Add method to return borrowed values for new name/email (GitoxideLabs#366)

Byron · Byron · commit 87fb932239e5 · 2022-03-28T19:57:45.000+08:00
That way, one _can_ optimize for performance and be zero copy
after the mail map has been created.
Maybe this can be useful in the estimate-hours program.
diff --git a/git-mailmap/src/lib.rs b/git-mailmap/src/lib.rs
@@ -14,7 +14,7 @@ pub fn parse_ignore_errors(buf: &[u8]) -> impl Iterator<Item = Entry<'_>> {
 
 mod entry;
 
-mod snapshot;
+pub mod snapshot;
 
 #[derive(Default, Clone)]
 pub struct Snapshot {
diff --git a/git-mailmap/src/snapshot.rs b/git-mailmap/src/snapshot.rs
@@ -1,9 +1,26 @@
 use crate::Snapshot;
 use bstr::{BStr, BString, ByteSlice};
-use git_actor::{Signature, SignatureRef};
+use git_actor::SignatureRef;
 use std::cmp::Ordering;
 use std::ops::Deref;
 
+pub struct ResolvedSignature<'a> {
+    pub name: Option<&'a BStr>,
+    pub email: Option<&'a BStr>,
+}
+
+impl<'a> ResolvedSignature<'a> {
+    fn try_new(new_email: Option<&'a BString>, new_name: Option<&'a BString>) -> Option<Self> {
+        match (new_email, new_name) {
+            (None, None) => None,
+            (new_email, new_name) => Some(ResolvedSignature {
+                email: new_email.map(|v| v.as_bstr()),
+                name: new_name.map(|v| v.as_bstr()),
+            }),
+        }
+    }
+}
+
 #[cfg_attr(test, derive(Debug))]
 #[derive(Clone)]
 enum EncodedString {
@@ -178,7 +195,7 @@ impl Snapshot {
         self
     }
 
-    pub fn try_resolve(&self, signature: &git_actor::SignatureRef<'_>) -> Option<git_actor::Signature> {
+    pub fn try_resolve_ref<'a>(&'a self, signature: &git_actor::SignatureRef<'_>) -> Option<ResolvedSignature<'a>> {
         let email: EncodedStringRef<'_> = signature.email.into();
         let pos = self
             .entries_by_old_email
@@ -191,24 +208,28 @@ impl Snapshot {
         match entry.entries_by_old_name.binary_search_by(|e| e.old_name.cmp_ref(name)) {
             Ok(pos) => {
                 let entry = &entry.entries_by_old_name[pos];
-                enriched_signature(signature, entry.new_email.as_ref(), entry.new_name.as_ref())
+                ResolvedSignature::try_new(entry.new_email.as_ref(), entry.new_name.as_ref())
             }
-            Err(_) => enriched_signature(signature, entry.new_email.as_ref(), entry.new_name.as_ref()),
+            Err(_) => ResolvedSignature::try_new(entry.new_email.as_ref(), entry.new_name.as_ref()),
         }
     }
 
+    pub fn try_resolve(&self, signature: &git_actor::SignatureRef<'_>) -> Option<git_actor::Signature> {
+        let new = self.try_resolve_ref(signature)?;
+        enriched_signature(signature, new)
+    }
+
     pub fn resolve(&self, signature: &git_actor::SignatureRef<'_>) -> git_actor::Signature {
         self.try_resolve(signature).unwrap_or_else(|| signature.to_owned())
     }
 }
 
 fn enriched_signature(
     SignatureRef { name, email, time }: &SignatureRef<'_>,
-    new_email: Option<&BString>,
-    new_name: Option<&BString>,
-) -> Option<Signature> {
+    new: ResolvedSignature<'_>,
+) -> Option<git_actor::Signature> {
     let time = *time;
-    match (new_email, new_name) {
+    match (new.email, new.name) {
         (Some(new_email), Some(new_name)) => git_actor::Signature {
             email: new_email.to_owned(),
             name: new_name.to_owned(),
@@ -227,7 +248,7 @@ fn enriched_signature(
             time,
         }
         .into(),
-        (None, None) => None,
+        (None, None) => unreachable!("BUG: ResolvedSignatures don't exist here when nothing is set"),
     }
 }
 
diff --git a/git-mailmap/tests/snapshot/mod.rs b/git-mailmap/tests/snapshot/mod.rs
@@ -23,7 +23,7 @@ fn try_resolve() {
     assert_eq!(
         snapshot.try_resolve(&signature("Jane", "jane@desktop.(none)").to_ref()),
         Some(signature("Jane Doe", "jane@example.com")),
-        "fix name and email by email"
+        "fix name and email by other email"
     );
 
     assert_eq!(
