Diff: src/variable.c

Revision:

0:158c61bb030f

diff -r 000000000000 -r 158c61bb030f src/variable.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/variable.c	Wed Mar 25 17:36:16 2015 +0000
@@ -0,0 +1,1163 @@
+/*
+** variable.c - mruby variables
+**
+** See Copyright Notice in mruby.h
+*/
+
+#include <ctype.h>
+#include "mruby.h"
+#include "mruby/array.h"
+#include "mruby/class.h"
+#include "mruby/proc.h"
+#include "mruby/string.h"
+
+typedef int (iv_foreach_func)(mrb_state*,mrb_sym,mrb_value,void*);
+
+#ifdef MRB_USE_IV_SEGLIST
+
+#ifndef MRB_SEGMENT_SIZE
+#define MRB_SEGMENT_SIZE 4
+#endif
+
+typedef struct segment {
+  mrb_sym key[MRB_SEGMENT_SIZE];
+  mrb_value val[MRB_SEGMENT_SIZE];
+  struct segment *next;
+} segment;
+
+/* Instance variable table structure */
+typedef struct iv_tbl {
+  segment *rootseg;
+  size_t size;
+  size_t last_len;
+} iv_tbl;
+
+/*
+ * Creates the instance variable table.
+ *
+ * Parameters
+ *   mrb
+ * Returns
+ *   the instance variable table.
+ */
+static iv_tbl*
+iv_new(mrb_state *mrb)
+{
+  iv_tbl *t;
+
+  t = mrb_malloc(mrb, sizeof(iv_tbl));
+  t->size = 0;
+  t->rootseg =  NULL;
+  t->last_len = 0;
+
+  return t;
+}
+
+/*
+ * Set the value for the symbol in the instance variable table.
+ *
+ * Parameters
+ *   mrb
+ *   t     the instance variable table to be set in.
+ *   sym   the symbol to be used as the key.
+ *   val   the value to be set.
+ */
+static void
+iv_put(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value val)
+{
+  segment *seg = t->rootseg;
+  segment *prev = NULL;
+  segment *matched_seg = NULL;
+  size_t matched_idx = 0;
+  size_t i;
+
+  while (seg) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+      /* Found room in last segment after last_len */
+      if (!seg->next && i >= t->last_len) {
+        seg->key[i] = sym;
+        seg->val[i] = val;
+        t->last_len = i+1;
+        t->size++;
+        return;
+      }
+      if (!matched_seg && key == 0) {
+        matched_seg = seg;
+        matched_idx = i;
+      }
+      else if (key == sym) {
+        seg->val[i] = val;
+        return;
+      }
+    }
+    prev = seg;
+    seg = seg->next;
+  }
+
+  /* Not found */
+  t->size++;
+  if (matched_seg) {
+    matched_seg->key[matched_idx] = sym;
+    matched_seg->val[matched_idx] = val;
+    return;
+  }
+
+  seg = mrb_malloc(mrb, sizeof(segment));
+  if (!seg) return;
+  seg->next = NULL;
+  seg->key[0] = sym;
+  seg->val[0] = val;
+  t->last_len = 1;
+  if (prev) {
+    prev->next = seg;
+  }
+  else {
+    t->rootseg = seg;
+  }
+}
+
+/*
+ * Get a value for a symbol from the instance variable table.
+ *
+ * Parameters
+ *   mrb
+ *   t     the variable table to be searched.
+ *   sym   the symbol to be used as the key.
+ *   vp    the value pointer. Receives the value if the specified symbol is
+ *         contained in the instance variable table.
+ * Returns
+ *   true if the specified symbol is contained in the instance variable table.
+ */
+static mrb_bool
+iv_get(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
+{
+  segment *seg;
+  size_t i;
+
+  seg = t->rootseg;
+  while (seg) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+
+      if (!seg->next && i >= t->last_len) {
+        return FALSE;
+      }
+      if (key == sym) {
+        if (vp) *vp = seg->val[i];
+        return TRUE;
+      }
+    }
+    seg = seg->next;
+  }
+  return FALSE;
+}
+
+/*
+ * Deletes the value for the symbol from the instance variable table.
+ *
+ * Parameters
+ *   t    the variable table to be searched.
