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.

--- a/src/fns.c	Sun Aug 28 10:34:54 2011 +0100
+++ b/src/fns.c	Sun Sep 04 19:51:35 2011 +0100
@@ -59,6 +59,7 @@
 Lisp_Object Qsome, Qevery, Qmaplist, Qmapl, Qmapcon, Qreduce, Qsubstitute;
 Lisp_Object Q_start1, Q_start2, Q_end1, Q_end2, Q_if_, Q_if_not, Q_stable;
 Lisp_Object Q_test_not, Q_count, Qnsubstitute, Qdelete_duplicates, Qmismatch;
+Lisp_Object Q_descend_structures;
 
 Lisp_Object Qintersection, Qset_difference, Qnset_difference;
 Lisp_Object Qnunion, Qnintersection, Qsubsetp, Qcar_less_than_car;
@@ -207,7 +208,7 @@
 /* Various test functions for #'member*, #'assoc* and the other functions
    that take both TEST and KEY arguments.  */
 
-static Boolint
+Boolint
 check_eq_nokey (Lisp_Object UNUSED (test), Lisp_Object UNUSED (key),
 		Lisp_Object item, Lisp_Object elt)
 {
@@ -9303,14 +9304,32 @@
 Any element of TREE which is `eql' to OLD is changed to NEW (via a call to
 `setcar').
 
-See `member*' for the meaning of the keywords.
-
-arguments: (NEW OLD TREE &key (TEST #'eql) (KEY #'identity) TEST-NOT)
+See `member*' for the meaning of the keywords.  The keyword
+:descend-structures, not specified by Common Lisp, allows callers to specify
+that non-cons objects (vectors and range tables, among others) should also
+undergo substitution.
+
+arguments: (NEW OLD TREE &key (TEST #'eql) (KEY #'identity) TEST-NOT DESCEND-STRUCTURES)
 */
        (int nargs, Lisp_Object *args))
 {
-  Lisp_Object result, alist = noseeum_cons (noseeum_cons (args[1], args[0]),
-                                            Qnil);
+  Lisp_Object new_ = args[0], old = args[1], tree = args[2], result, alist;
+  Boolint test_not_unboundp = 1;
+  check_test_func_t check_test = NULL;
+
+  PARSE_KEYWORDS (Fnsubst, nargs, args, 6, (test, if_, test_not, if_not, key,
+                                            descend_structures), NULL);
+  if (!NILP (descend_structures))
+    {
+      check_test = get_check_test_function (old, &test, test_not, if_, if_not,
+                                            key, &test_not_unboundp);
+
+      return nsubst_structures (new_, old, tree, check_test, test_not_unboundp,
+                                test, key);
+
+    }
+
+  alist = noseeum_cons (noseeum_cons (old, new_), Qnil);
   args[1] = alist;
   result = Fnsublis (nargs - 1, args + 1);
   free_cons (XCAR (alist));
@@ -11707,6 +11726,7 @@
   DEFKEYWORD (Q_test_not);
   DEFKEYWORD (Q_count);
   DEFKEYWORD (Q_stable);
+  DEFKEYWORD (Q_descend_structures);
 
   DEFSYMBOL (Qyes_or_no_p);