"", v.iter().map(|x| format_char(*x)).join(""))
}
})
}
}
pub fn escape_rulename(x: &str) -> String {
let x = x.replace("-", "_");
if x == "if"
|| x == "else"
|| x == "as"
|| x == "let"
|| x == "in"
|| x == "fn"
// TODO: remove when https://github.com/pest-parser/pest/pull/375 gets into a release
|| x == "whitespace"
{
x + "_"
} else {
x.clone()
}
}
fn format_char(x: usize) -> String {
if x <= usize::from(u8::max_value()) {
let x: u8 = x as u8;
if x.is_ascii_graphic() {
let x: char = x as char;
if x != '"' && x != '\'' && x != '\\' {
return x.to_string();
}
}
}
format!("\\u{{{:02X}}}", x)
}
/// Allow control over some of the pest properties of the outputted rule
pub struct PestyRule {
pub silent: bool,
pub elements: Alternation,
}
impl Pretty for (String, PestyRule) {
fn pretty(&self) -> Doc<'static, BoxDoc<'static, ()>> {
Doc::nil()
.append(Doc::text(self.0.clone()))
.append(Doc::text(" = "))
.append(Doc::text(if self.1.silent { "_" } else { "" }))
.append(Doc::text("{"))
.append(Doc::space().append(self.1.elements.pretty()).nest(2))
.append(Doc::space())
.append(Doc::text("}"))
.group()
}
}
/// Parse an abnf file. Returns a map of rules.
pub fn parse_abnf(
data: &[u8],
) -> Result<HashMap<String, PestyRule>, std::io::Error> {
let make_err =
|e| std::io::Error::new(std::io::ErrorKind::Other, format!("{}", e));
let rules: Vec<Rule> =
abnf::abnf::rulelist_comp(&data).map_err(make_err)?.1;
Ok(rules
.into_iter()
.map(|rule| {
let name = escape_rulename(&rule.name);
(
name.clone(),
PestyRule {
silent: false,
elements: rule.elements.clone(),
},
)
})
.collect())
}
pub fn render_rules_to_pest<I>(
rules: I,
) -> Doc<'static, BoxDoc<'static, ()>, ()>
where
I: IntoIterator<Item = (String, PestyRule)>,
{
let pretty_rules = rules.into_iter().map(|x| x.pretty());
let doc: Doc<_> = Doc::intersperse(pretty_rules, Doc::newline());
doc
}
|
