* configure.in: Check nextafter() availability.

* include/ruby/missing.h (nextafter): New optional declaration.

* missing/nextafter.c: New file.

* numeric.c: Float#next_float and Float#prev_float implemented.

   [ruby-core:62562] [Feature #9834]



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45982 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/-ext-/float/test_nextafter.rb

@@ -0,0 +1,57 @@
+require 'test/unit'
+require "-test-/float"
+
+class TestFloatExt < Test::Unit::TestCase
+  NEXTAFTER_VALUES = [
+    -Float::INFINITY,
+    -Float::MAX,
+    -100.0,
+    -1.0-Float::EPSILON,
+    -1.0,
+    -Float::EPSILON,
+    -Float::MIN/2,
+    -Math.ldexp(0.5, Float::MIN_EXP - Float::MANT_DIG + 1),
+    -0.0,
+    0.0,
+    Math.ldexp(0.5, Float::MIN_EXP - Float::MANT_DIG + 1),
+    Float::MIN/2,
+    Float::MIN,
+    Float::EPSILON,
+    1.0,
+    1.0+Float::EPSILON,
+    100.0,
+    Float::MAX,
+    Float::INFINITY,
+    Float::NAN
+  ]
+
+  test_number = 0
+  NEXTAFTER_VALUES.each {|n1|
+    NEXTAFTER_VALUES.each {|n2|
+      tag = n2.infinite? ? "ruby" : "other"
+      test_name = "test_nextafter_#{test_number}_#{tag}_#{n1}_#{n2}"
+      test_number += 1
+      define_method(test_name) {
+        v1 = Bug::Float.missing_nextafter(n1, n2)
+        v2 = Bug::Float.system_nextafter(n1, n2)
+        assert_kind_of(Float, v1)
+        assert_kind_of(Float, v2)
+        if v1.nan?
+          assert(v2.nan?, "Bug::Float.system_nextafter(#{n1}, #{n2}).nan?")
+        else
+          assert_equal(v1, v2,
+            "Bug::Float.missing_nextafter(#{'%a' % n1}, #{'%a' % n2}) = #{'%a' % v1} != " +
+            "#{'%a' % v2} = Bug::Float.system_nextafter(#{'%a' % n1}, #{'%a' % n2})")
+          if v1 == 0
+            s1 = 1.0/v1 < 0 ? "negative-zero" : "positive-zero"
+            s2 = 1.0/v2 < 0 ? "negative-zero" : "positive-zero"
+            assert_equal(s1, s2,
+            "Bug::Float.missing_nextafter(#{'%a' % n1}, #{'%a' % n2}) = #{'%a' % v1} != " +
+            "#{'%a' % v2} = Bug::Float.system_nextafter(#{'%a' % n1}, #{'%a' % n2})")
+          end
+        end
+      }
+    }
+  }
+
+end