From bbf22264263f0aa8842933f7d5c64f9df80919f5 Mon Sep 17 00:00:00 2001
From: Owen Stephens <owen@owenstephens.co.uk>
Date: Sun, 25 Mar 2018 13:37:12 +0100
Subject: [PATCH v5] range.c: allow cover? to accept Range argument

---
 range.c                 | 48 +++++++++++++++++++++++++++++++++++++----
 test/ruby/test_range.rb | 40 ++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 4 deletions(-)

diff --git a/range.c b/range.c
index bcc8d1a8f4..a914ca0678 100644
--- a/range.c
+++ b/range.c
@@ -1326,10 +1326,12 @@ range_include_internal(VALUE range, VALUE val)
     return Qundef;
 }
 
+static int r_cover_range_p(VALUE range, VALUE beg, VALUE end, VALUE val);
 
 /*
  *  call-seq:
- *     rng.cover?(obj)  ->  true or false
+ *     rng.cover?(obj)   ->  true or false
+ *     rng.cover?(range) ->  true or false
  *
  *  Returns <code>true</code> if +obj+ is between the begin and end of
  *  the range.
@@ -1337,11 +1339,21 @@ range_include_internal(VALUE range, VALUE val)
  *  This tests <code>begin <= obj <= end</code> when #exclude_end? is +false+
  *  and <code>begin <= obj < end</code> when #exclude_end? is +true+.
  *
- *     ("a".."z").cover?("c")    #=> true
- *     ("a".."z").cover?("5")    #=> false
- *     ("a".."z").cover?("cc")   #=> true
+ *  Returns <code>true</code> for a Range when it is covered by the receiver,
+ *  by comparing the begin and end values directly. In the specific case of
+ *  <code>(a..b).cover?(c...d)</code> with <code>a <= c && b < d</code> this is
+ *  not possible, and <code>(c...d).max</code> must be calculated, which can
+ *  raise or exhibit poor performance.
+ *
+ *     ("a".."z").cover?("c")  #=> true
+ *     ("a".."z").cover?("5")  #=> false
+ *     ("a".."z").cover?("cc") #=> true
+ *     (1..5).cover?(2..3)     #=> true
+ *     (1..5).cover?(0..6)     #=> false
+ *     (1..5).cover?(1...6)    #=> true
  */
 
+
 static VALUE
 range_cover(VALUE range, VALUE val)
 {
@@ -1349,9 +1361,37 @@ range_cover(VALUE range, VALUE val)
 
     beg = RANGE_BEG(range);
     end = RANGE_END(range);
+
+    if (rb_obj_is_kind_of(val, rb_cRange)) {
+    return RBOOL(r_cover_range_p(range, beg, end, val));
+    }
     return r_cover_p(range, beg, end, val);
 }
 
+static int
+r_cover_range_p(VALUE range, VALUE beg, VALUE end, VALUE val)
+{
+    VALUE val_beg, val_end;
+    int cmp_end;
+
+    val_beg = RANGE_BEG(val);
+    val_end = RANGE_END(val);
+
+    if (!r_cover_p(range, beg, end, val_beg)) return FALSE;
+
+    cmp_end = r_less(end, val_end);
+
+    if (EXCL(range) == EXCL(val)) {
+    return cmp_end >= 0;
+    } else if (EXCL(range)) {
+    return cmp_end > 0;
+    } else if (cmp_end >= 0) {
+    return TRUE;
+    }
+
+    return r_less(end, rb_funcallv(val, rb_intern("max"), 0, 0)) >= 0;
+}
+
 static VALUE
 r_cover_p(VALUE range, VALUE beg, VALUE end, VALUE val)
 {
diff --git a/test/ruby/test_range.rb b/test/ruby/test_range.rb
index eada19cfb6..d267d9a733 100644
--- a/test/ruby/test_range.rb
+++ b/test/ruby/test_range.rb
@@ -521,6 +521,46 @@ def test_cover
     assert_not_operator(5..., :cover?, 0)
     assert_not_operator(5..., :cover?, "a")
     assert_operator(5.., :cover?, 10)
+
+    assert_operator(2..5, :cover?, 2..5)
+    assert_operator(2...6, :cover?, 2...6)
+    assert_operator(2...6, :cover?, 2..5)
+    assert_operator(2..5, :cover?, 2...6)
+    assert_operator(2..5, :cover?, 2..4)
+    assert_operator(2..5, :cover?, 2...4)
+    assert_operator(2..5, :cover?, 2...5)
+    assert_operator(2..5, :cover?, 3..5)
+    assert_operator(2..5, :cover?, 3..4)
+    assert_operator(2..5, :cover?, 3...6)
+    assert_operator(2...6, :cover?, 2...5)
+    assert_operator(2...6, :cover?, 2..5)
+    assert_operator(2..6, :cover?, 2...6)
+    assert_operator(2.., :cover?, 2..)
+    assert_operator(2.., :cover?, 3..)
+    assert_operator(2.0..5.0, :cover?, 2..3)
+    assert_operator(2..5, :cover?, 2.0..3.0)
+    assert_operator(2..5, :cover?, 2.0...3.0)
+    assert_operator(2..5, :cover?, 2.0...5.0)
+    assert_operator(2.0..5.0, :cover?, 2.0...3.0)
+    assert_operator('aa'..'zz', :cover?, 'aa'...'bb')
+
+    assert_not_operator(2..5, :cover?, 1..5)
+    assert_not_operator(2...6, :cover?, 1..5)
+    assert_not_operator(2..5, :cover?, 1...6)
+    assert_not_operator(1..3, :cover?, 1...6)
+    assert_not_operator(2..5, :cover?, 2..6)
+    assert_not_operator(2...6, :cover?, 2..6)
+    assert_not_operator(2...6, :cover?, 2...7)
+    assert_not_operator(2..3, :cover?, 1..4)
+    assert_not_operator(1..2, :cover?, 1.0..3.0)
+    assert_not_operator(1.0..2.9, :cover?, 1.0..3.0)
+    assert_not_operator(1..2, :cover?, 4..3)
+    assert_not_operator(2..1, :cover?, 1..2)
+    assert_not_operator(1...2, :cover?, 1...3)
+    assert_not_operator(2.., :cover?, 1..)
+    assert_not_operator('aa'..'zz', :cover?, 'aa'...'zzz')
+
+    assert_raise(TypeError) { (1..10).cover?(1...10.1) }
   end
 
   def test_beg_len
-- 
2.18.0