Add colorMoved support to kitty diff kitten

Fixes #3241
Fixes #9644

Author: Copilot

kittens/diff/main.py

@@ -152,6 +152,12 @@ def main(args: list[str]) -> None:
 opt('added_margin_bg', '#cdffd8', option_type='to_color')
 opt('dark_added_margin_bg', '#31503d', option_type='to_color')
 
+opt('moved_bg', '#fffde7', option_type='to_color', long_text='Moved text backgrounds (same text that was removed in one place and added in another)')
+opt('dark_moved_bg', '#2c2200', option_type='to_color')
+
+opt('moved_margin_bg', '#fff3b0', option_type='to_color')
+opt('dark_moved_margin_bg', '#4a3800', option_type='to_color')
+
 opt('filler_bg', '#fafbfc', option_type='to_color', long_text='Filler (empty) line background')
 opt('dark_filler_bg', '#262c36', option_type='to_color')
 

kittens/diff/patch.go

@@ -14,6 +14,7 @@ import (
 	"sync"
 
 	parallel "github.com/kovidgoyal/go-parallel"
+	"github.com/kovidgoyal/kitty/tools/simdstring"
 	"github.com/kovidgoyal/kitty/tools/utils"
 	"github.com/kovidgoyal/kitty/tools/utils/images"
 	"github.com/kovidgoyal/kitty/tools/utils/shlex"
@@ -336,6 +337,7 @@ func (self *Hunk) finalize(left_lines, right_lines []string) error {
 type Patch struct {
 	all_hunks                                       []*Hunk
 	largest_line_number, added_count, removed_count int
+	left_moved_lines, right_moved_lines             *utils.Set[int]
 }
 
 func (self *Patch) Len() int { return len(self.all_hunks) }
@@ -451,6 +453,62 @@ func (self *Patch) compute_centers(left_lines, right_lines []string) error {
 	return nil
 }
 
+func (self *Patch) detect_moved_lines(left_lines, right_lines []string) {
+	// Build maps from line text to lists of line numbers for removed and added lines.
+	removed := make(map[string][]int) // text -> left line numbers
+	added := make(map[string][]int)   // text -> right line numbers
+	// Use SIMD to efficiently find non-blank lines: a line is non-blank if it
+	// contains at least one character that is not a space or tab.
+	is_non_blank := func(text string) bool {
+		for len(text) > 0 {
+			idx := simdstring.IndexByte2String(text, ' ', '\t')
+			if idx != 0 {
+				// idx < 0: no space/tab found, remaining chars are non-blank;
+				// idx > 0: non-blank chars exist before the first space/tab.
+				return true
+			}
+			text = text[1:]
+		}
+		return false
+	}
+	for _, hunk := range self.all_hunks {
+		for _, chunk := range hunk.chunks {
+			if !chunk.is_context {
+				for i := 0; i < chunk.left_count; i++ {
+					lnum := chunk.left_start + i
+					text := left_lines[lnum]
+					if is_non_blank(text) {
+						removed[text] = append(removed[text], lnum)
+					}
+				}
+				for i := 0; i < chunk.right_count; i++ {
+					rnum := chunk.right_start + i
+					text := right_lines[rnum]
+					if is_non_blank(text) {
+						added[text] = append(added[text], rnum)
+					}
+				}
+			}
+		}
+	}
+	// Lines that appear in both removed and added sets are moved lines. When a
+	// line appears multiple times on each side, only min(left_count,
+	// right_count) occurrences are marked as moved.
+	self.left_moved_lines = utils.NewSet[int]()
+	self.right_moved_lines = utils.NewSet[int]()
+	for text, lnums := range removed {
+		if rnums, ok := added[text]; ok {
+			count := min(len(lnums), len(rnums))
+			for _, lnum := range lnums[:count] {
+				self.left_moved_lines.Add(lnum)
+			}
+			for _, rnum := range rnums[:count] {
+				self.right_moved_lines.Add(rnum)
+			}
+		}
+	}
+}
+
 func parse_patch(raw string, left_lines, right_lines []string) (ans *Patch, err error) {
 	ans = &Patch{all_hunks: make([]*Hunk, 0, 32)}
 	var current_hunk *Hunk
@@ -486,6 +544,9 @@ func parse_patch(raw string, left_lines, right_lines []string) (ans *Patch, err
 		ans.largest_line_number = ans.all_hunks[len(ans.all_hunks)-1].largest_line_number
 	}
 	err = ans.compute_centers(left_lines, right_lines)
+	if err == nil {
+		ans.detect_moved_lines(left_lines, right_lines)
+	}
 	return
 }
 

kittens/diff/render.go

@@ -40,6 +40,7 @@ type HalfScreenLine struct {
 	marked_up_margin_text string
 	marked_up_text        string
 	is_filler             bool
+	is_moved              bool
 	cached_wcswidth       int
 }
 
