entered into RCS

[emacs.git] / src / lread.c

/* Lisp parsing and input streams.
   Copyright (C) 1985, 1986, 1987, 1988, 1989,
   1992 Free Software Foundation, Inc.

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
the Free Software Foundation; either version 2, or (at your option)
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.  */


#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <ctype.h>
#undef NULL
#include "config.h"
#include "lisp.h"

#ifndef standalone
#include "buffer.h"
#include "paths.h"
#include "commands.h"
#endif

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

#ifndef X_OK
#define X_OK 01
#endif

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

Lisp_Object Qread_char, Qget_file_char, Qstandard_input;
Lisp_Object Qvariable_documentation, Vvalues, Vstandard_input, Vafter_load_alist;

/* non-zero if inside `load' */
int load_in_progress;

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

/* 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;
\f
/* 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;

  if (XTYPE (readcharfun) == Lisp_Buffer)
    {
      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;
    }
  if (XTYPE (readcharfun) == Lisp_Marker)
    {
      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))
    return getc (instream);

  if (XTYPE (readcharfun) == Lisp_String)
    {
      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);

  if (NILP (tem))
    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;
{
  if (XTYPE (readcharfun) == Lisp_Buffer)
    {
      if (XBUFFER (readcharfun) == current_buffer)
        SET_PT (point - 1);
      else
        SET_BUF_PT (XBUFFER (readcharfun), BUF_PT (XBUFFER (readcharfun)) - 1);
    }
  else if (XTYPE (readcharfun) == Lisp_Marker)
    XMARKER (readcharfun)->bufpos--;
  else if (XTYPE (readcharfun) == Lisp_String)
    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 ();
\f
/* get a character from the tty */

DEFUN ("read-char", Fread_char, Sread_char, 0, 0, 0,
  "Read a character from the command input (keyboard or macro).\n\
It is returned as a number.")
  ()
{
  register Lisp_Object val;

#ifndef standalone
  val = read_char (0);
  if (XTYPE (val) != Lisp_Int)
    {
      unread_command_char = val;
      error ("Object read was not a character");
    }
#else
  val = getchar ();
#endif

  return val;
}

#ifdef HAVE_X_WINDOWS
DEFUN ("read-event", Fread_event, Sread_event, 0, 0, 0,
  "Read an event object from the input stream.")
  ()
{
  register Lisp_Object val;

  val = read_char (0);
  return val;
}
#endif

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.")
  ()
{
  register Lisp_Object val;

#ifndef standalone
  val = read_char (0);
  while (XTYPE (val) != Lisp_Int)
    val = read_char (0);
#else
  val = getchar ();
#endif

  return val;
}

DEFUN ("get-file-char", Fget_file_char, Sget_file_char, 0, 0, 0,
  "Don't use this yourself.")
  ()
{
  register Lisp_Object val;
  XSET (val, Lisp_Int, getc (instream));
  return val;
}
\f
static void readevalloop ();
static Lisp_Object load_unwind ();

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;
  register FILE **ptr;
  int count = specpdl_ptr - specpdl;
  Lisp_Object temp;
  struct gcpro gcpro1;
  Lisp_Object found;

  CHECK_STRING (str, 0);
  str = Fsubstitute_in_file_name (str);

  /* 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)
    {
      fd = openp (Vload_path, str, !NILP (nosuffix) ? "" : ".elc:.el:",
                  &found, 0);
    }

  if (fd < 0)
    {
      if (NILP (noerror))
        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;

      stat (XSTRING (found)->data, &s1);
      XSTRING (found)->data[XSTRING (found)->size - 1] = 0;
      result = stat (XSTRING (found)->data, &s2);
      if (result >= 0 && (unsigned) s1.st_mtime < (unsigned) s2.st_mtime)
        message ("Source file `%s' newer than byte-compiled file",
                 XSTRING (found)->data);
      XSTRING (found)->data[XSTRING (found)->size - 1] = 'c';
    }

  stream = fdopen (fd, "r");
  if (stream == 0)
    {
      close (fd);
      error ("Failure to create stdio stream for %s", XSTRING (str)->data);
    }

