Delete everything, I'm redesigning this.

I'll stop using a flat package and make things much more modular.
And also experiment with streaming APIs so large blobs don't OOM us.

3 files changed, 0 insertions, 566 deletions

diff --git a/difflines/difflines.go b/difflines/difflines.go
deleted file mode 100644
index db4c1a03..00000000
--- a/difflines/difflines.go
+++ /dev/null
@@ -1,223 +0,0 @@
-// Package difflines provides routines to perform line-based diffs.
-package difflines
-
-import "bytes"
-
-// DiffLines performs a line-based diff.
-// Lines are bytes up to and including '\n' (final line may lack '\n').
-func DiffLines(oldB, newB []byte) ([]LinesDiffChunk, error) {
-	type lineRef struct {
-		base  []byte
-		start int
-		end   int
-	}
-
-	split := func(b []byte) []lineRef {
-		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
-	}
-
-	oldLines := split(oldB)
-	newLines := split(newB)
-
-	n := len(oldLines)
-	m := len(newLines)
-	if n == 0 && m == 0 {
-		return nil, nil
-	}
-
-	idOf := make(map[string]int)
-	nextID := 0
-	oldIDs := make([]int, n)
-	for i, ln := range oldLines {
-		key := bytesToString(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 := bytesToString(ln.base[ln.start:ln.end])
-		id, ok := idOf[key]
-		if !ok {
-			id = nextID
-			idOf[key] = id
-			nextID++
-		}
-		newIDs[i] = id
-	}
-
-	max := n + m
-	offset := max
-	trace := make([][]int, 0, max+1)
-
-	Vprev := make([]int, 2*max+1)
-	for i := range Vprev {
-		Vprev[i] = -1
-	}
-
-	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...))
-
-	found := x0 >= n && y0 >= m
-
-	for D := 1; D <= max && !found; D++ {
-		V := make([]int, 2*max+1)
-		for i := range V {
-			V[i] = -1
-		}
-
-		for k := -D; k <= D; k += 2 {
-			var x int
-			if k == -D || (k != D && Vprev[offset+(k-1)] < Vprev[offset+(k+1)]) {
-				x = Vprev[offset+(k+1)]
-			} 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
-			}
-		}
-
-		if !found {
-			trace = append(trace, V)
-			Vprev = V
-		}
-	}
-
-	type edit struct {
-		kind    LinesDiffChunkKind
-		lineref lineRef
-	}
-	revEdits := make([]edit, 0, n+m)
-
-	x := n
-	y := m
-	for D := len(trace) - 1; D >= 0; D-- {
-		k := x - y
-
-		var (
-			prevK int
-			prevX int
-			prevY int
-		)
-		if D > 0 {
-			prevV := trace[D-1]
-			if k == -D || (k != D && prevV[offset+(k-1)] < prevV[offset+(k+1)]) {
-				prevK = k + 1
-			} else {
-				prevK = k - 1
-			}
-			prevX = prevV[offset+prevK]
-			prevY = prevX - prevK
-		}
-
-		for x > prevX && y > prevY {
-			x--
-			y--
-			revEdits = append(revEdits, edit{kind: LinesDiffChunkKindUnchanged, lineref: oldLines[x]})
-		}
-
-		if D == 0 {
-			break
-		}
-
-		if x == prevX {
-			y--
-			revEdits = append(revEdits, edit{kind: LinesDiffChunkKindAdded, lineref: newLines[y]})
-		} else {
-			x--
-			revEdits = append(revEdits, edit{kind: LinesDiffChunkKindDeleted, lineref: oldLines[x]})
-		}
-	}
-
-	for i, j := 0, len(revEdits)-1; i < j; i, j = i+1, j-1 {
-		revEdits[i], revEdits[j] = revEdits[j], revEdits[i]
-	}
-
-	var out []LinesDiffChunk
-	type meta struct {
-		base  []byte
-		start int
-		end   int
-	}
-	var metas []meta
-
-	for _, e := range revEdits {
-		curBase := e.lineref.base
-		curStart := e.lineref.start
-		curEnd := e.lineref.end
-
-		if len(out) == 0 || out[len(out)-1].Kind != e.kind {
-			out = append(out, LinesDiffChunk{Kind: e.kind, Data: curBase[curStart:curEnd]})
-			metas = append(metas, meta{base: curBase, start: curStart, end: curEnd})
-			continue
-		}
-
-		lastIdx := len(out) - 1
-		lastMeta := metas[lastIdx]
-
-		if bytes.Equal(lastMeta.base, curBase) && lastMeta.end == curStart {
-			metas[lastIdx].end = curEnd
-			out[lastIdx].Data = curBase[metas[lastIdx].start:metas[lastIdx].end]
-			continue
-		}
-
-		out[lastIdx].Data = append(out[lastIdx].Data, curBase[curStart:curEnd]...)
