mbed-mruby

Diff: mrbgems/mruby-struct/struct.c

Revision:

0:158c61bb030f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mrbgems/mruby-struct/struct.c	Wed Mar 25 17:36:16 2015 +0000
@@ -0,0 +1,864 @@
+/*
+** struct.c - Struct class
+**
+** See Copyright Notice in mruby.h
+*/
+
+#include <ctype.h>
+#include <string.h>
+#include "mruby.h"
+#include "mruby/array.h"
+#include "mruby/string.h"
+#include "mruby/class.h"
+#include "mruby/variable.h"
+#include "mruby/hash.h"
+#include "mruby/range.h"
+
+#define RSTRUCT_LEN(st) mrb_ary_ptr(st)->len
+#define RSTRUCT_PTR(st) mrb_ary_ptr(st)->ptr
+
+static struct RClass *
+struct_class(mrb_state *mrb)
+{
+  return mrb_class_get(mrb, "Struct");
+}
+
+static inline mrb_value
+struct_ivar_get(mrb_state *mrb, mrb_value c, mrb_sym id)
+{
+  struct RClass* kclass;
+  struct RClass* sclass = struct_class(mrb);
+  mrb_value ans;
+
+  for (;;) {
+    ans = mrb_iv_get(mrb, c, id);
+    if (!mrb_nil_p(ans)) return ans;
+    kclass = RCLASS_SUPER(c);
+    if (kclass == 0 || kclass == sclass)
+      return mrb_nil_value();
+    c = mrb_obj_value(kclass);
+  }
+}
+
+static mrb_value
+mrb_struct_s_members(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value members = struct_ivar_get(mrb, klass, mrb_intern_lit(mrb, "__members__"));
+
+  if (mrb_nil_p(members)) {
+    mrb_raise(mrb, E_TYPE_ERROR, "uninitialized struct");
+  }
+  if (!mrb_array_p(members)) {
+    mrb_raise(mrb, E_TYPE_ERROR, "corrupted struct");
+  }
+  return members;
+}
+
+static mrb_value
+mrb_struct_members(mrb_state *mrb, mrb_value s)
+{
+  mrb_value members = mrb_struct_s_members(mrb, mrb_obj_value(mrb_obj_class(mrb, s)));
+  if (!strcmp(mrb_class_name(mrb, mrb_obj_class(mrb, s)), "Struct")) {
+    if (RSTRUCT_LEN(s) != RARRAY_LEN(members)) {
+      mrb_raisef(mrb, E_TYPE_ERROR,
+                 "struct size differs (%S required %S given)",
+                 mrb_fixnum_value(RARRAY_LEN(members)), mrb_fixnum_value(RSTRUCT_LEN(s)));
+    }
+  }
+  return members;
+}
+
+static mrb_value
+mrb_struct_s_members_m(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value members, ary;
+
+  members = mrb_struct_s_members(mrb, klass);
+  ary = mrb_ary_new_capa(mrb, RARRAY_LEN(members));
+  mrb_ary_replace(mrb, ary, members);
+  return ary;
+}
+
+/* 15.2.18.4.6  */
+/*
+ *  call-seq:
+ *     struct.members    -> array
+ *
+ *  Returns an array of strings representing the names of the instance
+ *  variables.
