lread.c

早期freebsd实现

DEFUN ("eval-region", Feval_region, Seval_region, 2, 3, "r",
  "Execute the region as Lisp code.\n\
When called from programs, expects two arguments,\n\
giving starting and ending indices in the current buffer\n\
of the text to be executed.\n\
Programs can pass third argument PRINTFLAG which controls printing of output:\n\
nil means discard it; anything else is stream for print.")
  (b, e, printflag)
     Lisp_Object b, e, printflag;
{
  int count = specpdl_ptr - specpdl;
  Lisp_Object tem;

  if (NULL (printflag))
    tem = Qsymbolp;
  else
    tem = printflag;
  specbind (Qstandard_output, tem);
  if (NULL (printflag))
    record_unwind_protect (save_excursion_restore, save_excursion_save ());
  record_unwind_protect (save_restriction_restore, save_restriction_save ());
  /* This both uses b and checks its type.  */
  Fgoto_char (b);
  Fnarrow_to_region (make_number (BEGV), e);
  readevalloop (Fcurrent_buffer (), 0, Feval, !NULL (printflag));
  unbind_to (count);
  return Qnil;
}

#endif standalone

DEFUN ("read", Fread, Sread, 0, 1, 0,
  "Read one Lisp expression as text from STREAM, return as Lisp object.\n\
If STREAM is nil, use the value of standard-input (which see).\n\
STREAM or standard-input may be:\n\
 a buffer (read from point and advance it)\n\
 a marker (read from where it points and advance it)\n\
 a function (call it with no arguments for each character)\n\
 a string (takes text from string, starting at the beginning)\n\
 t (read text line using minibuffer and use it).")
  (readcharfun)
     Lisp_Object readcharfun;
{
  extern Lisp_Object Fread_minibuffer ();

  unrch = -1;	/* Allow buffering-back only within a read. */

  if (NULL (readcharfun))
    readcharfun = Vstandard_input;
  if (EQ (readcharfun, Qt))
    readcharfun = Qread_char;

#ifndef standalone
  if (EQ (readcharfun, Qread_char))
    return Fread_minibuffer (build_string ("Lisp expression: "), Qnil);
#endif

  if (XTYPE (readcharfun) == Lisp_String)
    return Fcar (Fread_from_string (readcharfun, Qnil, Qnil));

  return read0 (readcharfun);
}

DEFUN ("read-from-string", Fread_from_string, Sread_from_string, 1, 3, 0,
  "Read one Lisp expression which is represented as text by STRING.\n\
Returns a cons: (OBJECT-READ . FINAL-STRING-INDEX).\n\
START and END optionally delimit a substring of STRING from which to read;\n\
 they default to 0 and (length STRING) respectively.")
  (string, start, end)
     Lisp_Object string, start, end;
{
  int startval, endval;
  Lisp_Object tem;

  CHECK_STRING (string,0);

  if (NULL (end))
    endval = XSTRING (string)->size;
  else
    { CHECK_NUMBER (end,2);
      endval = XINT (end);
      if (endval < 0 || endval > XSTRING (string)->size)
	args_out_of_range (string, end);
    }

  if (NULL (start))
    startval = 0;
  else
    { CHECK_NUMBER (start,1);
      startval = XINT (start);
      if (startval < 0 || startval > endval)
	args_out_of_range (string, start);
    }

  read_from_string_index = startval;
  read_from_string_limit = endval;

  unrch = -1;	/* Allow buffering-back only within a read. */

  tem = read0 (string);
  return Fcons (tem, make_number (read_from_string_index));
}

