Side-by-side semantic diff tool with theme support and
hookable integration
feat: character-level diff highlights
+132
-16
+29
internal/diff.go
+29
internal/diff.go
···
329
329
return result
330
330
}
331
331
332
+
// CharDiffRanges computes a character-level diff between oldText and newText and
333
+
// returns the rune-position ranges [start, end) in each string that differ.
334
+
// Ranges are sorted and non-overlapping.
335
+
func CharDiffRanges(oldText, newText string) (oldRanges, newRanges [][2]int) {
336
+
if oldText == newText {
337
+
return nil, nil
338
+
}
339
+
dmp := diffmatchpatch.New()
340
+
diffs := dmp.DiffMain(oldText, newText, false)
341
+
diffs = dmp.DiffCleanupSemantic(diffs)
342
+
343
+
oldPos, newPos := 0, 0
344
+
for _, d := range diffs {
345
+
n := len([]rune(d.Text))
346
+
switch d.Type {
347
+
case diffmatchpatch.DiffEqual:
348
+
oldPos += n
349
+
newPos += n
350
+
case diffmatchpatch.DiffDelete:
351
+
oldRanges = append(oldRanges, [2]int{oldPos, oldPos + n})
352
+
oldPos += n
353
+
case diffmatchpatch.DiffInsert:
354
+
newRanges = append(newRanges, [2]int{newPos, newPos + n})
355
+
newPos += n
356
+
}
357
+
}
358
+
return
359
+
}
360
+
332
361
// SplitLines splits text by newlines, keeping each line without its terminator.
333
362
func SplitLines(s string) []string {
334
363
if s == "" {
+69
internal/highlight.go
+69
internal/highlight.go
···
4
4
"fmt"
5
5
"io"
6
6
"strings"
7
+
"unicode/utf8"
7
8
8
9
"github.com/alecthomas/chroma/v2"
9
10
"github.com/alecthomas/chroma/v2/lexers"
···
109
110
return bg + content + padding + bg + "\033[K\033[0m"
110
111
}
111
112
return bg + content + padding + "\033[0m"
113
+
}
114
+
115
+
// ApplyCharHighlights inserts background-color transitions into an ANSI-highlighted
116
+
// string so that the visible rune positions covered by ranges use charBg instead of
117
+
// normalBg. The caller is expected to set normalBg as the active background before
118
+
// this string is rendered (e.g. RenderCell prepends it).
119
+
// ranges must be sorted and contain non-overlapping [start, end) rune positions.
120
+
func ApplyCharHighlights(highlighted, normalBg, charBg string, ranges [][2]int) string {
121
+
if len(ranges) == 0 || charBg == "" || normalBg == "" {
122
+
return highlighted
123
+
}
124
+
nr, ng, nb := parseHex(normalBg)
125
+
cr, cg, cb := parseHex(charBg)
126
+
normalCode := fmt.Sprintf("\033[48;2;%d;%d;%dm", nr, ng, nb)
127
+
charCode := fmt.Sprintf("\033[48;2;%d;%d;%dm", cr, cg, cb)
128
+
129
+
inRange := func(pos int) bool {
130
+
for _, r := range ranges {
131
+
if r[0] > pos {
132
+
return false
133
+
}
134
+
if pos < r[1] {
135
+
return true
136
+
}
137
+
}
138
+
return false
139
+
}
140
+
141
+
var out strings.Builder
142
+
out.Grow(len(highlighted) + len(ranges)*2*(len(charCode)+len(normalCode)))
143
+
visiblePos := 0
144
+
inHL := false
145
+
146
+
i := 0
147
+
for i < len(highlighted) {
148
+
// Skip ANSI escape sequences verbatim.
149
+
if highlighted[i] == '\x1b' && i+1 < len(highlighted) && highlighted[i+1] == '[' {
150
+
j := i + 2
151
+
for j < len(highlighted) && highlighted[j] != 'm' {
152
+
j++
153
+
}
154
+
if j < len(highlighted) {
155
+
j++ // include 'm'
156
+
}
157
+
out.WriteString(highlighted[i:j])
158
+
i = j
159
+
continue
160
+
}
161
+
162
+
want := inRange(visiblePos)
163
+
if want && !inHL {
164
+
out.WriteString(charCode)
165
+
inHL = true
166
+
} else if !want && inHL {
167
+
out.WriteString(normalCode)
168
+
inHL = false
169
+
}
170
+
171
+
_, size := utf8.DecodeRuneInString(highlighted[i:])
172
+
out.WriteString(highlighted[i : i+size])
173
+
visiblePos++
174
+
i += size
175
+
}
176
+
177
+
if inHL {
178
+
out.WriteString(normalCode)
179
+
}
180
+
return out.String()
112
181
}
113
182
114
183
// parseHex parses a "#RRGGBB" hex colour string into R, G, B components.
