gdb/cp-valprint.c

   1 /* Support for printing C++ values for GDB, the GNU debugger.
   2    Copyright 1986, 1988, 1989, 1991 Free Software Foundation, Inc.
   3
   4 This file is part of GDB.
   5
   6 This program is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 #include "defs.h"
  21 #include "obstack.h"
  22 #include "symtab.h"
  23 #include "gdbtypes.h"
  24 #include "expression.h"
  25 #include "value.h"
  26 #include "command.h"
  27 #include "gdbcmd.h"
  28
  29 int vtblprint;                  /* Controls printing of vtbl's */
  30 int objectprint;                /* Controls looking up an object's derived type
  31                                    using what we find in its vtables.  */
  32 struct obstack dont_print_obstack;
  33
  34 static void
  35 cplus_print_value PARAMS ((struct type *, char *, FILE *, int, int,
  36                            enum val_prettyprint, struct type **));
  37
  38 /* BEGIN-FIXME:  Hooks into typeprint.c, find a better home for prototypes. */
  39
  40 extern void
  41 c_type_print_base PARAMS ((struct type *, FILE *, int, int));
  42
  43 extern void
  44 c_type_print_varspec_prefix PARAMS ((struct type *, FILE *, int, int));
  45
  46 extern void
  47 cp_type_print_method_args PARAMS ((struct type **, char *, char *, int,
  48                                    FILE *));
  49
  50 extern struct obstack dont_print_obstack;
  51
  52 /* END-FIXME */
  53
  54
  55 /* BEGIN-FIXME:  Hooks into c-valprint.c */
  56
  57 extern int
  58 c_val_print PARAMS ((struct type *, char *, CORE_ADDR, FILE *, int, int, int,
  59                      enum val_prettyprint));
  60 /* END-FIXME */
  61
  62
  63 /* Return truth value for assertion that TYPE is of the type
  64    "pointer to virtual function".  */
  65
  66 int
  67 cp_is_vtbl_ptr_type(type)
  68      struct type *type;
  69 {
  70   char *typename = type_name_no_tag (type);
  71   static const char vtbl_ptr_name[] =
  72     { CPLUS_MARKER,'v','t','b','l','_','p','t','r','_','t','y','p','e', 0 };
  73
  74   return (typename != NULL && !strcmp(typename, vtbl_ptr_name));
  75 }
  76
  77 /* Return truth value for the assertion that TYPE is of the type
  78    "pointer to virtual function table".  */
  79
  80 int
  81 cp_is_vtbl_member(type)
  82      struct type *type;
  83 {
  84   if (TYPE_CODE (type) == TYPE_CODE_PTR)
  85     type = TYPE_TARGET_TYPE (type);
  86   else
  87     return 0;
  88
  89   if (TYPE_CODE (type) == TYPE_CODE_ARRAY
  90       && TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_STRUCT)
  91     /* Virtual functions tables are full of pointers to virtual functions.  */
  92     return cp_is_vtbl_ptr_type (TYPE_TARGET_TYPE (type));
  93   return 0;
  94 }
  95
  96 /* Mutually recursive subroutines of cplus_print_value and c_val_print to
  97    print out a structure's fields: cp_print_value_fields and cplus_print_value.
  98
  99    TYPE, VALADDR, STREAM, RECURSE, and PRETTY have the
 100    same meanings as in cplus_print_value and c_val_print.