+ *
+ *     Customer = Struct.new(:name, :address, :zip)
+ *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
+ *     joe.members   #=> [:name, :address, :zip]
+ */
+
+static mrb_value
+mrb_struct_members_m(mrb_state *mrb, mrb_value obj)
+{
+  return mrb_struct_s_members_m(mrb, mrb_obj_value(mrb_obj_class(mrb, obj)));
+}
+
+static mrb_value
+mrb_struct_getmember(mrb_state *mrb, mrb_value obj, mrb_sym id)
+{
+  mrb_value members, slot, *ptr;
+  const mrb_value *ptr_members;
+  mrb_int i, len;
+
+  ptr = RSTRUCT_PTR(obj);
+  members = mrb_struct_members(mrb, obj);
+  ptr_members = RARRAY_PTR(members);
+  slot = mrb_symbol_value(id);
+  len = RARRAY_LEN(members);
+  for (i=0; i<len; i++) {
+    if (mrb_obj_equal(mrb, ptr_members[i], slot)) {
+      return ptr[i];
+    }
+  }
+  mrb_raisef(mrb, E_INDEX_ERROR, "`%S' is not a struct member", mrb_sym2str(mrb, id));
+  return mrb_nil_value();       /* not reached */
+}
+
+static mrb_value
+mrb_struct_ref(mrb_state *mrb, mrb_value obj)
+{
+  return mrb_struct_getmember(mrb, obj, mrb->c->ci->mid);
+}
+
+static mrb_value mrb_struct_ref0(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[0];}
+static mrb_value mrb_struct_ref1(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[1];}
+static mrb_value mrb_struct_ref2(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[2];}
+static mrb_value mrb_struct_ref3(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[3];}
+static mrb_value mrb_struct_ref4(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[4];}
+static mrb_value mrb_struct_ref5(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[5];}
+static mrb_value mrb_struct_ref6(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[6];}
+static mrb_value mrb_struct_ref7(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[7];}
+static mrb_value mrb_struct_ref8(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[8];}
+static mrb_value mrb_struct_ref9(mrb_state* mrb, mrb_value obj) {return RSTRUCT_PTR(obj)[9];}
+
+#define numberof(array) (int)(sizeof(array) / sizeof((array)[0]))
+#define N_REF_FUNC numberof(ref_func)
+
+static const mrb_func_t ref_func[] = {
+  mrb_struct_ref0,
+  mrb_struct_ref1,
+  mrb_struct_ref2,
+  mrb_struct_ref3,
+  mrb_struct_ref4,
+  mrb_struct_ref5,
+  mrb_struct_ref6,
+  mrb_struct_ref7,
+  mrb_struct_ref8,
+  mrb_struct_ref9,
+};
+
+static mrb_sym
+mrb_id_attrset(mrb_state *mrb, mrb_sym id)
+{
+  const char *name;
+  char *buf;
+  mrb_int len;
+  mrb_sym mid;
+
+  name = mrb_sym2name_len(mrb, id, &len);
+  buf = (char *)mrb_malloc(mrb, (size_t)len+2);
+  memcpy(buf, name, (size_t)len);
+  buf[len] = '=';
+  buf[len+1] = '\0';
+
+  mid = mrb_intern(mrb, buf, len+1);
+  mrb_free(mrb, buf);
+  return mid;
+}
+
+static mrb_value
+mrb_struct_set(mrb_state *mrb, mrb_value obj, mrb_value val)
+{
+  const char *name;
+  mrb_int i, len, slen;
+  mrb_sym mid;
+  mrb_value members, slot, *ptr;
+  const mrb_value *ptr_members;
+
+  /* get base id */
+  name = mrb_sym2name_len(mrb, mrb->c->ci->mid, &slen);
+  mid = mrb_intern(mrb, name, slen-1); /* omit last "=" */
+
+  members = mrb_struct_members(mrb, obj);
+  ptr_members = RARRAY_PTR(members);
+  len = RARRAY_LEN(members);
+  ptr = RSTRUCT_PTR(obj);
+  for (i=0; i<len; i++) {
+    slot = ptr_members[i];
+    if (mrb_symbol(slot) == mid) {
+      return ptr[i] = val;
+    }
+  }
+  mrb_raisef(mrb, E_INDEX_ERROR, "`%S' is not a struct member", mrb_sym2str(mrb, mid));
+  return mrb_nil_value();       /* not reached */
+}
+
+static mrb_value
+mrb_struct_set_m(mrb_state *mrb, mrb_value obj)
+{
+  mrb_value val;
+
+  mrb_get_args(mrb, "o", &val);
