lread.c 50.7 KB
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/* Lisp parsing and input streams.
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   Copyright (C) 1985, 1986, 1987, 1988, 1989, 
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   1993, 1994 Free Software Foundation, Inc.
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This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


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#include <config.h>
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#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
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#include <errno.h>
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#include "lisp.h"

#ifndef standalone
#include "buffer.h"
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#include <paths.h>
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#include "commands.h"
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#include "keyboard.h"
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#include "termhooks.h"
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#endif

#ifdef lint
#include <sys/inode.h>
#endif /* lint */

#ifndef X_OK
#define X_OK 01
#endif

#ifdef LISP_FLOAT_TYPE
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#ifdef STDC_HEADERS
#include <stdlib.h>
#endif
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#ifdef MSDOS
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#include "msdos.h"
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/* These are redefined (correctly, but differently) in values.h.  */
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#undef INTBITS
#undef LONGBITS
#undef SHORTBITS
#endif

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#include <math.h>
#endif /* LISP_FLOAT_TYPE */

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#ifndef O_RDONLY
#define O_RDONLY 0
#endif

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extern int errno;

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Lisp_Object Qread_char, Qget_file_char, Qstandard_input, Qcurrent_load_list;
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Lisp_Object Qvariable_documentation, Vvalues, Vstandard_input, Vafter_load_alist;
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Lisp_Object Qascii_character, Qload;
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extern Lisp_Object Qevent_symbol_element_mask;
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/* non-zero if inside `load' */
int load_in_progress;

/* Search path for files to be loaded. */
Lisp_Object Vload_path;

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/* This is the user-visible association list that maps features to
   lists of defs in their load files. */
Lisp_Object Vload_history;

/* This is useud to build the load history. */
Lisp_Object Vcurrent_load_list;

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/* List of descriptors now open for Fload.  */
static Lisp_Object load_descriptor_list;

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/* File for get_file_char to read from.  Use by load */
static FILE *instream;

/* When nonzero, read conses in pure space */
static int read_pure;

/* For use within read-from-string (this reader is non-reentrant!!) */
static int read_from_string_index;
static int read_from_string_limit;

/* Handle unreading and rereading of characters.
   Write READCHAR to read a character,
   UNREAD(c) to unread c to be read again. */

#define READCHAR readchar (readcharfun)
#define UNREAD(c) unreadchar (readcharfun, c)

static int
readchar (readcharfun)
     Lisp_Object readcharfun;
{
  Lisp_Object tem;
  register struct buffer *inbuffer;
  register int c, mpos;

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  if (BUFFERP (readcharfun))
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    {
      inbuffer = XBUFFER (readcharfun);

      if (BUF_PT (inbuffer) >= BUF_ZV (inbuffer))
	return -1;
      c = *(unsigned char *) BUF_CHAR_ADDRESS (inbuffer, BUF_PT (inbuffer));
      SET_BUF_PT (inbuffer, BUF_PT (inbuffer) + 1);

      return c;
    }
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  if (MARKERP (readcharfun))
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    {
      inbuffer = XMARKER (readcharfun)->buffer;

      mpos = marker_position (readcharfun);

      if (mpos > BUF_ZV (inbuffer) - 1)
	return -1;
      c = *(unsigned char *) BUF_CHAR_ADDRESS (inbuffer, mpos);
      if (mpos != BUF_GPT (inbuffer))
	XMARKER (readcharfun)->bufpos++;
      else
	Fset_marker (readcharfun, make_number (mpos + 1),
		     Fmarker_buffer (readcharfun));
      return c;
    }
  if (EQ (readcharfun, Qget_file_char))
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    {
      c = getc (instream);
#ifdef EINTR
      /* Interrupted reads have been observed while reading over the network */
      while (c == EOF && ferror (instream) && errno == EINTR)
	{
	  clearerr (instream);
	  c = getc (instream);
	}
#endif
      return c;
    }
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  if (STRINGP (readcharfun))
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    {
      register int c;
      /* This used to be return of a conditional expression,
	 but that truncated -1 to a char on VMS.  */
      if (read_from_string_index < read_from_string_limit)
	c = XSTRING (readcharfun)->data[read_from_string_index++];
      else
	c = -1;
      return c;
    }

  tem = call0 (readcharfun);

