mirror of git://gcc.gnu.org/git/gcc.git
521 lines
11 KiB
Go
521 lines
11 KiB
Go
// Copyright 2011 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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package terminal
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import (
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"io"
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"sync"
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)
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// EscapeCodes contains escape sequences that can be written to the terminal in
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// order to achieve different styles of text.
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type EscapeCodes struct {
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// Foreground colors
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Black, Red, Green, Yellow, Blue, Magenta, Cyan, White []byte
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// Reset all attributes
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Reset []byte
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}
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var vt100EscapeCodes = EscapeCodes{
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Black: []byte{keyEscape, '[', '3', '0', 'm'},
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Red: []byte{keyEscape, '[', '3', '1', 'm'},
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Green: []byte{keyEscape, '[', '3', '2', 'm'},
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Yellow: []byte{keyEscape, '[', '3', '3', 'm'},
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Blue: []byte{keyEscape, '[', '3', '4', 'm'},
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Magenta: []byte{keyEscape, '[', '3', '5', 'm'},
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Cyan: []byte{keyEscape, '[', '3', '6', 'm'},
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White: []byte{keyEscape, '[', '3', '7', 'm'},
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Reset: []byte{keyEscape, '[', '0', 'm'},
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}
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// Terminal contains the state for running a VT100 terminal that is capable of
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// reading lines of input.
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type Terminal struct {
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// AutoCompleteCallback, if non-null, is called for each keypress
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// with the full input line and the current position of the cursor.
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// If it returns a nil newLine, the key press is processed normally.
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// Otherwise it returns a replacement line and the new cursor position.
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AutoCompleteCallback func(line []byte, pos, key int) (newLine []byte, newPos int)
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// Escape contains a pointer to the escape codes for this terminal.
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// It's always a valid pointer, although the escape codes themselves
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// may be empty if the terminal doesn't support them.
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Escape *EscapeCodes
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// lock protects the terminal and the state in this object from
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// concurrent processing of a key press and a Write() call.
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lock sync.Mutex
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c io.ReadWriter
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prompt string
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// line is the current line being entered.
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line []byte
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// pos is the logical position of the cursor in line
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pos int
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// echo is true if local echo is enabled
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echo bool
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// cursorX contains the current X value of the cursor where the left
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// edge is 0. cursorY contains the row number where the first row of
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// the current line is 0.
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cursorX, cursorY int
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// maxLine is the greatest value of cursorY so far.
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maxLine int
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termWidth, termHeight int
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// outBuf contains the terminal data to be sent.
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outBuf []byte
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// remainder contains the remainder of any partial key sequences after
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// a read. It aliases into inBuf.
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remainder []byte
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inBuf [256]byte
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}
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// NewTerminal runs a VT100 terminal on the given ReadWriter. If the ReadWriter is
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// a local terminal, that terminal must first have been put into raw mode.
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// prompt is a string that is written at the start of each input line (i.e.
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// "> ").
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func NewTerminal(c io.ReadWriter, prompt string) *Terminal {
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return &Terminal{
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Escape: &vt100EscapeCodes,
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c: c,
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prompt: prompt,
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termWidth: 80,
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termHeight: 24,
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echo: true,
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}
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}
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const (
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keyCtrlD = 4
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keyEnter = '\r'
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keyEscape = 27
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keyBackspace = 127
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keyUnknown = 256 + iota
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keyUp
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keyDown
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keyLeft
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keyRight
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keyAltLeft
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keyAltRight
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)
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// bytesToKey tries to parse a key sequence from b. If successful, it returns
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// the key and the remainder of the input. Otherwise it returns -1.
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func bytesToKey(b []byte) (int, []byte) {
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if len(b) == 0 {
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return -1, nil
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}
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if b[0] != keyEscape {
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return int(b[0]), b[1:]
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}
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if len(b) >= 3 && b[0] == keyEscape && b[1] == '[' {
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switch b[2] {
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case 'A':
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return keyUp, b[3:]
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case 'B':
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return keyDown, b[3:]
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case 'C':
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return keyRight, b[3:]
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case 'D':
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return keyLeft, b[3:]
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}
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}
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if len(b) >= 6 && b[0] == keyEscape && b[1] == '[' && b[2] == '1' && b[3] == ';' && b[4] == '3' {
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switch b[5] {
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case 'C':
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return keyAltRight, b[6:]
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case 'D':
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return keyAltLeft, b[6:]
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}
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}
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// If we get here then we have a key that we don't recognise, or a
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// partial sequence. It's not clear how one should find the end of a
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// sequence without knowing them all, but it seems that [a-zA-Z] only
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// appears at the end of a sequence.
