struct.c

   1 /**********************************************************************
   2
   3   struct.c -
   4
   5   $Author$
   6   created at: Tue Mar 22 18:44:30 JST 1995
   7
   8   Copyright (C) 1993-2007 Yukihiro Matsumoto
   9
  10 **********************************************************************/
  11
  12 #include "ruby/ruby.h"
  13
  14 VALUE rb_cStruct;
  15
  16 static VALUE struct_alloc(VALUE);
  17
  18 VALUE
  19 rb_struct_iv_get(VALUE c, const char *name)
  20 {
  21     ID id;
  22
  23     id = rb_intern(name);
  24     for (;;) {
  25         if (rb_ivar_defined(c, id))
  26             return rb_ivar_get(c, id);
  27         c = RCLASS_SUPER(c);
  28         if (c == 0 || c == rb_cStruct)
  29             return Qnil;
  30     }
  31 }
  32
  33 VALUE
  34 rb_struct_s_members(VALUE klass)
  35 {
  36     VALUE members = rb_struct_iv_get(klass, "__members__");
  37
  38     if (NIL_P(members)) {
  39         rb_raise(rb_eTypeError, "uninitialized struct");
  40     }
  41     if (TYPE(members) != T_ARRAY) {
  42         rb_raise(rb_eTypeError, "corrupted struct");
  43     }
  44     return members;
  45 }
  46
  47 VALUE
  48 rb_struct_members(VALUE s)
  49 {
  50     VALUE members = rb_struct_s_members(rb_obj_class(s));
  51
  52     if (RSTRUCT_LEN(s) != RARRAY_LEN(members)) {
  53         rb_raise(rb_eTypeError, "struct size differs (%ld required %ld given)",
  54                  RARRAY_LEN(members), RSTRUCT_LEN(s));
  55     }
  56     return members;
  57 }
  58
  59 static VALUE
  60 rb_struct_s_members_m(VALUE klass)
  61 {
  62     VALUE members, ary;
  63     VALUE *p, *pend;
  64
  65     members = rb_struct_s_members(klass);
  66     ary = rb_ary_new2(RARRAY_LEN(members));
  67     p = RARRAY_PTR(members); pend = p + RARRAY_LEN(members);
  68     while (p < pend) {
  69         rb_ary_push(ary, *p);
  70         p++;
  71     }
  72
  73     return ary;
  74 }
  75
  76 /*
  77  *  call-seq:
  78  *     struct.members    => array
  79  *
  80  *  Returns an array of strings representing the names of the instance
  81  *  variables.
  82  *
  83  *     Customer = Struct.new(:name, :address, :zip)
  84  *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
  85  *     joe.members   #=> [:name, :address, :zip]
  86  */
  87
  88 static VALUE
  89 rb_struct_members_m(VALUE obj)
  90 {
  91     return rb_struct_s_members_m(rb_obj_class(obj));
  92 }
  93
  94 VALUE
  95 rb_struct_getmember(VALUE obj, ID id)
  96 {
  97     VALUE members, slot;
  98     long i;
  99
 100     members = rb_struct_members(obj);
 101     slot = ID2SYM(id);
 102     for (i=0; i<RARRAY_LEN(members); i++) {
 103         if (RARRAY_PTR(members)[i] == slot) {
 104             return RSTRUCT_PTR(obj)[i];
 105         }
 106     }
 107     rb_name_error(id, "%s is not struct member", rb_id2name(id));
 108     return Qnil;                /* not reached */
 109 }
 110
 111 static VALUE
 112 rb_struct_ref(VALUE obj)
 113 {
 114     return rb_struct_getmember(obj, rb_frame_this_func());
 115 }
 116
 117 static VALUE rb_struct_ref0(VALUE obj) {return RSTRUCT_PTR(obj)[0];}
 118 static VALUE rb_struct_ref1(VALUE obj) {return RSTRUCT_PTR(obj)[1];}
 119 static VALUE rb_struct_ref2(VALUE obj) {return RSTRUCT_PTR(obj)[2];}
 120 static VALUE rb_struct_ref3(VALUE obj) {return RSTRUCT_PTR(obj)[3];}
 121 static VALUE rb_struct_ref4(VALUE obj) {return RSTRUCT_PTR(obj)[4];}
 122 static VALUE rb_struct_ref5(VALUE obj) {return RSTRUCT_PTR(obj)[5];}
 123 static VALUE rb_struct_ref6(VALUE obj) {return RSTRUCT_PTR(obj)[6];}