 101
 102    DONT_PRINT is an array of baseclass types that we
 103    should not print, or zero if called from top level.  */
 104
 105 void
 106 cp_print_value_fields (type, valaddr, stream, format, recurse, pretty,
 107                        dont_print)
 108      struct type *type;
 109      char *valaddr;
 110      FILE *stream;
 111      int format;
 112      int recurse;
 113      enum val_prettyprint pretty;
 114      struct type **dont_print;
 115 {
 116   int i, len, n_baseclasses;
 117
 118   check_stub_type (type);
 119
 120   fprintf_filtered (stream, "{");
 121   len = TYPE_NFIELDS (type);
 122   n_baseclasses = TYPE_N_BASECLASSES (type);
 123
 124   /* Print out baseclasses such that we don't print
 125      duplicates of virtual baseclasses.  */
 126   if (n_baseclasses > 0)
 127     cplus_print_value (type, valaddr, stream, format, recurse+1, pretty,
 128                        dont_print);
 129
 130   if (!len && n_baseclasses == 1)
 131     fprintf_filtered (stream, "<No data fields>");
 132   else
 133     {
 134       extern int inspect_it;
 135       int fields_seen = 0;
 136
 137       for (i = n_baseclasses; i < len; i++)
 138         {
 139           /* Check if static field */
 140           if (TYPE_FIELD_STATIC (type, i))
 141             continue;
 142           if (fields_seen)
 143             fprintf_filtered (stream, ", ");
 144           else if (n_baseclasses > 0)
 145             {
 146               if (pretty)
 147                 {
 148                   fprintf_filtered (stream, "\n");
 149                   print_spaces_filtered (2 + 2 * recurse, stream);
 150                   fputs_filtered ("members of ", stream);
 151                   fputs_filtered (type_name_no_tag (type), stream);
 152                   fputs_filtered (": ", stream);
 153                 }
 154             }
 155           fields_seen = 1;
 156
 157           if (pretty)
 158             {
 159               fprintf_filtered (stream, "\n");
 160               print_spaces_filtered (2 + 2 * recurse, stream);
 161             }
 162           else
 163             {
 164               wrap_here (n_spaces (2 + 2 * recurse));
 165             }
 166           if (inspect_it)
 167             {
 168               if (TYPE_CODE (TYPE_FIELD_TYPE (type, i)) == TYPE_CODE_PTR)
 169                 fputs_filtered ("\"( ptr \"", stream);
 170               else
 171                 fputs_filtered ("\"( nodef \"", stream);
 172               fprint_symbol (stream, TYPE_FIELD_NAME (type, i));
 173               fputs_filtered ("\" \"", stream);
 174               fprint_symbol (stream, TYPE_FIELD_NAME (type, i));
 175               fputs_filtered ("\") \"", stream);
 176             }
 177           else
 178             {
 179               fprint_symbol (stream, TYPE_FIELD_NAME (type, i));
 180               fputs_filtered (" = ", stream);
 181             }
 182           if (TYPE_FIELD_PACKED (type, i))
 183             {
 184               value v;
 185
 186               /* Bitfields require special handling, especially due to byte
 187                  order problems.  */
 188               v = value_from_longest (TYPE_FIELD_TYPE (type, i),
 189                                    unpack_field_as_long (type, valaddr, i));
 190
 191               c_val_print (TYPE_FIELD_TYPE (type, i), VALUE_CONTENTS (v), 0,
 192                            stream, format, 0, recurse + 1, pretty);
 193             }
 194           else
 195             {
 196               c_val_print (TYPE_FIELD_TYPE (type, i),
 197                            valaddr + TYPE_FIELD_BITPOS (type, i) / 8,
 198                            0, stream, format, 0, recurse + 1, pretty);
 199             }
 200         }
 201       if (pretty)
 202         {
 203           fprintf_filtered (stream, "\n");
 204           print_spaces_filtered (2 * recurse, stream);
 205         }
 206     }
 207   fprintf_filtered (stream, "}");
 208 }
 209
 210 /* Special val_print routine to avoid printing multiple copies of virtual
 211    baseclasses.  */
 212
 213 static void
 214 cplus_print_value (type, valaddr, stream, format, recurse, pretty, dont_print)
 215      struct type *type;
 216      char *valaddr;
 217      FILE *stream;
 218      int format;
 219      int recurse;
 220      enum val_prettyprint pretty;
 221      struct type **dont_print;
 222 {
 223   struct obstack tmp_obstack;
 224   struct type **last_dont_print
 225     = (struct type **)obstack_next_free (&dont_print_obstack);
 226   int i, n_baseclasses = TYPE_N_BASECLASSES (type);
 227
 228   if (dont_print == 0)
 229     {
 230       /* If we're at top level, carve out a completely fresh
 231          chunk of the obstack and use that until this particular
 232          invocation returns.  */
