Add #'equalp as a hash test by default; add #'define-hash-table-test, GNU API tests/ChangeLog addition: 2010-04-05 Aidan Kehoe <kehoea@parhasard.net> * automated/hash-table-tests.el: Test the new built-in #'equalp hash table test. Test #'define-hash-table-test. * automated/lisp-tests.el: When asserting that two objects are #'equalp, also assert that their #'equalp-hash is identical. man/ChangeLog addition: 2010-04-03 Aidan Kehoe <kehoea@parhasard.net> * lispref/hash-tables.texi (Introduction to Hash Tables): Document that we now support #'equalp as a hash table test by default, and mention #'define-hash-table-test. (Working With Hash Tables): Document #'define-hash-table-test. src/ChangeLog addition: 2010-04-05 Aidan Kehoe <kehoea@parhasard.net> * elhash.h: * elhash.c (struct Hash_Table_Test, lisp_object_eql_equal) (lisp_object_eql_hash, lisp_object_equal_equal) (lisp_object_equal_hash, lisp_object_equalp_hash) (lisp_object_equalp_equal, lisp_object_general_hash) (lisp_object_general_equal, Feq_hash, Feql_hash, Fequal_hash) (Fequalp_hash, define_hash_table_test, Fdefine_hash_table_test) (init_elhash_once_early, mark_hash_table_tests, string_equalp_hash): * glyphs.c (vars_of_glyphs): Add a new hash table test in C, #'equalp. Make it possible to specify new hash table tests with functions define_hash_table_test, #'define-hash-table-test. Use define_hash_table_test() in glyphs.c. Expose the hash functions (besides that used for #'equal) to Lisp, for people writing functions to be used with #'define-hash-table-test. Call define_hash_table_test() very early in temacs, to create the built-in hash table tests. * ui-gtk.c (emacs_gtk_boxed_hash): * specifier.h (struct specifier_methods): * specifier.c (specifier_hash): * rangetab.c (range_table_entry_hash, range_table_hash): * number.c (bignum_hash, ratio_hash, bigfloat_hash): * marker.c (marker_hash): * lrecord.h (struct lrecord_implementation): * keymap.c (keymap_hash): * gui.c (gui_item_id_hash, gui_item_hash): * glyphs.c (image_instance_hash, glyph_hash): * glyphs-x.c (x_image_instance_hash): * glyphs-msw.c (mswindows_image_instance_hash): * glyphs-gtk.c (gtk_image_instance_hash): * frame-msw.c (mswindows_set_title_from_ibyte): * fontcolor.c (color_instance_hash, font_instance_hash): * fontcolor-x.c (x_color_instance_hash): * fontcolor-tty.c (tty_color_instance_hash): * fontcolor-msw.c (mswindows_color_instance_hash): * fontcolor-gtk.c (gtk_color_instance_hash): * fns.c (bit_vector_hash): * floatfns.c (float_hash): * faces.c (face_hash): * extents.c (extent_hash): * events.c (event_hash): * data.c (weak_list_hash, weak_box_hash): * chartab.c (char_table_entry_hash, char_table_hash): * bytecode.c (compiled_function_hash): * alloc.c (vector_hash): Change the various object hash methods to take a new EQUALP parameter, hashing appropriately for #'equalp if it is true.

--- a/src/fns.c	Mon Apr 05 00:18:49 2010 -0500
+++ b/src/fns.c	Mon Apr 05 13:03:35 2010 +0100
@@ -108,10 +108,49 @@
 		   sizeof (long)));
 }
 
+/* This needs to be algorithmically identical to internal_array_hash in
+   elhash.c when equalp is one, so arrays and bit vectors with the same
+   contents hash the same. It would be possible to enforce this by giving
+   internal_ARRAYLIKE_hash its own file and including it twice, but right
+   now that doesn't seem worth it. */
 static Hashcode
-bit_vector_hash (Lisp_Object obj, int UNUSED (depth))
+internal_bit_vector_equalp_hash (Lisp_Bit_Vector *v)
+{
+  int ii, size = bit_vector_length (v);
+  Hashcode hash = 0;
+
+  if (size <= 5)
+    {
+      for (ii = 0; ii < size; ii++)
+        {
+          hash = HASH2
+            (hash,
+             FLOAT_HASHCODE_FROM_DOUBLE ((double) (bit_vector_bit (v, ii))));
+        }
+      return hash;
+    }
+
+  /* just pick five elements scattered throughout the array.
+     A slightly better approach would be to offset by some
+     noise factor from the points chosen below. */
+  for (ii = 0; ii < 5; ii++)
+    hash = HASH2 (hash,
+                  FLOAT_HASHCODE_FROM_DOUBLE
+                  ((double) (bit_vector_bit (v, ii * size / 5))));
+
+  return hash;
+}
+
+static Hashcode
+bit_vector_hash (Lisp_Object obj, int UNUSED (depth), Boolint equalp)
 {
   Lisp_Bit_Vector *v = XBIT_VECTOR (obj);
+  if (equalp)
+    {
+      return HASH2 (bit_vector_length (v),
+                    internal_bit_vector_equalp_hash (v));
+    }
+
   return HASH2 (bit_vector_length (v),
 		memory_hash (v->bits,
 			     BIT_VECTOR_LONG_STORAGE (bit_vector_length (v)) *