add yaml support

README.md

@@ -7,12 +7,14 @@ When Enumer is applied to a type, it will generate:
 
 * A method `String()` that returns the string representation of the enum value. This makes the enum conform
 the `Stringer` interface, so whenever you print an enum value, you'll get the string name instead of a number.
-* A function `<Type>String(s string)` to get the enum value from its string representation. This is useful 
+* A function `<Type>String(s string)` to get the enum value from its string representation. This is useful
-when you need to read enum values from the command line arguments, from a configuration file, 
+when you need to read enum values from command line arguments, from a configuration file, or
-from a REST API request... In short, from those places where using the real enum value (an integer) would 
+from a REST API request... In short, from those places where using the real enum value (an integer) would
 be almost meaningless or hard to trace or use by a human.
-* When the flag `json` is provided, two more methods will be generated, `MarshalJSON()` and `UnmarshalJSON()`. Those make
+* When the flag `json` is provided, two additional methods will be generated, `MarshalJSON()` and `UnmarshalJSON()`. These make
-the enum conform the `json.Marshaler` and `json.Unmarshaler` interfaces. Very useful to use it in JSON APIs.
+the enum conform to the `json.Marshaler` and `json.Unmarshaler` interfaces. Very useful to use it in JSON APIs.
+* When the flag `yaml` is provided, two additional methods will be generated, `MarshalYAML()` and `UnmarshalYAML()`. These make
+the enum conform to the `gopkg.in/yaml.v2.Marshaler` and `gopkg.in/yaml.v2.Unmarshaler` interfaces.
 * When the flag `sql` is provided, the methods for implementing the Scanner and Valuer interfaces will be also generated.
 Useful when storing the enum in a database.
 
@@ -74,8 +76,9 @@ The generated code is exactly the same as the Stringer tool plus the mentioned a
 The usage of Enumer is the same as Stringer, so you can refer to the [Stringer docs](https://godoc.org/golang.org/x/tools/cmd/stringer)
 for more information.
 
-There are two flags added: `json` and `sql`. If the json flag is set to true (i.e. `enumer -type=Pill -json`), 
+There are three flags added: `json`, `yaml` and `sql`. If the json flag is set to true (i.e. `enumer -type=Pill -json`),
-the JSON related methods will be generated. And if the sql flag is set to true, the Scanner and Valuer interface will 
+the JSON related methods will be generated. Similarly if the yaml flag is set to true,
+the YAML related methods will be generated. And if the sql flag is set to true, the Scanner and Valuer interface will
 be implemented to seamlessly use the enum in a database model.
 
 ## Inspiring projects

enumer.go

@@ -57,3 +57,26 @@ func (i *%[1]s) UnmarshalJSON(data []byte) error {
 func (g *Generator) buildJSONMethods(runs [][]Value, typeName string, runsThreshold int) {
 	g.Printf(jsonMethods, typeName)
 }
+
+// Arguments to format are:
+//	[1]: type name
+const yamlMethods = `
+func (i %[1]s) MarshalYAML() (interface{}, error) {
+	return i.String(), nil
+}
+
+func (i *%[1]s) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+
+	var err error
+	*i, err = %[1]sString(s)
+	return err
+}
+`
+
+func (g *Generator) buildYAMLMethods(runs [][]Value, typeName string, runsThreshold int) {
+	g.Printf(yamlMethods, typeName)
+}

golden_test.go

@@ -34,6 +34,10 @@ var goldenJSON = []Golden{
 	{"prime", prime_json_in, prime_json_out},
 }
 
+var goldenYAML = []Golden{
+	{"prime", prime_yaml_in, prime_yaml_out},
+}
+
 var goldenSQL = []Golden{
 	{"prime", prime_sql_in, prime_sql_out},
 }
@@ -434,6 +438,90 @@ func (i *Prime) UnmarshalJSON(data []byte) error {
 }
 `
 