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

  GCPRO1 (str);
  /* We may not be able to store STREAM itself as a Lisp_Object pointer
     since that is guaranteed to work only for data that has been malloc'd.
     So malloc a full-size pointer, and record the address of that pointer.  */
  ptr = (FILE **) xmalloc (sizeof (FILE *));
  *ptr = stream;
  XSET (lispstream, Lisp_Internal_Stream, (int) ptr);
  record_unwind_protect (load_unwind, lispstream);
  load_in_progress++;
  readevalloop (Qget_file_char, stream, Feval, 0);
  unbind_to (count, Qnil);

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

  if (!noninteractive && NILP (nomessage))
    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;
{
  fclose (*(FILE **) XSTRING (stream));
  free (XPNTR (stream));
  if (--load_in_progress < 0) load_in_progress = 0;
  return Qnil;
}

\f
static int
complete_filename_p (pathname)
     Lisp_Object pathname;
{
  register unsigned char *s = XSTRING (pathname)->data;
  return (*s == '/'
#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;

  if (storeptr)
    *storeptr = Qnil;

  if (complete_filename_p (str))
    absolute = 1;

  for (; !NILP (path); path = Fcdr (path))
    {
      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
                fd = open (fn, 0, 0);

              if (fd >= 0)
                {
                  /* We succeeded; return this descriptor and filename.  */
                  if (storeptr)
                    *storeptr = build_string (fn);
                  return fd;
                }
            }

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

  return -1;
}

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

static void
readevalloop (readcharfun, stream, evalfun, printflag)
     Lisp_Object readcharfun;
     FILE *stream;     
     Lisp_Object (*evalfun) ();
     int printflag;
{
  register int c;
  register Lisp_Object val;
  int count = specpdl_ptr - specpdl;

  specbind (Qstandard_input, readcharfun);

  while (1)
    {
      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;

      if (!NILP (Vpurify_flag) && c == '(')
        {
          record_unwind_protect (unreadpure, Qnil);
          val = read_list (-1, readcharfun);
          unbind_to (count + 1, Qnil);
        }
      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);
        }
    }

  unbind_to (count, Qnil);
}

#ifndef standalone

DEFUN ("eval-buffer", Feval_buffer, Seval_buffer, 0, 2, "",
  "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\
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;

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

  if (NILP (printflag))
    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)));
  readevalloop (buf, 0, Feval, !NILP (printflag));
  unbind_to (count);

  return Qnil;
}

#if 0
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;
  Lisp_Object tem;

  if (NILP (printflag))
    tem = Qsymbolp;
  else
    tem = printflag;
  specbind (Qstandard_output, tem);
  record_unwind_protect (save_excursion_restore, save_excursion_save ());
  SET_PT (BEGV);
  readevalloop (Fcurrent_buffer (), 0, Feval, !NILP (printflag));
  return unbind_to (count, Qnil);
}
#endif

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;
  Lisp_Object tem;

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

  if (NILP (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, !NILP (printflag));

  return unbind_to (count, Qnil);
}

#endif /* standalone */
\f
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 ();

  if (NILP (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 (NILP (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 (NILP (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;

  tem = read0 (string);
  return Fcons (tem, make_number (read_from_string_index));
}
\f
/* 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;
}
\f
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':
      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;
      else
        return (c & (0200 | 037));

    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;
    }
}

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

    case '#':
      c = READCHAR;
      if (c == '[')
        {
          /* Accept compiled functions at read-time so that we don't have to
             build them using function calls.  */
          Lisp_Object tmp = read_vector (readcharfun);
          return Fmake_byte_code (XVECTOR(tmp)->size, XVECTOR (tmp)->contents);
        }
      UNREAD (c);
      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;

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

        if (c == '\\')
          XSET (val, Lisp_Int, read_escape (readcharfun));
        else
          XSET (val, Lisp_Int, c);

        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 */
            if (c < 0)
              {
                if (p == read_buffer)
                  cancel = 1;
              }
            else
              *p++ = c;
          }
        if (c < 0) return Fsignal (Qend_of_file, Qnil);

        /* 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 (!NILP (Vpurify_flag) && NILP (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);
      }

    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);

        if (! isdigit (next_char))
#endif
          {
            register Lisp_Object val;
            XSET (val, Lisp_Internal, c);
            return val;
          }

