1 files changed, 84 insertions, 0 deletions
diff --git a/slog/internal/buffer/buffer.go b/slog/internal/buffer/buffer.go
new file mode 100644
index 0000000..7786c16
--- /dev/null
+++ b/slog/internal/buffer/buffer.go
@@ -0,0 +1,84 @@
+// Copyright 2022 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 buffer provides a pool-allocated byte buffer.
+package buffer
+
+import (
+	"sync"
+)
+
+// Buffer adapted from go/src/fmt/print.go
+type Buffer []byte
+
+// Having an initial size gives a dramatic speedup.
+var bufPool = sync.Pool{
+	New: func() any {
+		b := make([]byte, 0, 1024)
+		return (*Buffer)(&b)
+	},
+}
+
+func New() *Buffer {
+	return bufPool.Get().(*Buffer)
+}
+
+func (b *Buffer) Free() {
+	// To reduce peak allocation, return only smaller buffers to the pool.
+	const maxBufferSize = 16 << 10
+	if cap(*b) <= maxBufferSize {
+		*b = (*b)[:0]
+		bufPool.Put(b)
+	}
+}
+
+func (b *Buffer) Reset() {
+	*b = (*b)[:0]
+}
+
+func (b *Buffer) Write(p []byte) (int, error) {
+	*b = append(*b, p...)
+	return len(p), nil
+}
+
+func (b *Buffer) WriteString(s string) {
+	*b = append(*b, s...)
+}
+
+func (b *Buffer) WriteByte(c byte) {
+	*b = append(*b, c)
+}
+
+func (b *Buffer) WritePosInt(i int) {
+	b.WritePosIntWidth(i, 0)
+}
+
+// WritePosIntWidth writes non-negative integer i to the buffer, padded on the left
+// by zeroes to the given width. Use a width of 0 to omit padding.
+func (b *Buffer) WritePosIntWidth(i, width int) {
+	// Cheap integer to fixed-width decimal ASCII.
+	// Copied from log/log.go.
+
+	if i < 0 {
+		panic("negative int")
+	}
+
+	// Assemble decimal in reverse order.
+	var bb [20]byte
+	bp := len(bb) - 1
+	for i >= 10 || width > 1 {
+		width--
+		q := i / 10
+		bb[bp] = byte('0' + i - q*10)
+		bp--
+		i = q
+	}
+	// i < 10
+	bb[bp] = byte('0' + i)
+	b.Write(bb[bp:])
+}
+
+func (b *Buffer) String() string {
+	return string(*b)
+}