Initial commit
diff --git a/claudetool/editbuf/editbuf.go b/claudetool/editbuf/editbuf.go
new file mode 100644
index 0000000..6b04310
--- /dev/null
+++ b/claudetool/editbuf/editbuf.go
@@ -0,0 +1,92 @@
+// Modified from rsc.io/edit
+
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package edit implements buffered position-based editing of byte slices.
+package editbuf
+
+import (
+ "fmt"
+ "sort"
+)
+
+// A Buffer is a queue of edits to apply to a given byte slice.
+type Buffer struct {
+ old []byte
+ q edits
+}
+
+// An edit records a single text modification: change the bytes in [start,end) to new.
+type edit struct {
+ start int
+ end int
+ new string
+}
+
+// An edits is a list of edits that is sortable by start offset, breaking ties by end offset.
+type edits []edit
+
+func (x edits) Len() int { return len(x) }
+func (x edits) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
+func (x edits) Less(i, j int) bool {
+ if x[i].start != x[j].start {
+ return x[i].start < x[j].start
+ }
+ return x[i].end < x[j].end
+}
+
+// NewBuffer returns a new buffer to accumulate changes to an initial data slice.
+// The returned buffer maintains a reference to the data, so the caller must ensure
+// the data is not modified until after the Buffer is done being used.
+func NewBuffer(old []byte) *Buffer {
+ return &Buffer{old: old}
+}
+
+// Insert inserts the new string at old[pos:pos].
+func (b *Buffer) Insert(pos int, new string) {
+ if pos < 0 || pos > len(b.old) {
+ panic("invalid edit position")
+ }
+ b.q = append(b.q, edit{pos, pos, new})
+}
+
+// Delete deletes the text old[start:end].
+func (b *Buffer) Delete(start, end int) {
+ if end < start || start < 0 || end > len(b.old) {
+ panic("invalid edit position")
+ }
+ b.q = append(b.q, edit{start, end, ""})
+}
+
+// Replace replaces old[start:end] with new.
+func (b *Buffer) Replace(start, end int, new string) {
+ if end < start || start < 0 || end > len(b.old) {
+ panic("invalid edit position")
+ }
+ b.q = append(b.q, edit{start, end, new})
+}
+
+// Bytes returns a new byte slice containing the original data
+// with the queued edits applied.
+func (b *Buffer) Bytes() ([]byte, error) {
+ // Sort edits by starting position and then by ending position.
+ // Breaking ties by ending position allows insertions at point x
+ // to be applied before a replacement of the text at [x, y).
+ sort.Stable(b.q)
+
+ var new []byte
+ offset := 0
+ for i, e := range b.q {
+ if e.start < offset {
+ e0 := b.q[i-1]
+ return nil, fmt.Errorf("overlapping edits: [%d,%d)->%q, [%d,%d)->%q", e0.start, e0.end, e0.new, e.start, e.end, e.new)
+ }
+ new = append(new, b.old[offset:e.start]...)
+ offset = e.end
+ new = append(new, e.new...)
+ }
+ new = append(new, b.old[offset:]...)
+ return new, nil
+}