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  if (NILP (tem))
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    return -1;
  return XINT (tem);
}

/* Unread the character C in the way appropriate for the stream READCHARFUN.
   If the stream is a user function, call it with the char as argument.  */

static void
unreadchar (readcharfun, c)
     Lisp_Object readcharfun;
     int c;
{
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  if (c == -1)
    /* Don't back up the pointer if we're unreading the end-of-input mark,
       since readchar didn't advance it when we read it.  */
    ;
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  else if (BUFFERP (readcharfun))
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    {
      if (XBUFFER (readcharfun) == current_buffer)
	SET_PT (point - 1);
      else
	SET_BUF_PT (XBUFFER (readcharfun), BUF_PT (XBUFFER (readcharfun)) - 1);
    }
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  else if (MARKERP (readcharfun))
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    XMARKER (readcharfun)->bufpos--;
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  else if (STRINGP (readcharfun))
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    read_from_string_index--;
  else if (EQ (readcharfun, Qget_file_char))
    ungetc (c, instream);
  else
    call1 (readcharfun, make_number (c));
}

static Lisp_Object read0 (), read1 (), read_list (), read_vector ();

/* get a character from the tty */

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extern Lisp_Object read_char ();

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/* Read input events until we get one that's acceptable for our purposes.

   If NO_SWITCH_FRAME is non-zero, switch-frame events are stashed
   until we get a character we like, and then stuffed into
   unread_switch_frame.

   If ASCII_REQUIRED is non-zero, we check function key events to see
   if the unmodified version of the symbol has a Qascii_character
   property, and use that character, if present.

   If ERROR_NONASCII is non-zero, we signal an error if the input we
   get isn't an ASCII character with modifiers.  If it's zero but
   ASCII_REQUIRED is non-zero, we just re-read until we get an ASCII
   character.  */
Lisp_Object
read_filtered_event (no_switch_frame, ascii_required, error_nonascii)
     int no_switch_frame, ascii_required, error_nonascii;
{
#ifdef standalone
  return make_number (getchar ());
#else
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  register Lisp_Object val, delayed_switch_frame;

  delayed_switch_frame = Qnil;
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  /* Read until we get an acceptable event.  */
 retry:
  val = read_char (0, 0, 0, Qnil, 0);

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  if (BUFFERP (val))
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    goto retry;

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  /* switch-frame events are put off until after the next ASCII
     character.  This is better than signalling an error just because
     the last characters were typed to a separate minibuffer frame,
     for example.  Eventually, some code which can deal with
     switch-frame events will read it and process it.  */
  if (no_switch_frame
      && EVENT_HAS_PARAMETERS (val)
      && EQ (EVENT_HEAD (val), Qswitch_frame))
    {
      delayed_switch_frame = val;
      goto retry;
    }

  if (ascii_required)
    {
      /* Convert certain symbols to their ASCII equivalents.  */
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      if (SYMBOLP (val))
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	{
	  Lisp_Object tem, tem1, tem2;
	  tem = Fget (val, Qevent_symbol_element_mask);
	  if (!NILP (tem))
	    {
	      tem1 = Fget (Fcar (tem), Qascii_character);
	      /* Merge this symbol's modifier bits
		 with the ASCII equivalent of its basic code.  */
	      if (!NILP (tem1))
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		XSETFASTINT (val, XINT (tem1) | XINT (Fcar (Fcdr (tem))));
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	    }
	}
	  
      /* If we don't have a character now, deal with it appropriately.  */
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      if (!INTEGERP (val))
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	{
	  if (error_nonascii)
	    {
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	      Vunread_command_events = Fcons (val, Qnil);
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	      error ("Non-character input-event");
	    }
	  else
	    goto retry;
	}
    }

  if (! NILP (delayed_switch_frame))
    unread_switch_frame = delayed_switch_frame;

  return val;
#endif
}

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DEFUN ("read-char", Fread_char, Sread_char, 0, 0, 0,
  "Read a character from the command input (keyboard or macro).\n\
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It is returned as a number.\n\
If the user generates an event which is not a character (i.e. a mouse\n\
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click or function key event), `read-char' signals an error.  As an\n\
exception, switch-frame events are put off until non-ASCII events can\n\
be read.\n\
If you want to read non-character events, or ignore them, call\n\
`read-event' or `read-char-exclusive' instead.")
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  ()
{
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  return read_filtered_event (1, 1, 1);
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}