 124 static VALUE rb_struct_ref7(VALUE obj) {return RSTRUCT_PTR(obj)[7];}
 125 static VALUE rb_struct_ref8(VALUE obj) {return RSTRUCT_PTR(obj)[8];}
 126 static VALUE rb_struct_ref9(VALUE obj) {return RSTRUCT_PTR(obj)[9];}
 127
 128 #define N_REF_FUNC (sizeof(ref_func) / sizeof(ref_func[0]))
 129
 130 static VALUE (*const ref_func[])(VALUE) = {
 131     rb_struct_ref0,
 132     rb_struct_ref1,
 133     rb_struct_ref2,
 134     rb_struct_ref3,
 135     rb_struct_ref4,
 136     rb_struct_ref5,
 137     rb_struct_ref6,
 138     rb_struct_ref7,
 139     rb_struct_ref8,
 140     rb_struct_ref9,
 141 };
 142
 143 static void
 144 rb_struct_modify(VALUE s)
 145 {
 146     if (OBJ_FROZEN(s)) rb_error_frozen("Struct");
 147     if (!OBJ_UNTRUSTED(s) && rb_safe_level() >= 4)
 148        rb_raise(rb_eSecurityError, "Insecure: can't modify Struct");
 149 }
 150
 151 static VALUE
 152 rb_struct_set(VALUE obj, VALUE val)
 153 {
 154     VALUE members, slot;
 155     long i;
 156
 157     members = rb_struct_members(obj);
 158     rb_struct_modify(obj);
 159     for (i=0; i<RARRAY_LEN(members); i++) {
 160         slot = RARRAY_PTR(members)[i];
 161         if (rb_id_attrset(SYM2ID(slot)) == rb_frame_this_func()) {
 162             return RSTRUCT_PTR(obj)[i] = val;
 163         }
 164     }
 165     rb_name_error(rb_frame_this_func(), "`%s' is not a struct member",
 166                   rb_id2name(rb_frame_this_func()));
 167     return Qnil;                /* not reached */
 168 }
 169
 170 static VALUE
 171 make_struct(VALUE name, VALUE members, VALUE klass)
 172 {
 173     VALUE nstr;
 174     ID id;
 175     long i;
 176
 177     OBJ_FREEZE(members);
 178     if (NIL_P(name)) {
 179         nstr = rb_class_new(klass);
 180         rb_make_metaclass(nstr, RBASIC(klass)->klass);
 181         rb_class_inherited(klass, nstr);
 182     }
 183     else {
 184         /* old style: should we warn? */
 185         name = rb_str_to_str(name);
 186         id = rb_to_id(name);
 187         if (!rb_is_const_id(id)) {
 188             rb_name_error(id, "identifier %s needs to be constant", StringValuePtr(name));
 189         }
 190         if (rb_const_defined_at(klass, id)) {
 191             rb_warn("redefining constant Struct::%s", StringValuePtr(name));
 192             rb_mod_remove_const(klass, ID2SYM(id));
 193         }
 194         nstr = rb_define_class_under(klass, rb_id2name(id), klass);
 195     }
 196     rb_iv_set(nstr, "__members__", members);
 197
 198     rb_define_alloc_func(nstr, struct_alloc);
 199     rb_define_singleton_method(nstr, "new", rb_class_new_instance, -1);
 200     rb_define_singleton_method(nstr, "[]", rb_class_new_instance, -1);
 201     rb_define_singleton_method(nstr, "members", rb_struct_s_members_m, 0);
 202     for (i=0; i< RARRAY_LEN(members); i++) {
 203         ID id = SYM2ID(RARRAY_PTR(members)[i]);
 204         if (rb_is_local_id(id) || rb_is_const_id(id)) {
 205             if (i < N_REF_FUNC) {
 206                 rb_define_method_id(nstr, id, ref_func[i], 0);
 207             }
 208             else {
 209                 rb_define_method_id(nstr, id, rb_struct_ref, 0);
 210             }
 211             rb_define_method_id(nstr, rb_id_attrset(id), rb_struct_set, 1);
 212         }
 213     }
 214
 215     return nstr;
 216 }
 217
 218 VALUE
 219 rb_struct_alloc_noinit(VALUE klass)
 220 {
 221     return struct_alloc(klass);
 222 }
 223
 224 VALUE
 225 rb_struct_define_without_accessor(const char *class_name, VALUE super, rb_alloc_func_t alloc, ...)
