3 files changed, 67 insertions, 8 deletions

diff --git a/crates/tools/src/bin/pre-commit.rs b/crates/tools/src/bin/pre-commit.rs
new file mode 100644
index 000000000..ca1909479
--- /dev/null
+++ b/crates/tools/src/bin/pre-commit.rs
@@ -0,0 +1,37 @@
+use std::{
+    process::{Command},
+};
+
+use tools::{Result, run_rustfmt, run, project_root};
+use failure::bail;
+
+fn main() -> tools::Result<()> {
+    run_rustfmt(tools::Overwrite)?;
+    update_staged()
+}
+
+fn update_staged() -> Result<()> {
+    let root = project_root();
+    let output = Command::new("git")
+        .arg("diff")
+        .arg("--name-only")
+        .arg("--cached")
+        .current_dir(&root)
+        .output()?;
+    if !output.status.success() {
+        bail!(
+            "`git diff --name-only --cached` exited with {}",
+            output.status
+        );
+    }
+    for line in String::from_utf8(output.stdout)?.lines() {
+        run(
+            &format!(
+                "git update-index --add {}",
+                root.join(line).to_string_lossy()
+            ),
+            ".",
+        )?;
+    }
+    Ok(())
+}
diff --git a/crates/tools/src/lib.rs b/crates/tools/src/lib.rs
index 674b9d11f..95d6e08f0 100644
--- a/crates/tools/src/lib.rs
+++ b/crates/tools/src/lib.rs
@@ -1,6 +1,8 @@
 use std::{
     path::{Path, PathBuf},
     process::{Command, Stdio},
+    fs::copy,
+    io::{Error, ErrorKind}
 };
 
 use failure::bail;
@@ -39,7 +41,7 @@ pub fn collect_tests(s: &str) -> Vec<(usize, Test)> {
         let (start_line, name) = loop {
             match block.next() {
                 Some((idx, line)) if line.starts_with("test ") => {
-                    break (idx, line["test ".len()..].to_string())
+                    break (idx, line["test ".len()..].to_string());
                 }
                 Some(_) => (),
                 None => continue 'outer,
@@ -65,7 +67,7 @@ pub fn generate(mode: Mode) -> Result<()> {
 }
 
 pub fn project_root() -> PathBuf {
-    Path::new(&std::env::var("CARGO_MANIFEST_DIR").unwrap())
+    Path::new(&env!("CARGO_MANIFEST_DIR"))
         .ancestors()
         .nth(2)
         .unwrap()
@@ -116,3 +118,18 @@ fn install_rustfmt() -> Result<()> {
         ".",
     )
 }
+
+pub fn install_format_hook() -> Result<()> {
+    let result_path = Path::new("./.git/hooks/pre-commit");
+    if !result_path.exists() {
+        run("cargo build --package tools --bin pre-commit", ".")?;
+        if cfg!(windows) {
+            copy("./target/debug/pre-commit.exe", result_path)?;
+        } else {
+            copy("./target/debug/pre-commit", result_path)?;
+        }
+    } else {
+        return Err(Error::new(ErrorKind::AlreadyExists, "Git hook already created").into());
+    }
+    Ok(())
+}
diff --git a/crates/tools/src/main.rs b/crates/tools/src/main.rs
index 36a7c83e2..9e90ac5c2 100644
--- a/crates/tools/src/main.rs
+++ b/crates/tools/src/main.rs
@@ -7,7 +7,7 @@ use std::{
 use clap::{App, Arg, SubCommand};
 use failure::bail;
 
-use tools::{collect_tests, generate, run, run_rustfmt, Mode, Overwrite, Result, Test, Verify};
+use tools::{collect_tests, generate, install_format_hook, run, run_rustfmt, Mode, Overwrite, Result, Test, Verify};
 
 const GRAMMAR_DIR: &str = "./crates/ra_syntax/src/grammar";
 const INLINE_TESTS_DIR: &str = "./crates/ra_syntax/tests/data/parser/inline";
@@ -25,17 +25,22 @@ fn main() -> Result<()> {
         .subcommand(SubCommand::with_name("gen-tests"))
         .subcommand(SubCommand::with_name("install-code"))
         .subcommand(SubCommand::with_name("format"))
+        .subcommand(SubCommand::with_name("format-hook"))
         .get_matches();
     let mode = if matches.is_present("verify") {
         Verify
     } else {
         Overwrite
     };
-    match matches.subcommand() {
-        ("install-code", _) => install_code_extension()?,
-        ("gen-tests", _) => gen_tests(mode)?,
-        ("gen-syntax", _) => generate(Overwrite)?,
-        ("format", _) => run_rustfmt(Overwrite)?,
+    match matches
+        .subcommand_name()
+        .expect("Subcommand must be specified")
+    {
+        "install-code" => install_code_extension()?,
+        "gen-tests" => gen_tests(mode)?,
+        "gen-syntax" => generate(Overwrite)?,
+        "format" => run_rustfmt(mode)?,
+        "format-hook" => install_format_hook()?,
         _ => unreachable!(),
     }
     Ok(())