+  return mrb_struct_set(mrb, obj, val);
+}
+
+static mrb_bool
+is_local_id(mrb_state *mrb, const char *name)
+{
+  if (!name) return FALSE;
+  return !ISUPPER(name[0]);
+}
+
+static mrb_bool
+is_const_id(mrb_state *mrb, const char *name)
+{
+  if (!name) return FALSE;
+  return ISUPPER(name[0]);
+}
+
+static void
+make_struct_define_accessors(mrb_state *mrb, mrb_value members, struct RClass *c)
+{
+  const mrb_value *ptr_members = RARRAY_PTR(members);
+  mrb_int i;
+  mrb_int len = RARRAY_LEN(members);
+  int ai = mrb_gc_arena_save(mrb);
+
+  for (i=0; i<len; i++) {
+    mrb_sym id = mrb_symbol(ptr_members[i]);
+    const char *name = mrb_sym2name_len(mrb, id, NULL);
+
+    if (is_local_id(mrb, name) || is_const_id(mrb, name)) {
+      if (i < N_REF_FUNC) {
+        mrb_define_method_id(mrb, c, id, ref_func[i], MRB_ARGS_NONE());
+      }
+      else {
+        mrb_define_method_id(mrb, c, id, mrb_struct_ref, MRB_ARGS_NONE());
+      }
+      mrb_define_method_id(mrb, c, mrb_id_attrset(mrb, id), mrb_struct_set_m, MRB_ARGS_REQ(1));
+      mrb_gc_arena_restore(mrb, ai);
+    }
+  }
+}
+
+static mrb_value
+make_struct(mrb_state *mrb, mrb_value name, mrb_value members, struct RClass * klass)
+{
+  mrb_value nstr;
+  mrb_sym id;
+  struct RClass *c;
+
+  if (mrb_nil_p(name)) {
+    c = mrb_class_new(mrb, klass);
+  }
+  else {
+    /* old style: should we warn? */
+    name = mrb_str_to_str(mrb, name);
+    id = mrb_obj_to_sym(mrb, name);
+    if (!is_const_id(mrb, mrb_sym2name_len(mrb, id, NULL))) {
+      mrb_name_error(mrb, id, "identifier %S needs to be constant", name);
+    }
+    if (mrb_const_defined_at(mrb, mrb_obj_value(klass), id)) {
+      mrb_warn(mrb, "redefining constant Struct::%S", name);
+      /* ?rb_mod_remove_const(klass, mrb_sym2name(mrb, id)); */
+    }
+    c = mrb_define_class_under(mrb, klass, RSTRING_PTR(name), klass);
+  }
+  MRB_SET_INSTANCE_TT(c, MRB_TT_ARRAY);
+  nstr = mrb_obj_value(c);
+  mrb_iv_set(mrb, nstr, mrb_intern_lit(mrb, "__members__"), members);
+
+  mrb_define_class_method(mrb, c, "new", mrb_instance_new, MRB_ARGS_ANY());
+  mrb_define_class_method(mrb, c, "[]", mrb_instance_new, MRB_ARGS_ANY());
+  mrb_define_class_method(mrb, c, "members", mrb_struct_s_members_m, MRB_ARGS_NONE());
+  /* RSTRUCT(nstr)->basic.c->super = c->c; */
+  make_struct_define_accessors(mrb, members, c);
+  return nstr;
+}
+
+/* 15.2.18.3.1  */
+/*
+ *  call-seq:
+ *     Struct.new( [aString] [, aSym]+> )    -> StructClass
+ *     StructClass.new(arg, ...)             -> obj
+ *     StructClass[arg, ...]                 -> obj
+ *
+ *  Creates a new class, named by <i>aString</i>, containing accessor
+ *  methods for the given symbols. If the name <i>aString</i> is
+ *  omitted, an anonymous structure class will be created. Otherwise,
+ *  the name of this struct will appear as a constant in class
+ *  <code>Struct</code>, so it must be unique for all
+ *  <code>Struct</code>s in the system and should start with a capital
+ *  letter. Assigning a structure class to a constant effectively gives
+ *  the class the name of the constant.
+ *
+ *  <code>Struct::new</code> returns a new <code>Class</code> object,
+ *  which can then be used to create specific instances of the new
+ *  structure. The number of actual parameters must be
+ *  less than or equal to the number of attributes defined for this
+ *  class; unset parameters default to <code>nil</code>.  Passing too many
+ *  parameters will raise an <code>ArgumentError</code>.
+ *
+ *  The remaining methods listed in this section (class and instance)
+ *  are defined for this generated class.
