83 lines
1.6 KiB
Go
83 lines
1.6 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// TODO(bradfitz,adg): move to util
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package godoc
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import "io"
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var spaces = []byte(" ") // 32 spaces seems like a good number
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const (
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indenting = iota
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collecting
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)
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// A tconv is an io.Writer filter for converting leading tabs into spaces.
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type tconv struct {
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output io.Writer
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state int // indenting or collecting
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indent int // valid if state == indenting
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p *Presentation
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}
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func (p *tconv) writeIndent() (err error) {
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i := p.indent
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for i >= len(spaces) {
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i -= len(spaces)
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if _, err = p.output.Write(spaces); err != nil {
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return
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}
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}
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// i < len(spaces)
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if i > 0 {
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_, err = p.output.Write(spaces[0:i])
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}
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return
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}
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func (p *tconv) Write(data []byte) (n int, err error) {
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if len(data) == 0 {
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return
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}
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pos := 0 // valid if p.state == collecting
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var b byte
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for n, b = range data {
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switch p.state {
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case indenting:
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switch b {
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case '\t':
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p.indent += p.p.TabWidth
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case '\n':
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p.indent = 0
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if _, err = p.output.Write(data[n : n+1]); err != nil {
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return
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}
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case ' ':
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p.indent++
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default:
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p.state = collecting
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pos = n
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if err = p.writeIndent(); err != nil {
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return
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}
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}
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case collecting:
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if b == '\n' {
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p.state = indenting
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p.indent = 0
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if _, err = p.output.Write(data[pos : n+1]); err != nil {
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return
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}
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}
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}
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}
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n = len(data)
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if pos < n && p.state == collecting {
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_, err = p.output.Write(data[pos:])
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}
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return
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}
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