-		metas[lastIdx] = meta{base: nil, start: 0, end: 0}
-	}
-
-	return out, nil
-}
-
-// LinesDiffChunk represents a contiguous region of lines categorized
-// as unchanged, deleted, or added.
-type LinesDiffChunk struct {
-	Kind LinesDiffChunkKind
-	Data []byte
-}
-
-// LinesDiffChunkKind enumerates the type of diff chunk.
-type LinesDiffChunkKind int
-
-const (
-	// LinesDiffChunkKindUnchanged represents an unchanged diff chunk.
-	LinesDiffChunkKindUnchanged LinesDiffChunkKind = iota
-	// LinesDiffChunkKindDeleted represents a deleted diff chunk.
-	LinesDiffChunkKindDeleted
-	// LinesDiffChunkKindAdded represents an added diff chunk.
-	LinesDiffChunkKindAdded
-)
diff --git a/difflines/difflines_test.go b/difflines/difflines_test.go
deleted file mode 100644
index 783c2d6e..00000000
--- a/difflines/difflines_test.go
+++ /dev/null
@@ -1,326 +0,0 @@
-package difflines
-
-import (
-	"bytes"
-	"strconv"
-	"strings"
-	"testing"
-)
-
-func TestDiffLines(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		name     string
-		oldInput string
-		newInput string
-		expected []LinesDiffChunk
-	}{
-		{
-			name:     "empty inputs produce no chunks",
-			oldInput: "",
-			newInput: "",
-			expected: []LinesDiffChunk{},
-		},
-		{
-			name:     "only additions",
-			oldInput: "",
-			newInput: "alpha\nbeta\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("alpha\nbeta\n")},
-			},
-		},
-		{
-			name:     "only deletions",
-			oldInput: "alpha\nbeta\n",
-			newInput: "",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("alpha\nbeta\n")},
-			},
-		},
-		{
-			name:     "unchanged content is grouped",
-			oldInput: "same\nlines\n",
-			newInput: "same\nlines\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("same\nlines\n")},
-			},
-		},
-		{
-			name:     "insertion in the middle",
-			oldInput: "a\nb\nc\n",
-			newInput: "a\nb\nX\nc\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("a\nb\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("X\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("c\n")},
-			},
-		},
-		{
-			name:     "replacement without trailing newline",
-			oldInput: "first\nsecond",
-			newInput: "first\nsecond\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("first\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("second")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("second\n")},
-			},
-		},
-		{
-			name:     "line replacement",
-			oldInput: "a\nb\nc\n",
-			newInput: "a\nB\nc\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("a\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("b\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("B\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("c\n")},
-			},
-		},
-		{
-			name:     "swap adjacent lines",
-			oldInput: "A\nB\n",
-			newInput: "B\nA\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("A\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("B\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("A\n")},
-			},
-		},
-		{
-			name:     "indentation change is a full line replacement",
-			oldInput: "func main() {\n\treturn\n}\n",
-			newInput: "func main() {\n    return\n}\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("func main() {\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("\treturn\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("    return\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("}\n")},
-			},
-		},
-		{
-			name:     "commenting out lines",
-			oldInput: "code\n",
-			newInput: "// code\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("code\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("// code\n")},
-			},
-		},
-		{
-			name:     "reducing repeating lines",
-			oldInput: "log\nlog\nlog\n",
-			newInput: "log\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("log\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("log\nlog\n")},
-			},
-		},
-		{
-			name:     "expanding repeating lines",
-			oldInput: "tick\n",
-			newInput: "tick\ntick\ntick\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("tick\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("tick\ntick\n")},
-			},
-		},
-		{
-			name:     "interleaved modifications",
-			oldInput: "keep\nchange\nkeep\nchange\n",
-			newInput: "keep\nfixed\nkeep\nfixed\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("keep\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("change\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("fixed\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("keep\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("change\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("fixed\n")},
-			},
-		},
-		{
-			name:     "large common header and footer",
-			oldInput: "header\nheader\nheader\nOLD\nfooter\nfooter\n",
-			newInput: "header\nheader\nheader\nNEW\nfooter\nfooter\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("header\nheader\nheader\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("OLD\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("NEW\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("footer\nfooter\n")},
-			},
-		},
-		{
-			name:     "completely different content",
-			oldInput: "apple\nbanana\n",
-			newInput: "cherry\ndate\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("apple\nbanana\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("cherry\ndate\n")},
-			},
-		},
-		{
-			name:     "unicode and emoji changes",
-			oldInput: "Hello 🌍\nYay\n",
-			newInput: "Hello 🌎\nYay\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("Hello 🌍\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("Hello 🌎\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("Yay\n")},