+ *   sym  the symbol to be used as the key.
+ *   vp   the value pointer. Receive the deleted value if the symbol is
+ *        contained in the instance variable table.
+ * Returns
+ *   true if the specified symbol is contained in the instance variable table.
+ */
+static mrb_bool
+iv_del(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
+{
+  segment *seg;
+  size_t i;
+
+  seg = t->rootseg;
+  while (seg) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+
+      if (!seg->next && i >= t->last_len) {
+        return FALSE;
+      }
+      if (key == sym) {
+        t->size--;
+        seg->key[i] = 0;
+        if (vp) *vp = seg->val[i];
+        return TRUE;
+      }
+    }
+    seg = seg->next;
+  }
+  return FALSE;
+}
+
+static mrb_bool
+iv_foreach(mrb_state *mrb, iv_tbl *t, iv_foreach_func *func, void *p)
+{
+  segment *seg;
+  size_t i;
+  int n;
+
+  seg = t->rootseg;
+  while (seg) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+
+      /* no value in last segment after last_len */
+      if (!seg->next && i >= t->last_len) {
+        return FALSE;
+      }
+      if (key != 0) {
+        n =(*func)(mrb, key, seg->val[i], p);
+        if (n > 0) return FALSE;
+        if (n < 0) {
+          t->size--;
+          seg->key[i] = 0;
+        }
+      }
+    }
+    seg = seg->next;
+  }
+  return TRUE;
+}
+
+static size_t
+iv_size(mrb_state *mrb, iv_tbl *t)
+{
+  segment *seg;
+  size_t size = 0;
+
+  if (!t) return 0;
+  if (t->size > 0) return t->size;
+  seg = t->rootseg;
+  while (seg) {
+    if (seg->next == NULL) {
+      size += t->last_len;
+      return size;
+    }
+    seg = seg->next;
+    size += MRB_SEGMENT_SIZE;
+  }
+  /* empty iv_tbl */
+  return 0;
+}
+
+static iv_tbl*
+iv_copy(mrb_state *mrb, iv_tbl *t)
+{
+  segment *seg;
+  iv_tbl *t2;
+
+  size_t i;
+
+  seg = t->rootseg;
+  t2 = iv_new(mrb);
+
+  while (seg != NULL) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+      mrb_value val = seg->val[i];
+
+      if ((seg->next == NULL) && (i >= t->last_len)) {
+        return t2;
+      }
+      iv_put(mrb, t2, key, val);
+    }
+    seg = seg->next;
+  }
+  return t2;
+}
+
+static void
+iv_free(mrb_state *mrb, iv_tbl *t)
+{
+  segment *seg;
+
+  seg = t->rootseg;
+  while (seg) {
+    segment *p = seg;
+    seg = seg->next;
+    mrb_free(mrb, p);
+  }
+  mrb_free(mrb, t);
+}
+
+#else
+
+#include "mruby/khash.h"
+
+#ifndef MRB_IVHASH_INIT_SIZE
+#define MRB_IVHASH_INIT_SIZE 8
+#endif
+
+KHASH_DECLARE(iv, mrb_sym, mrb_value, TRUE)
+KHASH_DEFINE(iv, mrb_sym, mrb_value, TRUE, kh_int_hash_func, kh_int_hash_equal)
+
+typedef struct iv_tbl {
+  khash_t(iv) h;
+} iv_tbl;
+
+static iv_tbl*
+iv_new(mrb_state *mrb)
+{
+  return (iv_tbl*)kh_init_size(iv, mrb, MRB_IVHASH_INIT_SIZE);
+}
+
+static void
+iv_put(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value val)
