Add GitCheckout

Cargo.toml

@@ -2,5 +2,3 @@
 name = "schematics"
 version = "0.1.0"
 authors = ["Adrian Heine <mail@adrianheine.de>"]
-
-[dependencies]

src/lib.rs

@@ -4,7 +4,11 @@
 trivial_casts, trivial_numeric_casts, unsafe_code,
 unstable_features, unused_extern_crates,
 unused_import_braces, unused_qualifications,
-unused_results, variant_size_differences
+variant_size_differences
+)]
+
+#![warn(
+unused_results
 )]
 
 /*

src/symbols/git.rs

@@ -0,0 +1,74 @@
+use std::fmt;
+use std::io;
+
+use command_runner::CommandRunner;
+use symbols::Symbol;
+
+pub struct GitCheckout<'a> {
+  target: &'a str,
+  source: &'a str,
+  branch: &'a str,
+  command_runner: &'a CommandRunner
+}
+
+impl<'a> GitCheckout<'a> {
+  pub fn new(target: &'a str, source: &'a str, branch: &'a str, command_runner: &'a CommandRunner) -> GitCheckout<'a> {
+    GitCheckout {
+      target: target,
+      source: source,
+      branch: branch,
+      command_runner: command_runner
+    }
+  }
+}
+
+impl<'a> fmt::Display for GitCheckout<'a> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "Checkout {} (branch {}) into {}", self.source, self.branch, self.target)
+  }
+}
+
+use std::fs::metadata;
+
+impl<'a> GitCheckout<'a> {
+  fn _run_in_target_repo(&self, args: &[&str]) -> Result<Vec<u8>, io::Error> {
+    let mut new_args = vec!["-C", self.target];
+    new_args.extend_from_slice(args);
+    self.command_runner.run_with_args("git", &new_args).map(|res| res.stdout)
+  }
+}
+
+impl<'a> Symbol for GitCheckout<'a> {
+  type Error = io::Error;
+  fn target_reached(&self) -> Result<bool, Self::Error> {
+    if let Err(e) = metadata(self.target) {
+      return if e.kind() == io::ErrorKind::NotFound {
+        Ok(false)
+      } else {
+        Err(e)
+      };
+    }
+    try!(self._run_in_target_repo(&["fetch", self.source, self.branch]));
+    let fetch_head = try!(self._run_in_target_repo(&["rev-parse", "FETCH_HEAD"]));
+    let head = try!(self._run_in_target_repo(&["rev-parse", "HEAD"]));
+    Ok(fetch_head == head)
+  }
+
+  fn execute(&self) -> Result<(), Self::Error> {
+    if let Err(e) = metadata(self.target) {
+      return if e.kind() == io::ErrorKind::NotFound {
+        try!(self.command_runner.run_with_args("git", &["clone", "-b", self.branch, self.source, self.target]));
+        Ok(())
+      } else {
+        Err(e)
+      };
+    }
+    try!(self._run_in_target_repo(&["fetch", self.source, self.branch]));
+    try!(self._run_in_target_repo(&["merge", "FETCH_HEAD"]));
+    Ok(())
+  }
+}
+
+#[cfg(test)]
+mod test {
+}

src/symbols/mod.rs

@@ -4,5 +4,6 @@ pub trait Symbol {
   fn execute(&self) -> Result<(), Self::Error>;
 }
 
+pub mod git;
 pub mod user;
 pub mod systemd;