 226 {
 227     VALUE klass;
 228     va_list ar;
 229     VALUE members;
 230     long i;
 231     char *name;
 232
 233     members = rb_ary_new2(0);
 234     va_start(ar, alloc);
 235     i = 0;
 236     while ((name = va_arg(ar, char*)) != NULL) {
 237         rb_ary_push(members, ID2SYM(rb_intern(name)));
 238     }
 239     va_end(ar);
 240     OBJ_FREEZE(members);
 241
 242     if (class_name) {
 243         klass = rb_define_class(class_name, super);
 244     }
 245     else {
 246         klass = rb_class_new(super);
 247         rb_make_metaclass(klass, RBASIC(super)->klass);
 248         rb_class_inherited(super, klass);
 249     }
 250
 251     rb_iv_set(klass, "__members__", members);
 252
 253     if (alloc)
 254         rb_define_alloc_func(klass, alloc);
 255     else
 256         rb_define_alloc_func(klass, struct_alloc);
 257
 258     return klass;
 259 }
 260
 261 VALUE
 262 rb_struct_define(const char *name, ...)
 263 {
 264     va_list ar;
 265     VALUE nm, ary;
 266     char *mem;
 267
 268     if (!name) nm = Qnil;
 269     else nm = rb_str_new2(name);
 270     ary = rb_ary_new();
 271
 272     va_start(ar, name);
 273     while ((mem = va_arg(ar, char*)) != 0) {
 274         ID slot = rb_intern(mem);
 275         rb_ary_push(ary, ID2SYM(slot));
 276     }
 277     va_end(ar);
 278
 279     return make_struct(nm, ary, rb_cStruct);
 280 }
 281
 282 /*
 283  *  call-seq:
 284  *     Struct.new( [aString] [, aSym]+> )    => StructClass
 285  *     StructClass.new(arg, ...)             => obj
 286  *     StructClass[arg, ...]                 => obj
 287  *
 288  *  Creates a new class, named by <i>aString</i>, containing accessor
 289  *  methods for the given symbols. If the name <i>aString</i> is
 290  *  omitted, an anonymous structure class will be created. Otherwise,
 291  *  the name of this struct will appear as a constant in class
 292  *  <code>Struct</code>, so it must be unique for all
 293  *  <code>Struct</code>s in the system and should start with a capital
 294  *  letter. Assigning a structure class to a constant effectively gives
 295  *  the class the name of the constant.
 296  *
 297  *  <code>Struct::new</code> returns a new <code>Class</code> object,
 298  *  which can then be used to create specific instances of the new
 299  *  structure. The number of actual parameters must be
 300  *  less than or equal to the number of attributes defined for this
 301  *  class; unset parameters default to \nil{}.  Passing too many
 302  *  parameters will raise an \E{ArgumentError}.
 303  *
 304  *  The remaining methods listed in this section (class and instance)
 305  *  are defined for this generated class.