+{
+  khash_t(iv) *h = &t->h;
+  khiter_t k;
+
+  k = kh_put(iv, mrb, h, sym);
+  kh_value(h, k) = val;
+}
+
+static mrb_bool
+iv_get(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
+{
+  khash_t(iv) *h = &t->h;
+  khiter_t k;
+
+  k = kh_get(iv, mrb, h, sym);
+  if (k != kh_end(h)) {
+    if (vp) *vp = kh_value(h, k);
+    return TRUE;
+  }
+  return FALSE;
+}
+
+static mrb_bool
+iv_del(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
+{
+  khash_t(iv) *h = &t->h;
+  khiter_t k;
+
+  if (h) {
+    k = kh_get(iv, mrb, h, sym);
+    if (k != kh_end(h)) {
+      mrb_value val = kh_value(h, k);
+      kh_del(iv, mrb, h, k);
+      if (vp) *vp = val;
+      return TRUE;
+    }
+  }
+  return FALSE;
+}
+
+static mrb_bool
+iv_foreach(mrb_state *mrb, iv_tbl *t, iv_foreach_func *func, void *p)
+{
+  khash_t(iv) *h = &t->h;
+  khiter_t k;
+  int n;
+
+  if (h) {
+    for (k = kh_begin(h); k != kh_end(h); k++) {
+      if (kh_exist(h, k)) {
+        n = (*func)(mrb, kh_key(h, k), kh_value(h, k), p);
+        if (n > 0) return FALSE;
+        if (n < 0) {
+          kh_del(iv, mrb, h, k);
+        }
+      }
+    }
+  }
+  return TRUE;
+}
+
+static size_t
+iv_size(mrb_state *mrb, iv_tbl *t)
+{
+  khash_t(iv) *h;
+
+  if (t && (h = &t->h)) {
+    return kh_size(h);
+  }
+  return 0;
+}
+
+static iv_tbl*
+iv_copy(mrb_state *mrb, iv_tbl *t)
+{
+  return (iv_tbl*)kh_copy(iv, mrb, &t->h);
+}
+
+static void
+iv_free(mrb_state *mrb, iv_tbl *t)
+{
+  kh_destroy(iv, mrb, &t->h);
+}
+
+#endif
+
+static int
+iv_mark_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_gc_mark_value(mrb, v);
+  return 0;
+}
+
+static void
+mark_tbl(mrb_state *mrb, iv_tbl *t)
+{
+  if (t) {
+    iv_foreach(mrb, t, iv_mark_i, 0);
+  }
+}
+
+void
+mrb_gc_mark_gv(mrb_state *mrb)
+{
+  mark_tbl(mrb, mrb->globals);
+}
+
+void
+mrb_gc_free_gv(mrb_state *mrb)
+{
+  if (mrb->globals)
+    iv_free(mrb, mrb->globals);
+}
+
+void
+mrb_gc_mark_iv(mrb_state *mrb, struct RObject *obj)
+{
+  mark_tbl(mrb, obj->iv);
+}
+
+size_t
+mrb_gc_mark_iv_size(mrb_state *mrb, struct RObject *obj)
+{
+  return iv_size(mrb, obj->iv);
+}
+
+void
+mrb_gc_free_iv(mrb_state *mrb, struct RObject *obj)
+{
+  if (obj->iv) {
+    iv_free(mrb, obj->iv);
+  }
+}
+
+mrb_value
+mrb_vm_special_get(mrb_state *mrb, mrb_sym i)
+{
+  return mrb_fixnum_value(0);
+}
+
+void
+mrb_vm_special_set(mrb_state *mrb, mrb_sym i, mrb_value v)
+{
+}
+
+static mrb_bool
+obj_iv_p(mrb_value obj)
+{
+  switch (mrb_type(obj)) {
+    case MRB_TT_OBJECT:
+    case MRB_TT_CLASS:
+    case MRB_TT_MODULE:
+    case MRB_TT_SCLASS:
+    case MRB_TT_HASH:
+    case MRB_TT_DATA:
+    case MRB_TT_EXCEPTION:
+      return TRUE;
+    default:
+      return FALSE;
+  }
+}
+
+MRB_API mrb_value
+mrb_obj_iv_get(mrb_state *mrb, struct RObject *obj, mrb_sym sym)
+{
+  mrb_value v;
+
