array.rb: add `Array#intersect?` from Ruby3.0.1.

1 files changed, 41 insertions, 0 deletions

diff --git a/mrbgems/mruby-array-ext/mrblib/array.rb b/mrbgems/mruby-array-ext/mrblib/array.rb
index 0195a6970..becfcb3ca 100644
--- a/mrbgems/mruby-array-ext/mrblib/array.rb
+++ b/mrbgems/mruby-array-ext/mrblib/array.rb
@@ -193,6 +193,47 @@ class Array
 
   ##
   # call-seq:
+  #   ary.intersect?(other_ary)   -> true or false
+  #
+  # Returns +true+ if the array and +other_ary+ have at least one element in
+  # common, otherwise returns +false+.
+  #
+  #    a = [ 1, 2, 3 ]
+  #    b = [ 3, 4, 5 ]
+  #    c = [ 5, 6, 7 ]
+  #    a.intersect?(b)   #=> true
+  #    a.intersect?(c)   #=> false
+  def intersect?(ary)
+    raise TypeError, "can't convert #{ary.class} into Array" unless ary.class == Array
+
+    hash = {}
+    if self.length > ary.length
+      shorter = ary
+      longer = self
+    else
+      shorter = self
+      longer = ary
+    end
+    idx = 0
+    len = shorter.size
+    while idx < len
+      hash[shorter[idx]] = true
+      idx += 1
+    end
+    idx = 0
+    len = size
+    while idx < len
+      v = longer[idx]
+      if hash[v]
+        return true
+      end
+      idx += 1
+    end
+    false
+  end
+
+  ##
+  # call-seq:
   #    ary.flatten -> new_ary
   #    ary.flatten(level) -> new_ary
   #