+ *
+ *     # Create a structure with a name in Struct
+ *     Struct.new("Customer", :name, :address)    #=> Struct::Customer
+ *     Struct::Customer.new("Dave", "123 Main")   #=> #<struct Struct::Customer name="Dave", address="123 Main">
+ *
+ *     # Create a structure named by its constant
+ *     Customer = Struct.new(:name, :address)     #=> Customer
+ *     Customer.new("Dave", "123 Main")           #=> #<struct Customer name="Dave", address="123 Main">
+ */
+static mrb_value
+mrb_struct_s_def(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value name, rest;
+  mrb_value *pargv;
+  mrb_int argcnt;
+  mrb_int i;
+  mrb_value b, st;
+  mrb_sym id;
+  mrb_value *argv;
+  mrb_int argc;
+
+  name = mrb_nil_value();
+  rest = mrb_nil_value();
+  mrb_get_args(mrb, "*&", &argv, &argc, &b);
+  if (argc == 0) { /* special case to avoid crash */
+    rest = mrb_ary_new(mrb);
+  }
+  else {
+    if (argc > 0) name = argv[0];
+    if (argc > 1) rest = argv[1];
+    if (mrb_array_p(rest)) {
+      if (!mrb_nil_p(name) && mrb_symbol_p(name)) {
+        /* 1stArgument:symbol -> name=nil rest=argv[0]-[n] */
+        mrb_ary_unshift(mrb, rest, name);
+        name = mrb_nil_value();
+      }
+    }
+    else {
+      pargv = &argv[1];
+      argcnt = argc-1;
+      if (!mrb_nil_p(name) && mrb_symbol_p(name)) {
+        /* 1stArgument:symbol -> name=nil rest=argv[0]-[n] */
+        name = mrb_nil_value();
+        pargv = &argv[0];
+        argcnt++;
+      }
+      rest = mrb_ary_new_from_values(mrb, argcnt, pargv);
+    }
+    for (i=0; i<RARRAY_LEN(rest); i++) {
+      id = mrb_obj_to_sym(mrb, RARRAY_PTR(rest)[i]);
+      mrb_ary_set(mrb, rest, i, mrb_symbol_value(id));
+    }
+  }
+  st = make_struct(mrb, name, rest, struct_class(mrb));
+  if (!mrb_nil_p(b)) {
+    mrb_yield_with_class(mrb, b, 1, &st, st, mrb_class_ptr(klass));
+  }
+
+  return st;
+}
+
+static mrb_int
+num_members(mrb_state *mrb, struct RClass *klass)
+{
+  mrb_value members;
+
+  members = struct_ivar_get(mrb, mrb_obj_value(klass), mrb_intern_lit(mrb, "__members__"));
+  if (!mrb_array_p(members)) {
+    mrb_raise(mrb, E_TYPE_ERROR, "broken members");
+  }
+  return RARRAY_LEN(members);
+}
+
+/* 15.2.18.4.8  */
+/*
+ */
+static mrb_value
+mrb_struct_initialize_withArg(mrb_state *mrb, mrb_int argc, mrb_value *argv, mrb_value self)
+{
+  struct RClass *klass = mrb_obj_class(mrb, self);
+  mrb_int i, n;
+
+  n = num_members(mrb, klass);
+  if (n < argc) {
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "struct size differs");
+  }
+
+  for (i = 0; i < argc; i++) {
+    mrb_ary_set(mrb, self, i, argv[i]);
+  }
+  for (i = argc; i < n; i++) {
+    mrb_ary_set(mrb, self, i, mrb_nil_value());
+  }
+  return self;
+}
+
+static mrb_value
+mrb_struct_initialize_m(mrb_state *mrb, /*int argc, mrb_value *argv,*/ mrb_value self)
+{
+  mrb_value *argv;
+  mrb_int argc;
+
+  mrb_get_args(mrb, "*", &argv, &argc);
+  return mrb_struct_initialize_withArg(mrb, argc, argv, self);
+}
+
+static mrb_value
+inspect_struct(mrb_state *mrb, mrb_value s, mrb_bool recur)
+{
+  const char *cn = mrb_class_name(mrb, mrb_obj_class(mrb, s));
+  mrb_value members, str = mrb_str_new_lit(mrb, "#<struct ");
+  mrb_value *ptr;
+  const mrb_value *ptr_members;
+  mrb_int i, len;
+
+  if (cn) {
+    mrb_str_append(mrb, str, mrb_str_new_cstr(mrb, cn));
+  }
+  if (recur) {
+    return mrb_str_cat_lit(mrb, str, ":...>");
+  }
+
+  members = mrb_struct_members(mrb, s);
+  ptr_members = RARRAY_PTR(members);
+  ptr = RSTRUCT_PTR(s);
+  len = RSTRUCT_LEN(s);
+  for (i=0; i<len; i++) {
+    mrb_value slot;
+    mrb_sym id;
+    const char *name;
+    mrb_int namelen;
+
+    if (i > 0) {
+      mrb_str_cat_lit(mrb, str, ", ");
+    }
+    else if (cn) {
+      mrb_str_cat_lit(mrb, str, " ");
+    }
+    slot = ptr_members[i];
+    id = mrb_symbol(slot);
+    name = mrb_sym2name_len(mrb, id, &namelen);
+    if (is_local_id(mrb, name) || is_const_id(mrb, name)) {
+      mrb_str_append(mrb, str, mrb_str_new(mrb, name, namelen));
+    }
+    else {
+      mrb_str_append(mrb, str, mrb_inspect(mrb, slot));
+    }
+    mrb_str_cat_lit(mrb, str, "=");
+    mrb_str_append(mrb, str, mrb_inspect(mrb, ptr[i]));
+  }
+  mrb_str_cat_lit(mrb, str, ">");
+
+  return str;
+}
+
+/*
+ * call-seq:
+ *   struct.to_s      -> string
+ *   struct.inspect   -> string
+ *
+ * Describe the contents of this struct in a string.