        /* 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.  */
      }
    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 == ')'
#ifndef LISP_FLOAT_TYPE
                   /* If we have floating-point support, then we need
                      to allow <digits><dot><digits>.  */
                   || 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 == '\\')
                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;
          if (c >= 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;
                }
            }
#ifdef LISP_FLOAT_TYPE
          if (isfloat_string (read_buffer))
            return make_float (atof (read_buffer));
#endif
        }

        return intern (read_buffer);
      }
    }
}
\f
#ifdef LISP_FLOAT_TYPE

#define LEAD_INT 1
#define DOT_CHAR 2
#define TRAIL_INT 4
#define E_CHAR 8
#define EXP_INT 16

int
isfloat_string (cp)
     register char *cp;
{
  register state;
  
  state = 0;
  if (*cp == '+' || *cp == '-')
    cp++;

  if (isdigit(*cp))
    {
      state |= LEAD_INT;
      while (isdigit (*cp))
        cp ++;
    }
  if (*cp == '.')
    {
      state |= DOT_CHAR;
      cp++;
    }
  if (isdigit(*cp))
    {
      state |= TRAIL_INT;
      while (isdigit (*cp))
        cp++;
    }
  if (*cp == 'e')
    {
      state |= E_CHAR;
      cp++;
    }
  if ((*cp == '+') || (*cp == '-'))
    cp++;

  if (isdigit (*cp))
    {
      state |= EXP_INT;
      while (isdigit (*cp))
        cp++;
    }
  return (*cp == 0
          && (state == (LEAD_INT|DOT_CHAR|TRAIL_INT)
              || state == (DOT_CHAR|TRAIL_INT)
              || state == (LEAD_INT|E_CHAR|EXP_INT)
              || state == (LEAD_INT|DOT_CHAR|TRAIL_INT|E_CHAR|EXP_INT)
              || state == (DOT_CHAR|TRAIL_INT|E_CHAR|EXP_INT)));
}
#endif /* LISP_FLOAT_TYPE */
\f
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 (!NILP (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 (!NILP (tail))
        XCONS (tail)->cdr = tem;
      else
        val = tem;
      tail = tem;
      if (defunflag < 0)
        defunflag = EQ (elt, Qdefun);
      else if (defunflag > 0)
        read_pure = 1;
    }
}
\f
Lisp_Object Vobarray;
Lisp_Object initial_obarray;

Lisp_Object
check_obarray (obarray)
     Lisp_Object obarray;
{
  while (XTYPE (obarray) != Lisp_Vector || XVECTOR (obarray)->size == 0)
    {
      /* If Vobarray is now invalid, force it to be valid.  */
      if (EQ (Vobarray, obarray)) Vobarray = initial_obarray;

      obarray = wrong_type_argument (Qvectorp, obarray);
    }
  return obarray;
}

static int hash_string ();
Lisp_Object oblookup ();

Lisp_Object
intern (str)
     char *str;
{
  Lisp_Object tem;
  int len = strlen (str);
  Lisp_Object obarray = Vobarray;

  if (XTYPE (obarray) != Lisp_Vector || XVECTOR (obarray)->size == 0)
    obarray = check_obarray (obarray);
  tem = oblookup (obarray, str, len);
  if (XTYPE (tem) == Lisp_Symbol)
    return tem;
  return Fintern ((!NILP (Vpurify_flag)
                   ? make_pure_string (str, len)
                   : make_string (str, len)),
                  obarray);
}

DEFUN ("intern", Fintern, Sintern, 1, 2, 0,
  "Return the canonical symbol whose name is STRING.\n\
If there is none, one is created by this function and returned.\n\
A second optional argument specifies the obarray to use;\n\
it defaults to the value of `obarray'.")
  (str, obarray)
     Lisp_Object str, obarray;
{
  register Lisp_Object tem, sym, *ptr;

  if (NILP (obarray)) obarray = Vobarray;
  obarray = check_obarray (obarray);

  CHECK_STRING (str, 0);

  tem = oblookup (obarray, XSTRING (str)->data, XSTRING (str)->size);
  if (XTYPE (tem) != Lisp_Int)
    return tem;

  if (!NILP (Vpurify_flag))
    str = Fpurecopy (str);
  sym = Fmake_symbol (str);

  ptr = &XVECTOR (obarray)->contents[XINT (tem)];
  if (XTYPE (*ptr) == Lisp_Symbol)
    XSYMBOL (sym)->next = XSYMBOL (*ptr);
  else
    XSYMBOL (sym)->next = 0;
  *ptr = sym;
  return sym;
}