/* Use this for recursive reads, in contexts where internal tokens are not allowed. */

static Lisp_Object
read0 (readcharfun)
     Lisp_Object readcharfun;
{
  register Lisp_Object val;
  char c;

  val = read1 (readcharfun);
  if (XTYPE (val) == Lisp_Internal)
    {
      c = XINT (val);
      return Fsignal (Qinvalid_read_syntax, Fcons (make_string (&c, 1), Qnil));
    }

  return val;
}

static int read_buffer_size;
static char *read_buffer;

static Lisp_Object
read1 (readcharfun)
     register Lisp_Object readcharfun;
{
  register int c;

 retry:

  c = READCHAR;
  if (c < 0) return Fsignal (Qend_of_file, Qnil);

  switch (c)
    {
    case '(':
      return read_list (0, readcharfun);

    case '[':
      return read_vector (readcharfun);

    case ')':
    case ']':
    case '.':
      {
	register Lisp_Object val;
	XSET (val, Lisp_Internal, c);
	return val;
      }

    case '#':
      return Fsignal (Qinvalid_read_syntax, Fcons (make_string ("#", 1), Qnil));

    case ';':
      while ((c = READCHAR) >= 0 && c != '\n');
      goto retry;

    case '\'':
      {
	return Fcons (Qquote, Fcons (read0 (readcharfun), Qnil));
      }

    case '?':
      {
	register Lisp_Object val;

	XSET (val, Lisp_Int, READCHAR);
	if (XFASTINT (val) == '\\')
	  XSETINT (val, read_escape (readcharfun));

	return val;
      }

    case '\"':
      {
	register char *p = read_buffer;
	register char *end = read_buffer + read_buffer_size;
	register int c;
	int cancel = 0;

	while ((c = READCHAR) >= 0 &&
		(c != '\"' || (c = READCHAR) == '\"'))
	  {
	    if (p == end)
	      {
		char *new = (char *) xrealloc (read_buffer, read_buffer_size *= 2);
		p += new - read_buffer;
		read_buffer += new - read_buffer;
		end = read_buffer + read_buffer_size;
	      }
	    if (c == '\\')
	      c = read_escape (readcharfun);
	    /* c is -1 if \ newline has just been seen */
	    if (c < 0)
	      {
		if (p == read_buffer)
		  cancel = 1;
	      }
	    else
	      *p++ = c;
	  }

	UNREAD (c);
	/* If purifying, and string starts with \ newline,
	   return zero instead.  This is for doc strings
	   that we are really going to find in etc/DOC.nn.nn  */
	if (!NULL (Vpurify_flag) && NULL (Vdoc_file_name) && cancel)
	  return make_number (0);

	if (read_pure)
	  return make_pure_string (read_buffer, p - read_buffer);
	else
	  return make_string (read_buffer, p - read_buffer);
      }

    default:
      if (c <= 040) goto retry;
      {
	register char *p = read_buffer;

	{
	  register char *end = read_buffer + read_buffer_size;

	  while (c > 040 && 
		 !(c == '\"' || c == '\'' || c == ';' || c == '?'
		   || c == '(' || c == ')' || c =='.'
		   || c == '[' || c == ']' || c == '#'
		   ))
	    {
	      if (p == end)
		{
		  register char *new = (char *) xrealloc (read_buffer, read_buffer_size *= 2);
		  p += new - read_buffer;
		  read_buffer += new - read_buffer;
		  end = read_buffer + read_buffer_size;
		}
	      if (c == '\\')
		c = READCHAR;
	      *p++ = c;
	      c = READCHAR;
	    }

	  if (p == end)
	    {
	      char *new = (char *) xrealloc (read_buffer, read_buffer_size *= 2);
	      p += new - read_buffer;
	      read_buffer += new - read_buffer;
/*	      end = read_buffer + read_buffer_size;  */
	    }
	  *p = 0;
	  UNREAD (c);
	}

