mit_commit/
trailer.rs

1use std::{
2    borrow::Cow,
3    convert::TryFrom,
4    hash::{Hash, Hasher},
5};
6
7use miette::Diagnostic;
8use thiserror::Error;
9
10use crate::{Fragment, body::Body};
11
12/// A [`Trailer`] you might see a in a [`CommitMessage`], for example
13/// 'Co-authored-by: Billie Thompson <billie@example.com>'
14#[derive(Debug, Clone, Eq, Ord, PartialOrd)]
15pub struct Trailer<'a> {
16    key: Cow<'a, str>,
17    value: Cow<'a, str>,
18}
19
20impl<'a> Trailer<'a> {
21    /// Create a new [`Trailer`]
22    ///
23    /// This creates a new element that represents the sort of [`Trailers`] you
24    /// get at the end of commits
25    ///
26    /// For example there's `Co-authored-by`, `Relates-to`, and `Signed-off-by`
27    ///
28    /// # Example
29    ///
30    /// ```
31    /// use std::convert::TryFrom;
32    ///
33    /// use mit_commit::{Body, Trailer};
34    /// assert_eq!(
35    ///     Trailer::new("Co-authored-by".into(), "#124".into()),
36    ///     Trailer::try_from(Body::from("Co-authored-by: #124"))
37    ///         .expect("There should have been a trailer in that body component")
38    /// )
39    /// ```
40    #[must_use]
41    pub const fn new(key: Cow<'a, str>, value: Cow<'a, str>) -> Self {
42        Self { key, value }
43    }
44
45    /// Get the key of the [`Trailer`]
46    ///
47    /// # Example
48    ///
49    /// ```
50    /// use std::convert::TryFrom;
51    ///
52    /// use mit_commit::{Body, Trailer};
53    /// assert_eq!(
54    ///     Trailer::new("Co-authored-by".into(), "#124".into()).get_key(),
55    ///     "Co-authored-by"
56    /// )
57    /// ```
58    #[must_use]
59    pub fn get_key(&self) -> String {
60        format!("{}", self.key)
61    }
62
63    /// Get the value of the [`Trailer`]
64    ///
65    /// # Example
66    ///
67    /// ```
68    /// use std::convert::TryFrom;
69    ///
70    /// use mit_commit::{Body, Trailer};
71    /// assert_eq!(
72    ///     Trailer::new("Co-authored-by".into(), "#124".into()).get_value(),
73    ///     "#124"
74    /// )
75    /// ```
76    #[must_use]
77    pub fn get_value(&self) -> String {
78        self.value.to_string()
79    }
80}
81
82impl PartialEq for Trailer<'_> {
83    fn eq(&self, other: &Self) -> bool {
84        self.key == other.key && self.value.trim_end() == other.value.trim_end()
85    }
86}
87
88impl Hash for Trailer<'_> {
89    fn hash<H: Hasher>(&self, state: &mut H) {
90        self.key.hash(state);
91        self.value.trim_end().hash(state);
92    }
93}
94
95impl From<Trailer<'_>> for String {
96    fn from(trailer: Trailer<'_>) -> Self {
97        format!("{}: {}", trailer.key, trailer.value)
98    }
99}
100
101impl<'a> From<Trailer<'a>> for Fragment<'a> {
102    fn from(trailer: Trailer<'_>) -> Self {
103        let trailer: String = trailer.into();
104        Body::from(trailer).into()
105    }
106}
107
108impl<'a> TryFrom<Body<'a>> for Trailer<'a> {
109    type Error = Error;
110
111    fn try_from(body: Body<'a>) -> Result<Self, Self::Error> {
112        let content: String = body.clone().into();
113        let mut value_and_key = content.split(": ").map(ToString::to_string);
114
115        let key: String = value_and_key
116            .next()
117            .ok_or_else(|| Error::new_not_a_trailer(&body))?;
118
119        let value: String = value_and_key
120            .next()
121            .ok_or_else(|| Error::new_not_a_trailer(&body))?;
122
123        Ok(Trailer::new(key.into(), value.into()))
124    }
125}
126
127/// Errors in parsing potential trailers
128#[derive(Error, Debug, Diagnostic)]
129pub enum Error {
130    /// When the given fragment is not a trailer
131    #[error("not a trailer")]
132    #[diagnostic(url(docsrs), code(mit_commit::trailer::error::not_atrailer))]
133    NotATrailer(
134        #[source_code] String,
135        #[label("no colon in body line")] (usize, usize),
136    ),
137}
138
139impl Error {
140    fn new_not_a_trailer(body: &Body<'_>) -> Self {
141        let text: String = body.clone().into();
