Re: hash-table-{to, from}-alist

[Ted Zlatanov]

On Wed, 03 Dec 2008 21:05:54 -0500 Stefan Monnier <address@hidden> wrote: 

>> I took your other suggestions, except I don't pass Qnil parameters to
>> make-hash-table to keep things clean.  I hope this version of the patch
>> is acceptable.

SM> Some nitpicks, see below.
SM> BTW, have you tried to delegate to some Elisp code?

Why at this point?  The C code is written, is there a problem with it?

SM> We like to avoid putting comment markers on their own line.  We like
SM> to terminate our comments like sentences: with a [d]ot followed by 2
SM> spaces.  We like to put the body of the `if' on a separate line.
SM> Comments should be capitalized.

All these are fixed, thanks for pointing them out.

>> +          Lisp_Object ht = Fmake_hash_table (param_count, params);
>> +          Lisp_Object key = Qnil;

SM> We recently decided it was OK to use ANSI C syntax for function headers,
SM> but I don't think ANSI C allows such variable declarations in the middle
SM> of a block.  So we should probably move the delcaration of those 2 vars
SM> higher up, or open up a new block.

Fixed.  Revised patch attached.

Thanks
Ted

? hashprint.patch
Index: lread.c
===================================================================
RCS file: /sources/emacs/emacs/src/lread.c,v
retrieving revision 1.401
diff -u -r1.401 lread.c
--- lread.c     7 Sep 2008 20:41:10 -0000       1.401
+++ lread.c     4 Dec 2008 15:02:39 -0000
@@ -80,6 +80,14 @@
 extern int errno;
 #endif
 
+/* hash table read constants */
+Lisp_Object Qhash_table, Qdata;
+Lisp_Object Qtest, Qsize;
+Lisp_Object Qweakness;
+Lisp_Object Qrehash_size;
+Lisp_Object Qrehash_threshold;
+extern Lisp_Object QCtest, QCsize, QCrehash_size, QCrehash_threshold, 
QCweakness;
+
 Lisp_Object Qread_char, Qget_file_char, Qstandard_input, Qcurrent_load_list;
 Lisp_Object Qvariable_documentation, Vvalues, Vstandard_input, 
Vafter_load_alist;
 Lisp_Object Qascii_character, Qload, Qload_file_name;
@@ -2341,6 +2349,78 @@
 
     case '#':
       c = READCHAR;
+      if (c == 's')
+       {
+         c = READCHAR;
+         if (c == '(')
+           {
+             /* Accept extended format for hashtables (extensible to
+                other types), e.g.
+                #s(hash-table size 2 test equal data (k1 v1 k2 v2)) */
+             Lisp_Object tmp = read_list (0, readcharfun);
+             Lisp_Object head = CAR_SAFE (tmp);
+             Lisp_Object data = Qnil;
+             Lisp_Object val = Qnil;
+             /* The size is 2 * number of allowed keywords to
+                make-hash-table. */
+             Lisp_Object params[10]; 
+             Lisp_Object ht;
+             Lisp_Object key = Qnil;
+             int param_count = 0;
+             int i;
+             
+             if (!EQ (head, Qhash_table))
+               error ("Invalid extended read marker at head of #s list "
+                      "(only hash-table allowed)");
+             
+             tmp = CDR_SAFE (tmp);
+
+             /* This is repetitive but fast and simple. */
+             params[param_count] = QCsize;
+             params[param_count+1] = Fplist_get (tmp, Qsize);
+             if (!NILP (params[param_count+1]))
+               param_count+=2;
+
+             params[param_count] = QCtest;
+             params[param_count+1] = Fplist_get (tmp, Qtest);
+             if (!NILP (params[param_count+1]))
+               param_count+=2;
+
+             params[param_count] = QCweakness;
+             params[param_count+1] = Fplist_get (tmp, Qweakness);
+             if (!NILP (params[param_count+1]))
+               param_count+=2;
+
+             params[param_count] = QCrehash_size;
+             params[param_count+1] = Fplist_get (tmp, Qrehash_size);
+             if (!NILP (params[param_count+1]))
+               param_count+=2;
+
+             params[param_count] = QCrehash_threshold;
+             params[param_count+1] = Fplist_get (tmp, Qrehash_threshold);
+             if (!NILP (params[param_count+1]))
+               param_count+=2;
+
+             /* This is the hashtable data. */
+             data = Fplist_get (tmp, Qdata);
+
+             /* Now use params to make a new hashtable and fill it. */
+             ht = Fmake_hash_table (param_count, params);
+             
+             while (CONSP (data))
+               {
+                 key = XCAR (data);
+                 data = XCDR (data);
+                 if (!CONSP (data))
+                   error ("Odd number of elements in hashtable data");
+                 val = XCAR (data);
+                 data = XCDR (data);
+                 Fputhash (key, val, ht);
+               }
+             
+             return ht;
+           }
+       }
       if (c == '^')
        {
          c = READCHAR;
@@ -4432,6 +4512,21 @@
 