+  if (obj->iv && iv_get(mrb, obj->iv, sym, &v))
+    return v;
+  return mrb_nil_value();
+}
+
+MRB_API mrb_value
+mrb_iv_get(mrb_state *mrb, mrb_value obj, mrb_sym sym)
+{
+  if (obj_iv_p(obj)) {
+    return mrb_obj_iv_get(mrb, mrb_obj_ptr(obj), sym);
+  }
+  return mrb_nil_value();
+}
+
+MRB_API void
+mrb_obj_iv_set(mrb_state *mrb, struct RObject *obj, mrb_sym sym, mrb_value v)
+{
+  iv_tbl *t = obj->iv;
+
+  if (!t) {
+    t = obj->iv = iv_new(mrb);
+  }
+  mrb_write_barrier(mrb, (struct RBasic*)obj);
+  iv_put(mrb, t, sym, v);
+}
+
+MRB_API void
+mrb_obj_iv_ifnone(mrb_state *mrb, struct RObject *obj, mrb_sym sym, mrb_value v)
+{
+  iv_tbl *t = obj->iv;
+
+  if (!t) {
+    t = obj->iv = iv_new(mrb);
+  }
+  else if (iv_get(mrb, t, sym, &v)) {
+    return;
+  }
+  mrb_write_barrier(mrb, (struct RBasic*)obj);
+  iv_put(mrb, t, sym, v);
+}
+
+MRB_API void
+mrb_iv_set(mrb_state *mrb, mrb_value obj, mrb_sym sym, mrb_value v)
+{
+  if (obj_iv_p(obj)) {
+    mrb_obj_iv_set(mrb, mrb_obj_ptr(obj), sym, v);
+  }
+  else {
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "cannot set instance variable");
+  }
+}
+
+MRB_API mrb_bool
+mrb_obj_iv_defined(mrb_state *mrb, struct RObject *obj, mrb_sym sym)
+{
+  iv_tbl *t;
+
+  t = obj->iv;
+  if (t) {
+    return iv_get(mrb, t, sym, NULL);
+  }
+  return FALSE;
+}
+
+MRB_API mrb_bool
+mrb_iv_defined(mrb_state *mrb, mrb_value obj, mrb_sym sym)
+{
+  if (!obj_iv_p(obj)) return FALSE;
+  return mrb_obj_iv_defined(mrb, mrb_obj_ptr(obj), sym);
+}
+
+#define identchar(c) (ISALNUM(c) || (c) == '_' || !ISASCII(c))
+
+MRB_API mrb_bool
+mrb_iv_p(mrb_state *mrb, mrb_sym iv_name)
+{
+  const char *s;
+  mrb_int i, len;
+
+  s = mrb_sym2name_len(mrb, iv_name, &len);
+  if (len < 2) return FALSE;
+  if (s[0] != '@') return FALSE;
+  if (s[1] == '@') return FALSE;
+  for (i=1; i<len; i++) {
+    if (!identchar(s[i])) return FALSE;
+  }
+  return TRUE;
+}
+
+MRB_API void
+mrb_iv_check(mrb_state *mrb, mrb_sym iv_name)
+{
+  if (!mrb_iv_p(mrb, iv_name)) {
+    mrb_name_error(mrb, iv_name, "`%S' is not allowed as an instance variable name", mrb_sym2str(mrb, iv_name));
+  }
+}
+
+MRB_API void
+mrb_iv_copy(mrb_state *mrb, mrb_value dest, mrb_value src)
+{
+  struct RObject *d = mrb_obj_ptr(dest);
+  struct RObject *s = mrb_obj_ptr(src);
+
+  if (d->iv) {
+    iv_free(mrb, d->iv);
+    d->iv = 0;
+  }
+  if (s->iv) {
+    mrb_write_barrier(mrb, (struct RBasic*)d);
+    d->iv = iv_copy(mrb, s->iv);
+  }
+}
+
+static int
+inspect_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_value str = *(mrb_value*)p;
+  const char *s;
+  mrb_int len;
+  mrb_value ins;
+  char *sp = RSTRING_PTR(str);
+
+  /* need not to show internal data */
+  if (sp[0] == '-') { /* first element */
+    sp[0] = '#';
+    mrb_str_cat_lit(mrb, str, " ");
+  }
+  else {
+    mrb_str_cat_lit(mrb, str, ", ");
+  }