DEFUN ("read-event", Fread_event, Sread_event, 0, 0, 0,
  "Read an event object from the input stream.")
  ()
{
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  return read_filtered_event (0, 0, 0);
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}

DEFUN ("read-char-exclusive", Fread_char_exclusive, Sread_char_exclusive, 0, 0, 0,
  "Read a character from the command input (keyboard or macro).\n\
It is returned as a number.  Non character events are ignored.")
  ()
{
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  return read_filtered_event (1, 1, 0);
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}

DEFUN ("get-file-char", Fget_file_char, Sget_file_char, 0, 0, 0,
  "Don't use this yourself.")
  ()
{
  register Lisp_Object val;
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  XSETINT (val, getc (instream));
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  return val;
}

static void readevalloop ();
static Lisp_Object load_unwind ();
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static Lisp_Object load_descriptor_unwind ();
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DEFUN ("load", Fload, Sload, 1, 4, 0,
  "Execute a file of Lisp code named FILE.\n\
First try FILE with `.elc' appended, then try with `.el',\n\
 then try FILE unmodified.\n\
This function searches the directories in `load-path'.\n\
If optional second arg NOERROR is non-nil,\n\
 report no error if FILE doesn't exist.\n\
Print messages at start and end of loading unless\n\
 optional third arg NOMESSAGE is non-nil.\n\
If optional fourth arg NOSUFFIX is non-nil, don't try adding\n\
 suffixes `.elc' or `.el' to the specified name FILE.\n\
Return t if file exists.")
  (str, noerror, nomessage, nosuffix)
     Lisp_Object str, noerror, nomessage, nosuffix;
{
  register FILE *stream;
  register int fd = -1;
  register Lisp_Object lispstream;
  int count = specpdl_ptr - specpdl;
  Lisp_Object temp;
  struct gcpro gcpro1;
  Lisp_Object found;
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  /* 1 means inhibit the message at the beginning.  */
  int nomessage1 = 0;
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  Lisp_Object handler;
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#ifdef DOS_NT
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  char *dosmode = "rt";
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#endif /* DOS_NT */
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  CHECK_STRING (str, 0);
  str = Fsubstitute_in_file_name (str);

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  /* If file name is magic, call the handler.  */
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  handler = Ffind_file_name_handler (str, Qload);
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  if (!NILP (handler))
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    return call5 (handler, Qload, str, noerror, nomessage, nosuffix);
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  /* Avoid weird lossage with null string as arg,
     since it would try to load a directory as a Lisp file */
  if (XSTRING (str)->size > 0)
    {
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      GCPRO1 (str);
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      fd = openp (Vload_path, str, !NILP (nosuffix) ? "" : ".elc:.el:",
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		  &found, 0);
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      UNGCPRO;
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    }

  if (fd < 0)
    {
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      if (NILP (noerror))
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	while (1)
	  Fsignal (Qfile_error, Fcons (build_string ("Cannot open load file"),
				       Fcons (str, Qnil)));
      else
	return Qnil;
    }

  if (!bcmp (&(XSTRING (found)->data[XSTRING (found)->size - 4]),
	     ".elc", 4))
    {
      struct stat s1, s2;
      int result;

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#ifdef DOS_NT
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      dosmode = "rb";
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#endif /* DOS_NT */
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      stat ((char *)XSTRING (found)->data, &s1);
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      XSTRING (found)->data[XSTRING (found)->size - 1] = 0;
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      result = stat ((char *)XSTRING (found)->data, &s2);
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      if (result >= 0 && (unsigned) s1.st_mtime < (unsigned) s2.st_mtime)
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	{
	  message ("Source file `%s' newer than byte-compiled file",
		   XSTRING (found)->data);
	  /* Don't immediately overwrite this message.  */
	  if (!noninteractive)
	    nomessage1 = 1;
	}
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      XSTRING (found)->data[XSTRING (found)->size - 1] = 'c';
    }

