1 files changed, 88 insertions, 0 deletions
diff --git a/internal/struct.h b/internal/struct.h
new file mode 100644
index 0000000000..f63b45007e
--- /dev/null
+++ b/internal/struct.h
@@ -0,0 +1,88 @@
+#ifndef INTERNAL_STRUCT_H /* -*- C -*- */
+#define INTERNAL_STRUCT_H
+/**
+ * @file
+ * @brief      Internal header for Struct.
+ * @author     \@shyouhei
+ * @copyright  This  file  is   a  part  of  the   programming  language  Ruby.
+ *             Permission  is hereby  granted,  to  either redistribute  and/or
+ *             modify this file, provided that  the conditions mentioned in the
+ *             file COPYING are met.  Consult the file for details.
+ */
+
+#define RSTRUCT_EMBED_LEN_MAX RSTRUCT_EMBED_LEN_MAX
+#define RSTRUCT_EMBED_LEN_MASK RSTRUCT_EMBED_LEN_MASK
+#define RSTRUCT_EMBED_LEN_SHIFT RSTRUCT_EMBED_LEN_SHIFT
+
+enum {
+    RSTRUCT_EMBED_LEN_MAX = RVALUE_EMBED_LEN_MAX,
+    RSTRUCT_EMBED_LEN_MASK = (RUBY_FL_USER2|RUBY_FL_USER1),
+    RSTRUCT_EMBED_LEN_SHIFT = (RUBY_FL_USHIFT+1),
+    RSTRUCT_TRANSIENT_FLAG = FL_USER3,
+
+    RSTRUCT_ENUM_END
+};
+
+#if USE_TRANSIENT_HEAP
+#define RSTRUCT_TRANSIENT_P(st) FL_TEST_RAW((obj), RSTRUCT_TRANSIENT_FLAG)
+#define RSTRUCT_TRANSIENT_SET(st) FL_SET_RAW((st), RSTRUCT_TRANSIENT_FLAG)
+#define RSTRUCT_TRANSIENT_UNSET(st) FL_UNSET_RAW((st), RSTRUCT_TRANSIENT_FLAG)
+#else
+#define RSTRUCT_TRANSIENT_P(st) 0
+#define RSTRUCT_TRANSIENT_SET(st) ((void)0)
+#define RSTRUCT_TRANSIENT_UNSET(st) ((void)0)
+#endif
+
+struct RStruct {
+    struct RBasic basic;
+    union {
+        struct {
+            long len;
+            const VALUE *ptr;
+        } heap;
+        const VALUE ary[RSTRUCT_EMBED_LEN_MAX];
+    } as;
+};
+
+#undef RSTRUCT_LEN
+#undef RSTRUCT_PTR
+#undef RSTRUCT_SET
+#undef RSTRUCT_GET
+#define RSTRUCT_EMBED_LEN(st)                               \
+    (long)((RBASIC(st)->flags >> RSTRUCT_EMBED_LEN_SHIFT) & \
+           (RSTRUCT_EMBED_LEN_MASK >> RSTRUCT_EMBED_LEN_SHIFT))
+#define RSTRUCT_LEN(st) rb_struct_len(st)
+#define RSTRUCT_LENINT(st) rb_long2int(RSTRUCT_LEN(st))
+#define RSTRUCT_CONST_PTR(st) rb_struct_const_ptr(st)
+#define RSTRUCT_PTR(st) ((VALUE *)RSTRUCT_CONST_PTR(RB_OBJ_WB_UNPROTECT_FOR(STRUCT, st)))
+#define RSTRUCT_SET(st, idx, v) RB_OBJ_WRITE(st, &RSTRUCT_CONST_PTR(st)[idx], (v))
+#define RSTRUCT_GET(st, idx)    (RSTRUCT_CONST_PTR(st)[idx])
+#define RSTRUCT(obj) (R_CAST(RStruct)(obj))
+
+/* struct.c */
+VALUE rb_struct_init_copy(VALUE copy, VALUE s);
+VALUE rb_struct_lookup(VALUE s, VALUE idx);
+VALUE rb_struct_s_keyword_init(VALUE klass);
+
+static inline long
+rb_struct_len(VALUE st)
+{
+    return (RBASIC(st)->flags & RSTRUCT_EMBED_LEN_MASK) ?
+        RSTRUCT_EMBED_LEN(st) : RSTRUCT(st)->as.heap.len;
+}
+
+static inline const VALUE *
+rb_struct_const_ptr(VALUE st)
+{
+    return FIX_CONST_VALUE_PTR((RBASIC(st)->flags & RSTRUCT_EMBED_LEN_MASK) ?
+        RSTRUCT(st)->as.ary : RSTRUCT(st)->as.heap.ptr);
+}
+
+static inline const VALUE *
+rb_struct_const_heap_ptr(VALUE st)
+{
+    /* TODO: check embed on debug mode */
+    return RSTRUCT(st)->as.heap.ptr;
+}
+
+#endif /* INTERNAL_STRUCT_H */