+  s = mrb_sym2name_len(mrb, sym, &len);
+  mrb_str_cat(mrb, str, s, len);
+  mrb_str_cat_lit(mrb, str, "=");
+  if (mrb_type(v) == MRB_TT_OBJECT) {
+    ins = mrb_any_to_s(mrb, v);
+  }
+  else {
+    ins = mrb_inspect(mrb, v);
+  }
+  mrb_str_append(mrb, str, ins);
+  return 0;
+}
+
+mrb_value
+mrb_obj_iv_inspect(mrb_state *mrb, struct RObject *obj)
+{
+  iv_tbl *t = obj->iv;
+  size_t len = iv_size(mrb, t);
+
+  if (len > 0) {
+    const char *cn = mrb_obj_classname(mrb, mrb_obj_value(obj));
+    mrb_value str = mrb_str_buf_new(mrb, 30);
+
+    mrb_str_cat_lit(mrb, str, "-<");
+    mrb_str_cat_cstr(mrb, str, cn);
+    mrb_str_cat_lit(mrb, str, ":");
+    mrb_str_concat(mrb, str, mrb_ptr_to_str(mrb, obj));
+
+    iv_foreach(mrb, t, inspect_i, &str);
+    mrb_str_cat_lit(mrb, str, ">");
+    return str;
+  }
+  return mrb_any_to_s(mrb, mrb_obj_value(obj));
+}
+
+MRB_API mrb_value
+mrb_iv_remove(mrb_state *mrb, mrb_value obj, mrb_sym sym)
+{
+  if (obj_iv_p(obj)) {
+    iv_tbl *t = mrb_obj_ptr(obj)->iv;
+    mrb_value val;
+
+    if (t && iv_del(mrb, t, sym, &val)) {
+      return val;
+    }
+  }
+  return mrb_undef_value();
+}
+
+mrb_value
+mrb_vm_iv_get(mrb_state *mrb, mrb_sym sym)
+{
+  /* get self */
+  return mrb_iv_get(mrb, mrb->c->stack[0], sym);
+}
+
+void
+mrb_vm_iv_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
+{
+  /* get self */
+  mrb_iv_set(mrb, mrb->c->stack[0], sym, v);
+}
+
+static int
+iv_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_value ary;
+  const char* s;
+  mrb_int len;
+
+  ary = *(mrb_value*)p;
+  s = mrb_sym2name_len(mrb, sym, &len);
+  if (len > 1 && s[0] == '@' && s[1] != '@') {
+    mrb_ary_push(mrb, ary, mrb_symbol_value(sym));
+  }
+  return 0;
+}
+
+/* 15.3.1.3.23 */
+/*
+ *  call-seq:
+ *     obj.instance_variables    -> array
+ *
+ *  Returns an array of instance variable names for the receiver. Note
+ *  that simply defining an accessor does not create the corresponding
+ *  instance variable.
+ *
+ *     class Fred
+ *       attr_accessor :a1
+ *       def initialize
+ *         @iv = 3
+ *       end
+ *     end
+ *     Fred.new.instance_variables   #=> [:@iv]
+ */
+mrb_value
+mrb_obj_instance_variables(mrb_state *mrb, mrb_value self)
+{
+  mrb_value ary;
+
+  ary = mrb_ary_new(mrb);
+  if (obj_iv_p(self) && mrb_obj_ptr(self)->iv) {
+    iv_foreach(mrb, mrb_obj_ptr(self)->iv, iv_i, &ary);
+  }
+  return ary;
+}
+
+static int
+cv_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_value ary;
+  const char* s;
+  mrb_int len;
+
+  ary = *(mrb_value*)p;
+  s = mrb_sym2name_len(mrb, sym, &len);
+  if (len > 2 && s[0] == '@' && s[1] == '@') {
+    mrb_ary_push(mrb, ary, mrb_symbol_value(sym));
+  }
+  return 0;
+}
+
+/* 15.2.2.4.19 */
+/*
+ *  call-seq:
+ *     mod.class_variables   -> array
+ *
+ *  Returns an array of the names of class variables in <i>mod</i>.
