keytab.c

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 * of '\E' to denote the escape key. Similarly, meta characters can be
 * given directly in binary or expressed as M- followed by the character.
 * Meta characters are recorded as two characters in the binary output
 * string, the first being the escape key, and the second being the key
 * that was modified by the meta key. This means that binding to
 * \EA or ^[A or M-A are all equivalent.
 *
 * Input:
 *  keyseq   char *  The key sequence being added.
 * Input/Output:
 *  binary   char *  The binary version of the key sequence will be
 *                   assigned to binary[], which must have at least
 *                   as many characters as keyseq[] plus the number
 *                   of embedded binary meta characters.
 *  nc        int *  The number of characters assigned to binary[]
 *                   will be recorded in *nc.
 * Output:
 *  return    int    0 - OK.
 *                   1 - Error.
 */
int _kt_parse_keybinding_string(const char *keyseq, char *binary,
				       int *nc)
{
  const char *iptr = keyseq;   /* Pointer into keyseq[] */
  char *optr = binary;         /* Pointer into binary[] */
/*
 * Parse the input characters until they are exhausted or the
 * output string becomes full.
 */
  while(*iptr) {
/*
 * Check for special characters.
 */
    switch(*iptr) {
    case '^':        /* A control character specification */
/*
 * Convert the caret expression into the corresponding control
 * character unless no character follows the caret, in which case
 * record a literal caret.
 */
      if(iptr[1]) {
	*optr++ = MAKE_CTRL(iptr[1]);
	iptr += 2;
      } else {
	*optr++ = *iptr++;
      };
      break;
/*
 * A backslash-escaped character?
 */
    case '\\':
/*
 * Convert the escape sequence to a binary character.
 */
      *optr++ = _kt_backslash_escape(iptr+1, &iptr);
      break;
/*
 * Possibly an emacs-style meta character?
 */
    case 'M':
      if(_kt_is_emacs_meta(iptr)) {
	*optr++ = GL_ESC_CHAR;
	iptr += 2;
      } else {
	*optr++ = *iptr++;
      };
      break;
/*
 * Possibly an emacs-style control character specification?
 */
    case 'C':
      if(_kt_is_emacs_ctrl(iptr)) {
	*optr++ = MAKE_CTRL(iptr[2]);
	iptr += 3;
      } else {
	*optr++ = *iptr++;
      };
      break;
    default:

/*
 * Convert embedded meta characters into an escape character followed
 * by the meta-unmodified character.
 */
      if(IS_META_CHAR(*iptr)) {
	*optr++ = GL_ESC_CHAR;
	*optr++ = META_TO_CHAR(*iptr);
	iptr++;
/*
 * To allow keysequences that start with printable characters to
 * be distinguished from the cursor-key keywords, prepend a backslash
 * to the former. This same operation is performed in gl_interpret_char()
 * before looking up a keysequence that starts with a printable character.
 */
      } else if(iptr==keyseq && !IS_CTRL_CHAR(*iptr) &&
		strcmp(keyseq, "up") != 0 && strcmp(keyseq, "down") != 0 &&
		strcmp(keyseq, "left") != 0 && strcmp(keyseq, "right") != 0) {
	*optr++ = '\\';
	*optr++ = *iptr++;
      } else {
	*optr++ = *iptr++;
      };
    };
  };
/*
 * How many characters were placed in the output array?
 */
  *nc = optr - binary;
  return 0;
}

/*.......................................................................
 * Add, remove or modify an action.
 *
 * Input:
 *  kt     KeyTab *  The key-binding table.
 *  action   char *  The name of the action.
 *  fn    KtKeyFn *  The function that implements the action, or NULL
 *                   to remove an existing action.
 * Output:
 *  return    int    0 - OK.
 *                   1 - Error.
 */
int _kt_set_action(KeyTab *kt, const char *action, KtKeyFn *fn)
{
  Symbol *sym;   /* The symbol table entry of the action */
/*
 * Check the arguments.
 */
  if(!kt || !action) {
    fprintf(stderr, "kt_set_action: NULL argument(s).\n");
    return 1;
  };
/*
 * If no function was provided, delete an existing action.
 */
  if(!fn) {
    sym = _del_HashSymbol(kt->actions, action);
    return 0;
  };
/*
 * If the action already exists, replace its action function.
 */
  sym = _find_HashSymbol(kt->actions, action);
  if(sym) {
    sym->fn = (void (*)(void))fn;
    return 0;
  };
/*
 * Add a new action.
 */
  if(!_new_HashSymbol(kt->actions, action, 0, (void (*)(void))fn, NULL, 0)) {
    fprintf(stderr, "Insufficient memory to record new key-binding action.\n");
    return 1;
  };
  return 0;
}

/*.......................................................................
 * Compare two strings of specified length which may contain embedded
 * ascii NUL's.
 *
 * Input:
 *  s1       char *  The first of the strings to be compared.
 *  n1        int    The length of the string in s1.
 *  s2       char *  The second of the strings to be compared.
 *  n2        int    The length of the string in s2.
 * Output:
 *  return    int    < 0 if(s1 < s2)
 *                     0 if(s1 == s2)
 *                   > 0 if(s1 > s2)
 */
static int _kt_compare_strings(const char *s1, int n1, const char *s2, int n2)
{
  int i;
/*
 * Find the first character where the two strings differ.
 */
  for(i=0; i<n1 && i<n2 && s1[i]==s2[i]; i++)
    ;
/*
 * Did we hit the end of either string before finding a difference?
 */
  if(i==n1 || i==n2) {
    if(n1 == n2)
      return 0;
    else if(n1==i)
      return -1;
    else
      return 1;
  };
/*
 * Compare the two characters that differed to determine which
 * string is greatest.
 */
  return s1[i] - s2[i];
}