 306  *
 307  *     # Create a structure with a name in Struct
 308  *     Struct.new("Customer", :name, :address)    #=> Struct::Customer
 309  *     Struct::Customer.new("Dave", "123 Main")   #=> #<struct Struct::Customer name="Dave", address="123 Main">
 310  *
 311  *     # Create a structure named by its constant
 312  *     Customer = Struct.new(:name, :address)     #=> Customer
 313  *     Customer.new("Dave", "123 Main")           #=> #<struct Customer name="Dave", address="123 Main">
 314  */
 315
 316 static VALUE
 317 rb_struct_s_def(int argc, VALUE *argv, VALUE klass)
 318 {
 319     VALUE name, rest;
 320     long i;
 321     VALUE st;
 322     ID id;
 323
 324     rb_scan_args(argc, argv, "1*", &name, &rest);
 325     if (!NIL_P(name) && SYMBOL_P(name)) {
 326         rb_ary_unshift(rest, name);
 327         name = Qnil;
 328     }
 329     for (i=0; i<RARRAY_LEN(rest); i++) {
 330         id = rb_to_id(RARRAY_PTR(rest)[i]);
 331         RARRAY_PTR(rest)[i] = ID2SYM(id);
 332     }
 333     st = make_struct(name, rest, klass);
 334     if (rb_block_given_p()) {
 335         rb_mod_module_eval(0, 0, st);
 336     }
 337
 338     return st;
 339 }
 340
 341 static size_t
 342 num_members(VALUE klass)
 343 {
 344     VALUE members;
 345     members = rb_struct_iv_get(klass, "__members__");
 346     if (TYPE(members) != T_ARRAY) {
 347         rb_raise(rb_eTypeError, "broken members");
 348     }
 349     return RARRAY_LEN(members);
 350 }
 351
 352 /*
 353  */
 354
 355 VALUE
 356 rb_struct_initialize(VALUE self, VALUE values)
 357 {
 358     VALUE klass = rb_obj_class(self);
 359     long n;
 360
 361     rb_struct_modify(self);
 362     n = num_members(klass);
 363     if (n < RARRAY_LEN(values)) {
 364         rb_raise(rb_eArgError, "struct size differs");
 365     }
 366     MEMCPY(RSTRUCT_PTR(self), RARRAY_PTR(values), VALUE, RARRAY_LEN(values));
 367     if (n > RARRAY_LEN(values)) {
 368         rb_mem_clear(RSTRUCT_PTR(self)+RARRAY_LEN(values),
 369                      n-RARRAY_LEN(values));
 370     }
 371     return Qnil;
 372 }
 373
 374 static VALUE
 375 struct_alloc(VALUE klass)
 376 {
 377     long n;
 378     NEWOBJ(st, struct RStruct);
 379     OBJSETUP(st, klass, T_STRUCT);
 380
 381     n = num_members(klass);
 382
 383     if (0 < n && n <= RSTRUCT_EMBED_LEN_MAX) {
 384         RBASIC(st)->flags &= ~RSTRUCT_EMBED_LEN_MASK;
 385         RBASIC(st)->flags |= n << RSTRUCT_EMBED_LEN_SHIFT;
 386         rb_mem_clear(st->as.ary, n);
 387     }
 388     else {
 389         st->as.heap.ptr = ALLOC_N(VALUE, n);
 390         rb_mem_clear(st->as.heap.ptr, n);
 391         st->as.heap.len = n;
 392     }
 393
 394     return (VALUE)st;
 395 }
 396
 397 VALUE
 398 rb_struct_alloc(VALUE klass, VALUE values)
 399 {
 400     return rb_class_new_instance(RARRAY_LEN(values), RARRAY_PTR(values), klass);
 401 }
 402
 403 VALUE
 404 rb_struct_new(VALUE klass, ...)
 405 {
 406     VALUE *mem;
 407     long size, i;
 408     va_list args;
 409
 410     size = num_members(klass);
 411     mem = ALLOCA_N(VALUE, size);
 412     va_start(args, klass);
 413     for (i=0; i<size; i++) {
 414         mem[i] = va_arg(args, VALUE);
 415     }
 416     va_end(args);
 417
 418     return rb_class_new_instance(size, mem, klass);
 419 }
 420
 421 /*
 422  *  call-seq:
 423  *     struct.each {|obj| block }  => struct
 424  *
 425  *  Calls <i>block</i> once for each instance variable, passing the
 426  *  value as a parameter.
 427  *
 428  *     Customer = Struct.new(:name, :address, :zip)
 429  *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 430  *     joe.each {|x| puts(x) }
 431  *
 432  *  <em>produces:</em>
 433  *
 434  *     Joe Smith
 435  *     123 Maple, Anytown NC
 436  *     12345
 437  */
 438
 439 static VALUE
 440 rb_struct_each(VALUE s)
 441 {
 442     long i;
 443
 444     RETURN_ENUMERATOR(s, 0, 0);
 445     for (i=0; i<RSTRUCT_LEN(s); i++) {
 446         rb_yield(RSTRUCT_PTR(s)[i]);
 447     }
 448     return s;
 449 }
 450
 451 /*
 452  *  call-seq:
 453  *     struct.each_pair {|sym, obj| block }     => struct
 454  *
 455  *  Calls <i>block</i> once for each instance variable, passing the name
 456  *  (as a symbol) and the value as parameters.