+ *
+ *     class One
+ *       @@var1 = 1
+ *     end
+ *     class Two < One
+ *       @@var2 = 2
+ *     end
+ *     One.class_variables   #=> [:@@var1]
+ *     Two.class_variables   #=> [:@@var2]
+ */
+mrb_value
+mrb_mod_class_variables(mrb_state *mrb, mrb_value mod)
+{
+  mrb_value ary;
+  struct RClass *c;
+
+  ary = mrb_ary_new(mrb);
+  c = mrb_class_ptr(mod);
+  while (c) {
+    if (c->iv) {
+      iv_foreach(mrb, c->iv, cv_i, &ary);
+    }
+    c = c->super;
+  }
+  return ary;
+}
+
+MRB_API mrb_value
+mrb_mod_cv_get(mrb_state *mrb, struct RClass * c, mrb_sym sym)
+{
+  struct RClass * cls = c;
+
+  while (c) {
+    if (c->iv) {
+      iv_tbl *t = c->iv;
+      mrb_value v;
+
+      if (iv_get(mrb, t, sym, &v))
+        return v;
+    }
+    c = c->super;
+  }
+  mrb_name_error(mrb, sym, "uninitialized class variable %S in %S",
+                 mrb_sym2str(mrb, sym), mrb_obj_value(cls));
+  /* not reached */
+  return mrb_nil_value();
+}
+
+MRB_API mrb_value
+mrb_cv_get(mrb_state *mrb, mrb_value mod, mrb_sym sym)
+{
+  return mrb_mod_cv_get(mrb, mrb_class_ptr(mod), sym);
+}
+
+MRB_API void
+mrb_mod_cv_set(mrb_state *mrb, struct RClass *c, mrb_sym sym, mrb_value v)
+{
+  struct RClass * cls = c;
+
+  while (c) {
+    if (c->iv) {
+      iv_tbl *t = c->iv;
+
+      if (iv_get(mrb, t, sym, NULL)) {
+        mrb_write_barrier(mrb, (struct RBasic*)c);
+        iv_put(mrb, t, sym, v);
+        return;
+      }
+    }
+    c = c->super;
+  }
+
+  if (!cls->iv) {
+    cls->iv = iv_new(mrb);
+  }
+
+  mrb_write_barrier(mrb, (struct RBasic*)cls);
+  iv_put(mrb, cls->iv, sym, v);
+}
+
+MRB_API void
+mrb_cv_set(mrb_state *mrb, mrb_value mod, mrb_sym sym, mrb_value v)
+{
+  mrb_mod_cv_set(mrb, mrb_class_ptr(mod), sym, v);
+}
+
+MRB_API mrb_bool
+mrb_mod_cv_defined(mrb_state *mrb, struct RClass * c, mrb_sym sym)
+{
+  while (c) {
+    if (c->iv) {
+      iv_tbl *t = c->iv;
+      if (iv_get(mrb, t, sym, NULL)) return TRUE;
+    }
+    c = c->super;
+  }
+
+  return FALSE;
+}
+
+MRB_API mrb_bool
+mrb_cv_defined(mrb_state *mrb, mrb_value mod, mrb_sym sym)
+{
+  return mrb_mod_cv_defined(mrb, mrb_class_ptr(mod), sym);
+}
+
+mrb_value
+mrb_vm_cv_get(mrb_state *mrb, mrb_sym sym)
+{
+  struct RClass *c = mrb->c->ci->proc->target_class;
+
+  if (!c) c = mrb->c->ci->target_class;
+
+  return mrb_mod_cv_get(mrb, c, sym);
+}
+
+void
+mrb_vm_cv_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
+{
+  struct RClass *c = mrb->c->ci->proc->target_class;
+
+  if (!c) c = mrb->c->ci->target_class;
+  mrb_mod_cv_set(mrb, c, sym, v);
+}
+
+static void
+mod_const_check(mrb_state *mrb, mrb_value mod)
+{
+  switch (mrb_type(mod)) {
+  case MRB_TT_CLASS:
+  case MRB_TT_MODULE:
+  case MRB_TT_SCLASS:
+    break;
+  default:
+    mrb_raise(mrb, E_TYPE_ERROR, "constant look-up for non class/module");
+    break;
+  }
+}
+
+static mrb_value
+const_get(mrb_state *mrb, struct RClass *base, mrb_sym sym)
+{
+  struct RClass *c = base;
+  mrb_value v;
+  iv_tbl *t;
+  mrb_bool retry = FALSE;
+  mrb_value name;
+
+L_RETRY:
+  while (c) {
+    if (c->iv) {
+      t = c->iv;
+      if (iv_get(mrb, t, sym, &v))
+        return v;
+    }
+    c = c->super;
+  }
+  if (!retry && base && base->tt == MRB_TT_MODULE) {
+    c = mrb->object_class;
+    retry = TRUE;
+    goto L_RETRY;
+  }
+  name = mrb_symbol_value(sym);
+  return mrb_funcall_argv(mrb, mrb_obj_value(base), mrb_intern_lit(mrb, "const_missing"), 1, &name);
