Refactor set/unset string type flags

Introduce `RSTR_SET_TYPE_FLAG` macro to set the specified string type flag and
clear the others.

include/mruby/string.h

@@ -34,6 +34,9 @@ struct RString {
   } as;
 };
 
+#define RSTR_SET_TYPE_FLAG(s, type) (RSTR_UNSET_TYPE_FLAG(s), (s)->flags |= MRB_STR_##type)
+#define RSTR_UNSET_TYPE_FLAG(s) ((s)->flags &= ~(MRB_STR_TYPE_MASK|MRB_STR_EMBED_LEN_MASK))
+
 #define RSTR_EMBED_P(s) ((s)->flags & MRB_STR_EMBED)
 #define RSTR_SET_EMBED_FLAG(s) ((s)->flags |= MRB_STR_EMBED)
 #define RSTR_UNSET_EMBED_FLAG(s) ((s)->flags &= ~(MRB_STR_EMBED|MRB_STR_EMBED_LEN_MASK))
@@ -103,11 +106,14 @@ MRB_API mrb_int mrb_str_strlen(mrb_state*, struct RString*);
 #define MRB_STR_SHARED    1
 #define MRB_STR_FSHARED   2
 #define MRB_STR_NOFREE    4
-#define MRB_STR_POOL      8
-#define MRB_STR_ASCII    16
-#define MRB_STR_EMBED    32
-#define MRB_STR_EMBED_LEN_MASK 0x7c0
+#define MRB_STR_EMBED     8  /* type flags up to here */
+#define MRB_STR_POOL     16  /* status flags from here */
+#define MRB_STR_ASCII    32
 #define MRB_STR_EMBED_LEN_SHIFT 6
+#define MRB_STR_EMBED_LEN_BITSIZE 5
+#define MRB_STR_EMBED_LEN_MASK (((1 << MRB_STR_EMBED_LEN_BITSIZE) - 1) << MRB_STR_EMBED_LEN_SHIFT)
+#define MRB_STR_TYPE_MASK (MRB_STR_POOL - 1)
+
 
 void mrb_gc_free_str(mrb_state*, struct RString*);
 

src/string.c

@@ -42,6 +42,7 @@ str_init_normal_capa(mrb_state *mrb, struct RString *s,
   s->as.heap.ptr = dst;
   s->as.heap.len = (mrb_int)len;
   s->as.heap.aux.capa = (mrb_int)capa;
+  RSTR_UNSET_TYPE_FLAG(s);
 }
 
 static void
@@ -55,7 +56,7 @@ str_init_embed(struct RString *s, const char *p, size_t len)
 {
   if (p) memcpy(s->as.ary, p, len);
   s->as.ary[len] = '\0';
-  RSTR_SET_EMBED_FLAG(s);
+  RSTR_SET_TYPE_FLAG(s, EMBED);
   RSTR_SET_EMBED_LEN(s, len);
 }
 
@@ -65,7 +66,7 @@ str_init_nofree(struct RString *s, const char *p, size_t len)
   s->as.heap.ptr = (char *)p;
   s->as.heap.len = (mrb_int)len;
   s->as.heap.aux.capa = 0;             /* nofree */
-  RSTR_SET_NOFREE_FLAG(s);
+  RSTR_SET_TYPE_FLAG(s, NOFREE);
 }
 
 static void
@@ -83,7 +84,7 @@ str_init_shared(mrb_state *mrb, const struct RString *orig, struct RString *s, m
   s->as.heap.ptr = orig->as.heap.ptr;
   s->as.heap.len = orig->as.heap.len;
   s->as.heap.aux.shared = shared;
-  RSTR_SET_SHARED_FLAG(s);
+  RSTR_SET_TYPE_FLAG(s, SHARED);
 }
 
 static void
@@ -92,7 +93,7 @@ str_init_fshared(const struct RString *orig, struct RString *s, struct RString *
   s->as.heap.ptr = orig->as.heap.ptr;
   s->as.heap.len = orig->as.heap.len;
   s->as.heap.aux.fshared = fshared;
-  RSTR_SET_FSHARED_FLAG(s);
+  RSTR_SET_TYPE_FLAG(s, FSHARED);
 }
 
