/usr/share/gocode/src/github.com/kr/text/colwriter/column.go is in golang-text-dev 0.0~git20130502-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 | // Package colwriter provides a write filter that formats
// input lines in multiple columns.
//
// The package is a straightforward translation from
// /src/cmd/draw/mc.c in Plan 9 from User Space.
package colwriter
import (
"bytes"
"io"
"unicode/utf8"
)
const (
tab = 4
)
const (
// Print each input line ending in a colon ':' separately.
BreakOnColon uint = 1 << iota
)
// A Writer is a filter that arranges input lines in as many columns as will
// fit in its width. Tab '\t' chars in the input are translated to sequences
// of spaces ending at multiples of 4 positions.
//
// If BreakOnColon is set, each input line ending in a colon ':' is written
// separately.
//
// The Writer assumes that all Unicode code points have the same width; this
// may not be true in some fonts.
type Writer struct {
w io.Writer
buf []byte
width int
flag uint
}
// NewWriter allocates and initializes a new Writer writing to w.
// Parameter width controls the total number of characters on each line
// across all columns.
func NewWriter(w io.Writer, width int, flag uint) *Writer {
return &Writer{
w: w,
width: width,
flag: flag,
}
}
// Write writes p to the writer w. The only errors returned are ones
// encountered while writing to the underlying output stream.
func (w *Writer) Write(p []byte) (n int, err error) {
var linelen int
var lastWasColon bool
for i, c := range p {
w.buf = append(w.buf, c)
linelen++
if c == '\t' {
w.buf[len(w.buf)-1] = ' '
for linelen%tab != 0 {
w.buf = append(w.buf, ' ')
linelen++
}
}
if w.flag&BreakOnColon != 0 && c == ':' {
lastWasColon = true
} else if lastWasColon {
if c == '\n' {
pos := bytes.LastIndex(w.buf[:len(w.buf)-1], []byte{'\n'})
if pos < 0 {
pos = 0
}
line := w.buf[pos:]
w.buf = w.buf[:pos]
if err = w.columnate(); err != nil {
if len(line) < i {
return i - len(line), err
}
return 0, err
}
if n, err := w.w.Write(line); err != nil {
if r := len(line) - n; r < i {
return i - r, err
}
return 0, err
}
}
lastWasColon = false
}
if c == '\n' {
linelen = 0
}
}
return len(p), nil
}
// Flush should be called after the last call to Write to ensure that any data
// buffered in the Writer is written to output.
func (w *Writer) Flush() error {
return w.columnate()
}
func (w *Writer) columnate() error {
words := bytes.Split(w.buf, []byte{'\n'})
w.buf = nil
if len(words[len(words)-1]) == 0 {
words = words[:len(words)-1]
}
maxwidth := 0
for _, wd := range words {
if n := utf8.RuneCount(wd); n > maxwidth {
maxwidth = n
}
}
maxwidth++ // space char
wordsPerLine := w.width / maxwidth
if wordsPerLine <= 0 {
wordsPerLine = 1
}
nlines := (len(words) + wordsPerLine - 1) / wordsPerLine
for i := 0; i < nlines; i++ {
col := 0
endcol := 0
for j := i; j < len(words); j += nlines {
endcol += maxwidth
_, err := w.w.Write(words[j])
if err != nil {
return err
}
col += utf8.RuneCount(words[j])
if j+nlines < len(words) {
for col < endcol {
_, err := w.w.Write([]byte{' '})
if err != nil {
return err
}
col++
}
}
}
_, err := w.w.Write([]byte{'\n'})
if err != nil {
return err
}
}
return nil
}
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