+}
+
+MRB_API mrb_value
+mrb_const_get(mrb_state *mrb, mrb_value mod, mrb_sym sym)
+{
+  mod_const_check(mrb, mod);
+  return const_get(mrb, mrb_class_ptr(mod), sym);
+}
+
+mrb_value
+mrb_vm_const_get(mrb_state *mrb, mrb_sym sym)
+{
+  struct RClass *c = mrb->c->ci->proc->target_class;
+
+  if (!c) c = mrb->c->ci->target_class;
+  if (c) {
+    struct RClass *c2;
+    mrb_value v;
+
+    if (c->iv && iv_get(mrb, c->iv, sym, &v)) {
+      return v;
+    }
+    c2 = c;
+    for (;;) {
+      c2 = mrb_class_outer_module(mrb, c2);
+      if (!c2) break;
+      if (c2->iv && iv_get(mrb, c2->iv, sym, &v)) {
+        return v;
+      }
+    }
+  }
+  return const_get(mrb, c, sym);
+}
+
+MRB_API void
+mrb_const_set(mrb_state *mrb, mrb_value mod, mrb_sym sym, mrb_value v)
+{
+  mod_const_check(mrb, mod);
+  mrb_iv_set(mrb, mod, sym, v);
+}
+
+void
+mrb_vm_const_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
+{
+  struct RClass *c = mrb->c->ci->proc->target_class;
+
+  if (!c) c = mrb->c->ci->target_class;
+  mrb_obj_iv_set(mrb, (struct RObject*)c, sym, v);
+}
+
+MRB_API void
+mrb_const_remove(mrb_state *mrb, mrb_value mod, mrb_sym sym)
+{
+  mod_const_check(mrb, mod);
+  mrb_iv_remove(mrb, mod, sym);
+}
+
+MRB_API void
+mrb_define_const(mrb_state *mrb, struct RClass *mod, const char *name, mrb_value v)
+{
+  mrb_obj_iv_set(mrb, (struct RObject*)mod, mrb_intern_cstr(mrb, name), v);
+}
+
+MRB_API void
+mrb_define_global_const(mrb_state *mrb, const char *name, mrb_value val)
+{
+  mrb_define_const(mrb, mrb->object_class, name, val);
+}
+
+static int
+const_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_value ary;
+  const char* s;
+  mrb_int len;
+
+  ary = *(mrb_value*)p;
+  s = mrb_sym2name_len(mrb, sym, &len);
+  if (len >= 1 && ISUPPER(s[0])) {
+    mrb_ary_push(mrb, ary, mrb_symbol_value(sym));
+  }
+  return 0;
+}
+
+/* 15.2.2.4.24 */
+/*
+ *  call-seq:
+ *     mod.constants    -> array
+ *
+ *  Returns an array of all names of contants defined in the receiver.
+ */
+mrb_value
+mrb_mod_constants(mrb_state *mrb, mrb_value mod)
+{
+  mrb_value ary;
+  mrb_bool inherit = TRUE;
+  struct RClass *c = mrb_class_ptr(mod);
+
+  mrb_get_args(mrb, "|b", &inherit);
+  ary = mrb_ary_new(mrb);
+  while (c) {
+    if (c->iv) {
+      iv_foreach(mrb, c->iv, const_i, &ary);
+    }
+    if (!inherit) break;
+    c = c->super;
+    if (c == mrb->object_class) break;
+  }
+  return ary;
+}
+
+MRB_API mrb_value
+mrb_gv_get(mrb_state *mrb, mrb_sym sym)
+{
+  mrb_value v;
+
+  if (!mrb->globals) {
+    return mrb_nil_value();
+  }
+  if (iv_get(mrb, mrb->globals, sym, &v))
+    return v;
+  return mrb_nil_value();
+}
+
+MRB_API void
+mrb_gv_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
+{
+  iv_tbl *t;
+
+  if (!mrb->globals) {
+    t = mrb->globals = iv_new(mrb);
+  }
+  else {
+    t = mrb->globals;
+  }
+  iv_put(mrb, t, sym, v);
+}
+
+MRB_API void
+mrb_gv_remove(mrb_state *mrb, mrb_sym sym)
+{
+  if (!mrb->globals) {
+    return;
+  }
+  iv_del(mrb, mrb->globals, sym, NULL);
+}
+
+static int
+gv_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_value ary;
+
+  ary = *(mrb_value*)p;
+  mrb_ary_push(mrb, ary, mrb_symbol_value(sym));
+  return 0;
+}
+
+/* 15.3.1.2.4  */
+/* 15.3.1.3.14 */
+/*
+ *  call-seq:
+ *     global_variables    -> array
+ *
+ *  Returns an array of the names of global variables.
