Ely Office: six offline-first desktop apps in Rust and GPUI

ElyDoc, ElyTable, ElyShow (LibreOfficeKit), ElyPDF (MuPDF), ElyTree (Git),
ElyMark (Milkdown and CodeMirror in CEF). ElyMail and ElyAgent follow.

apps/ely-tree/src/branches.rs

@@ -0,0 +1,125 @@
+//! Branches and tags as `for-each-ref` lists them (TREE-07).
+
+use std::{io, path::Path};
+
+use crate::git::Git;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Ref {
+    /// `main`, `origin/main`, `v1`.
+    pub name: String,
+    /// `refs/heads/main`: names a branch and a tag apart.
+    pub full: String,
+    pub kind: Kind,
+    pub current: bool,
+    pub upstream: Option<String>,
+    /// Ahead and behind; None without a live upstream.
+    pub track: Option<(usize, usize)>,
+    /// The commit it names, through an annotated tag.
+    pub commit: String,
+    pub subject: String,
+    pub at: i64,
+    /// An annotated tag's own message.
+    pub message: Option<String>,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Kind {
+    Local,
+    Remote,
+    Tag,
+}
+
+const FORMAT: &str = "--format=%(refname)%00%(HEAD)%00%(upstream:short)%00%(upstream:track,nobracket)%00%(objecttype)%00%(objectname)%00%(*objectname)%00%(contents:subject)%00%(*subject)%00%(creatordate:unix)%1e";
+
+fn bad(what: &str) -> io::Error {
+    io::Error::new(
+        io::ErrorKind::InvalidData,
+        format!("an unread ref {what:?}"),
+    )
+}
+
+/// `ahead 2, behind 1` as (2, 1); `gone` as none.
+fn track(words: &str) -> Option<(usize, usize)> {
+    if words == "gone" {
+        return None;
+    }
+    let mut counts = (0, 0);
+    for part in words.split(", ").filter(|part| !part.is_empty()) {
+        match part.split_once(' ')? {
+            ("ahead", n) => counts.0 = n.parse().ok()?,
+            ("behind", n) => counts.1 = n.parse().ok()?,
+            _ => return None,
+        }
+    }
+    Some(counts)
+}
+
+pub fn parse(bytes: &[u8]) -> io::Result<Vec<Ref>> {
+    let text = std::str::from_utf8(bytes).map_err(|_| bad("not UTF-8"))?;
+    let mut refs = Vec::new();
+    for record in text
+        .split('\u{1e}')
+        .map(|record| record.trim_start_matches('\n'))
+        .filter(|record| !record.is_empty())
+    {
+        let fields: Vec<&str> = record.split('\0').collect();
+        let [
+            full,
+            head,
+            upstream,
+            tracking,
+            object_kind,
+            object,
+            peeled,
+            subject,
+            peeled_subject,
+            at,
+        ] = fields[..]
+        else {
+            return Err(bad(record));
+        };
+        // Names come off the full ref; short ones clash.
+        let (kind, name) = if let Some(name) = full.strip_prefix("refs/heads/") {
+            (Kind::Local, name)
+        } else if let Some(name) = full
+            .strip_prefix("refs/remotes/")
+            .filter(|name| !name.ends_with("/HEAD"))
+        {
+            (Kind::Remote, name)
+        } else if let Some(name) = full.strip_prefix("refs/tags/") {
+            (Kind::Tag, name)
+        } else {
+            // `origin/HEAD` points at a branch; it is not one.
+            continue;
+        };
+        let annotated = object_kind == "tag";
+        refs.push(Ref {
+            name: name.to_string(),
+            full: full.to_string(),
+            kind,
+            current: head == "*",
+            upstream: (!upstream.is_empty()).then(|| upstream.to_string()),
+            track: (!upstream.is_empty()).then(|| track(tracking)).flatten(),
+            commit: if annotated { peeled } else { object }.to_string(),
+            subject: if annotated { peeled_subject } else { subject }.to_string(),
+            at: at.parse().map_err(|_| bad(record))?,
+            message: annotated.then(|| subject.to_string()),
+        });
+    }
+    Ok(refs)
+}
+
+/// Every branch, remote branch and tag.
+pub fn read(git: &Git, root: &Path) -> io::Result<Vec<Ref>> {
+    parse(&git.run(
+        root,
+        &[
+            "for-each-ref",
+            FORMAT,
+            "refs/heads",
+            "refs/remotes",
+            "refs/tags",
+        ],
+    )?)
+}