implement reading binary data from bson

spec/bson_spec.cr

@@ -335,4 +335,11 @@ describe BSON do
     fail "expected BSON" unless ary.is_a?(BSON)
     ary["0"].should eq(1)
   end
+
+  it "should be able to read binary data" do
+    bson = BSON.new
+    bson["bin"] = BSON::Binary.new(BSON::Binary::SubType::Binary, "binary".to_slice)
+    value = bson["bin"].as(BSON::Binary)
+    String.new(value.data).should eq("binary")
+  end
 end

src/bson/binary.cr

@@ -14,6 +14,25 @@ class BSON
     def initialize(@subtype : SubType, @data : Slice(UInt8))
     end
 
+    def self.new(binary : LibBSON::Binary)
+      data = Slice(UInt8).new(binary.data, binary.len)
+
+      case binary.sub_type
+      when LibBSON::SubType::BSON_SUBTYPE_BINARY
+        new(SubType::Binary, data)
+      when LibBSON::SubType::BSON_SUBTYPE_FUNCTION
+        new(SubType::Function, data)
+      when LibBSON::SubType::BSON_SUBTYPE_UUID
+        new(SubType::UUID, data)
+      when LibBSON::SubType::BSON_SUBTYPE_MD5
+        new(SubType::MD5, data)
+      when LibBSON::SubType::BSON_SUBTYPE_USER
+        new(SubType::User, data)
+      else
+        raise "unable to handle subtype #{binary.sub_type}"
+      end
+    end
+
     def to_raw_type
       case @subtype
       when SubType::Binary

src/bson/value.cr

@@ -68,6 +68,8 @@ class BSON
         MaxKey.new
       when LibBSON::Type::BSON_TYPE_MINKEY
         MinKey.new
+      when LibBSON::Type::BSON_TYPE_BINARY
+        Binary.new(v.v_binary)
       else
         raise "Invalid BSON Value type #{@handle.v_type}"
       end