 457  *
 458  *     Customer = Struct.new(:name, :address, :zip)
 459  *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 460  *     joe.each_pair {|name, value| puts("#{name} => #{value}") }
 461  *
 462  *  <em>produces:</em>
 463  *
 464  *     name => Joe Smith
 465  *     address => 123 Maple, Anytown NC
 466  *     zip => 12345
 467  */
 468
 469 static VALUE
 470 rb_struct_each_pair(VALUE s)
 471 {
 472     VALUE members;
 473     long i;
 474
 475     RETURN_ENUMERATOR(s, 0, 0);
 476     members = rb_struct_members(s);
 477     for (i=0; i<RSTRUCT_LEN(s); i++) {
 478         rb_yield_values(2, rb_ary_entry(members, i), RSTRUCT_PTR(s)[i]);
 479     }
 480     return s;
 481 }
 482
 483 static VALUE
 484 inspect_struct(VALUE s, VALUE dummy, int recur)
 485 {
 486     const char *cname = rb_class2name(rb_obj_class(s));
 487     VALUE str, members;
 488     long i;
 489
 490     if (recur) {
 491         return rb_sprintf("#<struct %s:...>", cname);
 492     }
 493
 494     members = rb_struct_members(s);
 495     if (cname[0] == '#') {
 496         str = rb_str_new2("#<struct ");
 497     }
 498     else {
 499         str = rb_sprintf("#<struct %s ", cname);
 500     }
 501     for (i=0; i<RSTRUCT_LEN(s); i++) {
 502         VALUE slot;
 503         ID id;
 504
 505         if (i > 0) {
 506             rb_str_cat2(str, ", ");
 507         }
 508         slot = RARRAY_PTR(members)[i];
 509         id = SYM2ID(slot);
 510         if (rb_is_local_id(id) || rb_is_const_id(id)) {
 511             rb_str_append(str, rb_id2str(id));
 512         }
 513         else {
 514             rb_str_append(str, rb_inspect(slot));
 515         }
 516         rb_str_cat2(str, "=");
 517         rb_str_append(str, rb_inspect(RSTRUCT_PTR(s)[i]));
 518     }
 519     rb_str_cat2(str, ">");
 520     OBJ_INFECT(str, s);
 521
 522     return str;
 523 }
 524
 525 /*
 526  * call-seq:
 527  *   struct.to_s      => string
 528  *   struct.inspect   => string
 529  *
 530  * Describe the contents of this struct in a string.
 531  */
 532
 533 static VALUE
 534 rb_struct_inspect(VALUE s)
 535 {
 536     return rb_exec_recursive(inspect_struct, s, 0);
 537 }
 538
 539 /*
 540  *  call-seq:
 541  *     struct.to_a     => array
 542  *     struct.values   => array
 543  *
 544  *  Returns the values for this instance as an array.
 545  *
 546  *     Customer = Struct.new(:name, :address, :zip)
 547  *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 548  *     joe.to_a[1]   #=> "123 Maple, Anytown NC"
 549  */
 550
 551 static VALUE
 552 rb_struct_to_a(VALUE s)
 553 {
 554     return rb_ary_new4(RSTRUCT_LEN(s), RSTRUCT_PTR(s));
 555 }
 556
 557 /* :nodoc: */
 558 static VALUE
 559 rb_struct_init_copy(VALUE copy, VALUE s)
 560 {
 561     if (copy == s) return copy;
 562     rb_check_frozen(copy);
 563     if (!rb_obj_is_instance_of(s, rb_obj_class(copy))) {
 564         rb_raise(rb_eTypeError, "wrong argument class");
 565     }
 566     if (RSTRUCT_LEN(copy) != RSTRUCT_LEN(s)) {
 567         rb_raise(rb_eTypeError, "struct size mismatch");
 568     }
 569     MEMCPY(RSTRUCT_PTR(copy), RSTRUCT_PTR(s), VALUE, RSTRUCT_LEN(copy));
 570
 571     return copy;
 572 }
 573
 574 static VALUE
 575 rb_struct_aref_id(VALUE s, ID id)
 576 {
 577     VALUE members;
 578     long i, len;
 579
 580     members = rb_struct_members(s);
 581     len = RARRAY_LEN(members);
 582     for (i=0; i<len; i++) {
 583         if (SYM2ID(RARRAY_PTR(members)[i]) == id) {
 584             return RSTRUCT_PTR(s)[i];
 585         }
 586     }
 587     rb_name_error(id, "no member '%s' in struct", rb_id2name(id));
 588     return Qnil;                /* not reached */
 589 }
 590
 591 /*
 592  *  call-seq:
 593  *     struct[symbol]    => anObject
 594  *     struct[fixnum]    => anObject
 595  *
 596  *  Attribute Reference---Returns the value of the instance variable
 597  *  named by <i>symbol</i>, or indexed (0..length-1) by
 598  *  <i>fixnum</i>. Will raise <code>NameError</code> if the named
 599  *  variable does not exist, or <code>IndexError</code> if the index is
 600  *  out of range.