   Vloads_in_progress = Qnil;
   staticpro (&Vloads_in_progress);
+
+  Qhash_table = intern ("hash-table");
+  staticpro (&Qhash_table);
+  Qdata = intern ("data");
+  staticpro (&Qdata);
+  Qtest = intern ("test");
+  staticpro (&Qtest);
+  Qsize = intern ("size");
+  staticpro (&Qsize);
+  Qweakness = intern ("weakness");
+  staticpro (&Qweakness);
+  Qrehash_size = intern ("rehash-size");
+  staticpro (&Qrehash_size);
+  Qrehash_threshold = intern ("rehash-threshold");
+  staticpro (&Qrehash_threshold);
 }
 
 /* arch-tag: a0d02733-0f96-4844-a659-9fd53c4f414d
Index: print.c
===================================================================
RCS file: /sources/emacs/emacs/src/print.c,v
retrieving revision 1.253
diff -u -r1.253 print.c
--- print.c     31 Jul 2008 05:33:53 -0000      1.253
+++ print.c     4 Dec 2008 15:02:39 -0000
@@ -1341,6 +1341,7 @@
  loop:
   if (STRINGP (obj) || CONSP (obj) || VECTORP (obj)
       || COMPILEDP (obj) || CHAR_TABLE_P (obj) || SUB_CHAR_TABLE_P (obj)
+      || HASH_TABLE_P (obj)
       || (! NILP (Vprint_gensym)
          && SYMBOLP (obj)
          && !SYMBOL_INTERNED_P (obj)))
@@ -1536,6 +1537,7 @@
   /* Detect circularities and truncate them.  */
   if (STRINGP (obj) || CONSP (obj) || VECTORP (obj)
       || COMPILEDP (obj) || CHAR_TABLE_P (obj) || SUB_CHAR_TABLE_P (obj)
+      || HASH_TABLE_P (obj)
       || (! NILP (Vprint_gensym)
          && SYMBOLP (obj)
          && !SYMBOL_INTERNED_P (obj)))
@@ -2036,6 +2038,7 @@
       else if (HASH_TABLE_P (obj))
        {
          struct Lisp_Hash_Table *h = XHASH_TABLE (obj);
+#if 0
          strout ("#<hash-table", -1, -1, printcharfun, 0);
          if (SYMBOLP (h->test))
            {
@@ -2052,6 +2055,67 @@
          sprintf (buf, " 0x%lx", (unsigned long) h);
          strout (buf, -1, -1, printcharfun, 0);
          PRINTCHAR ('>');
+#endif
+         /* Implement a readable output, e.g.:
+           #s(hash-table size 2 test equal data (k1 v1 k2 v2)) */
+         /* Always print the size. */
+         sprintf (buf, "#s(hash-table size %ld",
+                  (long) XVECTOR (h->next)->size);
+         strout (buf, -1, -1, printcharfun, 0);
+
+         if (!NILP (h->test))
+           {
+             strout (" test ", -1, -1, printcharfun, 0);
+             print_object (h->test, printcharfun, 0);
+           }
+
+         if (!NILP (h->weak))
+           {
+             strout (" weakness ", -1, -1, printcharfun, 0);
+             print_object (h->weak, printcharfun, 0);
+           }
+
+         if (!NILP (h->rehash_size))
+           {
+             strout (" rehash-size ", -1, -1, printcharfun, 0);
+             print_object (h->rehash_size, printcharfun, 0);
+           }
+
+         if (!NILP (h->rehash_threshold))
+           {
+             strout (" rehash-threshold ", -1, -1, printcharfun, 0);
+             print_object (h->rehash_threshold, printcharfun, 0);
+           }
+
+         strout (" data ", -1, -1, printcharfun, 0);
+
+         /* Print the data here as a plist. */
+         int i;
+
+         int real_size = HASH_TABLE_SIZE (h);
+         int size = real_size;
+
+         /* Don't print more elements than the specified maximum.  */
+         if (NATNUMP (Vprint_length)
+             && XFASTINT (Vprint_length) < size)
+           size = XFASTINT (Vprint_length);
+         
+         PRINTCHAR ('(');
+         for (i = 0; i < size; i++)
+           if (!NILP (HASH_HASH (h, i)))
+             {
+               if (i) PRINTCHAR (' ');
+               print_object (HASH_KEY (h, i), printcharfun, 0);
+               PRINTCHAR (' ');
+               print_object (HASH_VALUE (h, i), printcharfun, 0);
+             }
+
+         if (size < real_size)
+           strout (" ...", 4, 4, printcharfun, 0);
+
+         PRINTCHAR (')');
+         PRINTCHAR (')');
+
        }
       else if (BUFFERP (obj))
        {