forked from qur/withmock
/
rewrite.go
126 lines (100 loc) · 2.03 KB
/
rewrite.go
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// Copyright 2013 Julian Phillips. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package lib
import (
"bytes"
"io"
"os"
)
type rewriter struct {
w io.Writer
buf *bytes.Buffer
rewrites []rw
}
type rw struct {
match, replace []byte
}
func NewRewriter(w io.Writer) *rewriter {
return &rewriter{
w: w,
buf: &bytes.Buffer{},
}
}
func (r *rewriter) Rewrite(src, dst string) {
r.rewrites = append(r.rewrites, rw{[]byte(src), []byte(dst)})
}
func (r *rewriter) flushLines() error {
line, err := r.buf.ReadBytes('\n')
for err == nil {
for _, rw := range r.rewrites {
line = bytes.Replace(line, rw.match, rw.replace, -1)
}
_, err = r.w.Write(line)
if err != nil {
return err
}
line, err = r.buf.ReadBytes('\n')
}
// Rebuild the buffer without any data that we have processed, but including
// any data we have read out, but not yet processed.
buf := bytes.NewBuffer(line)
buf.Write(r.buf.Bytes())
r.buf = buf
if err != io.EOF {
return err
}
return nil
}
func (r *rewriter) flush() error {
if r.buf.Len() == 0 {
return nil
}
line := r.buf.Bytes()
for _, rw := range r.rewrites {
line = bytes.Replace(line, rw.match, rw.replace, -1)
}
_, err := r.w.Write(line)
if err != nil {
return err
}
r.buf.Reset()
return nil
}
func (r *rewriter) Write(p []byte) (int, error) {
r.buf.Write(p)
return len(p), r.flushLines()
}
func (r *rewriter) Close() error {
return r.flush()
}
func (r *rewriter) Change(w io.Writer) error {
err := r.Close()
if err != nil {
return err
}
r.w = w
return nil
}
func (rw *rewriter) Copy(src, dst string) error {
r, err := os.Open(src)
if err != nil {
return Cerr{"os.Open", err}
}
defer r.Close()
w, err := os.Create(dst)
if err != nil {
return Cerr{"os.Create", err}
}
defer w.Close()
err = rw.Change(w)
if err != nil {
return Cerr{"rw.Change", err}
}
defer rw.Close()
_, err = io.Copy(rw, r)
if err != nil {
return Cerr{"io.Copy", err}
}
return nil
}