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#ifdef DOS_NT
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  close (fd);
  stream = fopen ((char *) XSTRING (found)->data, dosmode);
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#else  /* not DOS_NT */
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  stream = fdopen (fd, "r");
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#endif /* not DOS_NT */
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  if (stream == 0)
    {
      close (fd);
      error ("Failure to create stdio stream for %s", XSTRING (str)->data);
    }

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  if (NILP (nomessage) && !nomessage1)
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    message ("Loading %s...", XSTRING (str)->data);

  GCPRO1 (str);
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  lispstream = Fcons (Qnil, Qnil);
  XSETFASTINT (XCONS (lispstream)->car, (EMACS_UINT)stream >> 16);
  XSETFASTINT (XCONS (lispstream)->cdr, (EMACS_UINT)stream & 0xffff);
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  record_unwind_protect (load_unwind, lispstream);
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  record_unwind_protect (load_descriptor_unwind, load_descriptor_list);
  load_descriptor_list
    = Fcons (make_number (fileno (stream)), load_descriptor_list);
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  load_in_progress++;
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  readevalloop (Qget_file_char, stream, str, Feval, 0);
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  unbind_to (count, Qnil);

  /* Run any load-hooks for this file.  */
  temp = Fassoc (str, Vafter_load_alist);
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  if (!NILP (temp))
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    Fprogn (Fcdr (temp));
  UNGCPRO;

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  if (!noninteractive && NILP (nomessage))
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    message ("Loading %s...done", XSTRING (str)->data);
  return Qt;
}

static Lisp_Object
load_unwind (stream)  /* used as unwind-protect function in load */
     Lisp_Object stream;
{
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  fclose ((FILE *) (XFASTINT (XCONS (stream)->car) << 16
		    | XFASTINT (XCONS (stream)->cdr)));
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  if (--load_in_progress < 0) load_in_progress = 0;
  return Qnil;
}

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static Lisp_Object
load_descriptor_unwind (oldlist)
     Lisp_Object oldlist;
{
  load_descriptor_list = oldlist;
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  return Qnil;
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}

/* Close all descriptors in use for Floads.
   This is used when starting a subprocess.  */

void
close_load_descs ()
{
  Lisp_Object tail;
  for (tail = load_descriptor_list; !NILP (tail); tail = XCONS (tail)->cdr)
    close (XFASTINT (XCONS (tail)->car));
}
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static int
complete_filename_p (pathname)
     Lisp_Object pathname;
{
  register unsigned char *s = XSTRING (pathname)->data;
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  return (IS_DIRECTORY_SEP (s[0])
	  || (XSTRING (pathname)->size > 2
	      && IS_DEVICE_SEP (s[1]) && IS_DIRECTORY_SEP (s[2]))
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#ifdef ALTOS
	  || *s == '@'
#endif
#ifdef VMS
	  || index (s, ':')
#endif /* VMS */
	  );
}

/* Search for a file whose name is STR, looking in directories
   in the Lisp list PATH, and trying suffixes from SUFFIX.
   SUFFIX is a string containing possible suffixes separated by colons.
   On success, returns a file descriptor.  On failure, returns -1.

   EXEC_ONLY nonzero means don't open the files,
   just look for one that is executable.  In this case,
   returns 1 on success.

   If STOREPTR is nonzero, it points to a slot where the name of
   the file actually found should be stored as a Lisp string.
   Nil is stored there on failure.  */

int
openp (path, str, suffix, storeptr, exec_only)
     Lisp_Object path, str;
     char *suffix;
     Lisp_Object *storeptr;
     int exec_only;
{
  register int fd;
  int fn_size = 100;
  char buf[100];
  register char *fn = buf;
  int absolute = 0;
  int want_size;
  register Lisp_Object filename;
  struct stat st;
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  struct gcpro gcpro1;
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  GCPRO1 (str);
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  if (storeptr)
    *storeptr = Qnil;

  if (complete_filename_p (str))
    absolute = 1;