+22
-16
internal/theme.go
+22
-16
internal/theme.go
···
29
29
type DiffColors struct {
30
30
AddedBg string `toml:"added_bg"`
31
31
AddedFg string `toml:"added_fg"`
32
+
AddedCharBg string `toml:"added_char_bg"`
32
33
RemovedBg string `toml:"removed_bg"`
33
34
RemovedFg string `toml:"removed_fg"`
35
+
RemovedCharBg string `toml:"removed_char_bg"`
34
36
EqualFg string `toml:"equal_fg"`
35
37
HeaderFg string `toml:"header_fg"`
36
38
LineNumberFg string `toml:"line_number_fg"`
···
46
48
}
47
49
48
50
type ThemeStyles struct {
49
-
HeaderSt lipgloss.Style
50
-
LineSt lipgloss.Style
51
-
StatusSt lipgloss.Style
52
-
HelpSt lipgloss.Style
53
-
AddedBgHex string // raw hex for composing with syntax-highlighted text
54
-
RemovedBgHex string
55
-
ChromaStyle string
56
-
CursorSymbol string
51
+
HeaderSt lipgloss.Style
52
+
LineSt lipgloss.Style
53
+
StatusSt lipgloss.Style
54
+
HelpSt lipgloss.Style
55
+
AddedBgHex string // raw hex for composing with syntax-highlighted text
56
+
AddedCharBgHex string // brighter bg for intra-line added characters
57
+
RemovedBgHex string
58
+
RemovedCharBgHex string // brighter bg for intra-line removed characters
59
+
ChromaStyle string
60
+
CursorSymbol string
57
61
}
58
62
59
63
// ── loader ────────────────────────────────────────────────────────────────────
···
93
97
func (t Theme) ToStyles() ThemeStyles {
94
98
d := t.Diff
95
99
return ThemeStyles{
96
-
HeaderSt: lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color(d.HeaderFg)),
97
-
LineSt: lipgloss.NewStyle().Foreground(lipgloss.Color(d.LineNumberFg)),
98
-
StatusSt: lipgloss.NewStyle().Foreground(lipgloss.Color(d.StatusFg)).Bold(true),
99
-
HelpSt: lipgloss.NewStyle().Foreground(lipgloss.Color(d.HelpFg)),
100
-
AddedBgHex: d.AddedBg,
101
-
RemovedBgHex: d.RemovedBg,
102
-
ChromaStyle: t.Chroma.Style,
103
-
CursorSymbol: d.CursorSymbol,
100
+
HeaderSt: lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color(d.HeaderFg)),
101
+
LineSt: lipgloss.NewStyle().Foreground(lipgloss.Color(d.LineNumberFg)),
102
+
StatusSt: lipgloss.NewStyle().Foreground(lipgloss.Color(d.StatusFg)).Bold(true),
103
+
HelpSt: lipgloss.NewStyle().Foreground(lipgloss.Color(d.HelpFg)),
104
+
AddedBgHex: d.AddedBg,
105
+
AddedCharBgHex: d.AddedCharBg,
106
+
RemovedBgHex: d.RemovedBg,
107
+
RemovedCharBgHex: d.RemovedCharBg,
108
+
ChromaStyle: t.Chroma.Style,
109
+
CursorSymbol: d.CursorSymbol,
104
110
}
105
111
}
+2
internal/themes/nord.toml
+2
internal/themes/nord.toml
+10
main.go
+10
main.go
···
445
445
case adiff.KindChanged:
446
446
lBgHex = st.RemovedBgHex
447
447
rBgHex = st.AddedBgHex
448
+
if st.RemovedCharBgHex != "" && st.AddedCharBgHex != "" {
449
+
lRanges, rRanges := adiff.CharDiffRanges(adiff.StripANSI(leftLine), adiff.StripANSI(rightLine))
450
+
leftLine = adiff.ApplyCharHighlights(leftLine, lBgHex, st.RemovedCharBgHex, lRanges)
451
+
rightLine = adiff.ApplyCharHighlights(rightLine, rBgHex, st.AddedCharBgHex, rRanges)
452
+
}
448
453
}
449
454
450
455
prefix := " "
···
583
588
case adiff.KindChanged:
584
589
lBgHex = st.RemovedBgHex
585
590
rBgHex = st.AddedBgHex
591
+
if st.RemovedCharBgHex != "" && st.AddedCharBgHex != "" {
592
+
lRanges, rRanges := adiff.CharDiffRanges(adiff.StripANSI(leftLine), adiff.StripANSI(rightLine))
593
+
leftLine = adiff.ApplyCharHighlights(leftLine, lBgHex, st.RemovedCharBgHex, lRanges)
594
+
rightLine = adiff.ApplyCharHighlights(rightLine, rBgHex, st.AddedCharBgHex, rRanges)
595
+
}
586
596
}
587
597
588
598
lNum := " "