Print file name and hunk number on every hunk

CHANGELOG.md

@@ -1,5 +1,11 @@
 ## 0.12 (unreleased)
 
+### Display
+
+Every hunk is now shown with the file name and a hunk number. This
+makes it easier to see which file you're looking at when there are
+many changes.
+
 ### Command Line Interface
 
 The difftastic binary is now named `difft`, to reduce typing during

src/bin/difft.rs

@@ -209,7 +209,7 @@ fn diff_file(display_path: &str, lhs_path: &str, rhs_path: &str) {
     let lhs_binary = is_probably_binary(&lhs_bytes);
     let rhs_binary = is_probably_binary(&rhs_bytes);
     if lhs_binary || rhs_binary {
-        println!("{}", style::header(display_path, "binary"));
+        print!("{}", style::header(display_path, 1, 1, "binary"));
         return;
     }
 
@@ -239,8 +239,6 @@ fn diff_file(display_path: &str, lhs_path: &str, rhs_path: &str) {
         ),
     };
 
-    println!("{}", style::header(display_path, lang_name));
-
     init_info(&lhs, &rhs);
     mark_syntax(lhs.get(0).copied(), rhs.get(0).copied());
 
@@ -265,6 +263,8 @@ fn diff_file(display_path: &str, lhs_path: &str, rhs_path: &str) {
     groups = join_overlapping(groups);
 
     if env::var("INLINE").is_ok() {
+        print!("{}", style::header(display_path, 1, 1, lang_name));
+
         print!(
             "{}",
             inline::display(&lhs_src, &rhs_src, &lhs_positions, &rhs_positions, &groups)
@@ -273,6 +273,8 @@ fn diff_file(display_path: &str, lhs_path: &str, rhs_path: &str) {
         print!(
             "{}",
             side_by_side::display(
+                display_path,
+                lang_name,
                 &lhs_src,
                 &rhs_src,
                 &lhs_positions,

src/side_by_side.rs

@@ -12,7 +12,7 @@ use crate::{
         codepoint_len, enforce_exact_length, enforce_max_length, format_line_num, LineGroup,
         LineNumber,
     },
-    style::apply_colors,
+    style::{apply_colors, header},
     syntax::{aligned_lines, MatchedPos},
 };
 
@@ -161,6 +161,8 @@ fn apply_group<S: AsRef<str>>(
 /// Display all the lines in `lhs` and `rhs` that are mentioned in
 /// `groups`, horizontally concatenating the matched lines.
 fn apply_groups(
+    display_path: &str,
+    lang_name: &str,
     lhs: &str,
     rhs: &str,
     groups: &[LineGroup],
@@ -172,6 +174,8 @@ fn apply_groups(
     let mut result = String::new();
 
     for (i, group) in groups.iter().enumerate() {
+        result.push_str(&header(display_path, i + 1, groups.len(), lang_name));
+
         result.push_str(&apply_group(
             &split_lines_nonempty(lhs),
             &split_lines_nonempty(rhs),
@@ -182,7 +186,7 @@ fn apply_groups(
             rhs_column_width,
         ));
         if i != groups.len() - 1 {
-            result.push_str("\n\n");
+            result.push('\n');
         }
     }
 
@@ -220,6 +224,8 @@ fn display_single_column(src: &str, color: Color) -> String {
 /// Display `lhs_src` and `rhs_src` in a side-by-side view with
 /// changed lines shown and highlighted.
 pub fn display(
+    display_path: &str,
+    lang_name: &str,
     lhs_src: &str,
     rhs_src: &str,
     lhs_positions: &[MatchedPos],
@@ -257,6 +263,8 @@ pub fn display(
     let rhs_colored = apply_colors(&rhs_src, false, rhs_positions);
 
     apply_groups(
+        display_path,
+        lang_name,
         &lhs_colored,
         &rhs_colored,
         groups,

src/style.rs

@@ -133,6 +133,12 @@ pub fn apply_colors(s: &str, is_lhs: bool, positions: &[MatchedPos]) -> String {
     apply(s, &styles)
 }
 
-pub fn header(file_name: &str, language_name: &str) -> String {
-    format!("{} -- {}", file_name.yellow().bold(), language_name)
+pub fn header(file_name: &str, hunk_num: usize, hunk_total: usize, language_name: &str) -> String {
+    format!(
+        "{} --- {}/{} --- {}\n",
+        file_name.yellow().bold(),
+        hunk_num,
+        hunk_total,
+        language_name
+    )
 }