feat: State::entry_by_path_and_stage() to find entries. (#427)

Author: Byron

git-index/src/access.rs

@@ -1,7 +1,8 @@
 use bstr::{BStr, ByteSlice};
 
-use crate::{extension, Entry, PathStorage, State, Version};
+use crate::{entry, extension, Entry, PathStorage, State, Version};
 
+/// General information and entries
 impl State {
     pub fn version(&self) -> Version {
         self.version
@@ -58,6 +59,20 @@ impl State {
             (e, path)
         })
     }
+
+    /// Find the entry index in [`entries()`][State::entries()] matching the given repository-relative
+    /// `path` and `stage`, or `None`.
+    ///
+    /// Use the index for accessing multiple stages if they exists, but at least the single matching entry.
+    pub fn entry_by_path_and_stage(&self, path: &BStr, stage: entry::Stage) -> Option<usize> {
+        self.entries
+            .binary_search_by(|e| e.path(self).cmp(path).then_with(|| e.stage().cmp(&stage)))
+            .ok()
+    }
+}
+
+/// Extensions
+impl State {
     pub fn tree(&self) -> Option<&extension::Tree> {
         self.tree.as_ref()
     }

git-index/src/entry.rs

@@ -1,5 +1,8 @@
 use bitflags::bitflags;
 
+/// The stage of an entry, one of 0 = base, 1 = ours, 2 = theirs
+pub type Stage = u32;
+
 bitflags! {
     pub struct Mode: u32 {
         /// directory (only used for sparse checkouts), equivalent to a tree
@@ -106,12 +109,12 @@ bitflags! {
 }
 
 impl Flags {
-    pub fn stage(&self) -> u32 {
+    pub fn stage(&self) -> Stage {
         (*self & Flags::STAGE_MASK).bits >> 12
     }
 }
 
-#[derive(PartialEq, Eq, Hash, Ord, PartialOrd, Clone, Copy)]
+#[derive(Debug, PartialEq, Eq, Hash, Ord, PartialOrd, Clone, Copy)]
 #[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
 pub struct Time {
     /// The amount of seconds elapsed since EPOCH
@@ -120,7 +123,7 @@ pub struct Time {
     pub nsecs: u32,
 }
 
-#[derive(PartialEq, Eq, Hash, Ord, PartialOrd, Clone, Copy)]
+#[derive(Debug, PartialEq, Eq, Hash, Ord, PartialOrd, Clone, Copy)]
 #[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
 pub struct Stat {
     pub mtime: Time,
@@ -136,7 +139,7 @@ pub struct Stat {
 mod access {
     use bstr::{BStr, ByteSlice};
 
-    use crate::{Entry, State};
+    use crate::{entry, Entry, State};
 
     impl Entry {
         pub fn path<'a>(&self, state: &'a State) -> &'a BStr {
@@ -147,7 +150,7 @@ mod access {
             (backing[self.path.clone()]).as_bstr()
         }
 
-        pub fn stage(&self) -> u32 {
+        pub fn stage(&self) -> entry::Stage {
             self.flags.stage()
         }
     }

git-index/src/lib.rs

@@ -37,7 +37,7 @@ pub enum Version {
 }
 
 /// An entry in the index, identifying a non-tree item on disk.
-#[derive(Clone)]
+#[derive(Debug, Clone, Eq, PartialEq)]
 pub struct Entry {
     pub stat: entry::Stat,
     pub id: git_hash::ObjectId,

git-index/tests/index/file/access.rs

@@ -1,5 +1,13 @@
+use crate::index::file::read;
+
 #[test]
-#[ignore]
-fn entry_by_path() {
-    todo!()
+fn entry_by_path_and_stage() {
+    let file = read::file("v4_more_files_IEOT");
+    for entry in file.entries() {
+        let path = entry.path(&file);
+        assert_eq!(
+            file.entry_by_path_and_stage(path, 0).map(|idx| &file.entries()[idx]),
+            Some(entry)
+        );
+    }
 }

git-index/tests/index/file/read.rs

@@ -18,7 +18,7 @@ fn loose_file(name: &str) -> git_index::File {
     let file = git_index::File::at(path, git_index::decode::Options::default()).unwrap();
     verify(file)
 }
-fn file(name: &str) -> git_index::File {
+pub(crate) fn file(name: &str) -> git_index::File {
     let file = git_index::File::at(crate::fixture_index_path(name), git_index::decode::Options::default()).unwrap();
     verify(file)
 }