git-commit: remove dependency on git-trailers

The git-trailers crate depends on parsing logic using nom. This is a
heavy dependency for something that can be done using git2.

Remove the dependency of git-trailers in git-commit and localise the
trailer types -- using git2 to parse the trailers out of the git
commit message.

Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett

git-commit/Cargo.toml

@@ -8,7 +8,7 @@ authors = [
   "Fintan Halpenny <fintan.halpenny@gmail.com>",
 ]
 description = "A small library for parsing, displaying and creating a git commit"
-keywords = ["git", "radicle"]
+keywords = ["git", "git-commit", "git-trailers", "radicle"]
 
 [dependencies]
 thiserror = "1"
@@ -17,7 +17,3 @@ thiserror = "1"
 version = "0.16.1"
 default-features = false
 features = ["vendored-libgit2"]
-
-[dependencies.git-trailers]
-version = "0.1.0"
-path = "../git-trailers"

git-commit/src/lib.rs

@@ -17,7 +17,6 @@ use std::{
 };
 
 use git2::{ObjectType, Oid};
-use git_trailers::{self as trailers, OwnedTrailer, Trailer};
 
 pub mod author;
 pub use author::Author;
@@ -25,6 +24,9 @@ pub use author::Author;
 pub mod headers;
 pub use headers::{Headers, Signature};
 
+pub mod trailers;
+pub use trailers::{OwnedTrailer, Trailer, Trailers};
+
 /// A git commit in its object description form, i.e. the output of
 /// `git cat-file` for a commit object.
 #[derive(Debug)]
@@ -162,8 +164,6 @@ pub mod error {
         InvalidFormat,
         #[error("missing '{0}' while parsing commit")]
         Missing(&'static str),
-        #[error(transparent)]
-        Token(#[from] git_trailers::InvalidToken),
         #[error("error occurred while checking for git-trailers: {0}")]
         Trailers(#[source] git2::Error),
         #[error(transparent)]
@@ -243,19 +243,14 @@ impl FromStr for Commit {
             }
         }
 
-        let (message, trailers) = message.lines().fold(
-            (Vec::new(), Vec::new()),
-            |(mut message, mut trailers), line| match trailers::parser::trailer(line, ": ") {
-                Ok((_, trailer)) => {
-                    trailers.push(trailer.into());
-                    (message, trailers)
-                },
-                Err(_) => {
-                    message.push(line);
-                    (message, trailers)
-                },
-            },
-        );
+        let trailers = trailers::Trailers::parse(message).map_err(error::Parse::Trailers)?;
+
+        let message = message
+            .strip_suffix(&trailers.to_string(": "))
+            .unwrap_or(message)
+            .to_string();
+
+        let trailers = trailers.iter().map(OwnedTrailer::from).collect();
 
         Ok(Self {
             tree,
@@ -263,7 +258,7 @@ impl FromStr for Commit {
             author: author.ok_or(error::Parse::Missing("author"))?,
             committer: committer.ok_or(error::Parse::Missing("committer"))?,
             headers,
-            message: message.join("\n"),
+            message,
             trailers,
         })
     }