/*.......................................................................
 * Assign a given action function to a binding table entry.
 *
 * Input:
 *  sym       KeySym *  The binding table entry to be modified.
 *  binder  KtBinder    The source of the binding.
 *  keyfn    KtKeyFn *  The action function.
 */
static void _kt_assign_action(KeySym *sym, KtBinder binder, KtKeyFn *keyfn)
{
/*
 * Record the action according to its source.
 */
  switch(binder) {
  case KTB_USER:
    sym->user_fn = keyfn;
    break;
  case KTB_TERM:
    sym->term_fn = keyfn;
    break;
  case KTB_NORM:
  default:
    sym->norm_fn = keyfn;
    break;
  };
/*
 * Which of the current set of bindings should be used?
 */
  if(sym->user_fn)
    sym->keyfn = sym->user_fn;
  else if(sym->norm_fn)
    sym->keyfn = sym->norm_fn;
  else
    sym->keyfn = sym->term_fn;
  return;
}

/*.......................................................................
 * Remove all key bindings that came from a specified source.
 *
 * Input:
 *  kt        KeyTab *  The table of key bindings.
 *  binder  KtBinder    The source of the bindings to be cleared.
 */
void _kt_clear_bindings(KeyTab *kt, KtBinder binder)
{
  int oldkey;   /* The index of a key in the original binding table */
  int newkey;   /* The index of a key in the updated binding table */
/*
 * If there is no table, then no bindings exist to be deleted.
 */
  if(!kt)
    return;
/*
 * Clear bindings of the given source.
 */
  for(oldkey=0; oldkey<kt->nkey; oldkey++)
    _kt_assign_action(kt->table + oldkey, binder, 0);
/*
 * Delete entries that now don't have a binding from any source.
 */
  newkey = 0;
  for(oldkey=0; oldkey<kt->nkey; oldkey++) {
    KeySym *sym = kt->table + oldkey;
    if(!sym->keyfn) {
      _del_StringMemString(kt->smem, sym->keyseq);
    } else {
      if(oldkey != newkey)
	kt->table[newkey] = *sym;
      newkey++;
    };
  };
/*
 * Record the number of keys that were kept.
 */
  kt->nkey = newkey;
  return;
}

/*.......................................................................
 * Translate a backslash escape sequence to a binary character.
 *
 * Input:
 *  string  const char *   The characters that follow the backslash.
 * Input/Output:
 *  endp    const char **  If endp!=NULL, on return *endp will be made to
 *                         point to the character in string[] which follows
 *                         the escape sequence.
 * Output:
 *  return        char     The binary character.
 */
static char _kt_backslash_escape(const char *string, const char **endp)
{
  char c;  /* The output character */
/*
 * Is the backslash followed by one or more octal digits?
 */
  switch(*string) {
  case '0': case '1': case '2': case '3':
  case '4': case '5': case '6': case '7':
    c = strtol(string, (char **)&string, 8);
    break;
  case 'a':
    c = '\a';
    string++;
    break;
  case 'b':
    c = '\b';
    string++;
    break;
  case 'e': case 'E': /* Escape */
    c = GL_ESC_CHAR;
    string++;
    break;
  case 'f':
    c = '\f';
    string++;
    break;
  case 'n':
    c = '\n';
    string++;
    break;
  case 'r':
    c = '\r';
    string++;
    break;
  case 't':
    c = '\t';
    string++;
    break;
  case 'v':
    c = '\v';
    string++;
    break;
  case '\0':
    c = '\\';
    break;
  default:
    c = *string++;
    break;
  };
/*
 * Report the character which follows the escape sequence.
 */
  if(endp)
    *endp = string;
  return c;
}

/*.......................................................................
 * Return non-zero if the next two characters are M- and a third character
 * follows. Otherwise return 0.
 *
 * Input:
 *  string   const char *  The sub-string to scan.
 * Output:
 *  return          int    1 - The next two characters are M- and these
 *                             are followed by at least one character.
 *                         0 - The next two characters aren't M- or no
 *                             character follows a M- pair.
 */
static int _kt_is_emacs_meta(const char *string)
{
  return *string++ == 'M' && *string++ == '-' && *string;
}

/*.......................................................................
 * Return non-zero if the next two characters are C- and a third character
 * follows. Otherwise return 0.
 *
 * Input:
 *  string   const char *  The sub-string to scan.
 * Output:
 *  return          int    1 - The next two characters are C- and these
 *                             are followed by at least one character.
 *                         0 - The next two characters aren't C- or no
 *                             character follows a C- pair.
 */
static int _kt_is_emacs_ctrl(const char *string)
{
  return *string++ == 'C' && *string++ == '-' && *string;
}

/*.......................................................................
 * Merge an array of bindings with existing bindings.
 *
 * Input:
 *  kt                    KeyTab *  The table of key bindings.
 *  binder              KtBinder    The source of the bindings.
 *  bindings  const KtKeyBinding *  The array of bindings.
 *  n                        int    The number of bindings in bindings[].
 * Output:
 *  return                   int    0 - OK.
 *                                  1 - Error.
 */
int _kt_add_bindings(KeyTab *kt, KtBinder binder, const KtKeyBinding *bindings,
		     unsigned n)
{
  int i;
/*
 * Check the arguments.
 */
  if(!kt || !bindings) {
    fprintf(stderr, "_kt_add_bindings: NULL argument(s).\n");
    return 1;
  };
/*
 * Install the array of bindings.
 */
  for(i=0; i<n; i++) {
    if(_kt_set_keybinding(kt, binder, bindings[i].keyseq, bindings[i].action))
      return 1;
  };
  return 0;
}