 static void
@@ -188,7 +189,6 @@ resize_capa(mrb_state *mrb, struct RString *s, size_t capacity)
   if (RSTR_EMBED_P(s)) {
     if (!RSTR_EMBEDDABLE_P(capacity)) {
       str_init_normal_capa(mrb, s, s->as.ary, RSTR_EMBED_LEN(s), capacity);
-      RSTR_UNSET_EMBED_FLAG(s);
     }
   }
   else {
@@ -469,29 +469,23 @@ str_make_shared(mrb_state *mrb, struct RString *orig, struct RString *s)
   mrb_assert(!RSTR_EMBED_P(orig));
   if (RSTR_NOFREE_P(orig)) {
     str_init_nofree(s, orig->as.heap.ptr, len);
-    RSTR_UNSET_EMBED_FLAG(s);
   }
   else if (RSTR_SHARED_P(orig)) {
     str_init_shared(mrb, orig, s, orig->as.heap.aux.shared);
-    RSTR_UNSET_EMBED_FLAG(s);
   }
   else if (RSTR_FSHARED_P(orig)) {
     str_init_fshared(orig, s, orig->as.heap.aux.fshared);
-    RSTR_UNSET_EMBED_FLAG(s);
   }
   else if (MRB_FROZEN_P(orig) && !RSTR_POOL_P(orig)) {
     str_init_fshared(orig, s, orig);
-    RSTR_UNSET_EMBED_FLAG(s);
   }
   else {
     if (orig->as.heap.aux.capa > orig->as.heap.len) {
       orig->as.heap.ptr = (char *)mrb_realloc(mrb, orig->as.heap.ptr, len+1);
     }
     str_init_shared(mrb, orig, s, NULL);
-    RSTR_UNSET_EMBED_FLAG(s);
     orig->as.heap.aux.shared = s->as.heap.aux.shared;
-    RSTR_SET_SHARED_FLAG(orig);
-    RSTR_UNSET_EMBED_FLAG(s);
+    RSTR_SET_TYPE_FLAG(orig, SHARED);
   }
 }
 
@@ -601,7 +595,6 @@ str_replace(mrb_state *mrb, struct RString *s1, struct RString *s2)
   RSTR_COPY_ASCII_FLAG(s1, s2);
   if (RSTR_SHARED_P(s1)) {
     str_decref(mrb, s1->as.heap.aux.shared);
-    RSTR_UNSET_SHARED_FLAG(s1);
   }
   else if (!RSTR_EMBED_P(s1) && !RSTR_NOFREE_P(s1) && !RSTR_FSHARED_P(s1)
            && s1->as.heap.ptr) {
@@ -609,8 +602,6 @@ str_replace(mrb_state *mrb, struct RString *s1, struct RString *s2)
   }
 
   len = (size_t)RSTR_LEN(s2);
-  RSTR_UNSET_FSHARED_FLAG(s1);
-  RSTR_UNSET_NOFREE_FLAG(s1);
   if (RSTR_EMBEDDABLE_P(len)) {
     str_init_embed(s1, RSTR_PTR(s2), len);
   }
@@ -736,29 +727,17 @@ mrb_str_modify_keep_ascii(mrb_state *mrb, struct RString *s)
     mrb_shared_string *shared = s->as.heap.aux.shared;
 
     if (shared->refcnt == 1 && s->as.heap.ptr == shared->ptr) {
-      s->as.heap.ptr = shared->ptr;
       s->as.heap.aux.capa = shared->len;
-      RSTR_PTR(s)[s->as.heap.len] = '\0';
+      s->as.heap.ptr[s->as.heap.len] = '\0';
       mrb_free(mrb, shared);
     }
     else {
-      char *p = RSTR_PTR(s);
-      size_t len = (size_t)s->as.heap.len;
-
-      str_init(mrb, s, p, len);
+      str_init(mrb, s, s->as.heap.ptr, (size_t)s->as.heap.len);
       str_decref(mrb, shared);
     }
-    RSTR_UNSET_SHARED_FLAG(s);
-    return;
   }
-  if (RSTR_NOFREE_P(s) || RSTR_FSHARED_P(s)) {
-    char *p = s->as.heap.ptr;
-    size_t len = (size_t)s->as.heap.len;
-
-    RSTR_UNSET_NOFREE_FLAG(s);
-    RSTR_UNSET_FSHARED_FLAG(s);
-    str_init(mrb, s, p, len);
-    return;
+  else if (RSTR_NOFREE_P(s) || RSTR_FSHARED_P(s)) {
+    str_init(mrb, s, s->as.heap.ptr, (size_t)s->as.heap.len);
   }
 }