+ */
+static mrb_value
+mrb_struct_inspect(mrb_state *mrb, mrb_value s)
+{
+  return inspect_struct(mrb, s, FALSE);
+}
+
+/* 15.2.18.4.9  */
+/* :nodoc: */
+static mrb_value
+mrb_struct_init_copy(mrb_state *mrb, mrb_value copy)
+{
+  mrb_value s;
+  mrb_int i, len;
+
+  mrb_get_args(mrb, "o", &s);
+
+  if (mrb_obj_equal(mrb, copy, s)) return copy;
+  if (!mrb_obj_is_instance_of(mrb, s, mrb_obj_class(mrb, copy))) {
+    mrb_raise(mrb, E_TYPE_ERROR, "wrong argument class");
+  }
+  if (!mrb_array_p(s)) {
+    mrb_raise(mrb, E_TYPE_ERROR, "corrupted struct");
+  }
+  if (RSTRUCT_LEN(copy) != RSTRUCT_LEN(s)) {
+    mrb_raise(mrb, E_TYPE_ERROR, "struct size mismatch");
+  }
+  len = RSTRUCT_LEN(copy);
+  for (i = 0; i < len; i++) {
+    mrb_ary_set(mrb, copy, i, RSTRUCT_PTR(s)[i]);
+  }
+  return copy;
+}
+
+static mrb_value
+struct_aref_sym(mrb_state *mrb, mrb_value s, mrb_sym id)
+{
+  mrb_value *ptr, members;
+  const mrb_value *ptr_members;
+  mrb_int i, len;
+
+  ptr = RSTRUCT_PTR(s);
+  members = mrb_struct_members(mrb, s);
+  ptr_members = RARRAY_PTR(members);
+  len = RARRAY_LEN(members);
+  for (i=0; i<len; i++) {
+    if (mrb_symbol(ptr_members[i]) == id) {
+      return ptr[i];
+    }
+  }
+  mrb_raisef(mrb, E_INDEX_ERROR, "no member '%S' in struct", mrb_sym2str(mrb, id));
+  return mrb_nil_value();       /* not reached */
+}
+
+static mrb_value
+struct_aref_int(mrb_state *mrb, mrb_value s, mrb_int i)
+{
+  if (i < 0) i = RSTRUCT_LEN(s) + i;
+  if (i < 0)
+      mrb_raisef(mrb, E_INDEX_ERROR,
+                 "offset %S too small for struct(size:%S)",
+                 mrb_fixnum_value(i), mrb_fixnum_value(RSTRUCT_LEN(s)));
+  if (RSTRUCT_LEN(s) <= i)
+    mrb_raisef(mrb, E_INDEX_ERROR,
+               "offset %S too large for struct(size:%S)",
+               mrb_fixnum_value(i), mrb_fixnum_value(RSTRUCT_LEN(s)));
+  return RSTRUCT_PTR(s)[i];
+}
+
+/* 15.2.18.4.2  */
+/*
+ *  call-seq:
+ *     struct[symbol]    -> anObject
+ *     struct[fixnum]    -> anObject
+ *
+ *  Attribute Reference---Returns the value of the instance variable
+ *  named by <i>symbol</i>, or indexed (0..length-1) by
+ *  <i>fixnum</i>. Will raise <code>NameError</code> if the named
+ *  variable does not exist, or <code>IndexError</code> if the index is
+ *  out of range.