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for i, c := range b[0:] {
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if c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' {
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return keyUnknown, b[i+1:]
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}
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}
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return -1, b
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}
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// queue appends data to the end of t.outBuf
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func (t *Terminal) queue(data []byte) {
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t.outBuf = append(t.outBuf, data...)
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}
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var eraseUnderCursor = []byte{' ', keyEscape, '[', 'D'}
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var space = []byte{' '}
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func isPrintable(key int) bool {
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return key >= 32 && key < 127
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}
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// moveCursorToPos appends data to t.outBuf which will move the cursor to the
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// given, logical position in the text.
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func (t *Terminal) moveCursorToPos(pos int) {
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if !t.echo {
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return
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}
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x := len(t.prompt) + pos
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y := x / t.termWidth
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x = x % t.termWidth
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up := 0
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if y < t.cursorY {
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up = t.cursorY - y
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}
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down := 0
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if y > t.cursorY {
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down = y - t.cursorY
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}
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left := 0
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if x < t.cursorX {
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left = t.cursorX - x
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}
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right := 0
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if x > t.cursorX {
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right = x - t.cursorX
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}
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t.cursorX = x
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t.cursorY = y
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t.move(up, down, left, right)
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}
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func (t *Terminal) move(up, down, left, right int) {
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movement := make([]byte, 3*(up+down+left+right))
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m := movement
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for i := 0; i < up; i++ {
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m[0] = keyEscape
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m[1] = '['
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m[2] = 'A'
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m = m[3:]
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}
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for i := 0; i < down; i++ {
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m[0] = keyEscape
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m[1] = '['
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m[2] = 'B'
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m = m[3:]
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}
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for i := 0; i < left; i++ {
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m[0] = keyEscape
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m[1] = '['
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m[2] = 'D'
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m = m[3:]
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}
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for i := 0; i < right; i++ {
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m[0] = keyEscape
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m[1] = '['
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m[2] = 'C'
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m = m[3:]
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}
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t.queue(movement)
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}
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func (t *Terminal) clearLineToRight() {
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op := []byte{keyEscape, '[', 'K'}
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t.queue(op)
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}
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const maxLineLength = 4096
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// handleKey processes the given key and, optionally, returns a line of text
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// that the user has entered.
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func (t *Terminal) handleKey(key int) (line string, ok bool) {
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switch key {
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case keyBackspace:
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if t.pos == 0 {
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return
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}
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t.pos--
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t.moveCursorToPos(t.pos)
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copy(t.line[t.pos:], t.line[1+t.pos:])
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t.line = t.line[:len(t.line)-1]
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if t.echo {
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t.writeLine(t.line[t.pos:])
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}
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t.queue(eraseUnderCursor)
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t.moveCursorToPos(t.pos)
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case keyAltLeft:
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// move left by a word.
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if t.pos == 0 {
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return
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}
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t.pos--
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for t.pos > 0 {
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if t.line[t.pos] != ' ' {
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break
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}
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t.pos--
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}
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for t.pos > 0 {
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if t.line[t.pos] == ' ' {
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t.pos++
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break
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}
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t.pos--
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}
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t.moveCursorToPos(t.pos)
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case keyAltRight:
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// move right by a word.
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for t.pos < len(t.line) {
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if t.line[t.pos] == ' ' {
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break
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}
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t.pos++
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}
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for t.pos < len(t.line) {
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if t.line[t.pos] != ' ' {
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break
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}
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t.pos++
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}
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t.moveCursorToPos(t.pos)
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case keyLeft:
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if t.pos == 0 {
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return
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}
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t.pos--
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t.moveCursorToPos(t.pos)
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case keyRight:
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if t.pos == len(t.line) {
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return
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}
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t.pos++
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t.moveCursorToPos(t.pos)
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case keyEnter:
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t.moveCursorToPos(len(t.line))
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t.queue([]byte("\r\n"))
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line = string(t.line)
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ok = true
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t.line = t.line[:0]
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t.pos = 0
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t.cursorX = 0
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t.cursorY = 0
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t.maxLine = 0
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default:
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if t.AutoCompleteCallback != nil {
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t.lock.Unlock()
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newLine, newPos := t.AutoCompleteCallback(t.line, t.pos, key)
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t.lock.Lock()
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if newLine != nil {
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if t.echo {
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t.moveCursorToPos(0)
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t.writeLine(newLine)
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for i := len(newLine); i < len(t.line); i++ {
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t.writeLine(space)
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}
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t.moveCursorToPos(newPos)
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}
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t.line = newLine
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t.pos = newPos
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return
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}
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}
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if !isPrintable(key) {
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return
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}
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if len(t.line) == maxLineLength {
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return
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}
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if len(t.line) == cap(t.line) {
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newLine := make([]byte, len(t.line), 2*(1+len(t.line)))
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copy(newLine, t.line)
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t.line = newLine
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}
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t.line = t.line[:len(t.line)+1]
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copy(t.line[t.pos+1:], t.line[t.pos:])
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t.line[t.pos] = byte(key)
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if t.echo {
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t.writeLine(t.line[t.pos:])
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}
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t.pos++
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t.moveCursorToPos(t.pos)
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}
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return
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}
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func (t *Terminal) writeLine(line []byte) {
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for len(line) != 0 {
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remainingOnLine := t.termWidth - t.cursorX
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todo := len(line)
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if todo > remainingOnLine {
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todo = remainingOnLine
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}
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t.queue(line[:todo])
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t.cursorX += todo
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line = line[todo:]
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if t.cursorX == t.termWidth {
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t.cursorX = 0
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t.cursorY++
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if t.cursorY > t.maxLine {
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t.maxLine = t.cursorY
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}
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}
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}
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}
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func (t *Terminal) Write(buf []byte) (n int, err error) {
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t.lock.Lock()
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defer t.lock.Unlock()
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if t.cursorX == 0 && t.cursorY == 0 {
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// This is the easy case: there's nothing on the screen that we
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// have to move out of the way.