 601  *
 602  *     Customer = Struct.new(:name, :address, :zip)
 603  *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 604  *
 605  *     joe["name"]   #=> "Joe Smith"
 606  *     joe[:name]    #=> "Joe Smith"
 607  *     joe[0]        #=> "Joe Smith"
 608  */
 609
 610 VALUE
 611 rb_struct_aref(VALUE s, VALUE idx)
 612 {
 613     long i;
 614
 615     if (TYPE(idx) == T_STRING || TYPE(idx) == T_SYMBOL) {
 616         return rb_struct_aref_id(s, rb_to_id(idx));
 617     }
 618
 619     i = NUM2LONG(idx);
 620     if (i < 0) i = RSTRUCT_LEN(s) + i;
 621     if (i < 0)
 622         rb_raise(rb_eIndexError, "offset %ld too small for struct(size:%ld)",
 623                  i, RSTRUCT_LEN(s));
 624     if (RSTRUCT_LEN(s) <= i)
 625         rb_raise(rb_eIndexError, "offset %ld too large for struct(size:%ld)",
 626                  i, RSTRUCT_LEN(s));
 627     return RSTRUCT_PTR(s)[i];
 628 }
 629
 630 static VALUE
 631 rb_struct_aset_id(VALUE s, ID id, VALUE val)
 632 {
 633     VALUE members;
 634     long i, len;
 635
 636     members = rb_struct_members(s);
 637     rb_struct_modify(s);
 638     len = RARRAY_LEN(members);
 639     if (RSTRUCT_LEN(s) != RARRAY_LEN(members)) {
 640         rb_raise(rb_eTypeError, "struct size differs (%ld required %ld given)",
 641                  RARRAY_LEN(members), RSTRUCT_LEN(s));
 642     }
 643     for (i=0; i<len; i++) {
 644         if (SYM2ID(RARRAY_PTR(members)[i]) == id) {
 645             RSTRUCT_PTR(s)[i] = val;
 646             return val;
 647         }
 648     }
 649     rb_name_error(id, "no member '%s' in struct", rb_id2name(id));
 650 }
 651
 652 /*
 653  *  call-seq:
 654  *     struct[symbol] = obj    => obj
 655  *     struct[fixnum] = obj    => obj
 656  *
 657  *  Attribute Assignment---Assigns to the instance variable named by
 658  *  <i>symbol</i> or <i>fixnum</i> the value <i>obj</i> and
 659  *  returns it. Will raise a <code>NameError</code> if the named
 660  *  variable does not exist, or an <code>IndexError</code> if the index
 661  *  is out of range.
 662  *
 663  *     Customer = Struct.new(:name, :address, :zip)
 664  *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 665  *
 666  *     joe["name"] = "Luke"
 667  *     joe[:zip]   = "90210"
 668  *
 669  *     joe.name   #=> "Luke"
 670  *     joe.zip    #=> "90210"
 671  */
 672
 673 VALUE
 674 rb_struct_aset(VALUE s, VALUE idx, VALUE val)
 675 {
 676     long i;
 677
 678     if (TYPE(idx) == T_STRING || TYPE(idx) == T_SYMBOL) {
 679         return rb_struct_aset_id(s, rb_to_id(idx), val);
 680     }
 681
 682     i = NUM2LONG(idx);
 683     if (i < 0) i = RSTRUCT_LEN(s) + i;
 684     if (i < 0) {
 685         rb_raise(rb_eIndexError, "offset %ld too small for struct(size:%ld)",
 686                  i, RSTRUCT_LEN(s));
 687     }
 688     if (RSTRUCT_LEN(s) <= i) {
 689         rb_raise(rb_eIndexError, "offset %ld too large for struct(size:%ld)",
 690                  i, RSTRUCT_LEN(s));
 691     }
 692     rb_struct_modify(s);
 693     return RSTRUCT_PTR(s)[i] = val;
 694 }
 695
 696 static VALUE
 697 struct_entry(VALUE s, long n)
 698 {
 699     return rb_struct_aref(s, LONG2NUM(n));
 700 }
 701
 702 /*
 703  * call-seq:
 704  *   struct.values_at(selector,... )  => an_array
 705  *
 706  *   Returns an array containing the elements in
 707  *   _self_ corresponding to the given selector(s). The selectors
 708  *   may be either integer indices or ranges.
