From: nobu.nakada@...
Date: 2000-01-24T19:35:49+09:00
Subject: [ruby-dev:9008] [PATCH] Array#flatten! for recursive array

なかだです。

b = [a = []]; a << b; a.inspect

が SystemStackError になったりする(rb_protect_inspect(),
rb_ary_includes() から呼ばれる a == b のところでお互いのシッポを
追っかけあってるような状態)ので、パッチです。

a = []; a << a; a.flatten!

が返って来なかったりするのも一緒に変更しちゃってますが、あるいは
こういう再帰的な構造に対して flatten! を使おうというがそもそも間
違ってるんでしょうか。いっそ raise すべき?


diff -ru2p dist/array.c build/array.c
--- dist/array.c	Tue Jan 18 23:10:12 2000
+++ build/array.c	Mon Jan 24 19:01:54 2000
@@ -791,6 +791,6 @@ rb_protect_inspect(func, obj, arg)
 {
     struct inspect_arg iarg;
-
     VALUE inspect_tbl;
+    VALUE id;
 
     if (!inspect_key) {
@@ -802,8 +802,9 @@ rb_protect_inspect(func, obj, arg)
 	rb_thread_local_aset(rb_thread_current(), inspect_key, inspect_tbl);
     }
-    if (rb_ary_includes(inspect_tbl, obj)) {
+    id = rb_obj_id(obj);
+    if (rb_ary_includes(inspect_tbl, id)) {
 	return (*func)(obj, arg);
     }
-    rb_ary_push(inspect_tbl, obj);
+    rb_ary_push(inspect_tbl, id);
     iarg.func = func;
     iarg.arg1 = obj;
@@ -822,5 +823,5 @@ rb_inspecting_p(obj)
     inspect_tbl = rb_thread_local_aref(rb_thread_current(), inspect_key);
     if (NIL_P(inspect_tbl)) return Qfalse;
-    return rb_ary_includes(inspect_tbl, obj);
+    return rb_ary_includes(inspect_tbl, rb_obj_id(obj));
 }
@@ -1501,4 +1502,5 @@ rb_ary_flatten_bang(ary)
     long i;
     int mod = 0;
+    VALUE flattening = Qnil;
 
     rb_ary_modify(ary);
@@ -1506,4 +1508,18 @@ rb_ary_flatten_bang(ary)
 	VALUE ary2 = RARRAY(ary)->ptr[i];
 	if (TYPE(ary2) == T_ARRAY) {
+	    if (ary == ary2) {
+		ary2 = Qnil;
+	    } else {
+		VALUE id;
+		if (NIL_P(flattening)) {
+		    flattening = rb_ary_new();
+		}
+		id = rb_obj_id(ary2);
+		if (rb_ary_includes(flattening, id)) {
+		    ary2 = Qnil;
+		} else {
+		    rb_ary_push(flattening, id);
+		}
+	    }
 	    rb_ary_replace(ary, i--, 1, ary2);
 	    mod = 1;

-- 
そうだ 強気に ちょっと インチキに☆彡
    中田 "Bugるくらいがちょうどいいかも;-)" 伸悦