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- package term
- import (
- "io"
- )
- // EscapeError is special error which returned by a TTY proxy reader's Read()
- // method in case its detach escape sequence is read.
- type EscapeError struct{}
- func (EscapeError) Error() string {
- return "read escape sequence"
- }
- // escapeProxy is used only for attaches with a TTY. It is used to proxy
- // stdin keypresses from the underlying reader and look for the passed in
- // escape key sequence to signal a detach.
- type escapeProxy struct {
- escapeKeys []byte
- escapeKeyPos int
- r io.Reader
- }
- // NewEscapeProxy returns a new TTY proxy reader which wraps the given reader
- // and detects when the specified escape keys are read, in which case the Read
- // method will return an error of type EscapeError.
- func NewEscapeProxy(r io.Reader, escapeKeys []byte) io.Reader {
- return &escapeProxy{
- escapeKeys: escapeKeys,
- r: r,
- }
- }
- func (r *escapeProxy) Read(buf []byte) (int, error) {
- nr, err := r.r.Read(buf)
- preserve := func() {
- // this preserves the original key presses in the passed in buffer
- nr += r.escapeKeyPos
- preserve := make([]byte, 0, r.escapeKeyPos+len(buf))
- preserve = append(preserve, r.escapeKeys[:r.escapeKeyPos]...)
- preserve = append(preserve, buf...)
- r.escapeKeyPos = 0
- copy(buf[0:nr], preserve)
- }
- if nr != 1 || err != nil {
- if r.escapeKeyPos > 0 {
- preserve()
- }
- return nr, err
- }
- if buf[0] != r.escapeKeys[r.escapeKeyPos] {
- if r.escapeKeyPos > 0 {
- preserve()
- }
- return nr, nil
- }
- if r.escapeKeyPos == len(r.escapeKeys)-1 {
- return 0, EscapeError{}
- }
- // Looks like we've got an escape key, but we need to match again on the next
- // read.
- // Store the current escape key we found so we can look for the next one on
- // the next read.
- // Since this is an escape key, make sure we don't let the caller read it
- // If later on we find that this is not the escape sequence, we'll add the
- // keys back
- r.escapeKeyPos++
- return nr - r.escapeKeyPos, nil
- }
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