 709  *   See also </code>.select<code>.
 710  *
 711  *      a = %w{ a b c d e f }
 712  *      a.values_at(1, 3, 5)
 713  *      a.values_at(1, 3, 5, 7)
 714  *      a.values_at(-1, -3, -5, -7)
 715  *      a.values_at(1..3, 2...5)
 716  */
 717
 718 static VALUE
 719 rb_struct_values_at(int argc, VALUE *argv, VALUE s)
 720 {
 721     return rb_get_values_at(s, RSTRUCT_LEN(s), argc, argv, struct_entry);
 722 }
 723
 724 /*
 725  *  call-seq:
 726  *     struct.select {|i| block }    => array
 727  *
 728  *  Invokes the block passing in successive elements from
 729  *  <i>struct</i>, returning an array containing those elements
 730  *  for which the block returns a true value (equivalent to
 731  *  <code>Enumerable#select</code>).
 732  *
 733  *     Lots = Struct.new(:a, :b, :c, :d, :e, :f)
 734  *     l = Lots.new(11, 22, 33, 44, 55, 66)
 735  *     l.select {|v| (v % 2).zero? }   #=> [22, 44, 66]
 736  */
 737
 738 static VALUE
 739 rb_struct_select(int argc, VALUE *argv, VALUE s)
 740 {
 741     VALUE result;
 742     long i;
 743
 744     if (argc > 0) {
 745         rb_raise(rb_eArgError, "wrong number of arguments (%d for 0)", argc);
 746     }
 747     result = rb_ary_new();
 748     for (i = 0; i < RSTRUCT_LEN(s); i++) {
 749         if (RTEST(rb_yield(RSTRUCT_PTR(s)[i]))) {
 750             rb_ary_push(result, RSTRUCT_PTR(s)[i]);
 751         }
 752     }
 753
 754     return result;
 755 }
 756
 757 /*
 758  *  call-seq:
 759  *     struct == other_struct     => true or false
 760  *
 761  *  Equality---Returns <code>true</code> if <i>other_struct</i> is
 762  *  equal to this one: they must be of the same class as generated by
 763  *  <code>Struct::new</code>, and the values of all instance variables
 764  *  must be equal (according to <code>Object#==</code>).
 765  *
 766  *     Customer = Struct.new(:name, :address, :zip)
 767  *     joe   = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 768  *     joejr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 769  *     jane  = Customer.new("Jane Doe", "456 Elm, Anytown NC", 12345)
 770  *     joe == joejr   #=> true
 771  *     joe == jane    #=> false
 772  */
 773
 774 static VALUE
 775 rb_struct_equal(VALUE s, VALUE s2)
 776 {
 777     long i;
 778
 779     if (s == s2) return Qtrue;
 780     if (TYPE(s2) != T_STRUCT) return Qfalse;
 781     if (rb_obj_class(s) != rb_obj_class(s2)) return Qfalse;
 782     if (RSTRUCT_LEN(s) != RSTRUCT_LEN(s2)) {
 783         rb_bug("inconsistent struct"); /* should never happen */
 784     }
 785
 786     for (i=0; i<RSTRUCT_LEN(s); i++) {
 787         if (!rb_equal(RSTRUCT_PTR(s)[i], RSTRUCT_PTR(s2)[i])) return Qfalse;
 788     }
 789     return Qtrue;
 790 }
 791
 792 /*
 793  * call-seq:
 794  *   struct.hash   => fixnum
 795  *
 796  * Return a hash value based on this struct's contents.
 797  */
 798
 799 static VALUE
 800 rb_struct_hash(VALUE s)
 801 {
 802     long i, h;
 803     VALUE n;
 804
 805     h = rb_hash(rb_obj_class(s));
 806     for (i = 0; i < RSTRUCT_LEN(s); i++) {
 807         h = (h << 1) | (h<0 ? 1 : 0);
 808         n = rb_hash(RSTRUCT_PTR(s)[i]);
 809         h ^= NUM2LONG(n);
 810     }
 811     return LONG2FIX(h);
 812 }
 813
 814 /*
 815  * code-seq:
 816  *   struct.eql?(other)   => true or false
 817  *
 818  * Two structures are equal if they are the same object, or if all their
 819  * fields are equal (using <code>eql?</code>).
