DockerCLI/vendor/github.com/jaguilar/vt100/scanner.go

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