+ *
+ *     Customer = Struct.new(:name, :address, :zip)
+ *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
+ *
+ *     joe["name"]   #=> "Joe Smith"
+ *     joe[:name]    #=> "Joe Smith"
+ *     joe[0]        #=> "Joe Smith"
+ */
+static mrb_value
+mrb_struct_aref(mrb_state *mrb, mrb_value s)
+{
+  mrb_value idx;
+
+  mrb_get_args(mrb, "o", &idx);
+  if (mrb_string_p(idx)) {
+    mrb_value sym = mrb_check_intern_str(mrb, idx);
+
+    if (mrb_nil_p(sym)) {
+      mrb_raisef(mrb, E_INDEX_ERROR, "no member '%S' in struct", idx);
+    }
+    idx = sym;
+  }
+  if (mrb_symbol_p(idx)) {
+    return struct_aref_sym(mrb, s, mrb_symbol(idx));
+  }
+  return struct_aref_int(mrb, s, mrb_int(mrb, idx));
+}
+
+static mrb_value
+mrb_struct_aset_sym(mrb_state *mrb, mrb_value s, mrb_sym id, mrb_value val)
+{
+  mrb_value members, *ptr;
+  const mrb_value *ptr_members;
+  mrb_int i, len;
+
+  members = mrb_struct_members(mrb, s);
+  len = RARRAY_LEN(members);
+  if (RSTRUCT_LEN(s) != len) {
+    mrb_raisef(mrb, E_TYPE_ERROR,
+               "struct size differs (%S required %S given)",
+               mrb_fixnum_value(len), mrb_fixnum_value(RSTRUCT_LEN(s)));
+  }
+  ptr = RSTRUCT_PTR(s);
+  ptr_members = RARRAY_PTR(members);
+  for (i=0; i<len; i++) {
+    if (mrb_symbol(ptr_members[i]) == id) {
+      ptr[i] = val;
+      return val;
+    }
+  }
+  mrb_raisef(mrb, E_INDEX_ERROR, "no member '%S' in struct", mrb_sym2str(mrb, id));
+  return val;                   /* not reach */
+}
+
+/* 15.2.18.4.3  */
+/*
+ *  call-seq:
+ *     struct[symbol] = obj    -> obj
+ *     struct[fixnum] = obj    -> obj
+ *
+ *  Attribute Assignment---Assigns to the instance variable named by
+ *  <i>symbol</i> or <i>fixnum</i> the value <i>obj</i> and
+ *  returns it. Will raise a <code>NameError</code> if the named
+ *  variable does not exist, or an <code>IndexError</code> if the index
+ *  is out of range.
+ *
+ *     Customer = Struct.new(:name, :address, :zip)
+ *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
+ *
+ *     joe["name"] = "Luke"
+ *     joe[:zip]   = "90210"
+ *
+ *     joe.name   #=> "Luke"
+ *     joe.zip    #=> "90210"
+ */
+
+static mrb_value
+mrb_struct_aset(mrb_state *mrb, mrb_value s)
+{
+  mrb_int i;
+  mrb_value idx;
+  mrb_value val;
+
+  mrb_get_args(mrb, "oo", &idx, &val);
+
+  if (mrb_string_p(idx)) {
+    mrb_value sym = mrb_check_intern_str(mrb, idx);
+
+    if (mrb_nil_p(sym)) {
+      mrb_raisef(mrb, E_INDEX_ERROR, "no member '%S' in struct", idx);
+    }
+    idx = sym;
+  }
+  if (mrb_symbol_p(idx)) {
+    return mrb_struct_aset_sym(mrb, s, mrb_symbol(idx), val);
+  }
+
+  i = mrb_int(mrb, idx);
+  if (i < 0) i = RSTRUCT_LEN(s) + i;
+  if (i < 0) {
+    mrb_raisef(mrb, E_INDEX_ERROR,
+               "offset %S too small for struct(size:%S)",
+               mrb_fixnum_value(i), mrb_fixnum_value(RSTRUCT_LEN(s)));
+  }
+  if (RSTRUCT_LEN(s) <= i) {
+    mrb_raisef(mrb, E_INDEX_ERROR,
+               "offset %S too large for struct(size:%S)",
+               mrb_fixnum_value(i), mrb_fixnum_value(RSTRUCT_LEN(s)));
+  }
+  return RSTRUCT_PTR(s)[i] = val;
+}
+
+/* 15.2.18.4.1  */
+/*
+ *  call-seq:
+ *     struct == other_struct     -> true or false
+ *
+ *  Equality---Returns <code>true</code> if <i>other_struct</i> is
+ *  equal to this one: they must be of the same class as generated by
+ *  <code>Struct::new</code>, and the values of all instance variables
+ *  must be equal (according to <code>Object#==</code>).
