Add --parse-ansi command

5 files changed, 30 insertions, 0 deletions

diff --git a/src/cli.rs b/src/cli.rs
index ec9b44cf..ee0f8272 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -299,6 +299,12 @@ pub struct Opt {
     #[structopt(long = "show-colors")]
     pub show_colors: bool,
 
+    /// Parse ANSI color escape sequences in input and display them as git style
+    /// strings. Example usage: git show --color=always | delta --parse-ansi
+    /// This can be used to help identify input style strings to use with map-styles.
+    #[structopt(long = "parse-ansi")]
+    pub parse_ansi: bool,
+
     #[structopt(long = "no-gitconfig")]
     /// Do not take any settings from git config. See GIT CONFIG section.
     pub no_gitconfig: bool,
diff --git a/src/main.rs b/src/main.rs
index 19d0d26e..5e6eab5e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -96,6 +96,8 @@ fn run_app() -> std::io::Result<i32> {
         ))
     } else if opt.show_colors {
         Some(subcommands::show_colors::show_colors())
+    } else if opt.parse_ansi {
+        Some(subcommands::parse_ansi::parse_ansi())
     } else {
         None
     };
diff --git a/src/options/set.rs b/src/options/set.rs
index 4cc2395e..0c640fd5 100644
--- a/src/options/set.rs
+++ b/src/options/set.rs
@@ -180,6 +180,7 @@ pub fn set_options(
             line_numbers_zero_style,
             pager,
             paging_mode,
+            parse_ansi,
             // Hack: plus-style must come before plus-*emph-style because the latter default
             // dynamically to the value of the former.
             plus_style,
diff --git a/src/subcommands/mod.rs b/src/subcommands/mod.rs
index 7669375e..26f04233 100644
--- a/src/subcommands/mod.rs
+++ b/src/subcommands/mod.rs
@@ -1,5 +1,6 @@
 pub mod diff;
 pub mod list_syntax_themes;
+pub mod parse_ansi;
 mod sample_diff;
 pub mod show_colors;
 pub mod show_config;
diff --git a/src/subcommands/parse_ansi.rs b/src/subcommands/parse_ansi.rs
new file mode 100644
index 00000000..51bebe56
--- /dev/null
+++ b/src/subcommands/parse_ansi.rs
@@ -0,0 +1,20 @@
+use std::io::{self, BufRead};
+
+#[cfg(not(tarpaulin_include))]
+pub fn parse_ansi() -> std::io::Result<()> {
+    use crate::{ansi, style::Style};
+
+    for line in io::stdin().lock().lines() {
+        for (ansi_term_style, s) in ansi::parse_style_sections(
+            &line.unwrap_or_else(|line| panic!("Invalid utf-8: {:?}", line)),
+        ) {
+            let style = Style {
+                ansi_term_style,
+                ..Style::default()
+            };
+            print!("({}){}", style.to_painted_string(), style.paint(s));
+        }
+        println!();
+    }
+    Ok(())
+}