DEFUN ("intern-soft", Fintern_soft, Sintern_soft, 1, 2, 0,
  "Return the canonical symbol whose name is STRING, or nil if none exists.\n\
A second optional argument specifies the obarray to use;\n\
it defaults to the value of `obarray'.")
  (str, obarray)
     Lisp_Object str, obarray;
{
  register Lisp_Object tem;

  if (NILP (obarray)) obarray = Vobarray;
  obarray = check_obarray (obarray);

  CHECK_STRING (str, 0);

  tem = oblookup (obarray, XSTRING (str)->data, XSTRING (str)->size);
  if (XTYPE (tem) != Lisp_Int)
    return tem;
  return Qnil;
}

Lisp_Object
oblookup (obarray, ptr, size)
     Lisp_Object obarray;
     register char *ptr;
     register int size;
{
  int hash, obsize;
  register Lisp_Object tail;
  Lisp_Object bucket, tem;

  if (XTYPE (obarray) != Lisp_Vector ||
      (obsize = XVECTOR (obarray)->size) == 0)
    {
      obarray = check_obarray (obarray);
      obsize = XVECTOR (obarray)->size;
    }
  /* Combining next two lines breaks VMS C 2.3.  */
  hash = hash_string (ptr, size);
  hash %= obsize;
  bucket = XVECTOR (obarray)->contents[hash];
  if (XFASTINT (bucket) == 0)
    ;
  else if (XTYPE (bucket) != Lisp_Symbol)
    error ("Bad data in guts of obarray"); /* Like CADR error message */
  else for (tail = bucket; ; XSET (tail, Lisp_Symbol, XSYMBOL (tail)->next))
      {
        if (XSYMBOL (tail)->name->size == size &&
            !bcmp (XSYMBOL (tail)->name->data, ptr, size))
          return tail;
        else if (XSYMBOL (tail)->next == 0)
          break;
      }
  XSET (tem, Lisp_Int, hash);
  return tem;
}

static int
hash_string (ptr, len)
     unsigned char *ptr;
     int len;
{
  register unsigned char *p = ptr;
  register unsigned char *end = p + len;
  register unsigned char c;
  register int hash = 0;

  while (p != end)
    {
      c = *p++;
      if (c >= 0140) c -= 40;
      hash = ((hash<<3) + (hash>>28) + c);
    }
  return hash & 07777777777;
}

void
map_obarray (obarray, fn, arg)
     Lisp_Object obarray;
     int (*fn) ();
     Lisp_Object arg;
{
  register int i;
  register Lisp_Object tail;
  CHECK_VECTOR (obarray, 1);
  for (i = XVECTOR (obarray)->size - 1; i >= 0; i--)
    {
      tail = XVECTOR (obarray)->contents[i];
      if (XFASTINT (tail) != 0)
        while (1)
          {
            (*fn) (tail, arg);
            if (XSYMBOL (tail)->next == 0)
              break;
            XSET (tail, Lisp_Symbol, XSYMBOL (tail)->next);
          }
    }
}

mapatoms_1 (sym, function)
     Lisp_Object sym, function;
{
  call1 (function, sym);
}

DEFUN ("mapatoms", Fmapatoms, Smapatoms, 1, 2, 0,
  "Call FUNCTION on every symbol in OBARRAY.\n\
OBARRAY defaults to the value of `obarray'.")
  (function, obarray)
     Lisp_Object function, obarray;
{
  Lisp_Object tem;

  if (NILP (obarray)) obarray = Vobarray;
  obarray = check_obarray (obarray);

  map_obarray (obarray, mapatoms_1, function);
  return Qnil;
}

#define OBARRAY_SIZE 509

void
init_obarray ()
{
  Lisp_Object oblength;
  int hash;
  Lisp_Object *tem;

  XFASTINT (oblength) = OBARRAY_SIZE;

  Qnil = Fmake_symbol (make_pure_string ("nil", 3));
  Vobarray = Fmake_vector (oblength, make_number (0));
  initial_obarray = Vobarray;
  staticpro (&initial_obarray);
  /* Intern nil in the obarray */
  /* These locals are to kludge around a pyramid compiler bug. */
  hash = hash_string ("nil", 3);
  /* Separate statement here to avoid VAXC bug. */
  hash %= OBARRAY_SIZE;
  tem = &XVECTOR (Vobarray)->contents[hash];
  *tem = Qnil;