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  for (; !NILP (path); path = Fcdr (path))
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    {
      char *nsuffix;

      filename = Fexpand_file_name (str, Fcar (path));
      if (!complete_filename_p (filename))
	/* If there are non-absolute elts in PATH (eg ".") */
	/* Of course, this could conceivably lose if luser sets
	   default-directory to be something non-absolute... */
	{
	  filename = Fexpand_file_name (filename, current_buffer->directory);
	  if (!complete_filename_p (filename))
	    /* Give up on this path element! */
	    continue;
	}

      /* Calculate maximum size of any filename made from
	 this path element/specified file name and any possible suffix.  */
      want_size = strlen (suffix) + XSTRING (filename)->size + 1;
      if (fn_size < want_size)
	fn = (char *) alloca (fn_size = 100 + want_size);

      nsuffix = suffix;

      /* Loop over suffixes.  */
      while (1)
	{
	  char *esuffix = (char *) index (nsuffix, ':');
	  int lsuffix = esuffix ? esuffix - nsuffix : strlen (nsuffix);

	  /* Concatenate path element/specified name with the suffix.  */
	  strncpy (fn, XSTRING (filename)->data, XSTRING (filename)->size);
	  fn[XSTRING (filename)->size] = 0;
	  if (lsuffix != 0)  /* Bug happens on CCI if lsuffix is 0.  */
	    strncat (fn, nsuffix, lsuffix);

	  /* Ignore file if it's a directory.  */
	  if (stat (fn, &st) >= 0
	      && (st.st_mode & S_IFMT) != S_IFDIR)
	    {
	      /* Check that we can access or open it.  */
	      if (exec_only)
		fd = (access (fn, X_OK) == 0) ? 1 : -1;
	      else
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		fd = open (fn, O_RDONLY, 0);
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	      if (fd >= 0)
		{
		  /* We succeeded; return this descriptor and filename.  */
		  if (storeptr)
		    *storeptr = build_string (fn);
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		  UNGCPRO;
		  return fd;
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		}
	    }

	  /* Advance to next suffix.  */
	  if (esuffix == 0)
	    break;
	  nsuffix += lsuffix + 1;
	}
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      if (absolute)
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	break;
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    }

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  UNGCPRO;
  return -1;
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}


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/* Merge the list we've accumulated of globals from the current input source
   into the load_history variable.  The details depend on whether
   the source has an associated file name or not. */

static void
build_load_history (stream, source)
     FILE *stream;
     Lisp_Object source;
{
  register Lisp_Object tail, prev, newelt;
  register Lisp_Object tem, tem2;
  register int foundit, loading;

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  /* Don't bother recording anything for preloaded files.  */
  if (!NILP (Vpurify_flag))
    return;

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  loading = stream || !NARROWED;

  tail = Vload_history;
  prev = Qnil;
  foundit = 0;
  while (!NILP (tail))
    {
      tem = Fcar (tail);

      /* Find the feature's previous assoc list... */
      if (!NILP (Fequal (source, Fcar (tem))))
	{
	  foundit = 1;

	  /*  If we're loading, remove it. */
	  if (loading)
	    {	  
	      if (NILP (prev))
		Vload_history = Fcdr (tail);
	      else
		Fsetcdr (prev, Fcdr (tail));
	    }

	  /*  Otherwise, cons on new symbols that are not already members.  */
	  else
	    {
	      tem2 = Vcurrent_load_list;

	      while (CONSP (tem2))
		{
		  newelt = Fcar (tem2);

		  if (NILP (Fmemq (newelt, tem)))
		    Fsetcar (tail, Fcons (Fcar (tem),
					  Fcons (newelt, Fcdr (tem))));

		  tem2 = Fcdr (tem2);
		  QUIT;
		}
	    }
	}
      else
	prev = tail;
      tail = Fcdr (tail);
      QUIT;
    }

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  /* If we're loading, cons the new assoc onto the front of load-history,
     the most-recently-loaded position.  Also do this if we didn't find
     an existing member for the current source.  */
  if (loading || !foundit)
    Vload_history = Fcons (Fnreverse (Vcurrent_load_list),
			   Vload_history);
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}

