Shell: Support basic line editing with left/right arrow keys.

Shell/LineEditor.cpp

@@ -25,18 +25,21 @@ void LineEditor::clear_line()
  fputc(0x8, stdout);
  fflush(stdout);
  m_buffer.clear();
+ m_cursor = 0;
 }
 
 void LineEditor::append(const String& string)
 {
  m_buffer.append(string.characters(), string.length());
  fputs(string.characters(), stdout);
  fflush(stdout);
+ m_cursor = m_buffer.size();
 }
 
 String LineEditor::get_line()
 {
  m_history_cursor = m_history.size();
+ m_cursor = 0;
  for (;;) {
  char keybuf[16];
  ssize_t nread = read(0, keybuf, sizeof(keybuf));
@@ -92,9 +95,19 @@ String LineEditor::get_line()
  m_state = InputState::Free;
  continue;
  case 'D': // left
+ if (m_cursor > 0) {
+ --m_cursor;
+ fputs("\033[D", stdout);
+ fflush(stdout);
+ }
  m_state = InputState::Free;
  continue;
  case 'C': // right
+ if (m_cursor < m_buffer.size()) {
+ ++m_cursor;
+ fputs("\033[C", stdout);
+ fflush(stdout);
+ }
  m_state = InputState::Free;
  continue;
  default:
@@ -117,10 +130,16 @@ String LineEditor::get_line()
  }
 
  if (ch == 8 || ch == g.termios.c_cc[VERASE]) {
- if (m_buffer.is_empty())
+ if (m_cursor == 0)
  continue;
- m_buffer.take_last();
+ m_buffer.remove(m_cursor - 1);
+ --m_cursor;
  putchar(8);
+ fputs("\033[s", stdout);
+ fputs("\033[K", stdout);
+ for (int i = m_cursor; i < m_buffer.size(); ++i)
+ fputc(m_buffer[i], stdout);
+ fputs("\033[u", stdout);
  fflush(stdout);
  continue;
  }
@@ -150,13 +169,26 @@ String LineEditor::get_line()
  }
  putchar(ch);
  fflush(stdout);
- if (ch != '\n') {
- m_buffer.append(ch);
- } else {
+ if (ch == '\n') {
  auto string = String::copy(m_buffer);
  m_buffer.clear();
  return string;
  }
+
+ if (m_cursor == m_buffer.size()) {
+ m_buffer.append(ch);
+ ++m_cursor;
+ continue;
+ }
+ fputs("\033[s", stdout);
+ fputs("\033[K", stdout);
+ for (int i = m_cursor; i < m_buffer.size(); ++i)
+ fputc(m_buffer[i], stdout);
+ fputs("\033[u", stdout);
+ fflush(stdout);
+ m_buffer.insert(m_cursor, move(ch));
+ ++m_cursor;
+
  }
  }
 }

Shell/main.cpp

@@ -295,7 +295,7 @@ static int run_command(const String& cmd)
 
  int rc = execvp(argv[0], const_cast<char* const*>(argv.data()));
  if (rc < 0) {
- perror("execvp");
+ fprintf(stderr, "execvp(%s): %s\n", argv[0], strerror(errno));
  exit(1);
  }
  ASSERT_NOT_REACHED();