  Qunbound = Fmake_symbol (make_pure_string ("unbound", 7));
  XSYMBOL (Qnil)->function = Qunbound;
  XSYMBOL (Qunbound)->value = Qunbound;
  XSYMBOL (Qunbound)->function = Qunbound;

  Qt = intern ("t");
  XSYMBOL (Qnil)->value = Qnil;
  XSYMBOL (Qnil)->plist = Qnil;
  XSYMBOL (Qt)->value = Qt;

  /* Qt is correct even if CANNOT_DUMP.  loadup.el will set to nil at end.  */
  Vpurify_flag = Qt;

  Qvariable_documentation = intern ("variable-documentation");

  read_buffer_size = 100;
  read_buffer = (char *) malloc (read_buffer_size);
}
\f
void
defsubr (sname)
     struct Lisp_Subr *sname;
{
  Lisp_Object sym;
  sym = intern (sname->symbol_name);
  XSET (XSYMBOL (sym)->function, Lisp_Subr, sname);
}

#ifdef NOTDEF /* use fset in subr.el now */
void
defalias (sname, string)
     struct Lisp_Subr *sname;
     char *string;
{
  Lisp_Object sym;
  sym = intern (string);
  XSET (XSYMBOL (sym)->function, Lisp_Subr, sname);
}
#endif /* NOTDEF */

/* New replacement for DefIntVar; it ignores the doc string argument
   on the assumption that make-docfile will handle that.  */
/* Define an "integer variable"; a symbol whose value is forwarded
 to a C variable of type int.  Sample call: */
  /* DEFVARINT ("indent-tabs-mode", &indent_tabs_mode, "Documentation");  */

void
defvar_int (namestring, address, doc)
     char *namestring;
     int *address;
     char *doc;
{
  Lisp_Object sym;
  sym = intern (namestring);
  XSET (XSYMBOL (sym)->value, Lisp_Intfwd, address);
}

/* Similar but define a variable whose value is T if address contains 1,
 NIL if address contains 0 */

void
defvar_bool (namestring, address, doc)
     char *namestring;
     int *address;
     char *doc;
{
  Lisp_Object sym;
  sym = intern (namestring);
  XSET (XSYMBOL (sym)->value, Lisp_Boolfwd, address);
}

/* Similar but define a variable whose value is the Lisp Object stored at address. */

void
defvar_lisp (namestring, address, doc)
     char *namestring;
     Lisp_Object *address;
     char *doc;
{
  Lisp_Object sym;
  sym = intern (namestring);
  XSET (XSYMBOL (sym)->value, Lisp_Objfwd, address);
  staticpro (address);
}

/* Similar but don't request gc-marking of the C variable.
   Used when that variable will be gc-marked for some other reason,
   since marking the same slot twice can cause trouble with strings.  */

void
defvar_lisp_nopro (namestring, address, doc)
     char *namestring;
     Lisp_Object *address;
     char *doc;
{
  Lisp_Object sym;
  sym = intern (namestring);
  XSET (XSYMBOL (sym)->value, Lisp_Objfwd, address);
}

#ifndef standalone

/* Similar but define a variable whose value is the Lisp Object stored in
 the current buffer.  address is the address of the slot in the buffer that is current now. */

void
defvar_per_buffer (namestring, address, doc)
     char *namestring;
     Lisp_Object *address;
     char *doc;
{
  Lisp_Object sym;
  int offset;
  extern struct buffer buffer_local_symbols;

  sym = intern (namestring);
  offset = (char *)address - (char *)current_buffer;

  XSET (XSYMBOL (sym)->value, Lisp_Buffer_Objfwd,
        (Lisp_Object *) offset);
  *(Lisp_Object *)(offset + (char *)&buffer_local_symbols) = sym;
  if (*(int *)(offset + (char *)&buffer_local_flags) == 0)
    /* Did a DEFVAR_PER_BUFFER without initializing the corresponding
       slot of buffer_local_flags */
    abort ();
}

#endif /* standalone */
\f
init_lread ()
{
  char *normal;

