feat(ref): oh god, implement refs and ref sets

Author: chrisdickinson

src/lib.rs

@@ -7,6 +7,7 @@ pub mod errors;
 pub mod stores;
 pub mod objects;
 pub mod packindex;
+pub mod refs;
 
 #[cfg(test)]
 mod tests {

src/refs.rs

@@ -0,0 +1,137 @@
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use std::fs::File;
+use std::io::Read;
+
+use crate::id::Id;
+
+#[derive(Copy, Clone)]
+enum Kind {
+    Local,
+    Remote,
+    Tag
+}
+
+enum RefPtr {
+    Indirect(String),
+    Direct(Id)
+}
+
+struct Ref {
+    kind: Kind,
+    ptr: RefPtr
+}
+
+impl Ref {
+    pub fn load(path: &Path, kind: Kind) -> Result<Ref, std::io::Error> {
+        let mut f = File::open(path)?;
+        let mut buffer = Vec::new();
+        f.read_to_end(&mut buffer)?;
+
+        if let Ok(contents) = std::str::from_utf8(&buffer) {
+            if contents.len() < 5 {
+                return Err(std::io::ErrorKind::InvalidData.into());
+            }
+
+            if &contents[0..5] == "ref: " {
+                return Ok(Ref {
+                    kind,
+                    ptr: RefPtr::Indirect(String::from(&contents[6..]))
+                });
+            }
+
+            if buffer.len() == 40 {
+                if let Some(id) = Id::from_str(contents) {
+                    return Ok(Ref {
+                        ptr: RefPtr::Direct(id),
+                        kind
+                    });
+                }
+            }
+        }
+
+        return Err(std::io::ErrorKind::InvalidData.into());
+    }
+}
+
+struct RefSet(HashMap<String, Ref>);
+
+fn recurse_dir<'a>(
+    root: &mut PathBuf,
+    dirs: &mut Vec<String>,
+    map: &mut HashMap<String, Ref>,
+    k: Kind
+) -> Result<(), std::io::Error> {
+    for entry in std::fs::read_dir(root.as_path())? {
+        let entry = entry?;
+
+        let typ = entry.file_type()?;
+        let os_filename = entry.file_name();
+        let opt_filename = os_filename.to_str();
+        if opt_filename.is_none() {
+            continue
+        }
+        let filename = opt_filename.unwrap();
+
+        dirs.push(String::from(filename));
+        if typ.is_dir() {
+            recurse_dir(&mut entry.path(), dirs, map, k)?;
+        } else {
+            let ref_name: String = dirs.join("/");
+            if let Ok(reference) = Ref::load(&entry.path(), k) {
+                map.insert(ref_name, reference);
+            }
+        }
+        dirs.pop();
+    }
+
+    Ok(())
+}
+
+impl RefSet {
+    pub fn from_path(path: &Path) -> Result<RefSet, std::io::Error> {
+        let mut root = std::path::PathBuf::new();
+        let mut map = HashMap::new();
+        let mut dirs = Vec::new();
+        root.push(path);
+        root.push(".git");
+        root.push("refs");
+        root.push("heads");
+        recurse_dir(&mut root, &mut dirs, &mut map, Kind::Local)?;
+        root.pop();
+        root.push("remotes");
+        recurse_dir(&mut root, &mut dirs, &mut map, Kind::Remote)?;
+        root.pop();
+        root.push("tags");
+        recurse_dir(&mut root, &mut dirs, &mut map, Kind::Tag)?;
+        root.pop();
+        root.pop();
+        root.push("HEAD");
+        if let Ok(reference) = Ref::load(root.as_path(), Kind::Local) {
+            map.insert(String::from("HEAD"), reference);
+        };
+
+        Ok(RefSet {
+            0: map
+        })
+    }
+
+    pub fn deref(&self, name: &str) -> Option<&Id> {
+        let mut reference = self.0.get(name);
+        loop {
+            match reference {
+                Some(xs) => {
+                    match xs.ptr {
+                        RefPtr::Direct(ref id) => return Some(&id),
+                        RefPtr::Indirect(ref string) => {
+                            reference = self.0.get(string.as_str());
+                        }
+                    }
+                },
+                None => return None
+            }
+        }
+
+        None
+    }
+}