83 lines
1.6 KiB
Go
83 lines
1.6 KiB
Go
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// Copyright 2014-2017 Ulrich Kunitz. 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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package randtxt
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import (
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"bufio"
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"io"
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"unicode"
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)
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// GroupReader groups the incoming text in groups of 5, whereby the
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// number of groups per line can be controlled.
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type GroupReader struct {
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R io.ByteReader
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GroupsPerLine int
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off int64
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eof bool
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}
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// NewGroupReader creates a new group reader.
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func NewGroupReader(r io.Reader) *GroupReader {
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return &GroupReader{R: bufio.NewReader(r)}
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}
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// Read formats the data provided by the internal reader in groups of 5
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// characters. If GroupsPerLine hasn't been initialized 8 groups per
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// line will be produced.
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func (r *GroupReader) Read(p []byte) (n int, err error) {
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if r.eof {
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return 0, io.EOF
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}
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groupsPerLine := r.GroupsPerLine
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if groupsPerLine < 1 {
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groupsPerLine = 8
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}
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lineLen := int64(groupsPerLine * 6)
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var c byte
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for i := range p {
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switch {
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case r.off%lineLen == lineLen-1:
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if i+1 == len(p) && len(p) > 1 {
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return i, nil
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}
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c = '\n'
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case r.off%6 == 5:
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if i+1 == len(p) && len(p) > 1 {
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return i, nil
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}
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c = ' '
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default:
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c, err = r.R.ReadByte()
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if err == io.EOF {
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r.eof = true
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if i > 0 {
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switch p[i-1] {
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case ' ':
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p[i-1] = '\n'
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fallthrough
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case '\n':
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return i, io.EOF
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}
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}
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p[i] = '\n'
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return i + 1, io.EOF
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}
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if err != nil {
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return i, err
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}
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switch {
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case c == ' ':
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c = '_'
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case !unicode.IsPrint(rune(c)):
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c = '-'
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}
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}
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p[i] = c
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r.off++
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}
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return len(p), nil
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}
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