 820  */
 821
 822 static VALUE
 823 rb_struct_eql(VALUE s, VALUE s2)
 824 {
 825     long i;
 826
 827     if (s == s2) return Qtrue;
 828     if (TYPE(s2) != T_STRUCT) return Qfalse;
 829     if (rb_obj_class(s) != rb_obj_class(s2)) return Qfalse;
 830     if (RSTRUCT_LEN(s) != RSTRUCT_LEN(s2)) {
 831         rb_bug("inconsistent struct"); /* should never happen */
 832     }
 833
 834     for (i=0; i<RSTRUCT_LEN(s); i++) {
 835         if (!rb_eql(RSTRUCT_PTR(s)[i], RSTRUCT_PTR(s2)[i])) return Qfalse;
 836     }
 837     return Qtrue;
 838 }
 839
 840 /*
 841  *  call-seq:
 842  *     struct.length    => fixnum
 843  *     struct.size      => fixnum
 844  *
 845  *  Returns the number of instance variables.
 846  *
 847  *     Customer = Struct.new(:name, :address, :zip)
 848  *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 849  *     joe.length   #=> 3
 850  */
 851
 852 static VALUE
 853 rb_struct_size(VALUE s)
 854 {
 855     return LONG2FIX(RSTRUCT_LEN(s));
 856 }
 857
 858 /*
 859  *  A <code>Struct</code> is a convenient way to bundle a number of
 860  *  attributes together, using accessor methods, without having to write
 861  *  an explicit class.
 862  *
 863  *  The <code>Struct</code> class is a generator of specific classes,
 864  *  each one of which is defined to hold a set of variables and their
 865  *  accessors. In these examples, we'll call the generated class
 866  *  ``<i>Customer</i>Class,'' and we'll show an example instance of that
 867  *  class as ``<i>Customer</i>Inst.''
 868  *
 869  *  In the descriptions that follow, the parameter <i>symbol</i> refers
 870  *  to a symbol, which is either a quoted string or a
 871  *  <code>Symbol</code> (such as <code>:name</code>).
 872  */
 873 void
 874 Init_Struct(void)
 875 {
 876     rb_cStruct = rb_define_class("Struct", rb_cObject);
 877     rb_include_module(rb_cStruct, rb_mEnumerable);
 878
 879     rb_undef_alloc_func(rb_cStruct);
 880     rb_define_singleton_method(rb_cStruct, "new", rb_struct_s_def, -1);
 881
 882     rb_define_method(rb_cStruct, "initialize", rb_struct_initialize, -2);
 883     rb_define_method(rb_cStruct, "initialize_copy", rb_struct_init_copy, 1);
 884
 885     rb_define_method(rb_cStruct, "==", rb_struct_equal, 1);
 886     rb_define_method(rb_cStruct, "eql?", rb_struct_eql, 1);
 887     rb_define_method(rb_cStruct, "hash", rb_struct_hash, 0);
 888
 889     rb_define_method(rb_cStruct, "to_s", rb_struct_inspect, 0);
 890     rb_define_method(rb_cStruct, "inspect", rb_struct_inspect, 0);
 891     rb_define_method(rb_cStruct, "to_a", rb_struct_to_a, 0);
 892     rb_define_method(rb_cStruct, "values", rb_struct_to_a, 0);
 893     rb_define_method(rb_cStruct, "size", rb_struct_size, 0);
 894     rb_define_method(rb_cStruct, "length", rb_struct_size, 0);
 895
 896     rb_define_method(rb_cStruct, "each", rb_struct_each, 0);
 897     rb_define_method(rb_cStruct, "each_pair", rb_struct_each_pair, 0);
 898     rb_define_method(rb_cStruct, "[]", rb_struct_aref, 1);
 899     rb_define_method(rb_cStruct, "[]=", rb_struct_aset, 2);
 900     rb_define_method(rb_cStruct, "select", rb_struct_select, -1);
 901     rb_define_method(rb_cStruct, "values_at", rb_struct_values_at, -1);
 902
 903     rb_define_method(rb_cStruct, "members", rb_struct_members_m, 0);
 904 }