From 7793021260ca97cf10dfedf2f7942876f949100c Mon Sep 17 00:00:00 2001
From: Kyle Isom <kyle@imap.cc>
Date: Sat, 5 Feb 2022 15:00:39 -0800
Subject: [PATCH] New package: seekbuf (a seekable buffer).

---
 seekbuf/seekbuf.go | 50 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 seekbuf/seekbuf.go

diff --git a/seekbuf/seekbuf.go b/seekbuf/seekbuf.go
new file mode 100644
index 0000000..8285fa4
--- /dev/null
+++ b/seekbuf/seekbuf.go
@@ -0,0 +1,50 @@
+package seekbuf
+
+import "io"
+
+// Buffer is a ReadWriteCloser that supports seeking. It's intended to
+// replicate the functionality of bytes.Buffer that I use in my projects.
+//
+// Note that the seeking is limited to the read marker; all writes are
+// append-only.
+type Buffer struct {
+	data []byte
+	pos  int
+}
+
+func New(data []byte) *Buffer {
+	return &Buffer{
+		data: data,
+	}
+}
+
+func (b *Buffer) Read(p []byte) (int, error) {
+	if b.pos >= len(b.data) {
+		return 0, io.EOF
+	}
+
+	n := copy(p, b.data[b.pos:])
+	b.pos += n
+	return n, nil
+}
+
+func (b *Buffer) Write(p []byte) (int, error) {
+	b.data = append(b.data, p...)
+	return len(p), nil
+}
+
+// Seek sets the read pointer to pos.
+func (b *Buffer) Seek(pos int) {
+	b.pos = pos
+}
+
+// Rewind resets the read pointer to 0.
+func (b *Buffer) Rewind() {
+	b.pos = 0
+}
+
+// Close clears all the data out of the buffer and sets the read position to 0.
+func (b *Buffer) Close() error {
+	b.Clear()
+	return nil
+}