Define #succ and #pred methods

Example:

  ip = IPAddress("192.168.45.23/16")

  ip.pred.to_string
    => "192.168.45.22/16"

  ip6 = IPAddress("2001:db8::8:800:200c:417a/64")

  ip6.succ.to_string
    => "2001:db8::8:800:200c:417b/64"

This allows to use IPAddress objects in Range:

  range = IPAddress("192.168.1.15")..IPAddress("192.168.45.80")

  range.include IPAddress("192.168.22.47")
    => true

  range.include IPAddress("192.168.0.3")
    => false

Signed-off-by: Alexey I. Froloff <raorn@raorn.name>

Author: raorn

lib/ipaddress/ipv4.rb

@@ -476,6 +476,35 @@ def each
       end
     end
 
+    #
+    # Returns the successor to the IP address
+    #
+    # Example:
+    #
+    #   ip = IPAddress("192.168.45.23/16")
+    #
+    #   ip.succ.to_string
+    #     => "192.168.45.24/16"
+    #
+    def succ
+      self.class.new("#{IPAddress.ntoa(to_u32.succ % 0x100000000)}/#{prefix}")
+    end
+    alias_method :next, :succ
+
+    #
+    # Returns the predecessor to the IP address
+    #
+    # Example:
+    #
+    #   ip = IPAddress("192.168.45.23/16")
+    #
+    #   ip.pred.to_string
+    #     => "192.168.45.22/16"
+    #
+    def pred
+      self.class.new("#{IPAddress.ntoa(to_u32.pred % 0x100000000)}/#{prefix}")
+    end
+
     #
     # Spaceship operator to compare IPv4 objects
     #

lib/ipaddress/ipv6.rb

@@ -454,6 +454,35 @@ def each
       end
     end
 
+    #
+    # Returns the successor to the IP address
+    #
+    # Example:
+    #
+    #   ip6 = IPAddress("2001:db8::8:800:200c:417a/64")
+    #
+    #   ip6.succ.to_string
+    #     => "2001:db8::8:800:200c:417b/64"
+    #
+    def succ
+      IPAddress::IPv6.parse_u128(to_u128.succ, prefix)
+    end
+    alias_method :next, :succ
+
+    #
+    # Returns the predecessor to the IP address
+    #
+    # Example:
+    #
+    #   ip6 = IPAddress("2001:db8::8:800:200c:417a/64")
+    #
+    #   ip6.pred.to_string
+    #     => "2001:db8::8:800:200c:4179/64"
+    #
+    def pred
+      IPAddress::IPv6.parse_u128(to_u128.pred, prefix)
+    end
+
     #
     # Spaceship operator to compare IPv6 objects
     #

test/ipaddress/ipv4_test.rb

@@ -241,6 +241,36 @@ def test_method_each
     assert_equal expected, arr
   end
 
+  def test_method_succ
+    ip = @klass.new("192.168.100.0/24")
+    assert_instance_of @klass, ip.succ
+    assert_equal  "192.168.100.1/24", ip.succ.to_string
+    ip = @klass.new("192.168.100.50/24")
+    assert_instance_of @klass, ip.succ
+    assert_equal  "192.168.100.51/24", ip.succ.to_string
+    ip = @klass.new("0.0.0.0/32")
+    assert_instance_of @klass, ip.succ
+    assert_equal  "0.0.0.1/32", ip.succ.to_string
+    ip = @klass.new("255.255.255.255/32")
+    assert_instance_of @klass, ip.succ
+    assert_equal  "0.0.0.0/32", ip.succ.to_string
+  end
+
+  def test_method_pred
+    ip = @klass.new("192.168.100.0/24")
+    assert_instance_of @klass, ip.pred
+    assert_equal  "192.168.99.255/24", ip.pred.to_string
+    ip = @klass.new("192.168.100.50/24")
+    assert_instance_of @klass, ip.pred
+    assert_equal  "192.168.100.49/24", ip.pred.to_string
+    ip = @klass.new("0.0.0.0/32")
+    assert_instance_of @klass, ip.pred
+    assert_equal  "255.255.255.255/32", ip.pred.to_string
+    ip = @klass.new("255.255.255.255/32")
+    assert_instance_of @klass, ip.pred
+    assert_equal  "255.255.255.254/32", ip.pred.to_string
+  end
+
   def test_method_size
     ip = @klass.new("10.0.0.1/29")
     assert_equal 8, ip.size

test/ipaddress/ipv6_test.rb

@@ -228,6 +228,36 @@ def test_method_each
     assert_equal expected, arr
   end
 
+  def test_method_succ
+    ip = @klass.new("2001:db8:0:cd30::/64")
+    assert_instance_of @klass, ip.succ
+    assert_equal  "2001:db8:0:cd30::1/64", ip.succ.to_string
+    ip = @klass.new("::")
+    assert_instance_of @klass, ip.succ
+    assert_equal  "::1/128", ip.succ.to_string
+    ip = @klass.new("::1")
+    assert_instance_of @klass, ip.succ
+    assert_equal  "::2/128", ip.succ.to_string
+    ip = @klass.new("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff/64")
+    assert_instance_of @klass, ip.succ
+    assert_equal  "::/64", ip.succ.to_string
+  end
+
+  def test_method_pred
+    ip = @klass.new("2001:db8:0:cd30::/64")
+    assert_instance_of @klass, ip.pred
+    assert_equal  "2001:db8:0:cd2f:ffff:ffff:ffff:ffff/64", ip.pred.to_string
+    ip = @klass.new("::")
+    assert_instance_of @klass, ip.pred
+    assert_equal  "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff/128", ip.pred.to_string
+    ip = @klass.new("::1")
+    assert_instance_of @klass, ip.pred
+    assert_equal  "::/128", ip.pred.to_string
+    ip = @klass.new("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff/64")
+    assert_instance_of @klass, ip.pred
+    assert_equal  "ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe/64", ip.pred.to_string
+  end
+
   def test_method_compare
     ip1 = @klass.new("2001:db8:1::1/64")
     ip2 = @klass.new("2001:db8:2::1/64")