+ *
+ *     global_variables.grep /std/   #=> [:$stdin, :$stdout, :$stderr]
+ */
+mrb_value
+mrb_f_global_variables(mrb_state *mrb, mrb_value self)
+{
+  iv_tbl *t = mrb->globals;
+  mrb_value ary = mrb_ary_new(mrb);
+  size_t i;
+  char buf[3];
+
+  if (t) {
+    iv_foreach(mrb, t, gv_i, &ary);
+  }
+  buf[0] = '$';
+  buf[2] = 0;
+  for (i = 1; i <= 9; ++i) {
+    buf[1] = (char)(i + '0');
+    mrb_ary_push(mrb, ary, mrb_symbol_value(mrb_intern(mrb, buf, 2)));
+  }
+  return ary;
+}
+
+static mrb_bool
+mrb_const_defined_0(mrb_state *mrb, mrb_value mod, mrb_sym id, mrb_bool exclude, mrb_bool recurse)
+{
+  struct RClass *klass = mrb_class_ptr(mod);
+  struct RClass *tmp;
+  mrb_bool mod_retry = 0;
+
+  tmp = klass;
+retry:
+  while (tmp) {
+    if (tmp->iv && iv_get(mrb, tmp->iv, id, NULL)) {
+      return TRUE;
+    }
+    if (!recurse && (klass != mrb->object_class)) break;
+    tmp = tmp->super;
+  }
+  if (!exclude && !mod_retry && (klass->tt == MRB_TT_MODULE)) {
+    mod_retry = 1;
+    tmp = mrb->object_class;
+    goto retry;
+  }
+  return FALSE;
+}
+
+MRB_API mrb_bool
+mrb_const_defined(mrb_state *mrb, mrb_value mod, mrb_sym id)
+{
+  return mrb_const_defined_0(mrb, mod, id, TRUE, TRUE);
+}
+
+MRB_API mrb_bool
+mrb_const_defined_at(mrb_state *mrb, mrb_value mod, mrb_sym id)
+{
+  return mrb_const_defined_0(mrb, mod, id, TRUE, FALSE);
+}
+
+MRB_API mrb_value
+mrb_attr_get(mrb_state *mrb, mrb_value obj, mrb_sym id)
+{
+  return mrb_iv_get(mrb, obj, id);
+}
+
+struct csym_arg {
+  struct RClass *c;
+  mrb_sym sym;
+};
+
+static int
+csym_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  struct csym_arg *a = (struct csym_arg*)p;
+  struct RClass *c = a->c;
+
+  if (mrb_type(v) == c->tt && mrb_class_ptr(v) == c) {
+    a->sym = sym;
+    return 1;     /* stop iteration */
+  }
+  return 0;
+}
+
+mrb_sym
+mrb_class_sym(mrb_state *mrb, struct RClass *c, struct RClass *outer)
+{
+  mrb_value name;
+
+  name = mrb_obj_iv_get(mrb, (struct RObject*)c, mrb_intern_lit(mrb, "__classid__"));
+  if (mrb_nil_p(name)) {
+
+    if (!outer) return 0;
+    else {
+      struct csym_arg arg;
+
+      arg.c = c;
+      arg.sym = 0;
+      iv_foreach(mrb, outer->iv, csym_i, &arg);
+      return arg.sym;
+    }
+  }
+  return mrb_symbol(name);
+}
+