git_rs 0.1.0

A (work in progress) pure rust git implementation.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138

use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::str::FromStr;
use std::fs::File;
use std::io::Read;

use crate::id::Id;

#[derive(Copy, Clone, Debug)]
pub enum Kind {
    Local,
    Remote,
    Tag
}

#[derive(Debug)]
pub enum RefPtr {
    Indirect(String),
    Direct(Id)
}

#[derive(Debug)]
pub struct Ref {
    kind: Kind,
    ptr: RefPtr
}

pub struct RefSet(HashMap<String, Ref>);

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..16] == "ref: refs/heads/" {
                return Ok(Ref {
                    kind,
                    ptr: RefPtr::Indirect(String::from(contents[16..].trim()))
                });
            }

            if buffer.len() >= 40 {
                if let Ok(id) = Id::from_str(&contents[0..40]) {
                    return Ok(Ref {
                        ptr: RefPtr::Direct(id),
                        kind
                    });
                }
            }
        }

        Err(std::io::ErrorKind::InvalidData.into())
    }
}

fn recurse_dir(
    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
            }
        }
    }
}