Handle git blame output

Fixes #426

Partial versions of these changes were previously in master and then
reverted multiple times.

See #746
0745f85
3aab5d1

Cargo.toml

@@ -15,6 +15,8 @@ name = "delta"
 path = "src/main.rs"
 
 [dependencies]
+chrono = "0.4.19"
+chrono-humanize = "0.2.1"
 ansi_colours = "1.0.4"
 ansi_term = "0.12.1"
 atty = "0.2.14"

README.md

@@ -23,6 +23,7 @@
     show = delta
     log = delta
     reflog = delta
+    blame = delta  # see default-language to enable `git blame` syntax highlighting
 
 [interactive]
     diffFilter = delta --color-only
@@ -152,6 +153,7 @@ Here's what `git show` can look like with git configured to use delta:
 - `diff-highlight` and `diff-so-fancy` emulation modes
 - Stylable box/line decorations to draw attention to commit, file and hunk header sections.
 - Support for Git's `--color-moved` feature.
+- Customizable `git blame` with syntax highlighting (`--hyperlinks` formats commits as links to GitHub/GitLab/Bitbucket etc)
 - Code can be copied directly from the diff (`-/+` markers are removed by default).
 - `n` and `N` keybindings to move between files in large diffs, and between diffs in `log -p` views (`--navigate`)
 - Commit hashes can be formatted as terminal [hyperlinks](https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda) to the GitHub/GitLab/Bitbucket page (`--hyperlinks`).
@@ -400,6 +402,28 @@ In contrast, the long replacement line in the right panel overflows by almost an
 For control over the details of line wrapping, see `--wrap-max-lines`, `--wrap-left-symbol`, `--wrap-right-symbol`, `--wrap-right-percent`, `--wrap-right-prefix-symbol`, `--inline-hint-style`.
 Line wrapping was implemented by @th1000s.
 
+### git blame
+
+Set delta as the pager for `git blame`, along with the standard diff-generating git operations:
+
+```gitconfig
+[pager]
+    diff = delta
+    show = delta
+    log = delta
+    reflog = delta
+    blame = delta  # see default-language to enable `git blame` syntax highlighting
+```
+
+However, in order to activate syntax highlighting of `git blame` output, you must tell delta which language the file is written in by using the `default-language` option.
+If you are working in a repository that mostly contains files in a single language, the most convenient way to do this is by editing the _repository-specific_ git config file, i.e. the one at `/path/to/repo/.git/config`, as opposed to the one in your home directory:
+Add an entry like this, but using
+
+```gitconfig
+[delta]
+    default-language = rs  # substitute the language file extension you want here!
+```
+
 ### "Features": named groups of settings
 
 All delta options can go under the `[delta]` section in your git config file. However, you can also use named "features" to keep things organized: these are sections in git config like `[delta "my-feature"]`. Here's an example using two custom features:
@@ -486,6 +510,12 @@ In order to support this feature, Delta has to look at the raw colors it receive
 
 Use the `navigate` feature to activate navigation keybindings. In this mode, pressing `n` will jump forward to the next file in the diff, and `N` will jump backwards. If you are viewing multiple commits (e.g. via `git log -p`) then navigation will also visit commit boundaries.
 
+### Git blame
+
+Delta will render `git blame` output in its own way, if you have `pager.blame = delta` set in your `gitconfig`. Example:
+
+<table><tr><td><img width=300px src="https://user-images.githubusercontent.com/52205/140330813-91b198af-c396-4c5e-9a30-26ee35b78e7e.png" alt="image" /></td></tr></table>
+
 ### 24 bit color (truecolor)
 
 Delta looks best if your terminal application supports 24 bit colors. See https://github.com/termstandard/colors#readme. For example, on MacOS, iTerm2 supports 24-bit colors but Terminal.app does not.

src/cli.rs

@@ -420,6 +420,27 @@ pub struct Opt {
     /// (underline), 'ol' (overline), or the combination 'ul ol'.
     pub hunk_header_decoration_style: String,
 
+    /// Format string for git blame commit metadata. Available placeholders are
+    /// "{timestamp}", "{author}", and "{commit}".
+    #[structopt(
+        long = "blame-format",
+        default_value = "{timestamp:<15} {author:<15.14} {commit:<8} │ "
+    )]
+    pub blame_format: String,
+
+    /// Background colors used for git blame lines (space-separated string).
+    /// Lines added by the same commit are painted with the same color; colors
+    /// are recycled as needed.
+    #[structopt(long = "blame-palette")]
+    pub blame_palette: Option<String>,
+
+    /// Format of `git blame` timestamp in raw git output received by delta.
+    #[structopt(
+        long = "blame-timestamp-format",
+        default_value = "%Y-%m-%d %H:%M:%S %z"
+    )]
+    pub blame_timestamp_format: String,
+
     /// Default language used for syntax highlighting when this cannot be
     /// inferred from a filename. It will typically make sense to set this in
     /// per-repository git config (.git/config)