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Lisp_Object
unreadpure ()	/* Used as unwind-protect function in readevalloop */
{
  read_pure = 0;
  return Qnil;
}

static void
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readevalloop (readcharfun, stream, sourcename, evalfun, printflag)
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     Lisp_Object readcharfun;
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     FILE *stream;
     Lisp_Object sourcename;
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     Lisp_Object (*evalfun) ();
     int printflag;
{
  register int c;
  register Lisp_Object val;
  int count = specpdl_ptr - specpdl;
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  struct gcpro gcpro1;
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  struct buffer *b = 0;

  if (BUFFERP (readcharfun))
    b = XBUFFER (readcharfun);
  else if (MARKERP (readcharfun))
    b = XMARKER (readcharfun)->buffer;
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  specbind (Qstandard_input, readcharfun);
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  specbind (Qcurrent_load_list, Qnil);
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  GCPRO1 (sourcename);
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  LOADHIST_ATTACH (sourcename);

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  while (1)
    {
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      if (b != 0 && NILP (b->name))
	error ("Reading from killed buffer");

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      instream = stream;
      c = READCHAR;
      if (c == ';')
	{
	  while ((c = READCHAR) != '\n' && c != -1);
	  continue;
	}
      if (c < 0) break;
      if (c == ' ' || c == '\t' || c == '\n' || c == '\f') continue;

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      if (!NILP (Vpurify_flag) && c == '(')
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	{
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	  int count1 = specpdl_ptr - specpdl;
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	  record_unwind_protect (unreadpure, Qnil);
	  val = read_list (-1, readcharfun);
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	  unbind_to (count1, Qnil);
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	}
      else
	{
	  UNREAD (c);
	  val = read0 (readcharfun);
	}

      val = (*evalfun) (val);
      if (printflag)
	{
	  Vvalues = Fcons (val, Vvalues);
	  if (EQ (Vstandard_output, Qt))
	    Fprin1 (val, Qnil);
	  else
	    Fprint (val, Qnil);
	}
    }

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  build_load_history (stream, sourcename);
  UNGCPRO;

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  unbind_to (count, Qnil);
}

#ifndef standalone

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DEFUN ("eval-buffer", Feval_buffer, Seval_buffer, 0, 2, "",
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  "Execute the current buffer as Lisp code.\n\
Programs can pass two arguments, BUFFER and PRINTFLAG.\n\
BUFFER is the buffer to evaluate (nil means use current buffer).\n\
PRINTFLAG controls printing of output:\n\
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nil means discard it; anything else is stream for print.\n\
\n\
If there is no error, point does not move.  If there is an error,\n\
point remains at the end of the last character read from the buffer.")
  (bufname, printflag)
     Lisp_Object bufname, printflag;
{
  int count = specpdl_ptr - specpdl;
  Lisp_Object tem, buf;

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  if (NILP (bufname))
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    buf = Fcurrent_buffer ();
  else
    buf = Fget_buffer (bufname);
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  if (NILP (buf))
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    error ("No such buffer.");

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  if (NILP (printflag))
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    tem = Qsymbolp;
  else
    tem = printflag;
  specbind (Qstandard_output, tem);
  record_unwind_protect (save_excursion_restore, save_excursion_save ());
  BUF_SET_PT (XBUFFER (buf), BUF_BEGV (XBUFFER (buf)));
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  readevalloop (buf, 0, XBUFFER (buf)->filename, Feval, !NILP (printflag));
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  unbind_to (count, Qnil);
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  return Qnil;
}

#if 0
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DEFUN ("eval-current-buffer", Feval_current_buffer, Seval_current_buffer, 0, 1, "",
  "Execute the current buffer as Lisp code.\n\
Programs can pass argument PRINTFLAG which controls printing of output:\n\
nil means discard it; anything else is stream for print.\n\
\n\
If there is no error, point does not move.  If there is an error,\n\
point remains at the end of the last character read from the buffer.")
  (printflag)
     Lisp_Object printflag;
{
  int count = specpdl_ptr - specpdl;
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  Lisp_Object tem, cbuf;

  cbuf = Fcurrent_buffer ()
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  if (NILP (printflag))
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    tem = Qsymbolp;
  else
    tem = printflag;
  specbind (Qstandard_output, tem);
  record_unwind_protect (save_excursion_restore, save_excursion_save ());
  SET_PT (BEGV);
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  readevalloop (cbuf, 0, XBUFFER (cbuf)->filename, Feval, !NILP (printflag));
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  return unbind_to (count, Qnil);
}
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#endif
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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 output:\n\
nil means discard it; anything else is stream for printing it.\n\
\n\
If there is no error, point does not move.  If there is an error,\n\
point remains at the end of the last character read from the buffer.")
  (b, e, printflag)
     Lisp_Object b, e, printflag;
{
  int count = specpdl_ptr - specpdl;
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  Lisp_Object tem, cbuf;

  cbuf = Fcurrent_buffer ();
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  if (NILP (printflag))
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    tem = Qsymbolp;
  else
    tem = printflag;
  specbind (Qstandard_output, tem);

