Added to_json/as_json method

Updated to use cidr method when return address with prefix in #as_json

Author: taketo1113

lib/ipaddr.rb

@@ -227,6 +227,22 @@ def to_string
     return str
   end
 
+  # Returns a string containing the IP address representation with prefix.
+  def as_json(*)
+    if ipv4? && prefix == 32
+      to_s
+    elsif ipv6? && prefix == 128
+      to_s
+    else
+      cidr
+    end
+  end
+
+  # Returns a json string containing the IP address representation.
+  def to_json(*)
+    format("\"%s\"", as_json)
+  end
+
   # Returns a string containing the IP address representation in
   # cidr notation
   def cidr

test/test_ipaddr.rb

@@ -260,6 +260,20 @@ def test_to_s
     assert_equal("3ffe:505:2::1", IPAddr.new("3ffe:505:2::1").to_s)
   end
 
+  def test_as_json
+    assert_equal("192.168.1.2", IPAddr.new("192.168.1.2").as_json)
+    assert_equal("192.168.1.0/24", IPAddr.new("192.168.1.2/24").as_json)
+    assert_equal("2001:200:300::1", IPAddr.new("2001:200:300::1").as_json)
+    assert_equal("2001:200:300::/48", IPAddr.new("2001:200:300::/48").as_json)
+  end
+
+  def test_to_json
+    assert_equal("\"192.168.1.2\"", IPAddr.new("192.168.1.2").to_json)
+    assert_equal("\"192.168.1.0/24\"", IPAddr.new("192.168.1.2/24").to_json)
+    assert_equal("\"2001:200:300::1\"", IPAddr.new("2001:200:300::1").to_json)
+    assert_equal("\"2001:200:300::/48\"", IPAddr.new("2001:200:300::/48").to_json)
+  end
+
   def test_netmask
     a = IPAddr.new("192.168.1.2/8")
     assert_equal(a.netmask, "255.0.0.0")