+const prime_yaml_in = `type Prime int
+const (
+	p2 Prime = 2
+	p3 Prime = 3
+	p5 Prime = 5
+	p7 Prime = 7
+	p77 Prime = 7 // Duplicate; note that p77 doesn't appear below.
+	p11 Prime = 11
+	p13 Prime = 13
+	p17 Prime = 17
+	p19 Prime = 19
+	p23 Prime = 23
+	p29 Prime = 29
+	p37 Prime = 31
+	p41 Prime = 41
+	p43 Prime = 43
+)
+`
+
+const prime_yaml_out = `
+const _Prime_name = "p2p3p5p7p11p13p17p19p23p29p37p41p43"
+
+var _Prime_map = map[Prime]string{
+	2:  _Prime_name[0:2],
+	3:  _Prime_name[2:4],
+	5:  _Prime_name[4:6],
+	7:  _Prime_name[6:8],
+	11: _Prime_name[8:11],
+	13: _Prime_name[11:14],
+	17: _Prime_name[14:17],
+	19: _Prime_name[17:20],
+	23: _Prime_name[20:23],
+	29: _Prime_name[23:26],
+	31: _Prime_name[26:29],
+	41: _Prime_name[29:32],
+	43: _Prime_name[32:35],
+}
+
+func (i Prime) String() string {
+	if str, ok := _Prime_map[i]; ok {
+		return str
+	}
+	return fmt.Sprintf("Prime(%d)", i)
+}
+
+var _PrimeNameToValue_map = map[string]Prime{
+	_Prime_name[0:2]:   2,
+	_Prime_name[2:4]:   3,
+	_Prime_name[4:6]:   5,
+	_Prime_name[6:8]:   7,
+	_Prime_name[8:11]:  11,
+	_Prime_name[11:14]: 13,
+	_Prime_name[14:17]: 17,
+	_Prime_name[17:20]: 19,
+	_Prime_name[20:23]: 23,
+	_Prime_name[23:26]: 29,
+	_Prime_name[26:29]: 31,
+	_Prime_name[29:32]: 41,
+	_Prime_name[32:35]: 43,
+}
+
+func PrimeString(s string) (Prime, error) {
+	if val, ok := _PrimeNameToValue_map[s]; ok {
+		return val, nil
+	}
+	return 0, fmt.Errorf("%s does not belong to Prime values", s)
+}
+
+func (i Prime) MarshalYAML() (interface{}, error) {
+	return i.String(), nil
+}
+
+func (i *Prime) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+
+	var err error
+	*i, err = PrimeString(s)
+	return err
+}
+`
+
 const prime_sql_in = `type Prime int
 const (
 	p2 Prime = 2
@@ -645,20 +733,23 @@ func (i *Prime) Scan(value interface{}) error {
 
 func TestGolden(t *testing.T) {
 	for _, test := range golden {
-		runGoldenTest(t, test, false, false)
+		runGoldenTest(t, test, false, false, false)
 	}
 	for _, test := range goldenJSON {
-		runGoldenTest(t, test, true, false)
+		runGoldenTest(t, test, true, false, false)
+	}
+	for _, test := range goldenYAML {
+		runGoldenTest(t, test, false, true, false)
 	}
 	for _, test := range goldenSQL {
-		runGoldenTest(t, test, false, true)
+		runGoldenTest(t, test, false, false, true)
 	}
 	for _, test := range goldenJSONAndSQL {
-		runGoldenTest(t, test, true, true)
+		runGoldenTest(t, test, true, false, true)
 	}
 }
 
-func runGoldenTest(t *testing.T, test Golden, generateJSON, generateSQL bool) {
+func runGoldenTest(t *testing.T, test Golden, generateJSON, generateYAML, generateSQL bool) {
 	var g Generator
 	input := "package test\n" + test.input
 	file := test.name + ".go"
@@ -668,7 +759,7 @@ func runGoldenTest(t *testing.T, test Golden, generateJSON, generateSQL bool) {
 	if len(tokens) != 3 {
 		t.Fatalf("%s: need type declaration on first line", test.name)
 	}
-	g.generate(tokens[1], generateJSON, generateSQL)
+	g.generate(tokens[1], generateJSON, generateYAML, generateSQL)
 	got := string(g.format())
 	if got != test.output {
 		t.Errorf("%s: got\n====\n%s====\nexpected\n====%s", test.name, got, test.output)

stringer.go

@@ -84,6 +84,7 @@ var (
 	typeNames = flag.String("type", "", "comma-separated list of type names; must be set")
 	sql       = flag.Bool("sql", false, "if true, the Scanner and Valuer interface will be implemented.")
 	json      = flag.Bool("json", false, "if true, json marshaling methods will be generated. Default: false")
+	yaml      = flag.Bool("yaml", false, "if true, yaml marshaling methods will be generated. Default: false")
 	output    = flag.String("output", "", "output file name; default srcdir/<type>_string.go")
 )
 
@@ -146,7 +147,7 @@ func main() {
 
 	// Run generate for each type.
 	for _, typeName := range types {
-		g.generate(typeName, *json, *sql)
+		g.generate(typeName, *json, *yaml, *sql)
 	}
 
 	// Format the output.
@@ -282,7 +283,7 @@ func (pkg *Package) check(fs *token.FileSet, astFiles []*ast.File) {
 }
 
 // generate produces the String method for the named type.
-func (g *Generator) generate(typeName string, includeJSON, includeSQL bool) {
+func (g *Generator) generate(typeName string, includeJSON, includeYAML, includeSQL bool) {
 	values := make([]Value, 0, 100)
 	for _, file := range g.pkg.files {
 		// Set the state for this run of the walker.
@@ -324,7 +325,9 @@ func (g *Generator) generate(typeName string, includeJSON, includeSQL bool) {
 	if includeJSON {
 		g.buildJSONMethods(runs, typeName, runsThreshold)
 	}
-
+	if includeYAML {
+		g.buildYAMLMethods(runs, typeName, runsThreshold)
+	}
 	if includeSQL {
 		g.addValueAndScanMethod(typeName)
 	}