return nil if self.size == result.size
self.replace(result)
end
+
+ ##
+ # call-seq:
+ # ary.index(val) -> int or nil
+ # ary.index {|item| block } -> int or nil
+ #
+ # Returns the _index_ of the first object in +ary+ such that the object is
+ # <code>==</code> to +obj+.
+ #
+ # If a block is given instead of an argument, returns the _index_ of the
+ # first object for which the block returns +true+. Returns +nil+ if no
+ # match is found.
+ #
+ # ISO 15.2.12.5.14
+ def index(val=NONE, &block)
+ return to_enum(:find_index, val) if !block && val == NONE
+
+ if block
+ idx = 0
+ self.each do |*e|
+ return idx if block.call(*e)
+ idx += 1
+ end
+ else
+ return self.__ary_index(val)
+ end
+ nil
+ end
end