@@ -81,6 +82,9 @@ func (self *LogicalLine) render_screen_line(n int, lp *loop.Loop, margin_size, c
 	if sl.left.is_filler {
 		left_margin = format_as_sgr.margin_filler + left_margin
 		left_text = format_as_sgr.filler + left_text
+	} else if sl.left.is_moved {
+		left_margin = format_as_sgr.moved_margin + left_margin
+		left_text = format_as_sgr.moved + left_text
 	} else {
 		switch self.line_type {
 		case CHANGE_LINE, IMAGE_LINE:
@@ -104,6 +108,9 @@ func (self *LogicalLine) render_screen_line(n int, lp *loop.Loop, margin_size, c
 	if sl.right.is_filler {
 		right_margin = format_as_sgr.margin_filler + right_margin
 		right_text = format_as_sgr.filler + right_text
+	} else if sl.right.is_moved {
+		right_margin = format_as_sgr.moved_margin + right_margin
+		right_text = format_as_sgr.moved + right_text
 	} else {
 		switch self.line_type {
 		case CHANGE_LINE, IMAGE_LINE:
@@ -156,7 +163,7 @@ func place_in(text string, sz int) string {
 }
 
 var format_as_sgr struct {
-	title, margin, added, removed, added_margin, removed_margin, filler, margin_filler, hunk_margin, hunk, selection, search string
+	title, margin, added, removed, added_margin, removed_margin, filler, margin_filler, hunk_margin, hunk, selection, search, moved, moved_margin string
 }
 
 var statusline_format, added_count_format, removed_count_format, message_format func(...any) string
@@ -175,6 +182,8 @@ type ResolvedColors struct {
 	Margin_bg            style.RGBA
 	Margin_fg            style.RGBA
 	Margin_filler_bg     style.NullableColor
+	Moved_bg             style.RGBA
+	Moved_margin_bg      style.RGBA
 	Removed_bg           style.RGBA
 	Removed_margin_bg    style.RGBA
 	Search_bg            style.RGBA
@@ -202,6 +211,8 @@ func create_formatters() {
 		rc.Margin_bg = conf.Dark_margin_bg
 		rc.Margin_fg = conf.Dark_margin_fg
 		rc.Margin_filler_bg = conf.Dark_margin_filler_bg
+		rc.Moved_bg = conf.Dark_moved_bg
+		rc.Moved_margin_bg = conf.Dark_moved_margin_bg
 		rc.Removed_bg = conf.Dark_removed_bg
 		rc.Removed_margin_bg = conf.Dark_removed_margin_bg
 		rc.Search_bg = conf.Dark_search_bg
@@ -223,6 +234,8 @@ func create_formatters() {
 		rc.Margin_bg = conf.Margin_bg
 		rc.Margin_fg = conf.Margin_fg
 		rc.Margin_filler_bg = conf.Margin_filler_bg
+		rc.Moved_bg = conf.Moved_bg
+		rc.Moved_margin_bg = conf.Moved_margin_bg
 		rc.Removed_bg = conf.Removed_bg
 		rc.Removed_margin_bg = conf.Removed_margin_bg
 		rc.Search_bg = conf.Search_bg
@@ -248,6 +261,8 @@ func create_formatters() {
 	format_as_sgr.added_margin = only_open(fmt.Sprintf("fg=%s bg=%s", rc.Margin_fg.AsRGBSharp(), rc.Added_margin_bg.AsRGBSharp()))
 	format_as_sgr.removed = only_open("bg=" + rc.Removed_bg.AsRGBSharp())
 	format_as_sgr.removed_margin = only_open(fmt.Sprintf("fg=%s bg=%s", rc.Margin_fg.AsRGBSharp(), rc.Removed_margin_bg.AsRGBSharp()))
+	format_as_sgr.moved = only_open("bg=" + rc.Moved_bg.AsRGBSharp())
+	format_as_sgr.moved_margin = only_open(fmt.Sprintf("fg=%s bg=%s", rc.Margin_fg.AsRGBSharp(), rc.Moved_margin_bg.AsRGBSharp()))
 	format_as_sgr.title = only_open(fmt.Sprintf("fg=%s bg=%s bold", rc.Title_fg.AsRGBSharp(), rc.Title_bg.AsRGBSharp()))
 	format_as_sgr.margin = only_open(fmt.Sprintf("fg=%s bg=%s", rc.Margin_fg.AsRGBSharp(), rc.Margin_bg.AsRGBSharp()))
 	format_as_sgr.hunk = only_open(fmt.Sprintf("fg=%s bg=%s", rc.Margin_fg.AsRGBSharp(), rc.Hunk_bg.AsRGBSharp()))
@@ -532,7 +547,9 @@ type DiffData struct {
 	left_path, right_path       string
 	available_cols, margin_size int
 