	/* Is it an integer? */
	{
	  register char *p1;
	  register Lisp_Object val;
	  p1 = read_buffer;
	  if (*p1 == '+' || *p1 == '-') p1++;
	  if (p1 != p)
	    {
	      while (p1 != p && (c = *p1) >= '0' && c <= '9') p1++;
	      if (p1 == p)
		/* It is. */
		{
		  XSET (val, Lisp_Int, atoi (read_buffer));
		  return val;
		}
	    }
	}

	return intern (read_buffer);
      }
    }
}

static Lisp_Object
read_vector (readcharfun)
     Lisp_Object readcharfun;
{
  register int i;
  register int size;
  register Lisp_Object *ptr;
  register Lisp_Object tem, vector;
  register struct Lisp_Cons *otem;
  Lisp_Object len;

  tem = read_list (1, readcharfun);
  len = Flength (tem);
  vector = (read_pure ? make_pure_vector (XINT (len)) : Fmake_vector (len, Qnil));


  size = XVECTOR (vector)->size;
  ptr = XVECTOR (vector)->contents;
  for (i = 0; i < size; i++)
    {
      ptr[i] = read_pure ? Fpurecopy (Fcar (tem)) : Fcar (tem);
      otem = XCONS (tem);
      tem = Fcdr (tem);
      free_cons (otem);
    }
  return vector;
}
  
/* flag = 1 means check for ] to terminate rather than ) and .
   flag = -1 means check for starting with defun
    and make structure pure.  */

static Lisp_Object
read_list (flag, readcharfun)
     int flag;
     register Lisp_Object readcharfun;
{
  /* -1 means check next element for defun,
     0 means don't check,
     1 means already checked and found defun. */
  int defunflag = flag < 0 ? -1 : 0;
  Lisp_Object val, tail;
  register Lisp_Object elt, tem;
  struct gcpro gcpro1, gcpro2;

  val = Qnil;
  tail = Qnil;

  while (1)
    {
      GCPRO2 (val, tail);
      elt = read1 (readcharfun);
      UNGCPRO;
      if (XTYPE (elt) == Lisp_Internal)
	{
	  if (flag > 0)
	    {
	      if (XINT (elt) == ']')
		return val;
	      return Fsignal (Qinvalid_read_syntax, Fcons (make_string (") or . in a vector", 18), Qnil));
	    }
	  if (XINT (elt) == ')')
	    return val;
	  if (XINT (elt) == '.')
	    {
	      GCPRO2 (val, tail);
	      if (!NULL (tail))
		XCONS (tail)->cdr = read0 (readcharfun);
	      else
		val = read0 (readcharfun);
	      elt = read1 (readcharfun);
	      UNGCPRO;
	      if (XTYPE (elt) == Lisp_Internal && XINT (elt) == ')')
		return val;
	      return Fsignal (Qinvalid_read_syntax, Fcons (make_string (". in wrong context", 18), Qnil));
	    }
	  return Fsignal (Qinvalid_read_syntax, Fcons (make_string ("] in a list", 11), Qnil));
	}
      tem = (read_pure && flag <= 0
	     ? pure_cons (elt, Qnil)
	     : Fcons (elt, Qnil));
      if (!NULL (tail))
	XCONS (tail)->cdr = tem;
      else
	val = tem;
      tail = tem;
      if (defunflag < 0)
	defunflag = EQ (elt, Qdefun);
      else if (defunflag > 0)
	read_pure = 1;
    }
}

static int
read_escape (readcharfun)
     Lisp_Object readcharfun;
{
  register int c = READCHAR;
  switch (c)
    {
    case 'a':
      return 007;
    case 'b':
      return '\b';
    case 'e':
      return 033;
    case 'f':
      return '\f';
    case 'n':
      return '\n';
    case 'r':
      return '\r';
    case 't':
      return '\t';
    case 'v':
      return '\v';
    case '\n':
      return -1;

    case 'M':
      c = READCHAR;
      if (c != '-')
	error ("Invalid escape character syntax");
      c = READCHAR;
      if (c == '\\')
	c = read_escape (readcharfun);
      return c | 0200;

    case 'C':
      c = READCHAR;
      if (c != '-')
	error ("Invalid escape character syntax");
    case '^':
      c = READCHAR;
      if (c == '\\')
	c = read_escape (readcharfun);
      if (c == '?')
	return 0177;
      return (c & 0200) | (c & 037);
      
    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
      {
	register int i = c - '0';
	register int count = 0;
	while (++count < 3)
	  {
	    if ((c = READCHAR) >= '0' && c <= '7')
	      {
		i *= 8;