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return t.c.Write(buf)
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}
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// We have a prompt and possibly user input on the screen. We
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// have to clear it first.
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t.move(0 /* up */, 0 /* down */, t.cursorX /* left */, 0 /* right */)
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t.cursorX = 0
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t.clearLineToRight()
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for t.cursorY > 0 {
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t.move(1 /* up */, 0, 0, 0)
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t.cursorY--
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t.clearLineToRight()
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}
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if _, err = t.c.Write(t.outBuf); err != nil {
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return
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}
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t.outBuf = t.outBuf[:0]
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if n, err = t.c.Write(buf); err != nil {
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return
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}
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t.queue([]byte(t.prompt))
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chars := len(t.prompt)
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if t.echo {
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t.queue(t.line)
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chars += len(t.line)
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}
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t.cursorX = chars % t.termWidth
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t.cursorY = chars / t.termWidth
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t.moveCursorToPos(t.pos)
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if _, err = t.c.Write(t.outBuf); err != nil {
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return
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}
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t.outBuf = t.outBuf[:0]
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return
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}
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// ReadPassword temporarily changes the prompt and reads a password, without
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// echo, from the terminal.
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func (t *Terminal) ReadPassword(prompt string) (line string, err error) {
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t.lock.Lock()
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defer t.lock.Unlock()
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oldPrompt := t.prompt
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t.prompt = prompt
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t.echo = false
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line, err = t.readLine()
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t.prompt = oldPrompt
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t.echo = true
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return
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}
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// ReadLine returns a line of input from the terminal.
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func (t *Terminal) ReadLine() (line string, err error) {
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t.lock.Lock()
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defer t.lock.Unlock()
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return t.readLine()
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}
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func (t *Terminal) readLine() (line string, err error) {
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// t.lock must be held at this point
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if t.cursorX == 0 && t.cursorY == 0 {
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t.writeLine([]byte(t.prompt))
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t.c.Write(t.outBuf)
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t.outBuf = t.outBuf[:0]
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}
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for {
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rest := t.remainder
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lineOk := false
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for !lineOk {
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var key int
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key, rest = bytesToKey(rest)
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if key < 0 {
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break
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}
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if key == keyCtrlD {
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return "", io.EOF
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}
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line, lineOk = t.handleKey(key)
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}
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if len(rest) > 0 {
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n := copy(t.inBuf[:], rest)
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t.remainder = t.inBuf[:n]
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} else {
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t.remainder = nil
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}
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t.c.Write(t.outBuf)
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t.outBuf = t.outBuf[:0]
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if lineOk {
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return
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}
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// t.remainder is a slice at the beginning of t.inBuf
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// containing a partial key sequence
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readBuf := t.inBuf[len(t.remainder):]
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var n int
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t.lock.Unlock()
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n, err = t.c.Read(readBuf)
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t.lock.Lock()
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if err != nil {
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return
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}
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t.remainder = t.inBuf[:n+len(t.remainder)]
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}
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panic("unreachable")
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}
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// SetPrompt sets the prompt to be used when reading subsequent lines.
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func (t *Terminal) SetPrompt(prompt string) {
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t.lock.Lock()
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defer t.lock.Unlock()
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t.prompt = prompt
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}
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func (t *Terminal) SetSize(width, height int) {
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t.lock.Lock()
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defer t.lock.Unlock()
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t.termWidth, t.termHeight = width, height
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}
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