Implement print-circle, allowing recursive and circular structures to be read. src/ChangeLog addition: 2011-09-04 Aidan Kehoe <kehoea@parhasard.net> * alloc.c: * alloc.c (ALLOC_FROB_BLOCK_LISP_OBJECT_1): * alloc.c (ALLOC_FROB_BLOCK_LISP_OBJECT): * alloc.c (cons_print_preprocess): * alloc.c (vector_print_preprocess): * alloc.c (vector_nsubst_structures_descend): * alloc.c (Fmake_symbol): * alloc.c (UNMARK_symbol): * alloc.c (sweep_symbols): * alloc.c (reinit_alloc_objects_early): * alloc.c (reinit_alloc_early): * bytecode.c: * bytecode.c (compiled_function_print_preprocess): * bytecode.c (compiled_function_nsubst_structures_descend): * bytecode.c (set_compiled_function_arglist): * bytecode.c (set_compiled_function_interactive): * bytecode.c (bytecode_objects_create): * chartab.c: * chartab.c (print_preprocess_mapper): * chartab.c (nsubst_structures_mapper): * chartab.c (char_table_nsubst_structures_descend): * chartab.c (chartab_objects_create): * elhash.c: * elhash.c (nsubst_structures_map_hash_table): * elhash.c (hash_table_nsubst_structures_descend): * elhash.c (print_preprocess_mapper): * elhash.c (hash_table_print_preprocess): * elhash.c (inchash_eq): * elhash.c (hash_table_objects_create): * elhash.c (syms_of_elhash): * elhash.h: * emacs.c (main_1): * fns.c: * fns.c (check_eq_nokey): * fns.c (Fnsubst): * fns.c (syms_of_fns): * lisp.h: * lisp.h (struct Lisp_Symbol): * lisp.h (IN_OBARRAY): * lisp.h (struct): * lisp.h (PRINT_PREPROCESS): * lread.c (read1): * lrecord.h: * lrecord.h (struct lrecord_implementation): * lrecord.h (DEFINE_DUMPABLE_MODULE_LISP_OBJECT): * print.c: * print.c (PRINT_CIRCLE_LIMIT): * print.c (print_continuous_numbering_changed): * print.c (print_prepare): * print.c (print_finish): * print.c (Fprin1_to_string): * print.c (print_cons): * print.c (print_preprocess_inchash_eq): * print.c (print_preprocess): * print.c (print_sort_get_numbers): * print.c (print_sort_compare_ordinals): * print.c (print_gensym_or_circle): * print.c (nsubst_structures_descend): * print.c (nsubst_structures): * print.c (print_internal): * print.c (print_symbol): * print.c (vars_of_print): * rangetab.c: * rangetab.c (range_table_print_preprocess): * rangetab.c (range_table_nsubst_structures_descend): * rangetab.c (rangetab_objects_create): * rangetab.c (syms_of_rangetab): * symbols.c: * symbols.c (symbol_print_preprocess): * symbols.c (Fintern): * symbols.c (Funintern): * symbols.c (reinit_symbol_objects_early): * symbols.c (init_symbols_once_early): * symsinit.h: Implement print-circle, printing circular structures in a readable fashion, and treating them appropriately on read. This is by means of two new object methods, print_preprocess (detecting circularities), and nsubst_structures_descend (replacing placeholders with the read objects). Expose the substitution to Lisp via #'nsubst and its new :descend-structures keyword. Store information as to whether symbols are interned in obarray or not in their header, making checking for keywords and uninterned symbols (and thus printing) cheaper. Default print_gensym to t, as Common Lisp does, and as a more-than-decade old comment suggests. lisp/ChangeLog addition: 2011-09-04 Aidan Kehoe <kehoea@parhasard.net> * bytecomp.el (byte-compile-output-file-form): * bytecomp.el (byte-compile-output-docform): Bind print-circle, print-continuous-numbering in these functions, now those variables are available. * lisp.el (forward-sexp): * lisp.el (backward-sexp): Recognise leading #N= as being part of an expression. tests/ChangeLog addition: 2011-09-04 Aidan Kehoe <kehoea@parhasard.net> * automated/lisp-reader-tests.el: * automated/lisp-tests.el (literal-with-uninterned): * automated/symbol-tests.el (foo): Test print-circle, for printing (mutually-)recursive and circular structures. Bind print-continuous-numbering where appropriate.

/* Primitives for work of the "widget" library.
   Copyright (C) 1997 Free Software Foundation, Inc.

This file is part of XEmacs.

XEmacs 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 3 of the License, or (at your
option) any later version.

XEmacs 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 XEmacs.  If not, see <http://www.gnu.org/licenses/>. */

/* Synched up with: Not in FSF. */

/* In an ideal world, this file would not have been necessary.
   However, elisp function calls being as slow as they are, it turns
   out that some functions in the widget library (wid-edit.el) are the
   bottleneck of Widget operation.  Here is their translation to C,
   for the sole reason of efficiency.  */

#include <config.h>
#include "lisp.h"
#include "buffer.h"


Lisp_Object Qwidget_type;


DEFUN ("widget-plist-member", Fwidget_plist_member, 2, 2, 0, /*
Like `plist-get', but returns the tail of PLIST whose car is PROP.
*/
       (plist, prop))
{
  while (!NILP (plist) && !EQ (Fcar (plist), prop))
    {
      /* Check for QUIT, so a circular plist doesn't lock up the
         editor. */
      QUIT;
      plist = Fcdr (Fcdr (plist));
    }
  return plist;
}

DEFUN ("widget-put", Fwidget_put, 3, 3, 0, /*
In WIDGET set PROPERTY to VALUE.
The value can later be retrieved with `widget-get'.
*/
       (widget, property, value))
{
  CHECK_CONS (widget);
  XCDR (widget) = Fplist_put (XCDR (widget), property, value);
  return widget;
}

DEFUN ("widget-get", Fwidget_get, 2, 2, 0, /*
  In WIDGET, get the value of PROPERTY.
The value could either be specified when the widget was created, or
later with `widget-put'.
*/
       (widget, property))
{
  Lisp_Object value = Qnil;

  while (1)
    {
      Lisp_Object tmp = Fwidget_plist_member (Fcdr (widget), property);
      if (!NILP (tmp))
	{
	  value = Fcar (Fcdr (tmp));
	  break;
	}
      tmp = Fcar (widget);
      if (!NILP (tmp))
	{
	  widget = Fget (tmp, Qwidget_type, Qnil);
	  continue;
	}
      break;
    }
  return value;
}

DEFUN ("widget-apply", Fwidget_apply, 2, MANY, 0, /*
Apply the value of WIDGET's PROPERTY to the widget itself.
ARGS are passed as extra arguments to the function.

arguments: (WIDGET PROPERTY &rest ARGS)
*/
       (int nargs, Lisp_Object *args))
{
  /* This function can GC */
  Lisp_Object newargs[3];
  struct gcpro gcpro1;

  newargs[0] = Fwidget_get (args[0], args[1]);
  newargs[1] = args[0];
  newargs[2] = Flist (nargs - 2, args + 2);
  GCPRO1 (newargs[2]);
  RETURN_UNGCPRO (Fapply (3, newargs));
}

void
syms_of_widget (void)
{
  DEFSYMBOL (Qwidget_type);

  DEFSUBR (Fwidget_plist_member);
  DEFSUBR (Fwidget_put);
  DEFSUBR (Fwidget_get);
  DEFSUBR (Fwidget_apply);
}