 233       tmp_obstack = dont_print_obstack;
 234       /* Bump up the high-water mark.  Now alpha is omega.  */
 235       obstack_finish (&dont_print_obstack);
 236     }
 237
 238   for (i = 0; i < n_baseclasses; i++)
 239     {
 240       char *baddr;
 241       int err;
 242
 243       if (BASETYPE_VIA_VIRTUAL (type, i))
 244         {
 245           struct type **first_dont_print
 246             = (struct type **)obstack_base (&dont_print_obstack);
 247
 248           int j = (struct type **)obstack_next_free (&dont_print_obstack)
 249             - first_dont_print;
 250
 251           while (--j >= 0)
 252             if (TYPE_BASECLASS (type, i) == first_dont_print[j])
 253               goto flush_it;
 254
 255           obstack_ptr_grow (&dont_print_obstack, TYPE_BASECLASS (type, i));
 256         }
 257
 258       /* Fix to use baseclass_offset instead. FIXME */
 259       baddr = baseclass_addr (type, i, valaddr, 0, &err);
 260       if (err == 0 && baddr == 0)
 261         error ("could not find virtual baseclass `%s'\n",
 262                type_name_no_tag (TYPE_BASECLASS (type, i)));
 263
 264       if (pretty)
 265         {
 266           fprintf_filtered (stream, "\n");
 267           print_spaces_filtered (2 * recurse, stream);
 268         }
 269       fputs_filtered ("<", stream);
 270       fputs_filtered (type_name_no_tag (TYPE_BASECLASS (type, i)), stream);
 271       fputs_filtered ("> = ", stream);
 272       if (err != 0)
 273         fprintf_filtered (stream, "<invalid address 0x%x>", baddr);
 274       else
 275         cp_print_value_fields (TYPE_BASECLASS (type, i), baddr, stream, format,
 276                                recurse, pretty,
 277                                (struct type **) obstack_base (&dont_print_obstack));
 278       fputs_filtered (", ", stream);
 279
 280     flush_it:
 281       ;
 282     }
 283
 284   if (dont_print == 0)
 285     {
 286       /* Free the space used to deal with the printing
 287          of this type from top level.  */
 288       obstack_free (&dont_print_obstack, last_dont_print);
 289       /* Reset watermark so that we can continue protecting
 290          ourselves from whatever we were protecting ourselves.  */
 291       dont_print_obstack = tmp_obstack;
 292     }
 293 }
 294
 295 void
 296 cp_print_class_member (valaddr, domain, stream, prefix)
 297      char *valaddr;
 298      struct type *domain;
 299      FILE *stream;
 300      char *prefix;
 301 {
 302
 303   /* VAL is a byte offset into the structure type DOMAIN.
 304      Find the name of the field for that offset and
 305      print it.  */
 306   int extra = 0;
 307   int bits = 0;
 308   register unsigned int i;
 309   unsigned len = TYPE_NFIELDS (domain);
 310   /* @@ Make VAL into bit offset */
 311   LONGEST val = unpack_long (builtin_type_int, valaddr) << 3;
 312   for (i = TYPE_N_BASECLASSES (domain); i < len; i++)
 313     {
 314       int bitpos = TYPE_FIELD_BITPOS (domain, i);
 315       QUIT;
 316       if (val == bitpos)
 317         break;
 318       if (val < bitpos && i != 0)
 319         {
 320           /* Somehow pointing into a field.  */
 321           i -= 1;
 322           extra = (val - TYPE_FIELD_BITPOS (domain, i));
 323           if (extra & 0x7)
 324             bits = 1;
 325           else
 326             extra >>= 3;
 327           break;
 328         }
 329     }
 330   if (i < len)
 331     {
 332       char *name;
 333       fprintf_filtered (stream, prefix);
 334       name = type_name_no_tag (domain);
 335       if (name)
 336         fputs_filtered (name, stream);
 337       else
 338         c_type_print_base (domain, stream, 0, 0);
 339       fprintf_filtered (stream, "::");
 340       fputs_filtered (TYPE_FIELD_NAME (domain, i), stream);
 341       if (extra)
 342         fprintf_filtered (stream, " + %d bytes", extra);
 343       if (bits)
 344         fprintf_filtered (stream, " (offset in bits)");
 345     }
 346   else
 347     fprintf_filtered (stream, "%d", val >> 3);
 348 }
 349
 350 void
 351 _initialize_cp_valprint ()
 352 {
 353   add_show_from_set
 354     (add_set_cmd ("vtbl", class_support, var_boolean, (char *)&vtblprint,
 355                   "Set printing of C++ virtual function tables.",
 356                   &setprintlist),
 357      &showprintlist);
 358
 359   add_show_from_set
 360     (add_set_cmd ("object", class_support, var_boolean, (char *)&objectprint,
 361           "Set printing of object's derived type based on vtable info.",
 362                   &setprintlist),
 363      &showprintlist);
 364
 365   /* Give people the defaults which they are used to.  */
 366   objectprint = 0;
 367   vtblprint = 0;
 368   obstack_begin (&dont_print_obstack, 32 * sizeof (struct type *));
 369 }