98 lines
2.3 KiB
Go
98 lines
2.3 KiB
Go
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package vt100
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import (
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"bytes"
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"fmt"
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"io"
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"unicode"
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)
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// Decode decodes one ANSI terminal command from s.
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//
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// s should be connected to a client program that expects an
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// ANSI terminal on the other end. It will push bytes to us that we are meant
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// to intepret as terminal control codes, or text to place onto the terminal.
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//
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// This Command alone does not actually update the terminal. You need to pass
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// it to VT100.Process().
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//
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// You should not share s with any other reader, because it could leave
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// the stream in an invalid state.
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func Decode(s io.RuneScanner) (Command, error) {
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r, size, err := s.ReadRune()
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if err != nil {
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return nil, err
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}
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if r == unicode.ReplacementChar && size == 1 {
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return nil, fmt.Errorf("non-utf8 data from reader")
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}
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if r == escape || r == monogramCsi { // At beginning of escape sequence.
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s.UnreadRune()
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return scanEscapeCommand(s)
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}
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if unicode.IsControl(r) {
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return controlCommand(r), nil
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}
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return runeCommand(r), nil
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}
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const (
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// There are two ways to begin an escape sequence. One is to put the escape byte.
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// The other is to put the single-rune control sequence indicator, which is equivalent
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// to putting "\u001b[".
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escape = '\u001b'
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monogramCsi = '\u009b'
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)
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var (
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csEnd = &unicode.RangeTable{R16: []unicode.Range16{{Lo: 64, Hi: 126, Stride: 1}}}
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)
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// scanEscapeCommand scans to the end of the current escape sequence. The scanner
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// must be positioned at an escape rune (esc or the unicode CSI).
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func scanEscapeCommand(s io.RuneScanner) (Command, error) {
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csi := false
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esc, _, err := s.ReadRune()
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if err != nil {
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return nil, err
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}
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if esc != escape && esc != monogramCsi {
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return nil, fmt.Errorf("invalid content")
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}
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if esc == monogramCsi {
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csi = true
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}
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var args bytes.Buffer
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quote := false
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for i := 0; ; i++ {
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r, _, err := s.ReadRune()
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if err != nil {
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return nil, err
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}
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if i == 0 && r == '[' {
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csi = true
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continue
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}
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if !csi {
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return escapeCommand{r, ""}, nil
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} else if quote == false && unicode.Is(csEnd, r) {
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return escapeCommand{r, args.String()}, nil
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}
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if r == '"' {
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quote = !quote
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}
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// Otherwise, we're still in the args, and this rune is one of those args.
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if _, err := args.WriteRune(r); err != nil {
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panic(err) // WriteRune cannot return an error from bytes.Buffer.
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}
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}
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}
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