-	left_lines, right_lines []string
+	left_lines, right_lines   []string
+	left_moved_lines          *utils.Set[int]
+	right_moved_lines         *utils.Set[int]
 }
 
 func hunk_title(hunk *Hunk) string {
@@ -567,7 +584,7 @@ func splitlines(text string, width int) []string {
 	return style.WrapTextAsLines(text, width, style.WrapOptions{})
 }
 
-func render_half_line(line_number int, line, ltype string, available_cols int, center Center, ans []HalfScreenLine) []HalfScreenLine {
+func render_half_line(line_number int, line, ltype string, available_cols int, center Center, is_moved bool, ans []HalfScreenLine) []HalfScreenLine {
 	var regions []Region
 	if ltype == "remove" {
 		regions = center.left_regions
@@ -583,7 +600,7 @@ func render_half_line(line_number int, line, ltype string, available_cols int, c
 	}
 	lnum := strconv.Itoa(line_number + 1)
 	for _, sc := range splitlines(line, available_cols) {
-		ans = append(ans, HalfScreenLine{marked_up_margin_text: lnum, marked_up_text: sc})
+		ans = append(ans, HalfScreenLine{marked_up_margin_text: lnum, marked_up_text: sc, is_moved: is_moved})
 		lnum = ""
 	}
 	return ans
@@ -601,13 +618,15 @@ func lines_for_diff_chunk(data *DiffData, _ int, chunk *Chunk, _ int, ans []*Log
 		}
 		if i < chunk.left_count {
 			left_lnum = chunk.left_start + i
-			ll = render_half_line(left_lnum, data.left_lines[left_lnum], "remove", data.available_cols, center, ll)
+			left_is_moved := data.left_moved_lines != nil && data.left_moved_lines.Has(left_lnum)
+			ll = render_half_line(left_lnum, data.left_lines[left_lnum], "remove", data.available_cols, center, left_is_moved, ll)
 			left_lnum++
 		}
 
 		if i < chunk.right_count {
 			right_lnum = chunk.right_start + i
-			rl = render_half_line(right_lnum, data.right_lines[right_lnum], "add", data.available_cols, center, rl)
+			right_is_moved := data.right_moved_lines != nil && data.right_moved_lines.Has(right_lnum)
+			rl = render_half_line(right_lnum, data.right_lines[right_lnum], "add", data.available_cols, center, right_is_moved, rl)
 			right_lnum++
 		}
 
@@ -663,7 +682,10 @@ func lines_for_diff(left_path string, right_path string, patch *Patch, columns,
 		return append(ans, &ht), nil
 	}
 	available_cols := columns/2 - margin_size
-	data := DiffData{left_path: left_path, right_path: right_path, available_cols: available_cols, margin_size: margin_size}
+	data := DiffData{
+		left_path: left_path, right_path: right_path, available_cols: available_cols, margin_size: margin_size,
+		left_moved_lines: patch.left_moved_lines, right_moved_lines: patch.right_moved_lines,
+	}
 	if left_path != "" {
 		data.left_lines, err = highlighted_lines_for_path(left_path)
 		if err != nil {
@@ -720,7 +742,7 @@ func all_lines(path string, columns, margin_size int, is_add bool, ans []*Logica
 	}
 	for line_number, line := range lines {
 		hlines := make([]HalfScreenLine, 0, 8)
-		hlines = render_half_line(line_number, line, ltype, available_cols, Center{}, hlines)
+		hlines = render_half_line(line_number, line, ltype, available_cols, Center{}, false, hlines)
 		l := ll
 		if is_add {
 			l.right_reference.linenum = line_number + 1