adds nilable casting for greater parity with JSON::Any (#4963)

samueleaton · RX14 · commit 28484f824d0a · 2017-09-13T15:24:59.000+01:00
diff --git a/spec/std/yaml/any_spec.cr b/spec/std/yaml/any_spec.cr
@@ -9,14 +9,20 @@ describe YAML::Any do
 
     it "gets string" do
       YAML.parse("hello").as_s.should eq("hello")
+      YAML.parse("hello").as_s?.should eq("hello")
+      YAML.parse("hello:\n- cruel\n- world\n").as_s?.should be_nil
     end
 
     it "gets array" do
       YAML.parse("- foo\n- bar\n").as_a.should eq(["foo", "bar"])
+      YAML.parse("- foo\n- bar\n").as_a?.should eq(["foo", "bar"])
+      YAML.parse("hello").as_a?.should be_nil
     end
 
     it "gets hash" do
       YAML.parse("foo: bar").as_h.should eq({"foo" => "bar"})
+      YAML.parse("foo: bar").as_h?.should eq({"foo" => "bar"})
+      YAML.parse("foo: bar")["foo"].as_h?.should be_nil
     end
   end
 
diff --git a/src/yaml/any.cr b/src/yaml/any.cr
@@ -157,18 +157,36 @@ struct YAML::Any
     @raw.as(String)
   end
 
+  # Checks that the underlying value is `String`, and returns its value.
+  # Returns `nil` otherwise.
+  def as_s? : String?
+    as_s if @raw.is_a?(String)
+  end
+
   # Checks that the underlying value is `Array`, and returns its value.
   # Raises otherwise.
   def as_a : Array(Type)
     @raw.as(Array)
   end
 
+  # Checks that the underlying value is `Array`, and returns its value.
+  # Returns `nil` otherwise.
+  def as_a? : Array(Type)?
+    as_a if @raw.is_a?(Array(Type))
+  end
+
   # Checks that the underlying value is `Hash`, and returns its value.
   # Raises otherwise.
   def as_h : Hash(Type, Type)
     @raw.as(Hash)
   end
 
+  # Checks that the underlying value is `Hash`, and returns its value.
+  # Returns `nil` otherwise.
+  def as_h? : Hash(Type, Type)?
+    as_h if @raw.is_a?(Hash(Type, Type))
+  end
+
   # :nodoc:
   def inspect(io)
     @raw.inspect(io)