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  if (NILP (printflag))
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    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);
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  readevalloop (cbuf, 0, XBUFFER (cbuf)->filename, Feval, !NILP (printflag));
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  return unbind_to (count, 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 the value of `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\
     call it with a char as argument to push a char back)\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 ();

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  if (NILP (readcharfun))
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    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

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  if (STRINGP (readcharfun))
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    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);

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  if (NILP (end))
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    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);
    }

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  if (NILP (start))
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    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;

  tem = read0 (string);
  return Fcons (tem, make_number (read_from_string_index));
}

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/* Use this for recursive reads, in contexts where internal tokens
   are not allowed. */
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static Lisp_Object
read0 (readcharfun)
     Lisp_Object readcharfun;
{
  register Lisp_Object val;
  char c;

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  val = read1 (readcharfun, &c);
  if (c)
    Fsignal (Qinvalid_read_syntax, Fcons (make_string (&c, 1), Qnil));
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  return val;
}

static int read_buffer_size;
static char *read_buffer;

static int
read_escape (readcharfun)
     Lisp_Object readcharfun;
{
  register int c = READCHAR;
  switch (c)
    {
    case 'a':
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      return '\007';
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    case 'b':
      return '\b';
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    case 'd':
      return 0177;
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    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);
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      return c | meta_modifier;
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    case 'S':
      c = READCHAR;
      if (c != '-')
	error ("Invalid escape character syntax");
      c = READCHAR;
      if (c == '\\')
	c = read_escape (readcharfun);
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      return c | shift_modifier;

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

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

    case 's':
      c = READCHAR;
      if (c != '-')
	error ("Invalid escape character syntax");
      c = READCHAR;
      if (c == '\\')
	c = read_escape (readcharfun);
      return c | super_modifier;
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    case 'C':
      c = READCHAR;
      if (c != '-')
	error ("Invalid escape character syntax");
    case '^':
      c = READCHAR;
      if (c == '\\')
	c = read_escape (readcharfun);
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      if ((c & 0177) == '?')
	return 0177 | c;
      /* ASCII control chars are made from letters (both cases),
	 as well as the non-letters within 0100...0137.  */
      else if ((c & 0137) >= 0101 && (c & 0137) <= 0132)
	return (c & (037 | ~0177));
      else if ((c & 0177) >= 0100 && (c & 0177) <= 0137)
	return (c & (037 | ~0177));
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      else
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	return c | ctrl_modifier;
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    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
      /* An octal escape, as in ANSI C.  */
      {
	register int i = c - '0';
	register int count = 0;
	while (++count < 3)
	  {
	    if ((c = READCHAR) >= '0' && c <= '7')
	      {
		i *= 8;
		i += c - '0';
	      }
	    else
	      {
		UNREAD (c);
		break;
	      }
	  }
	return i;
      }

    case 'x':
      /* A hex escape, as in ANSI C.  */
      {
	int i = 0;
	while (1)
	  {
	    c = READCHAR;
	    if (c >= '0' && c <= '9')
	      {
		i *= 16;
		i += c - '0';
	      }
	    else if ((c >= 'a' && c <= 'f')
		     || (c >= 'A' && c <= 'F'))
	      {
		i *= 16;
		if (c >= 'a' && c <= 'f')
		  i += c - 'a' + 10;
		else
		  i += c - 'A' + 10;
	      }
	    else
	      {
		UNREAD (c);
		break;
	      }
	  }
	return i;
      }

