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// Copyright 2013 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.
// TODO(bradfitz,adg): move to util
package godoc
import "io"
var spaces = []byte(" ") // 32 spaces seems like a good number
const (
indenting = iota
collecting
)
// A tconv is an io.Writer filter for converting leading tabs into spaces.
type tconv struct {
output io.Writer
state int // indenting or collecting
indent int // valid if state == indenting
p *Presentation
}
func (p *tconv) writeIndent() (err error) {
i := p.indent
for i >= len(spaces) {
i -= len(spaces)
if _, err = p.output.Write(spaces); err != nil {
return
}
}
// i < len(spaces)
if i > 0 {
_, err = p.output.Write(spaces[0:i])
}
return
}
func (p *tconv) Write(data []byte) (n int, err error) {
if len(data) == 0 {
return
}
pos := 0 // valid if p.state == collecting
var b byte
for n, b = range data {
switch p.state {
case indenting:
switch b {
case '\t':
p.indent += p.p.TabWidth
case '\n':
p.indent = 0
if _, err = p.output.Write(data[n : n+1]); err != nil {
return
}
case ' ':
p.indent++
default:
p.state = collecting
pos = n
if err = p.writeIndent(); err != nil {
return
}
}
case collecting:
if b == '\n' {
p.state = indenting
p.indent = 0
if _, err = p.output.Write(data[pos : n+1]); err != nil {
return
}
}
}
}
n = len(data)
if pos < n && p.state == collecting {
_, err = p.output.Write(data[pos:])
}
return
}
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