git-commit/src/trailers.rs

@@ -0,0 +1,214 @@
+use std::{borrow::Cow, fmt, fmt::Write, ops::Deref, str::FromStr};
+
+use git2::{MessageTrailersStrs, MessageTrailersStrsIterator};
+
+/// A Git commit's set of trailers that are left in the commit's
+/// message.
+///
+/// Trailers are key/value pairs in the last paragraph of a message,
+/// not including any patches or conflicts that may be present.
+///
+/// # Usage
+///
+/// To construct `Trailers`, you can use [`Trailers::parse`] or its
+/// `FromStr` implementation.
+///
+/// To iterate over the trailers, you can use [`Trailers::iter`].
+///
+/// To render the trailers to a `String`, you can use
+/// [`Trailers::to_string`] or its `Display` implementation (note that
+/// it will default to using `": "` as the separator.
+///
+/// # Examples
+///
+/// ```text
+/// Add new functionality
+///
+/// Making code better with new functionality.
+///
+/// X-Signed-Off-By: Alex Sellier
+/// X-Co-Authored-By: Fintan Halpenny
+/// ```
+///
+/// The trailers in the above example are:
+///
+/// ```text
+/// X-Signed-Off-By: Alex Sellier
+/// X-Co-Authored-By: Fintan Halpenny
+/// ```
+pub struct Trailers {
+    inner: MessageTrailersStrs,
+}
+
+impl Trailers {
+    pub fn parse(message: &str) -> Result<Self, git2::Error> {
+        Ok(Self {
+            inner: git2::message_trailers_strs(message)?,
+        })
+    }
+
+    pub fn iter(&self) -> Iter<'_> {
+        Iter {
+            inner: self.inner.iter(),
+        }
+    }
+
+    pub fn to_string<'a, S>(&self, sep: S) -> String
+    where
+        S: Separator<'a>,
+    {
+        let mut buf = String::new();
+        for (i, trailer) in self.iter().enumerate() {
+            if i > 0 {
+                writeln!(buf).ok();
+            }
+
+            write!(buf, "{}", trailer.display(sep.sep_for(&trailer.token))).ok();
+        }
+        writeln!(buf).ok();
+        buf
+    }
+}
+
+impl fmt::Display for Trailers {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(&self.to_string(": "))
+    }
+}
+
+pub trait Separator<'a> {
+    fn sep_for(&self, token: &Token) -> &'a str;
+}
+
+impl<'a> Separator<'a> for &'a str {
+    fn sep_for(&self, _: &Token) -> &'a str {
+        self
+    }
+}
+
+impl<'a, F> Separator<'a> for F
+where
+    F: Fn(&Token) -> &'a str,
+{
+    fn sep_for(&self, token: &Token) -> &'a str {
+        self(token)
+    }
+}
+
+impl FromStr for Trailers {
+    type Err = git2::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Self::parse(s)
+    }
+}
+
+pub struct Iter<'a> {
+    inner: MessageTrailersStrsIterator<'a>,
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = Trailer<'a>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let (token, value) = self.inner.next()?;
+        Some(Trailer {
+            token: Token(token),
+            value: Cow::Borrowed(value),
+        })
+    }
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct Token<'a>(&'a str);
+
+impl Deref for Token<'_> {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+
+pub struct Display<'a> {
+    trailer: &'a Trailer<'a>,
+    separator: &'a str,
+}
+
+impl<'a> fmt::Display for Display<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "{}{}{}",
+            self.trailer.token.deref(),
+            self.separator,
+            self.trailer.value,
+        )
+    }
+}
+
+/// A trailer is a key/value pair found in the last paragraph of a Git
+/// commit message, not including any patches or conflicts that may be
+/// present.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct Trailer<'a> {
+    pub token: Token<'a>,
+    pub value: Cow<'a, str>,
+}
+
+impl<'a> Trailer<'a> {
+    pub fn display(&'a self, separator: &'a str) -> Display<'a> {
+        Display {
+            trailer: self,
+            separator,
+        }
+    }
+
+    pub fn to_owned(&self) -> OwnedTrailer {
+        OwnedTrailer::from(self)
+    }
+}
+
+/// A version of the [`Trailer`] which owns its token and
+/// value. Useful for when you need to carry trailers around in a long
+/// lived data structure.
+#[derive(Debug)]
+pub struct OwnedTrailer {
+    pub token: OwnedToken,
+    pub value: String,
+}
+
+#[derive(Debug)]
+pub struct OwnedToken(String);
+
+impl Deref for OwnedToken {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a> From<&Trailer<'a>> for OwnedTrailer {
+    fn from(t: &Trailer<'a>) -> Self {
+        OwnedTrailer {
+            token: OwnedToken(t.token.0.to_string()),
+            value: t.value.to_string(),
+        }
+    }
+}
+
+impl<'a> From<Trailer<'a>> for OwnedTrailer {
+    fn from(t: Trailer<'a>) -> Self {
+        (&t).into()
+    }
+}
+
+impl<'a> From<&'a OwnedTrailer> for Trailer<'a> {
+    fn from(t: &'a OwnedTrailer) -> Self {
+        Trailer {
+            token: Token(t.token.0.as_str()),
+            value: Cow::from(&t.value),
+        }
+    }
+}

git-commit/t/Cargo.toml

@@ -14,7 +14,7 @@ doc = false
 [features]
 test = []
 
-[dependencies.git-commit]
+[dev-dependencies.git-commit]
 path = ".."
 
 [dev-dependencies.git2]