bantam-cpp/editor.cpp

/* editor.cpp — GNU readline line editor, history and term helpers
 * (is_terminal, term_width). The interactive prompt is handled by
 * libreadline instead of a hand-rolled raw-mode terminal editor. */
#include "bantam.hpp"
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <readline/readline.h>
#include <readline/history.h>
#include <sys/ioctl.h>
#include <unistd.h>

/* ----------------------------- globals ------------------------------- */
static std::string g_hist_file;

static std::string home_dir() {
  const char *h = std::getenv("HOME");
  if (h && *h) return h;
  return ".";
}

/* ----------------------------- history -------------------------------- */
void load_history() {
  g_hist_file = home_dir() + "/.bantam_history";
  using_history();
  /* A missing history file is not an error. */
  read_history(g_hist_file.c_str());
}
void add_history(std::string_view s) {
  if (s.empty()) return;
  std::string line(s);
  /* Skip an entry identical to the immediately preceding one. */
  if (history_length > 0) {
    HIST_ENTRY *last = history_get(history_base + history_length - 1);
    if (last && last->line && line == last->line) return;
  }
  ::add_history(line.c_str());
}
void save_history() {
  if (g_hist_file.empty()) return;
  write_history(g_hist_file.c_str());
}

/* ----------------------------- read helpers --------------------------- */
std::string read_plain(std::string_view prompt, bool &ok) {
  if (!prompt.empty()) fputs(std::string(prompt).c_str(), stdout);
  fflush(stdout);
  char *line = nullptr; size_t cap = 0; ssize_t n = getline(&line, &cap, stdin);
  if (n < 0) { free(line); clearerr(stdin); ok = false; return ""; }
  while (n > 0 && (line[n - 1] == '\n' || line[n - 1] == '\r')) line[--n] = '\0';
  std::string r(line, (size_t)n);
  free(line);
  ok = true;
  return r;
}

/* ----------------------------- readline editor ------------------------ */
static void ensure_readline_init() {
  static bool initialized = false;
  if (initialized) return;
  initialized = true;
  rl_initialize();
#if !defined(__APPLE__) && defined(RL_READLINE_VERSION) && (RL_READLINE_VERSION >= 0x0500)
  /* On GNU Readline (Linux, FreeBSD), terminal raw mode clears ICRNL so
   * Enter sends '\r' (rl_newline = submit) while Ctrl+J sends '\n'
   * (rl_insert = literal newline). On macOS / BSD libedit (EditLine),
   * ICRNL remains enabled in termios (translating Enter '\r' into '\n') and
   * '\n' is the sole accept-line key (ed-newline), so rebinding '\n' to
   * rl_insert prevents submitting any prompt. */
  if (!rl_library_version || std::strncmp(rl_library_version, "EditLine", 8) != 0) {
    rl_bind_key('\n', rl_insert);
    rl_bind_key('\r', rl_newline);
  }
#endif
}

std::string read_line(std::string_view prompt, bool &ok) {
  if (!is_terminal(STDIN_FILENO)) return read_plain(prompt, ok);
  ensure_readline_init();
  char *line = readline(prompt.empty() ? "" : std::string(prompt).c_str());
  setup_signal_handler();
  if (!line) {
    if (g_interrupted) {
      g_interrupted = 0;
      std::fputc('\n', stdout);
      std::fflush(stdout);
      ok = true;
      return "";
    }
    ok = false;
    return "";
  }
  std::string r(line);
  free(line);
  ok = true;
  return r;
}

/* ----------------------------- term helpers --------------------------- */
int is_terminal(int fd) { return isatty(fd) != 0; }

int term_width() {
#ifdef TIOCGWINSZ
  struct winsize ws{};
  if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == 0 && ws.ws_col > 0) return (int)ws.ws_col;
  if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) == 0 && ws.ws_col > 0) return (int)ws.ws_col;
  if (ioctl(STDERR_FILENO, TIOCGWINSZ, &ws) == 0 && ws.ws_col > 0) return (int)ws.ws_col;
#endif
  const char *c = std::getenv("COLUMNS");
  if (c && *c) { int n = std::atoi(c); if (n > 0) return n; }
  return 80;
}