+ *
+ *     Customer = Struct.new(:name, :address, :zip)
+ *     joe   = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
+ *     joejr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
+ *     jane  = Customer.new("Jane Doe", "456 Elm, Anytown NC", 12345)
+ *     joe == joejr   #=> true
+ *     joe == jane    #=> false
+ */
+
+static mrb_value
+mrb_struct_equal(mrb_state *mrb, mrb_value s)
+{
+  mrb_value s2;
+  mrb_value *ptr, *ptr2;
+  mrb_int i, len;
+  mrb_bool equal_p;
+
+  mrb_get_args(mrb, "o", &s2);
+  if (mrb_obj_equal(mrb, s, s2)) {
+    equal_p = 1;
+  }
+  else if (!strcmp(mrb_class_name(mrb, mrb_obj_class(mrb, s)), "Struct") ||
+           mrb_obj_class(mrb, s) != mrb_obj_class(mrb, s2)) {
+    equal_p = 0;
+  }
+  else if (RSTRUCT_LEN(s) != RSTRUCT_LEN(s2)) {
+    mrb_bug(mrb, "inconsistent struct"); /* should never happen */
+    equal_p = 0; /* This substuture is just to suppress warnings. never called. */
+  }
+  else {
+    ptr = RSTRUCT_PTR(s);
+    ptr2 = RSTRUCT_PTR(s2);
+    len = RSTRUCT_LEN(s);
+    equal_p = 1;
+    for (i=0; i<len; i++) {
+      if (!mrb_equal(mrb, ptr[i], ptr2[i])) {
+        equal_p = 0;
+        break;
+      }
+    }
+  }
+
+  return mrb_bool_value(equal_p);
+}
+
+/* 15.2.18.4.12(x)  */
+/*
+ * code-seq:
+ *   struct.eql?(other)   -> true or false
+ *
+ * Two structures are equal if they are the same object, or if all their
+ * fields are equal (using <code>eql?</code>).
+ */
+static mrb_value
+mrb_struct_eql(mrb_state *mrb, mrb_value s)
+{
+  mrb_value s2;
+  mrb_value *ptr, *ptr2;
+  mrb_int i, len;
+  mrb_bool eql_p;
+
+  mrb_get_args(mrb, "o", &s2);
+  if (mrb_obj_equal(mrb, s, s2)) {
+    eql_p = 1;
+  }
+  else if (strcmp(mrb_class_name(mrb, mrb_obj_class(mrb, s2)), "Struct") ||
+           mrb_obj_class(mrb, s) != mrb_obj_class(mrb, s2)) {
+    eql_p = 0;
+  }
+  else if (RSTRUCT_LEN(s) != RSTRUCT_LEN(s2)) {
+    mrb_bug(mrb, "inconsistent struct"); /* should never happen */
+    eql_p = 0; /* This substuture is just to suppress warnings. never called. */
+  }
+  else {
+    ptr = RSTRUCT_PTR(s);
+    ptr2 = RSTRUCT_PTR(s2);
+    len = RSTRUCT_LEN(s);
+    eql_p = 1;
+    for (i=0; i<len; i++) {
+      if (!mrb_eql(mrb, ptr[i], ptr2[i])) {
+        eql_p = 0;
+        break;
+      }
+    }
+  }
+
+  return mrb_bool_value(eql_p);
+}
+
+/*
+ * call-seq:
+ *    struct.length   -> Fixnum
+ *    struct.size     -> Fixnum
+ *
+ * Returns number of struct members.
+ */
+static mrb_value
+mrb_struct_len(mrb_state *mrb, mrb_value self)
+{
+  return mrb_fixnum_value(RSTRUCT_LEN(self));
+}
+
+/*
+ * call-seq:
+ *    struct.to_a    -> array
+ *    struct.values  -> array
+ *
+ * Create an array from struct values.
+ */
+static mrb_value
+mrb_struct_to_a(mrb_state *mrb, mrb_value self)
+{
+  return mrb_ary_new_from_values(mrb, RSTRUCT_LEN(self), RSTRUCT_PTR(self));
+}
+
+/*
+ * call-seq:
+ *    struct.to_h -> hash
+ *
+ * Create a hash from member names and struct values.
