From ab7501be34032fb9e5c48726a68ae90a917af9eb Mon Sep 17 00:00:00 2001
From: Runxi Yu
Date: Wed, 4 Mar 2026 08:26:56 +0800
Subject: *: Lint

---
 diff/lines/diff.go | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

(limited to 'diff/lines/diff.go')

diff --git a/diff/lines/diff.go b/diff/lines/diff.go
index bdcb4d93..ca34f371 100644
--- a/diff/lines/diff.go
+++ b/diff/lines/diff.go
@@ -5,7 +5,7 @@ import "bytes"
 
 // Diff performs a line-based diff.
 // Lines are bytes up to and including '\n' (final line may lack '\n').
-func Diff(oldB, newB []byte) ([]Chunk, error) {
+func Diff(oldB, newB []byte) ([]Chunk, error) { //nolint:maintidx
 	type lineRef struct {
 		base  []byte
 		start int
@@ -16,17 +16,22 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 		if len(b) == 0 {
 			return nil
 		}
+
 		var res []lineRef
+
 		start := 0
+
 		for i := range b {
 			if b[i] == '\n' {
 				res = append(res, lineRef{base: b, start: start, end: i + 1})
 				start = i + 1
 			}
 		}
+
 		if start < len(b) {
 			res = append(res, lineRef{base: b, start: start, end: len(b)})
 		}
+
 		return res
 	}
 
@@ -34,6 +39,7 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 	newLines := split(newB)
 
 	n := len(oldLines)
+
 	m := len(newLines)
 	if n == 0 && m == 0 {
 		return nil, nil
@@ -42,25 +48,32 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 	idOf := make(map[string]int)
 	nextID := 0
 	oldIDs := make([]int, n)
+
 	for i, ln := range oldLines {
 		key := string(ln.base[ln.start:ln.end])
+
 		id, ok := idOf[key]
 		if !ok {
 			id = nextID
 			idOf[key] = id
 			nextID++
 		}
+
 		oldIDs[i] = id
 	}
+
 	newIDs := make([]int, m)
+
 	for i, ln := range newLines {
 		key := string(ln.base[ln.start:ln.end])
+
 		id, ok := idOf[key]
 		if !ok {
 			id = nextID
 			idOf[key] = id
 			nextID++
 		}
+
 		newIDs[i] = id
 	}
 
@@ -74,11 +87,13 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 	}
 
 	x0 := 0
+
 	y0 := 0
 	for x0 < n && y0 < m && oldIDs[x0] == newIDs[y0] {
 		x0++
 		y0++
 	}
+
 	Vprev[offset+0] = x0
 	trace = append(trace, append([]int(nil), Vprev...))
 
@@ -97,17 +112,20 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 			} else {
 				x = Vprev[offset+(k-1)] + 1
 			}
+
 			y := x - k
 
 			for x < n && y < m && oldIDs[x] == newIDs[y] {
 				x++
 				y++
 			}
+
 			V[offset+k] = x
 
 			if x >= n && y >= m {
 				trace = append(trace, V)
 				found = true
+
 				break
 			}
 		}
@@ -122,9 +140,11 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 		kind    ChunkKind
 		lineref lineRef
 	}
+
 	revEdits := make([]edit, 0, n+m)
 
 	x := n
+
 	y := m
 	for D := len(trace) - 1; D >= 0; D-- {
 		k := x - y
@@ -134,6 +154,7 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 			prevX int
 			prevY int
 		)
+
 		if D > 0 {
 			prevV := trace[D-1]
 			if k == -D || (k != D && prevV[offset+(k-1)] < prevV[offset+(k+1)]) {
@@ -141,6 +162,7 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 			} else {
 				prevK = k - 1
 			}
+
 			prevX = prevV[offset+prevK]
 			prevY = prevX - prevK
 		}
@@ -148,6 +170,7 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 		for x > prevX && y > prevY {
 			x--
 			y--
+
 			revEdits = append(revEdits, edit{kind: ChunkKindUnchanged, lineref: oldLines[x]})
 		}
 
@@ -169,11 +192,13 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 	}
 
 	var out []Chunk
+
 	type meta struct {
 		base  []byte
 		start int
 		end   int
 	}
+
 	var metas []meta
 
 	for _, e := range revEdits {
@@ -184,6 +209,7 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 		if len(out) == 0 || out[len(out)-1].Kind != e.kind {
 			out = append(out, Chunk{Kind: e.kind, Data: curBase[curStart:curEnd]})
 			metas = append(metas, meta{base: curBase, start: curStart, end: curEnd})
+
 			continue
 		}
 
@@ -193,6 +219,7 @@ func Diff(oldB, newB []byte) ([]Chunk, error) {
 		if bytes.Equal(lastMeta.base, curBase) && lastMeta.end == curStart {
 			metas[lastIdx].end = curEnd
 			out[lastIdx].Data = curBase[metas[lastIdx].start:metas[lastIdx].end]
+
 			continue
 		}
 
-- 
cgit v1.3.1-10-gc9f91