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// Copyright 2013-2015 Bowery, Inc.
package prompt
import (
"os"
"unicode/utf8"
)
// Buffer contains state for line editing and writing.
type Buffer struct {
Out *os.File
Prompt string
Echo bool
Cols int
pos int
size int
data []rune
}
// NewBuffer creates a buffer writing to out if echo is true.
func NewBuffer(prompt string, out *os.File, echo bool) *Buffer {
return &Buffer{
Out: out,
Prompt: prompt,
Echo: echo,
}
}
// String returns the data as a string.
func (buf *Buffer) String() string {
return string(buf.data[:buf.size])
}
// Insert inserts characters at the cursors position.
func (buf *Buffer) Insert(rs ...rune) error {
rsLen := len(rs)
total := buf.size + rsLen
if total > len(buf.data) {
buf.data = append(buf.data, make([]rune, rsLen)...)
}
// Shift characters to make room in the correct pos.
if buf.size != buf.pos {
copy(buf.data[buf.pos+rsLen:buf.size+rsLen], buf.data[buf.pos:buf.size])
}
for _, r := range rs {
buf.data[buf.pos] = r
buf.pos++
buf.size++
}
return buf.Refresh()
}
// Set sets the content in the buffer.
func (buf *Buffer) Set(rs ...rune) error {
rsLen := len(rs)
buf.data = rs
buf.pos = rsLen
buf.size = rsLen
return buf.Refresh()
}
// Start moves the cursor to the start.
func (buf *Buffer) Start() error {
if buf.pos <= 0 {
return nil
}
buf.pos = 0
return buf.Refresh()
}
// End moves the cursor to the end.
func (buf *Buffer) End() error {
if buf.pos >= buf.size {
return nil
}
buf.pos = buf.size
return buf.Refresh()
}
// Left moves the cursor one character left.
func (buf *Buffer) Left() error {
if buf.pos <= 0 {
return nil
}
buf.pos--
return buf.Refresh()
}
// Right moves the cursor one character right.
func (buf *Buffer) Right() error {
if buf.pos >= buf.size {
return nil
}
buf.pos++
return buf.Refresh()
}
// Del removes the character at the cursor position.
func (buf *Buffer) Del() error {
if buf.pos >= buf.size {
return nil
}
// Shift characters after position back one.
copy(buf.data[buf.pos:], buf.data[buf.pos+1:buf.size])
buf.size--
return buf.Refresh()
}
// DelLeft removes the character to the left.
func (buf *Buffer) DelLeft() error {
if buf.pos <= 0 {
return nil
}
// Shift characters from position back one.
copy(buf.data[buf.pos-1:], buf.data[buf.pos:buf.size])
buf.pos--
buf.size--
return buf.Refresh()
}
// EndLine ends the line with CRLF.
func (buf *Buffer) EndLine() error {
_, err := buf.Out.Write(crlf)
return err
}
// toBytes converts a slice of runes to its equivalent in bytes.
func toBytes(runes []rune) []byte {
var bytes []byte
char := make([]byte, utf8.UTFMax)
for _, r := range runes {
n := utf8.EncodeRune(char, r)
bytes = append(bytes, char[:n]...)
}
return bytes
}
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