vendor

vendor/github.com/ulikunitz/xz/internal/randtxt/groupreader.go

@@ -0,0 +1,82 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package randtxt
+
+import (
+	"bufio"
+	"io"
+	"unicode"
+)
+
+// GroupReader groups the incoming text in groups of 5, whereby the
+// number of groups per line can be controlled.
+type GroupReader struct {
+	R             io.ByteReader
+	GroupsPerLine int
+	off           int64
+	eof           bool
+}
+
+// NewGroupReader creates a new group reader.
+func NewGroupReader(r io.Reader) *GroupReader {
+	return &GroupReader{R: bufio.NewReader(r)}
+}
+
+// Read formats the data provided by the internal reader in groups of 5
+// characters. If GroupsPerLine hasn't been initialized 8 groups per
+// line will be produced.
+func (r *GroupReader) Read(p []byte) (n int, err error) {
+	if r.eof {
+		return 0, io.EOF
+	}
+	groupsPerLine := r.GroupsPerLine
+	if groupsPerLine < 1 {
+		groupsPerLine = 8
+	}
+	lineLen := int64(groupsPerLine * 6)
+	var c byte
+	for i := range p {
+		switch {
+		case r.off%lineLen == lineLen-1:
+			if i+1 == len(p) && len(p) > 1 {
+				return i, nil
+			}
+			c = '\n'
+		case r.off%6 == 5:
+			if i+1 == len(p) && len(p) > 1 {
+				return i, nil
+			}
+			c = ' '
+		default:
+			c, err = r.R.ReadByte()
+			if err == io.EOF {
+				r.eof = true
+				if i > 0 {
+					switch p[i-1] {
+					case ' ':
+						p[i-1] = '\n'
+						fallthrough
+					case '\n':
+						return i, io.EOF
+					}
+				}
+				p[i] = '\n'
+				return i + 1, io.EOF
+			}
+			if err != nil {
+				return i, err
+			}
+			switch {
+			case c == ' ':
+				c = '_'
+			case !unicode.IsPrint(rune(c)):
+				c = '-'
+			}
+		}
+		p[i] = c
+		r.off++
+	}
+	return len(p), nil
+}