+ */
+static mrb_value
+mrb_struct_to_h(mrb_state *mrb, mrb_value self)
+{
+  mrb_value members, ret;
+  mrb_int i;
+
+  members = mrb_struct_s_members(mrb, mrb_obj_value(mrb_class(mrb, self)));
+  ret = mrb_hash_new_capa(mrb, RARRAY_LEN(members));
+
+  for (i = 0; i < RARRAY_LEN(members); ++i) {
+    mrb_hash_set(mrb, ret, RARRAY_PTR(members)[i], RSTRUCT_PTR(self)[i]);
+  }
+
+  return ret;
+}
+
+static mrb_value
+mrb_struct_values_at(mrb_state *mrb, mrb_value self)
+{
+  mrb_int argc;
+  mrb_value *argv;
+
+  mrb_get_args(mrb, "*", &argv, &argc);
+
+  return mrb_get_values_at(mrb, self, RSTRUCT_LEN(self), argc, argv, struct_aref_int);
+}
+
+/*
+ *  A <code>Struct</code> is a convenient way to bundle a number of
+ *  attributes together, using accessor methods, without having to write
+ *  an explicit class.
+ *
+ *  The <code>Struct</code> class is a generator of specific classes,
+ *  each one of which is defined to hold a set of variables and their
+ *  accessors. In these examples, we'll call the generated class
+ *  ``<i>Customer</i>Class,'' and we'll show an example instance of that
+ *  class as ``<i>Customer</i>Inst.''
+ *
+ *  In the descriptions that follow, the parameter <i>symbol</i> refers
+ *  to a symbol, which is either a quoted string or a
+ *  <code>Symbol</code> (such as <code>:name</code>).
+ */
+void
+mrb_mruby_struct_gem_init(mrb_state* mrb)
+{
+  struct RClass *st;
+  st = mrb_define_class(mrb, "Struct",  mrb->object_class);
+
+  mrb_define_class_method(mrb, st, "new",             mrb_struct_s_def,       MRB_ARGS_ANY());  /* 15.2.18.3.1  */
+
+  mrb_define_method(mrb, st,       "==",              mrb_struct_equal,       MRB_ARGS_REQ(1)); /* 15.2.18.4.1  */
+  mrb_define_method(mrb, st,       "[]",              mrb_struct_aref,        MRB_ARGS_REQ(1)); /* 15.2.18.4.2  */
+  mrb_define_method(mrb, st,       "[]=",             mrb_struct_aset,        MRB_ARGS_REQ(2)); /* 15.2.18.4.3  */
+  mrb_define_method(mrb, st,       "members",         mrb_struct_members_m,   MRB_ARGS_NONE()); /* 15.2.18.4.6  */
+  mrb_define_method(mrb, st,       "initialize",      mrb_struct_initialize_m,MRB_ARGS_ANY());  /* 15.2.18.4.8  */
+  mrb_define_method(mrb, st,       "initialize_copy", mrb_struct_init_copy,   MRB_ARGS_REQ(1)); /* 15.2.18.4.9  */
+  mrb_define_method(mrb, st,       "inspect",         mrb_struct_inspect,     MRB_ARGS_NONE()); /* 15.2.18.4.10(x)  */
+  mrb_define_alias(mrb, st,        "to_s", "inspect");                                      /* 15.2.18.4.11(x)  */
+  mrb_define_method(mrb, st,       "eql?",            mrb_struct_eql,         MRB_ARGS_REQ(1)); /* 15.2.18.4.12(x)  */
+
+  mrb_define_method(mrb, st,        "size",           mrb_struct_len,         MRB_ARGS_NONE());
+  mrb_define_method(mrb, st,        "length",         mrb_struct_len,         MRB_ARGS_NONE());
+  mrb_define_method(mrb, st,        "to_a",           mrb_struct_to_a,        MRB_ARGS_NONE());
+  mrb_define_method(mrb, st,        "values",         mrb_struct_to_a,        MRB_ARGS_NONE());
+  mrb_define_method(mrb, st,        "to_h",           mrb_struct_to_h,        MRB_ARGS_NONE());
+  mrb_define_method(mrb, st,        "values_at",      mrb_struct_values_at,   MRB_ARGS_NONE());
+}
+
+void
+mrb_mruby_struct_gem_final(mrb_state* mrb)
+{
+}
+