  /* Compute the default load-path.  */
#ifdef CANNOT_DUMP
  normal = PATH_LOADSEARCH;
  Vload_path = decode_env_path (0, normal);
#else
  if (NILP (Vpurify_flag))
    normal = PATH_LOADSEARCH;
  else
    normal = PATH_DUMPLOADSEARCH;

  /* In a dumped Emacs, we normally have to reset the value of
     Vload_path from PATH_LOADSEARCH, since the value that was dumped
     uses ../lisp, instead of the path of the installed elisp
     libraries.  However, if it appears that Vload_path was changed
     from the default before dumping, don't override that value.  */
  if (initialized)
    {
      Lisp_Object dump_path;

      dump_path = decode_env_path (0, PATH_DUMPLOADSEARCH);
      if (! NILP (Fequal (dump_path, Vload_path)))
        Vload_path = decode_env_path (0, normal);
    }
  else
    Vload_path = decode_env_path (0, normal);
#endif

  /* Warn if dirs in the *standard* path don't exist.  */
  {
    Lisp_Object path_tail;

    for (path_tail = Vload_path;
         !NILP (path_tail);
         path_tail = XCONS (path_tail)->cdr)
      {
        Lisp_Object dirfile;
        dirfile = Fcar (path_tail);
        if (XTYPE (dirfile) == Lisp_String)
          {
            dirfile = Fdirectory_file_name (dirfile);
            if (access (XSTRING (dirfile)->data, 0) < 0)
              printf ("Warning: lisp library (%s) does not exist.\n",
                      XSTRING (Fcar (path_tail))->data);
          }
      }
  }

  /* If the EMACSLOADPATH environment variable is set, use its value.
     This doesn't apply if we're dumping.  */
  if (NILP (Vpurify_flag)
      && egetenv ("EMACSLOADPATH"))
    Vload_path = decode_env_path ("EMACSLOADPATH", normal);

  Vvalues = Qnil;

  load_in_progress = 0;
}

void
syms_of_lread ()
{
  defsubr (&Sread);
  defsubr (&Sread_from_string);
  defsubr (&Sintern);
  defsubr (&Sintern_soft);
  defsubr (&Sload);
  defsubr (&Seval_buffer);
  defsubr (&Seval_region);
  defsubr (&Sread_char);
  defsubr (&Sread_char_exclusive);
#ifdef HAVE_X_WINDOWS
  defsubr (&Sread_event);
#endif /* HAVE_X_WINDOWS */
  defsubr (&Sget_file_char);
  defsubr (&Smapatoms);

  DEFVAR_LISP ("obarray", &Vobarray,
    "Symbol table for use by `intern' and `read'.\n\
It is a vector whose length ought to be prime for best results.\n\
The vector's contents don't make sense if examined from Lisp programs;\n\
to find all the symbols in an obarray, use `mapatoms'.");

  DEFVAR_LISP ("values", &Vvalues,
    "List of values of all expressions which were read, evaluated and printed.\n\
Order is reverse chronological.");

  DEFVAR_LISP ("standard-input", &Vstandard_input,
    "Stream for read to get input from.\n\
See documentation of `read' for possible values.");
  Vstandard_input = Qt;

  DEFVAR_LISP ("load-path", &Vload_path,
    "*List of directories to search for files to load.\n\
Each element is a string (directory name) or nil (try default directory).\n\
Initialized based on EMACSLOADPATH environment variable, if any,\n\
otherwise to default specified in by file `paths.h' when Emacs was built.");

  DEFVAR_BOOL ("load-in-progress", &load_in_progress,
    "Non-nil iff inside of `load'.");

  DEFVAR_LISP ("after-load-alist", &Vafter_load_alist,
    "An alist of expressions to be evalled when particular files are loaded.\n\
Each element looks like (FILENAME FORMS...).\n\
When `load' is run and the file-name argument is FILENAME,\n\
the FORMS in the corresponding element are executed at the end of loading.\n\n\
FILENAME must match exactly!  Normally FILENAME is the name of a library,\n\
with no directory specified, since that is how `load' is normally called.\n\
An error in FORMS does not undo the load,\n\
but does prevent execution of the rest of the FORMS.");
  Vafter_load_alist = Qnil;

  Qstandard_input = intern ("standard-input");
  staticpro (&Qstandard_input);

  Qread_char = intern ("read-char");
  staticpro (&Qread_char);

  Qget_file_char = intern ("get-file-char");
  staticpro (&Qget_file_char);
}