Emit description of file mode change (#605)

Fixes #583

3 files changed, 84 insertions, 20 deletions

diff --git a/src/delta.rs b/src/delta.rs
index 56114f76..cfafe3dc 100644
--- a/src/delta.rs
+++ b/src/delta.rs
@@ -62,7 +62,9 @@ struct StateMachine<'a> {
     source: Source,
     minus_file: String,
     plus_file: String,
-    file_event: parse::FileEvent,
+    minus_file_event: parse::FileEvent,
+    plus_file_event: parse::FileEvent,
+    file_paths_from_diff_line: (Option<String>, Option<String>),
     painter: Painter<'a>,
     config: &'a Config,
 
@@ -91,7 +93,9 @@ impl<'a> StateMachine<'a> {
             source: Source::Unknown,
             minus_file: "".to_string(),
             plus_file: "".to_string(),
-            file_event: parse::FileEvent::NoEvent,
+            minus_file_event: parse::FileEvent::NoEvent,
+            plus_file_event: parse::FileEvent::NoEvent,
+            file_paths_from_diff_line: (None, None),
             current_file_pair: None,
             handled_file_meta_header_line_file_pair: None,
             painter: Painter::new(writer, config),
@@ -122,13 +126,15 @@ impl<'a> StateMachine<'a> {
             } else if (self.state == State::FileMeta || self.source == Source::DiffUnified)
                 && (line.starts_with("--- ")
                     || line.starts_with("rename from ")
-                    || line.starts_with("copy from "))
+                    || line.starts_with("copy from ")
+                    || line.starts_with("old mode "))
             {
                 self.handle_file_meta_minus_line()?
             } else if (self.state == State::FileMeta || self.source == Source::DiffUnified)
                 && (line.starts_with("+++ ")
                     || line.starts_with("rename to ")
-                    || line.starts_with("copy to "))
+                    || line.starts_with("copy to ")
+                    || line.starts_with("new mode "))
             {
                 self.handle_file_meta_plus_line()?
             } else if line.starts_with("@@") {
@@ -253,13 +259,14 @@ impl<'a> StateMachine<'a> {
         self.painter.paint_buffered_minus_and_plus_lines();
         self.state = State::FileMeta;
         self.handled_file_meta_header_line_file_pair = None;
+        self.file_paths_from_diff_line = parse::get_file_paths_from_diff_line(&self.line);
         Ok(false)
     }
 
     fn handle_file_meta_minus_line(&mut self) -> std::io::Result<bool> {
         let mut handled_line = false;
 
-        let parsed_file_meta_line = parse::parse_file_meta_line(
+        let (path_or_mode, file_event) = parse::parse_file_meta_line(
             &self.line,
             self.source == Source::GitDiff,
             if self.config.relative_paths {
@@ -268,8 +275,14 @@ impl<'a> StateMachine<'a> {
                 None
             },
         );
-        self.minus_file = parsed_file_meta_line.0;
-        self.file_event = parsed_file_meta_line.1;
+        // In the case of ModeChange only, the file path is taken from the diff
+        // --git line (since that is the only place the file path occurs);
+        // otherwise it is taken from the --- / +++ line.
+        self.minus_file = match (&file_event, &self.file_paths_from_diff_line) {
+            (parse::FileEvent::ModeChange(_), (Some(file), _)) => file.clone(),
+            _ => path_or_mode,
+        };
+        self.minus_file_event = file_event;
 
         if self.source == Source::DiffUnified {
             self.state = State::FileMeta;
@@ -300,7 +313,7 @@ impl<'a> StateMachine<'a> {
 
     fn handle_file_meta_plus_line(&mut self) -> std::io::Result<bool> {
         let mut handled_line = false;
-        let parsed_file_meta_line = parse::parse_file_meta_line(
+        let (path_or_mode, file_event) = parse::parse_file_meta_line(
             &self.line,
             self.source == Source::GitDiff,
             if self.config.relative_paths {
@@ -309,7 +322,14 @@ impl<'a> StateMachine<'a> {
                 None
             },
         );
-        self.plus_file = parsed_file_meta_line.0;
+        // In the case of ModeChange only, the file path is taken from the diff
+        // --git line (since that is the only place the file path occurs);
+        // otherwise it is taken from the --- / +++ line.
+        self.plus_file = match (&file_event, &self.file_paths_from_diff_line) {
+            (parse::FileEvent::ModeChange(_), (_, Some(file))) => file.clone(),
+            _ => path_or_mode,
+        };
+        self.plus_file_event = file_event;
         self.painter
             .set_syntax(parse::get_file_extension_from_file_meta_line_file_path(
                 &self.plus_file,
@@ -344,7 +364,8 @@ impl<'a> StateMachine<'a> {
             &self.minus_file,
             &self.plus_file,
             comparing,
-            &self.file_event,
+            &self.minus_file_event,
+            &self.plus_file_event,
             self.config,
         );
         // FIXME: no support for 'raw'
diff --git a/src/parse.rs b/src/parse.rs
index ab51702e..3329248b 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -25,6 +25,7 @@ pub enum FileEvent {
     Change,
     Copy,
     Rename,
+    ModeChange(String),
     NoEvent,
 }
 
