* string.c (sym_find): Add Symbol.find(str), which returns whether given

  string is defined as symbol or not. [Feature #7854]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45175 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 22 insertions, 0 deletions

diff --git a/string.c b/string.c
index 4e30cb338a..1e26a25bb7 100644
--- a/string.c
+++ b/string.c
@@ -8231,6 +8231,27 @@ str_scrub_bang(int argc, VALUE *argv, VALUE str)
 
 /*
  *  call-seq:
+ *     Symbol.find(str)   -> symbol or nil
+ *
+ *  Return the related symbol if the symbol already exists.
+ *  Return nil if not.
+ */
+
+static VALUE
+sym_find(VALUE dummy, VALUE sym)
+{
+    ID id = rb_check_id(&sym);
+
+    if (id) {
+	return ID2SYM(id);
+    }
+    else {
+	return Qnil;
+    }
+}
+
+/*
+ *  call-seq:
  *     sym == obj   -> true or false
  *
  *  Equality---If <i>sym</i> and <i>obj</i> are exactly the same
@@ -8787,6 +8808,7 @@ Init_String(void)
     rb_undef_alloc_func(rb_cSymbol);
     rb_undef_method(CLASS_OF(rb_cSymbol), "new");
     rb_define_singleton_method(rb_cSymbol, "all_symbols", rb_sym_all_symbols, 0); /* in parse.y */
+    rb_define_singleton_method(rb_cSymbol, "find", sym_find, 1);
 
     rb_define_method(rb_cSymbol, "==", sym_equal, 1);
     rb_define_method(rb_cSymbol, "===", sym_equal, 1);