From 737254588b272ea898ebddd9fc4307fa555ddc35 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Sat, 17 Apr 2021 17:38:44 +0900
Subject: array.rb: add `Array#intersect?` from Ruby3.0.1.

---
 mrbgems/mruby-array-ext/mrblib/array.rb | 41 +++++++++++++++++++++++++++++++++
 mrbgems/mruby-array-ext/test/array.rb   |  8 +++++++
 2 files changed, 49 insertions(+)

(limited to 'mrbgems/mruby-array-ext')

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
@@ -191,6 +191,47 @@ class Array
     ary
   end
 
+  ##
+  # 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
diff --git a/mrbgems/mruby-array-ext/test/array.rb b/mrbgems/mruby-array-ext/test/array.rb
index 2955ef391..3f73ad8b9 100644
--- a/mrbgems/mruby-array-ext/test/array.rb
+++ b/mrbgems/mruby-array-ext/test/array.rb
@@ -119,6 +119,14 @@ assert("Array#intersection") do
   assert_equal [1, 8], a.intersection(b,c)
 end
 
+assert("Array#intersect?") do
+  a = [ 1, 2, 3 ]
+  b = [ 3, 4, 5 ]
+  c = [ 5, 6, 7 ]
+  assert_true(a.intersect?(b))
+  assert_false(a.intersect?(c))
+end
+
 assert("Array#flatten") do
   assert_equal [1, 2, "3", {4=>5}, :'6'],    [1, 2, "3", {4=>5}, :'6'].flatten
   assert_equal [1, 2, 3, 4, 5, 6], [1, 2,    [3, 4, 5], 6].flatten
-- 
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