@@ -33,7 +34,7 @@ pub fn parse_file_meta_line(
     git_diff_name: bool,
     relative_path_base: Option<&str>,
 ) -> (String, FileEvent) {
-    let (mut path, file_event) = match line {
+    let (mut path_or_mode, file_event) = match line {
         line if line.starts_with("--- ") || line.starts_with("+++ ") => {
             let offset = 4;
             let file = _parse_file_path(&line[offset..], git_diff_name);
@@ -51,18 +52,35 @@ pub fn parse_file_meta_line(
         line if line.starts_with("copy to ") => {
             (line[8..].to_string(), FileEvent::Copy) // "copy to ".len()
         }
+        line if line.starts_with("old mode ") => {
+            ("".to_string(), FileEvent::ModeChange(line[9..].to_string())) // "old mode ".len()
+        }
+        line if line.starts_with("new mode ") => {
+            ("".to_string(), FileEvent::ModeChange(line[9..].to_string())) // "new mode ".len()
+        }
         _ => ("".to_string(), FileEvent::NoEvent),
     };
 
     if let Some(base) = relative_path_base {
-        if let Some(relative_path) = pathdiff::diff_paths(&path, base) {
+        if let FileEvent::ModeChange(_) = file_event {
+        } else if let Some(relative_path) = pathdiff::diff_paths(&path_or_mode, base) {
             if let Some(relative_path) = relative_path.to_str() {
-                path = relative_path.to_owned();
+                path_or_mode = relative_path.to_owned();
             }
         }
     }
 
-    (path, file_event)
+    (path_or_mode, file_event)
+}
+
+/// Given input like "diff --git a/src/main.rs b/src/main.rs"
+/// return (Some("src/main.rs"), Some("src/main.rs"))
+pub fn get_file_paths_from_diff_line(line: &str) -> (Option<String>, Option<String>) {
+    let mut iter = line.split(' ').skip(2);
+    (
+        iter.next().map(|s| _parse_file_path(&s[2..], true)),
+        iter.next().map(|s| _parse_file_path(&s[2..], true)),
+    )
 }
 
 fn _parse_file_path(s: &str, git_diff_name: bool) -> String {
@@ -117,7 +135,8 @@ pub fn get_file_change_description_from_file_paths(
     minus_file: &str,
     plus_file: &str,
     comparing: bool,
-    file_event: &FileEvent,
+    minus_file_event: &FileEvent,
+    plus_file_event: &FileEvent,
     config: &Config,
 ) -> String {
     if comparing {
@@ -137,23 +156,33 @@ pub fn get_file_change_description_from_file_paths(
                 Cow::from(file)
             }
         };
-        match (minus_file, plus_file) {
-            (minus_file, plus_file) if minus_file == plus_file => format!(
+        match (minus_file, plus_file, minus_file_event, plus_file_event) {
+            (
+                minus_file,
+                plus_file,
+                FileEvent::ModeChange(old_mode),
+                FileEvent::ModeChange(new_mode),
+            ) if minus_file == plus_file => {
+                format!("{}: {} ⟶   {}", plus_file, old_mode, new_mode)
+            }
+            (minus_file, plus_file, _, _) if minus_file == plus_file => format!(
                 "{}{}",
                 format_label(&config.file_modified_label),
                 format_file(minus_file)
             ),
-            (minus_file, "/dev/null") => format!(
+            (minus_file, "/dev/null", _, _) => format!(
                 "{}{}",
                 format_label(&config.file_removed_label),
                 format_file(minus_file)
             ),
-            ("/dev/null", plus_file) => format!(
+            ("/dev/null", plus_file, _, _) => format!(
                 "{}{}",
                 format_label(&config.file_added_label),
                 format_file(plus_file)
             ),
-            (minus_file, plus_file) => format!(
+            // minus_file_event == plus_file_event, except in the ModeChange
+            // case above.
+            (minus_file, plus_file, file_event, _) => format!(
                 "{}{} ⟶   {}",
                 format_label(match file_event {
                     FileEvent::Rename => &config.file_renamed_label,
diff --git a/src/tests/test_example_diffs.rs b/src/tests/test_example_diffs.rs
index de35535a..a4d0b854 100644
--- a/src/tests/test_example_diffs.rs
+++ b/src/tests/test_example_diffs.rs
@@ -1569,6 +1569,14 @@ src/align.rs:71: impl<'a> Alignment<'a> { │
         ));
     }
 
+    #[test]
+    fn test_file_mode_change() {
+        let config = integration_test_utils::make_config_from_args(&[]);
+        let output = integration_test_utils::run_delta(GIT_DIFF_FILE_MODE_CHANGE, &config);
+        let output = strip_ansi_codes(&output);
+        assert!(output.contains(r"src/delta.rs: 100644 ⟶   100755"));
+    }
+
     const GIT_DIFF_SINGLE_HUNK: &str = "\
 commit 94907c0f136f46dc46ffae2dc92dca9af7eb7c2e
 Author: Dan Davison <dandavison7@gmail.com>
@@ -2172,4 +2180,10 @@ Date:   Sun Nov 1 15:28:53 2020 -0500
 \ No newline at end of file
 +]
 "#;
+
+    const GIT_DIFF_FILE_MODE_CHANGE: &str = "
+diff --git a/src/delta.rs b/src/delta.rs
+old mode 100644
+new mode 100755
+";
 }