src/color.rs

@@ -162,3 +162,9 @@ const DARK_THEME_PLUS_COLOR_256: Color = Color::Fixed(22);
 const DARK_THEME_PLUS_EMPH_COLOR: Color = Color::RGB(0x00, 0x60, 0x00);
 
 const DARK_THEME_PLUS_EMPH_COLOR_256: Color = Color::Fixed(28);
+
+// blame
+
+pub const LIGHT_THEME_BLAME_PALETTE: &[&str] = &["#FFFFFF", "#DDDDDD", "#BBBBBB"];
+
+pub const DARK_THEME_BLAME_PALETTE: &[&str] = &["#000000", "#222222", "#444444"];

src/config.rs

@@ -57,6 +57,9 @@ fn adapt_wrap_max_lines_argument(arg: String) -> usize {
 pub struct Config {
     pub available_terminal_width: usize,
     pub background_color_extends_to_terminal_width: bool,
+    pub blame_format: String,
+    pub blame_palette: Vec<String>,
+    pub blame_timestamp_format: String,
     pub commit_style: Style,
     pub color_only: bool,
     pub commit_regex: Regex,
@@ -213,6 +216,8 @@ impl From<cli::Opt> for Config {
             _ => *style::GIT_DEFAULT_PLUS_STYLE,
         };
 
+        let blame_palette = make_blame_palette(opt.blame_palette, opt.computed.is_light_mode);
+
         let file_added_label = opt.file_added_label;
         let file_copied_label = opt.file_copied_label;
         let file_modified_label = opt.file_modified_label;
@@ -257,6 +262,9 @@ impl From<cli::Opt> for Config {
             background_color_extends_to_terminal_width: opt
                 .computed
                 .background_color_extends_to_terminal_width,
+            blame_format: opt.blame_format,
+            blame_palette,
+            blame_timestamp_format: opt.blame_timestamp_format,
             commit_style,
             color_only: opt.color_only,
             commit_regex,
@@ -603,6 +611,23 @@ fn make_commit_file_hunk_header_styles(opt: &cli::Opt) -> (Style, Style, Style,
     )
 }
 
+fn make_blame_palette(blame_palette: Option<String>, is_light_mode: bool) -> Vec<String> {
+    match (blame_palette, is_light_mode) {
+        (Some(string), _) => string
+            .split_whitespace()
+            .map(|s| s.to_owned())
+            .collect::<Vec<String>>(),
+        (None, true) => color::LIGHT_THEME_BLAME_PALETTE
+            .iter()
+            .map(|s| s.to_string())
+            .collect::<Vec<String>>(),
+        (None, false) => color::DARK_THEME_BLAME_PALETTE
+            .iter()
+            .map(|s| s.to_string())
+            .collect::<Vec<String>>(),
+    }
+}
+
 /// Did the user supply `option` on the command line?
 pub fn user_supplied_option(option: &str, arg_matches: &clap::ArgMatches) -> bool {
     arg_matches.occurrences_of(option) > 0

src/delta.rs

@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::HashMap;
 use std::io::BufRead;
 use std::io::Write;
 
@@ -21,6 +22,7 @@ pub enum State {
     HunkPlus(Option<String>), // In hunk; added line (raw_line)
     SubmoduleLog, // In a submodule section, with gitconfig diff.submodule = log
     SubmoduleShort(String), // In a submodule section, with gitconfig diff.submodule = short
+    Blame(String, Option<String>), // In a line of `git blame` output (commit, repeat_blame_line).
     Unknown,
     // The following elements are created when a line is wrapped to display it:
     HunkZeroWrapped,  // Wrapped unchanged line
@@ -67,6 +69,7 @@ pub struct StateMachine<'a> {
     // avoid emitting the file meta header line twice (#245).
     pub current_file_pair: Option<(String, String)>,
     pub handled_file_meta_header_line_file_pair: Option<(String, String)>,
+    pub blame_commit_colors: HashMap<String, String>,
 }
 
 pub fn delta<I>(lines: ByteLines<I>, writer: &mut dyn Write, config: &Config) -> std::io::Result<()>
@@ -92,6 +95,7 @@ impl<'a> StateMachine<'a> {
             handled_file_meta_header_line_file_pair: None,
             painter: Painter::new(writer, config),
             config,
+            blame_commit_colors: HashMap::new(),
         }
     }
 
@@ -116,6 +120,7 @@ impl<'a> StateMachine<'a> {
                 || self.handle_submodule_log_line()?
                 || self.handle_submodule_short_line()?
                 || self.handle_hunk_line()?
+                || self.handle_blame_line()?
                 || self.should_skip_line()
                 || self.emit_line_unchanged()?;
         }