feat: add extensions for params (#789)

* feat: add extensions for params

README.md

@@ -458,6 +458,8 @@ Besides that, `swag` also accepts aliases for some MIME Types as follows:
 // @Param int query int false "int valid" minimum(1) maximum(10)
 // @Param default query string false "string default" default(A)
 // @Param collection query []string false "string collection" collectionFormat(multi)
+// @Param extensions query []string false "string collection" extensions(x-example=test,x-nullable)
+
 ```
 
 It also works for the struct fields:
@@ -484,6 +486,7 @@ Field Name | Type | Description
 <a name="parameterEnums"></a>enums | [\*] | See https://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-5.5.1.
 <a name="parameterFormat"></a>format | `string` | The extending format for the previously mentioned [`type`](#parameterType). See [Data Type Formats](https://swagger.io/specification/v2/#dataTypeFormat) for further details.
 <a name="parameterCollectionFormat"></a>collectionFormat | `string` |Determines the format of the array if type array is used. Possible values are: <ul><li>`csv` - comma separated values `foo,bar`. <li>`ssv` - space separated values `foo bar`. <li>`tsv` - tab separated values `foo\tbar`. <li>`pipes` - pipe separated values <code>foo&#124;bar</code>. <li>`multi` - corresponds to multiple parameter instances instead of multiple values for a single instance `foo=bar&foo=baz`. This is valid only for parameters [`in`](#parameterIn) "query" or "formData". </ul> Default value is `csv`.
+<a name="parameterExtensions"></a>extensions | `string` | Add extension to parameters.
 
 ### Future
 

operation.go

@@ -346,6 +346,8 @@ var regexAttributes = map[string]*regexp.Regexp{
 	"maxlength": regexp.MustCompile(`(?i)\s+maxlength\(.*\)`),
 	// for format(email)
 	"format": regexp.MustCompile(`(?i)\s+format\(.*\)`),
+	// for extensions(x-example=test)
+	"extensions": regexp.MustCompile(`(?i)\s+extensions\(.*\)`),
 	// for collectionFormat(csv)
 	"collectionFormat": regexp.MustCompile(`(?i)\s+collectionFormat\(.*\)`),
 }
@@ -395,13 +397,17 @@ func (operation *Operation) parseAndExtractionParamAttribute(commentLine, object
 			param.MinLength = &n
 		case "format":
 			param.Format = attr
+		case "extensions":
+			param.Extensions = map[string]interface{}{}
+			setExtensionParam(attr, param)
 		case "collectionFormat":
 			n, err := setCollectionFormatParam(attrKey, objectType, attr, commentLine)
 			if err != nil {
 				return err
 			}
 			param.CollectionFormat = n
 		}
+
 	}
 
 	return nil
@@ -465,6 +471,18 @@ func setEnumParam(attr, objectType, schemaType string, param *spec.Parameter) er
 	return nil
 }
 
+func setExtensionParam(attr string, param *spec.Parameter) error {
+	for _, val := range strings.Split(attr, ",") {
+		parts := strings.SplitN(val, "=", 2)
+		if len(parts) == 2 {
+			param.Extensions.Add(parts[0], parts[1])
+		} else {
+			param.Extensions.Add(parts[0], true)
+		}
+	}
+	return nil
+}
+
 func setCollectionFormatParam(name, schemaType, attr, commentLine string) (string, error) {
 	if schemaType == ARRAY {
 		return TransToValidCollectionFormat(attr), nil

operation_test.go

@@ -1806,6 +1806,30 @@ func TestParseAndExtractionParamAttribute(t *testing.T) {
 	assert.NoError(t, err)
 }
 
+func TestParseParamCommentByExtensions(t *testing.T) {
+	comment := `@Param some_id path int true "Some ID" extensions(x-example=test,x-custom=Goopher,x-custom2)`
+	operation := NewOperation(nil)
+	err := operation.ParseComment(comment, nil)
+
+	assert.NoError(t, err)
+	b, _ := json.MarshalIndent(operation, "", "    ")
+	expected := `{
+    "parameters": [
+        {
+            "type": "integer",
+            "x-custom": "Goopher",
+            "x-custom2": true,
+            "x-example": "test",
+            "description": "Some ID",
+            "name": "some_id",
+            "in": "path",
+            "required": true
+        }
+    ]
+}`
+	assert.Equal(t, expected, string(b))
+}
+
 func TestParseIdComment(t *testing.T) {
 	t.Parallel()