    default:
      return c;
    }
}

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/* If the next token is ')' or ']' or '.', we store that character
   in *PCH and the return value is not interesting.  Else, we store
   zero in *PCH and we read and return one lisp object.  */
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static Lisp_Object
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read1 (readcharfun, pch)
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     register Lisp_Object readcharfun;
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     char *pch;
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{
  register int c;
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  *pch = 0;
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 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 ']':
      {
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	*pch = c;
	return Qnil;
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      }

    case '#':
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      c = READCHAR;
      if (c == '[')
	{
	  /* Accept compiled functions at read-time so that we don't have to
	     build them using function calls.  */
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	  Lisp_Object tmp;
	  tmp = read_vector (readcharfun);
	  return Fmake_byte_code (XVECTOR (tmp)->size,
				  XVECTOR (tmp)->contents);
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	}
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#ifdef USE_TEXT_PROPERTIES
      if (c == '(')
	{
	  Lisp_Object tmp;
	  struct gcpro gcpro1;
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	  char ch;
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	  /* Read the string itself.  */
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	  tmp = read1 (readcharfun, &ch);
	  if (ch != 0 || !STRINGP (tmp))
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	    Fsignal (Qinvalid_read_syntax, Fcons (make_string ("#", 1), Qnil));
	  GCPRO1 (tmp);
	  /* Read the intervals and their properties.  */
	  while (1)
	    {
	      Lisp_Object beg, end, plist;

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	      beg = read1 (readcharfun, &ch);
	      if (ch == ')')
		break;
	      if (ch == 0)
		end = read1 (readcharfun, &ch);
	      if (ch == 0)
		plist = read1 (readcharfun, &ch);
	      if (ch)
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		Fsignal (Qinvalid_read_syntax,
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			 Fcons (build_string ("invalid string property list"),
				Qnil));
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	      Fset_text_properties (beg, end, plist, tmp);
	    }
	  UNGCPRO;
	  return tmp;
	}
#endif
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      UNREAD (c);
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      Fsignal (Qinvalid_read_syntax, Fcons (make_string ("#", 1), Qnil));
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    case ';':
      while ((c = READCHAR) >= 0 && c != '\n');
      goto retry;

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

    case '?':
      {
	register Lisp_Object val;

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

	if (c == '\\')
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	  XSETINT (val, read_escape (readcharfun));
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	else
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	  XSETINT (val, c);
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	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 != '\"')
	  {
	    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 */
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	    if (c == -1)
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	      {
		if (p == read_buffer)
		  cancel = 1;
	      }
	    else
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	      {
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		/* Allow `\C- ' and `\C-?'.  */
		if (c == (CHAR_CTL | ' '))
		  c = 0;
		else if (c == (CHAR_CTL | '?'))
		  c = 127;

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		if (c & CHAR_META)
		  /* Move the meta bit to the right place for a string.  */
		  c = (c & ~CHAR_META) | 0x80;
		if (c & ~0xff)
		  error ("Invalid modifier in string");
		*p++ = c;
	      }
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	  }
	if (c < 0) return Fsignal (Qend_of_file, Qnil);

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

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    case '.':
      {
#ifdef LISP_FLOAT_TYPE
	/* If a period is followed by a number, then we should read it
	   as a floating point number.  Otherwise, it denotes a dotted
	   pair.  */
	int next_char = READCHAR;
	UNREAD (next_char);

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	if (! (next_char >= '0' && next_char <= '9'))
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#endif
	  {
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	    *pch = c;
	    return Qnil;
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	  }

	/* Otherwise, we fall through!  Note that the atom-reading loop
	   below will now loop at least once, assuring that we will not
	   try to UNREAD two characters in a row.  */
      }
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    default:
      if (c <= 040) goto retry;
      {
	register char *p = read_buffer;
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	int quoted = 0;
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	{
	  register char *end = read_buffer + read_buffer_size;

	  while (c > 040 && 
		 !(c == '\"' || c == '\'' || c == ';' || c == '?'
		   || c == '(' || c == ')'
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#ifndef LISP_FLOAT_TYPE
		   /* If we have floating-point support, then we need
		      to allow <digits><dot><digits>.  */
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		   || c =='.'
#endif /* not LISP_FLOAT_TYPE */
		   || 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 == '\\')
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		{
		  c = READCHAR;
		  quoted = 1;
		}
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