-			},
-		},
-		{
-			name:     "binary data with embedded newlines",
-			oldInput: "\x00\x01\n\x02\x03\n",
-			newInput: "\x00\x01\n\x02\xFF\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("\x00\x01\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("\x02\x03\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("\x02\xFF\n")},
-			},
-		},
-		{
-			name:     "adding trailing newline to last line",
-			oldInput: "Line 1\nLine 2",
-			newInput: "Line 1\nLine 2\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("Line 1\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("Line 2")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("Line 2\n")},
-			},
-		},
-		{
-			name:     "removing trailing newline",
-			oldInput: "A\nB\n",
-			newInput: "A\nB",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("A\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("B\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("B")},
-			},
-		},
-		{
-			name:     "inserting blank lines",
-			oldInput: "A\nB\n",
-			newInput: "A\n\n\nB\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("A\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("\n\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("B\n")},
-			},
-		},
-		{
-			name:     "collapsing blank lines",
-			oldInput: "A\n\n\n\nB\n",
-			newInput: "A\nB\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("A\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("\n\n\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("B\n")},
-			},
-		},
-		{
-			name:     "case sensitivity check",
-			oldInput: "FOO\nbar\n",
-			newInput: "foo\nbar\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("FOO\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("foo\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("bar\n")},
-			},
-		},
-		{
-			name:     "partial line match is full mismatch",
-			oldInput: "The quick brown fox\n",
-			newInput: "The quick brown fox jumps\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("The quick brown fox\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("The quick brown fox jumps\n")},
-			},
-		},
-		{
-			name:     "inserting middle content",
-			oldInput: "Top\nBottom\n",
-			newInput: "Top\nMiddle\nBottom\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("Top\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("Middle\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("Bottom\n")},
-			},
-		},
-		{
-			name:     "block move simulated",
-			oldInput: "BlockA\nBlockB\nBlockC\n",
-			newInput: "BlockA\nBlockC\nBlockB\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("BlockA\n")},
-				{Kind: LinesDiffChunkKindDeleted, Data: []byte("BlockB\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("BlockC\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("BlockB\n")},
-			},
-		},
-		{
-			name:     "alternating additions",
-			oldInput: "A\nB\nC\n",
-			newInput: "A\n1\nB\n2\nC\n",
-			expected: []LinesDiffChunk{
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("A\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("1\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("B\n")},
-				{Kind: LinesDiffChunkKindAdded, Data: []byte("2\n")},
-				{Kind: LinesDiffChunkKindUnchanged, Data: []byte("C\n")},
-			},
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			chunks, err := DiffLines([]byte(tt.oldInput), []byte(tt.newInput))
-			if err != nil {
-				t.Fatalf("DiffLines returned error: %v", err)
-			}
-
-			if len(chunks) != len(tt.expected) {
-				t.Fatalf("expected %d chunks, got %d: %s", len(tt.expected), len(chunks), formatChunks(chunks))
-			}
-
-			for i := range tt.expected {
-				if chunks[i].Kind != tt.expected[i].Kind {
-					t.Fatalf("chunk %d kind mismatch: got %v, want %v; chunks: %s", i, chunks[i].Kind, tt.expected[i].Kind, formatChunks(chunks))
-				}
-				if !bytes.Equal(chunks[i].Data, tt.expected[i].Data) {
-					t.Fatalf("chunk %d data mismatch: got %q, want %q; chunks: %s", i, string(chunks[i].Data), string(tt.expected[i].Data), formatChunks(chunks))
-				}
-			}
-		})
-	}
-}
-
-func formatChunks(chunks []LinesDiffChunk) string {
-	var b strings.Builder
-	b.WriteByte('[')
-	for i, chunk := range chunks {
-		if i > 0 {
-			b.WriteString(", ")
-		}
-		b.WriteString(chunkKindName(chunk.Kind))
-		b.WriteByte(':')
-		b.WriteString(strconv.Quote(string(chunk.Data)))
-	}
-	b.WriteByte(']')
-	return b.String()
-}
-
-func chunkKindName(kind LinesDiffChunkKind) string {
-	switch kind {
-	case LinesDiffChunkKindUnchanged:
-		return "U"
-	case LinesDiffChunkKindDeleted:
-		return "D"
-	case LinesDiffChunkKindAdded:
-		return "A"
-	default:
-		return "?"
-	}
-}
diff --git a/difflines/unsafe.go b/difflines/unsafe.go
deleted file mode 100644
index 6e7ac5fd..00000000
--- a/difflines/unsafe.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package difflines
-
-import "unsafe"
-
-// // stringToBytes converts a string to a byte slice without copying the string.
-// // Memory is borrowed from the string.
-// // The resulting byte slice must not be modified in any form.
-// func stringToBytes(s string) (bytes []byte) {
-// 	return unsafe.Slice(unsafe.StringData(s), len(s)) //#nosec G103
-// }
-
-// bytesToString converts a byte slice to a string without copying the bytes.
-// Memory is borrowed from the byte slice.
-// The source byte slice must not be modified.
-func bytesToString(b []byte) string {
-	return unsafe.String(unsafe.SliceData(b), len(b)) //#nosec G103
-}