1use anyhow::{anyhow, Context, Result};
2use smallvec::SmallVec;
3use std::{collections::BTreeMap, ops::Range};
4
5#[derive(Default)]
6pub struct Snippet {
7 pub text: String,
8 pub tabstops: Vec<TabStop>,
9}
10
11type TabStop = SmallVec<[Range<isize>; 2]>;
12
13impl Snippet {
14 pub fn parse(source: &str) -> Result<Self> {
15 let mut text = String::with_capacity(source.len());
16 let mut tabstops = BTreeMap::new();
17 parse_snippet(source, false, &mut text, &mut tabstops)
18 .context("failed to parse snippet")?;
19
20 let len = text.len() as isize;
21 let final_tabstop = tabstops.remove(&0);
22 let mut tabstops = tabstops.into_values().collect::<Vec<_>>();
23
24 if let Some(final_tabstop) = final_tabstop {
25 tabstops.push(final_tabstop);
26 } else {
27 let end_tabstop = [len..len].into_iter().collect();
28 if !tabstops.last().map_or(false, |t| *t == end_tabstop) {
29 tabstops.push(end_tabstop);
30 }
31 }
32
33 Ok(Snippet { text, tabstops })
34 }
35}
36
37fn parse_snippet<'a>(
38 mut source: &'a str,
39 nested: bool,
40 text: &mut String,
41 tabstops: &mut BTreeMap<usize, TabStop>,
42) -> Result<&'a str> {
43 loop {
44 match source.chars().next() {
45 None => return Ok(""),
46 Some('$') => {
47 source = parse_tabstop(&source[1..], text, tabstops)?;
48 }
49 Some('\\') => {
50 source = &source[1..];
51 if let Some(c) = source.chars().next() {
52 text.push(c);
53 source = &source[c.len_utf8()..];
54 }
55 }
56 Some('}') => {
57 if nested {
58 return Ok(source);
59 } else {
60 text.push('}');
61 source = &source[1..];
62 }
63 }
64 Some(_) => {
65 let chunk_end = source.find(['}', '$', '\\']).unwrap_or(source.len());
66 let (chunk, rest) = source.split_at(chunk_end);
67 text.push_str(chunk);
68 source = rest;
69 }
70 }
71 }
72}
73
74fn parse_tabstop<'a>(
75 mut source: &'a str,
76 text: &mut String,
77 tabstops: &mut BTreeMap<usize, TabStop>,
78) -> Result<&'a str> {
79 let tabstop_start = text.len();
80 let tabstop_index;
81 if source.starts_with('{') {
82 let (index, rest) = parse_int(&source[1..])?;
83 tabstop_index = index;
84 source = rest;
85
86 if source.starts_with(':') {
87 source = parse_snippet(&source[1..], true, text, tabstops)?;
88 }
89
90 if source.starts_with('}') {
91 source = &source[1..];
92 } else {
93 return Err(anyhow!("expected a closing brace"));
94 }
95 } else {
96 let (index, rest) = parse_int(source)?;
97 tabstop_index = index;
98 source = rest;
99 }
100
101 tabstops
102 .entry(tabstop_index)
103 .or_default()
104 .push(tabstop_start as isize..text.len() as isize);
105 Ok(source)
106}
107
108fn parse_int(source: &str) -> Result<(usize, &str)> {
109 let len = source
110 .find(|c: char| !c.is_ascii_digit())
111 .unwrap_or(source.len());
112 if len == 0 {
113 return Err(anyhow!("expected an integer"));
114 }
115 let (prefix, suffix) = source.split_at(len);
116 Ok((prefix.parse()?, suffix))
117}
118
119#[cfg(test)]
120mod tests {
121 use super::*;
122
123 #[test]
124 fn test_snippet_without_tabstops() {
125 let snippet = Snippet::parse("one-two-three").unwrap();
126 assert_eq!(snippet.text, "one-two-three");
127 assert_eq!(tabstops(&snippet), &[vec![13..13]]);
128 }
129
130 #[test]
131 fn test_snippet_with_tabstops() {
132 let snippet = Snippet::parse("one$1two").unwrap();
133 assert_eq!(snippet.text, "onetwo");
134 assert_eq!(tabstops(&snippet), &[vec![3..3], vec![6..6]]);
135
136 // Multi-digit numbers
137 let snippet = Snippet::parse("one$123-$99-two").unwrap();
138 assert_eq!(snippet.text, "one--two");
139 assert_eq!(tabstops(&snippet), &[vec![4..4], vec![3..3], vec![8..8]]);
140 }
141
142 #[test]
143 fn test_snippet_with_last_tabstop_at_end() {
144 let snippet = Snippet::parse(r#"foo.$1"#).unwrap();
145
146 // If the final tabstop is already at the end of the text, don't insert
147 // an additional tabstop at the end.
148 assert_eq!(snippet.text, r#"foo."#);
149 assert_eq!(tabstops(&snippet), &[vec![4..4]]);
150 }
151
152 #[test]
153 fn test_snippet_with_explicit_final_tabstop() {
154 let snippet = Snippet::parse(r#"<div class="$1">$0</div>"#).unwrap();
155
156 // If the final tabstop is explicitly specified via '$0', then
157 // don't insert an additional tabstop at the end.
158 assert_eq!(snippet.text, r#"<div class=""></div>"#);
159 assert_eq!(tabstops(&snippet), &[vec![12..12], vec![14..14]]);
160 }
161
162 #[test]
163 fn test_snippet_with_placeholders() {
164 let snippet = Snippet::parse("one${1:two}three${2:four}").unwrap();
165 assert_eq!(snippet.text, "onetwothreefour");
166 assert_eq!(
167 tabstops(&snippet),
168 &[vec![3..6], vec![11..15], vec![15..15]]
169 );
170 }
171
172 #[test]
173 fn test_snippet_with_nested_placeholders() {
174 let snippet = Snippet::parse(
175 "for (${1:var ${2:i} = 0; ${2:i} < ${3:${4:array}.length}; ${2:i}++}) {$0}",
176 )
177 .unwrap();
178 assert_eq!(snippet.text, "for (var i = 0; i < array.length; i++) {}");
179 assert_eq!(
180 tabstops(&snippet),
181 &[
182 vec![5..37],
183 vec![9..10, 16..17, 34..35],
184 vec![20..32],
185 vec![20..25],
186 vec![40..40],
187 ]
188 );
189 }
190
191 #[test]
192 fn test_snippet_parsing_with_escaped_chars() {
193 let snippet = Snippet::parse("\"\\$schema\": $1").unwrap();
194 assert_eq!(snippet.text, "\"$schema\": ");
195 assert_eq!(tabstops(&snippet), &[vec![11..11]]);
196
197 let snippet = Snippet::parse("{a\\}").unwrap();
198 assert_eq!(snippet.text, "{a}");
199 assert_eq!(tabstops(&snippet), &[vec![3..3]]);
200 }
201
202 fn tabstops(snippet: &Snippet) -> Vec<Vec<Range<isize>>> {
203 snippet.tabstops.iter().map(|t| t.to_vec()).collect()
204 }
205}