feature: add Trailers impl and trailers method to Commit

crates/mono-repository/src/repository.rs

@@ -30,6 +30,7 @@ use std::path::Path;
 use std::process::Command;
 
 pub mod commit;
+pub mod commits;
 mod error;
 pub mod id;
 pub mod versions;

crates/mono-repository/src/repository/commit.rs

@@ -32,10 +32,12 @@ use super::id::Id;
 use super::Repository;
 
 mod delta;
-mod iter;
+mod deltas;
+mod trailers;
 
-pub use delta::{Delta, Deltas};
-pub use iter::Commits;
+pub use delta::Delta;
+pub use deltas::Deltas;
+pub use trailers::Trailers;
 
 // ----------------------------------------------------------------------------
 // Structs
@@ -166,10 +168,7 @@ impl fmt::Debug for Commit<'_> {
 ///
 /// [`Error::Git`]: crate::repository::Error::Git
 pub fn trim_trailers(message: &str) -> Result<&str> {
-    // We must add two line feeds to the message, or the trailers would not be
-    // discoverable, since git assumes that we pass the entire commit message
-    let prepared = format!("\n\n{message}");
-    let trailers = git2::message_trailers_strs(prepared.as_str())?;
+    let trailers: Trailers = message.parse()?;
     if let Some((key, _)) = trailers.iter().next() {
         Ok(message.split_once(key).map_or(message, |(body, _)| body))
     } else {

crates/mono-repository/src/repository/commit/delta.rs

@@ -27,10 +27,6 @@
 
 use std::path::PathBuf;
 
-mod iter;
-
-pub use iter::Deltas;
-
 // ----------------------------------------------------------------------------
 // Enums
 // ----------------------------------------------------------------------------

crates/mono-repository/src/repository/commit/delta/iter.rs → crates/mono-repository/src/repository/commit/deltas.rs

@@ -28,7 +28,7 @@
 use crate::repository::commit::Commit;
 use crate::repository::Result;
 
-use super::Delta;
+use super::delta::Delta;
 
 // ----------------------------------------------------------------------------
 // Structs

crates/mono-repository/src/repository/commit/trailers.rs

@@ -0,0 +1,151 @@
+// Copyright (c) 2025 Zensical and contributors
+
+// SPDX-License-Identifier: MIT
+// Third-party contributions licensed under DCO
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+// ----------------------------------------------------------------------------
+
+//! Commit trailer set.
+
+use std::fmt;
+use std::str::FromStr;
+
+use crate::repository::commit::Commit;
+use crate::repository::{Error, Result};
+
+// ----------------------------------------------------------------------------
+// Structs
+// ----------------------------------------------------------------------------
+
+/// Commit trailer set.
+pub struct Trailers {
+    /// Git trailers.
+    inner: git2::MessageTrailersStrs,
+}
+
+// ----------------------------------------------------------------------------
+// Implementations
+// ----------------------------------------------------------------------------
+
+impl Commit<'_> {
+    /// Returns the trailer set of the commit.
+    ///
+    /// We must add two line feeds to the message, or the trailers would not be
+    /// discoverable, since git assumes that we pass the entire commit message
+    ///
+    /// # Errors
+    ///
+    /// This method returns [`Error::Git`] if the operation fails.
+    #[allow(clippy::missing_panics_doc)]
+    #[inline]
+    pub fn trailers(&self) -> Result<Trailers> {
+        Trailers::from_str(self.inner.body().unwrap_or_default())
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+impl Trailers {
+    /// Returns a reference to the value identified by the key.
+    pub fn get<K>(&self, key: K) -> Option<&str>
+    where
+        K: AsRef<str>,
+    {
+        let mut iter = self.inner.iter();
+        iter.find_map(|(candidate, value)| {
+            (candidate == key.as_ref()).then_some(value)
+        })
+    }
+
+    /// Returns whether the commit trailer set contains the key.
+    pub fn contains_key<K>(&self, key: K) -> bool
+    where
+        K: AsRef<str>,
+    {
+        let mut iter = self.inner.iter();
+        iter.any(|(candidate, _)| candidate == key.as_ref())
+    }
+
+    /// Creates an iterator over the commit trailer set.
+    #[inline]
+    #[must_use]
+    pub fn iter(&self) -> git2::MessageTrailersStrsIterator<'_> {
+        self.into_iter()
+    }
+}
+
+#[allow(clippy::must_use_candidate)]
+impl Trailers {
+    /// Returns the number of trailers.
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.inner.len()
+    }
+
+    /// Returns whether there are any trailers.
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.inner.len() == 0
+    }
+}
+
+// ----------------------------------------------------------------------------
+// Trait implementations
+// ----------------------------------------------------------------------------
+
+impl FromStr for Trailers {
+    type Err = Error;
+
+    /// Attempts to create a commit trailer set from a string.
+    ///
+    /// # Errors
+    ///
+    /// This method returns [`Error::Git`] if the operation fails.
+    fn from_str(value: &str) -> Result<Self> {
+        // We must add two line feeds to the message or the trailers wouldn't be
+        // discoverable, as git assumes that we pass the entire commit message
+        let prepared = format!("\n\n{value}");
+        Ok(Self {
+            inner: git2::message_trailers_strs(prepared.as_str())?,
+        })
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+impl<'a> IntoIterator for &'a Trailers {
+    type Item = (&'a str, &'a str);
+    type IntoIter = git2::MessageTrailersStrsIterator<'a>;
+
+    /// Creates an iterator over the commit trailer set.
+    fn into_iter(self) -> Self::IntoIter {
+        self.inner.iter()
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+impl fmt::Debug for Trailers {
+    /// Formats the commit trailer set for debugging.
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_map().entries(self).finish()
+    }
+}

crates/mono-repository/src/repository/commit/iter.rs → crates/mono-repository/src/repository/commits.rs

@@ -30,7 +30,7 @@ use std::ops::{Bound, RangeBounds};
 use crate::repository::id::Id;
 use crate::repository::{Error, Repository, Result};
 
-use super::Commit;
+use super::commit::Commit;
 
 // ----------------------------------------------------------------------------
 // Structs

crates/mono-repository/src/repository/id.rs

@@ -80,7 +80,7 @@ impl From<git2::Oid> for Id {
 
 impl fmt::Display for Id {
     /// Formats the object identifier for display.
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.0.fmt(f)
     }
 }

crates/mono-repository/src/repository/versions.rs

@@ -32,7 +32,7 @@ use std::fmt;
 use std::iter::Rev;
 use std::ops::RangeBounds;
 
-use super::commit::Commits;
+use super::commits::Commits;
 use super::error::{Error, Result};
 use super::id::Id;
 use super::Repository;