142        Self::NotATrailer(text.clone(), (0, text.len()))
143    }
144}
145
146#[cfg(test)]
147mod tests {
148    use std::{
149        collections::hash_map::DefaultHasher,
150        convert::TryFrom,
151        hash::{Hash, Hasher},
152    };
153
154    use super::Trailer;
155    use crate::{Fragment, body::Body};
156
157    #[test]
158    fn it_can_tell_me_its_key() {
159        let trailer = Trailer::new("Relates-to".into(), "#128".into());
160
161        assert_eq!(trailer.get_key(), String::from("Relates-to"));
162    }
163
164    #[test]
165    fn it_can_tell_me_its_value() {
166        let trailer = Trailer::new("Relates-to".into(), "#128".into());
167
168        assert_eq!(trailer.get_value(), String::from("#128"));
169    }
170
171    #[test]
172    fn it_does_not_take_trailing_whitespace_into_account_in_equality_checks() {
173        let a = Trailer::new("Relates-to".into(), "#128\n".into());
174        let b = Trailer::new("Relates-to".into(), "#128".into());
175
176        assert_eq!(a, b);
177    }
178
179    #[test]
180    fn it_does_not_match_on_differing_vales() {
181        let a = Trailer::new("Relates-to".into(), "#129".into());
182        let b = Trailer::new("Relates-to".into(), "#128".into());
183
184        assert_ne!(a, b);
185    }
186
187    #[test]
188    fn it_does_not_match_on_differing_names() {
189        let a = Trailer::new("Another".into(), "#128".into());
190        let b = Trailer::new("Relates-to".into(), "#128".into());
191
192        assert_ne!(a, b);
193    }
194
195    #[test]
196    fn it_does_not_take_trailing_whitespace_into_account_in_hashing() {
197        let mut hasher_a = DefaultHasher::new();
198        Trailer::new("Relates-to".into(), "#128\n".into()).hash(&mut hasher_a);
199
200        let mut hasher_b = DefaultHasher::new();
201        Trailer::new("Relates-to".into(), "#128".into()).hash(&mut hasher_b);
202
203        assert_eq!(hasher_a.finish(), hasher_b.finish());
204    }
205
206    #[test]
207    fn it_differing_relates_headers_do_not_match_hashes() {
208        let mut hasher_a = DefaultHasher::new();
209        Trailer::new("Relates".into(), "#128".into()).hash(&mut hasher_a);
210
211        let mut hasher_b = DefaultHasher::new();
212        Trailer::new("Relates-to".into(), "#128".into()).hash(&mut hasher_b);
213
214        assert_ne!(hasher_a.finish(), hasher_b.finish());
215    }
216
217    #[test]
218    fn it_differing_relates_values_do_not_match_hashes() {
219        let mut hasher_a = DefaultHasher::new();
220        Trailer::new("Relates-to".into(), "#129".into()).hash(&mut hasher_a);
221
222        let mut hasher_b = DefaultHasher::new();
223        Trailer::new("Relates-to".into(), "#128".into()).hash(&mut hasher_b);
224
225        assert_ne!(hasher_a.finish(), hasher_b.finish());
226    }
227
228    #[test]
229    fn it_can_give_me_itself_as_a_string() {
230        let trailer = Trailer::new("Relates-to".into(), "#128".into());
231
232        assert_eq!(String::from(trailer), String::from("Relates-to: #128"));
233    }
234
235    #[test]
236    fn can_generate_itself_from_body() {
237        let trailer = Trailer::try_from(Body::from("Relates-to: #128"));
238
239        assert_eq!(
240            String::from(trailer.expect("Could not parse from string")),
241            String::from("Relates-to: #128")
242        );
243    }
244
245    #[test]
246    fn it_preserves_preceding_whitespace() {
247        let trailer = Trailer::try_from(Body::from("Relates-to:      #128\n"));
248
249        assert_eq!(
250            String::from(trailer.expect("Could not parse from string")),
251            String::from("Relates-to:      #128\n")
252        );
253    }
254
255    #[test]
256    fn can_generate_from_body() {
257        let trailer = Trailer::new("Relates-to".into(), "#128".into());
258        let body: Fragment<'_> = Fragment::from(trailer);
259
260        assert_eq!(body, Fragment::Body(Body::from("Relates-to: #128")));
261    }
262}
mit_commit/trailer.rs

mit_commit/
trailer.rs
