Write V2 Index Files (with TREE and EOIE extensions)

git-index/src/entry.rs

@@ -1,3 +1,4 @@
+use crate::Version;
 use bitflags::bitflags;
 
 /// The stage of an entry, one of 0 = base, 1 = ours, 2 = theirs
@@ -42,6 +43,13 @@ pub(crate) mod at_rest {
         }
     }
 
+    impl Flags {
+        pub fn to_memory(self) -> super::Flags {
+            super::Flags::from_bits((self & (Flags::PATH_LEN | Flags::STAGE_MASK | Flags::ASSUME_VALID)).bits as u32)
+                .expect("PATHLEN is part of memory representation")
+        }
+    }
+
     bitflags! {
         /// Extended flags - add flags for serialization here and offset them down to u16.
         pub struct FlagsExtended: u16 {
@@ -56,13 +64,6 @@ pub(crate) mod at_rest {
         }
     }
 
-    impl Flags {
-        pub fn to_memory(self) -> super::Flags {
-            super::Flags::from_bits((self & (Flags::PATH_LEN | Flags::STAGE_MASK | Flags::ASSUME_VALID)).bits as u32)
-                .expect("PATHLEN is part of memory representation")
-        }
-    }
-
     #[cfg(test)]
     mod tests {
         use super::*;
@@ -112,6 +113,11 @@ impl Flags {
     pub fn stage(&self) -> Stage {
         (*self & Flags::STAGE_MASK).bits >> 12
     }
+
+    pub fn to_storage(&self, version: Version) -> at_rest::Flags {
+        assert_eq!(version, Version::V2, "Can only encode V2 flags at the moment");
+        at_rest::Flags::from_bits(self.bits() as u16).unwrap()
+    }
 }
 
 #[derive(Debug, PartialEq, Eq, Hash, Ord, PartialOrd, Clone, Copy)]
@@ -173,3 +179,20 @@ mod _impls {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::entry::at_rest;
+    use crate::Version;
+
+    #[test]
+    fn in_mem_flags_to_storage_flags_v2() {
+        let flag_bytes = u16::from_be_bytes(*b"\x00\x01");
+        let flags_at_rest = at_rest::Flags::from_bits(flag_bytes).unwrap();
+        let in_memory_flags = flags_at_rest.to_memory();
+
+        let output = in_memory_flags.to_storage(Version::V2);
+
+        assert_eq!(output.bits(), flag_bytes);
+    }
+}

git-index/src/extension/mod.rs

@@ -14,7 +14,7 @@ pub struct Iter<'a> {
 ///
 /// It allows to more quickly build trees by avoiding as it can quickly re-use portions of the index and its associated tree ids
 /// if there was no change to them. Portions of this tree are invalidated as the index is changed.
-#[derive(Clone)]
+#[derive(PartialEq, Eq, Clone, Debug)]
 pub struct Tree {
     pub name: SmallVec<[u8; 23]>,
     /// The id of the directory tree of the associated tree object.

git-index/src/file/mod.rs

@@ -32,3 +32,4 @@ mod impl_ {
 }
 pub mod init;
 pub mod verify;
+pub mod write;

git-index/src/file/write.rs

@@ -0,0 +1,12 @@
+use crate::{write, File};
+use git_features::hash;
+
+impl File {
+    pub fn write_to(&self, mut out: &mut impl std::io::Write, options: write::Options) -> std::io::Result<()> {
+        let mut hasher = hash::Write::new(&mut out, options.hash_kind);
+        self.state.write_to(&mut hasher, options)?;
+
+        let hash = hasher.hash.digest();
+        out.write_all(&hash)
+    }
+}