Add a new "text" flag for TextMarshaler methods

enumer.go

@@ -60,6 +60,24 @@ func (g *Generator) buildJSONMethods(runs [][]Value, typeName string, runsThresh
 	g.Printf(jsonMethods, typeName)
 }
 
+// Arguments to format are:
+//	[1]: type name
+const textMethods = `
+func (i %[1]s) MarshalText() ([]byte, error) {
+	return []byte(i.String()), nil
+}
+
+func (i *%[1]s) UnmarshalText(text []byte) error {
+	var err error
+	*i, err = %[1]sString(string(text))
+	return err
+}
+`
+
+func (g *Generator) buildTextMethods(runs [][]Value, typeName string, runsThreshold int) {
+	g.Printf(textMethods, typeName)
+}
+
 // Arguments to format are:
 //	[1]: type name
 const yamlMethods = `

golden_test.go

@@ -33,6 +33,9 @@ var golden = []Golden{
 var goldenJSON = []Golden{
 	{"prime", prime_json_in, prime_json_out},
 }
+var goldenText = []Golden{
+	{"prime", prime_text_in, prime_text_out},
+}
 
 var goldenYAML = []Golden{
 	{"prime", prime_yaml_in, prime_yaml_out},
@@ -456,6 +459,87 @@ func (i *Prime) UnmarshalJSON(data []byte) error {
 }
 `
 
+const prime_text_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_text_out = `
+const _PrimeName = "p2p3p5p7p11p13p17p19p23p29p37p41p43"
+
+var _PrimeMap = map[Prime]string{
+	2:  _PrimeName[0:2],
+	3:  _PrimeName[2:4],
+	5:  _PrimeName[4:6],
+	7:  _PrimeName[6:8],
+	11: _PrimeName[8:11],
+	13: _PrimeName[11:14],
+	17: _PrimeName[14:17],
+	19: _PrimeName[17:20],
+	23: _PrimeName[20:23],
+	29: _PrimeName[23:26],
+	31: _PrimeName[26:29],
+	41: _PrimeName[29:32],
+	43: _PrimeName[32:35],
+}
+
+func (i Prime) String() string {
+	if str, ok := _PrimeMap[i]; ok {
+		return str
+	}
+	return fmt.Sprintf("Prime(%d)", i)
+}
+
+var _PrimeNameToValueMap = map[string]Prime{
+	_PrimeName[0:2]:   2,
+	_PrimeName[2:4]:   3,
+	_PrimeName[4:6]:   5,
+	_PrimeName[6:8]:   7,
+	_PrimeName[8:11]:  11,
+	_PrimeName[11:14]: 13,
+	_PrimeName[14:17]: 17,
+	_PrimeName[17:20]: 19,
+	_PrimeName[20:23]: 23,
+	_PrimeName[23:26]: 29,
+	_PrimeName[26:29]: 31,
+	_PrimeName[29:32]: 41,
+	_PrimeName[32:35]: 43,
+}
+
+// PrimeString retrieves an enum value from the enum constants string name.
+// Throws an error if the param is not part of the enum.
+func PrimeString(s string) (Prime, error) {
+	if val, ok := _PrimeNameToValueMap[s]; ok {
+		return val, nil
+	}
+	return 0, fmt.Errorf("%s does not belong to Prime values", s)
+}
+
+func (i Prime) MarshalText() ([]byte, error) {
+	return []byte(i.String()), nil
+}
+
+func (i *Prime) UnmarshalText(text []byte) error {
+	var err error
+	*i, err = PrimeString(string(text))
+	return err
+}
+`
+
 const prime_yaml_in = `type Prime int
 const (
 	p2 Prime = 2
@@ -769,26 +853,29 @@ const (
 
 func TestGolden(t *testing.T) {
 	for _, test := range golden {
-		runGoldenTest(t, test, false, false, false, "")
+		runGoldenTest(t, test, false, false, false, false, "")
 	}
 	for _, test := range goldenJSON {
-		runGoldenTest(t, test, true, false, false, "")
+		runGoldenTest(t, test, true, false, false, false, "")
+	}
+	for _, test := range goldenText {
+		runGoldenTest(t, test, false, false, false, true, "")
 	}
 	for _, test := range goldenYAML {
-		runGoldenTest(t, test, false, true, false, "")
+		runGoldenTest(t, test, false, true, false, false, "")
 	}
 	for _, test := range goldenSQL {
-		runGoldenTest(t, test, false, false, true, "")
+		runGoldenTest(t, test, false, false, true, false, "")
 	}
 	for _, test := range goldenJSONAndSQL {
-		runGoldenTest(t, test, true, false, true, "")
+		runGoldenTest(t, test, true, false, true, false, "")
 	}
 	for _, test := range goldenPrefix {
-		runGoldenTest(t, test, false, false, false, "Day")
+		runGoldenTest(t, test, false, false, false, false, "Day")
 	}
 }
 
-func runGoldenTest(t *testing.T, test Golden, generateJSON, generateYAML, generateSQL bool, prefix string) {
+func runGoldenTest(t *testing.T, test Golden, generateJSON, generateYAML, generateSQL, generateText bool, prefix string) {
 	var g Generator
 	input := "package test\n" + test.input
 	file := test.name + ".go"
@@ -798,7 +885,7 @@ func runGoldenTest(t *testing.T, test Golden, generateJSON, generateYAML, genera
 	if len(tokens) != 3 {
 		t.Fatalf("%s: need type declaration on first line", test.name)
 	}
-	g.generate(tokens[1], generateJSON, generateYAML, generateSQL, "noop", prefix)
+	g.generate(tokens[1], generateJSON, generateYAML, generateSQL, generateText, "noop", prefix)
 	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

@@ -91,6 +91,7 @@ var (
 	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")
+	text            = flag.Bool("text", false, "if true, text marshaling methods will be generated. Default: false")
 	output          = flag.String("output", "", "output file name; default srcdir/<type>_string.go")
 	transformMethod = flag.String("transform", "noop", "enum item name transformation method. Default: noop")
 	trimPrefix      = flag.String("trimprefix", "", "transform each item name by removing a prefix. Default: \"\"")
@@ -156,7 +157,7 @@ func main() {
 
 	// Run generate for each type.
 	for _, typeName := range types {
-		g.generate(typeName, *json, *yaml, *sql, *transformMethod, *trimPrefix)
+		g.generate(typeName, *json, *yaml, *sql, *text, *transformMethod, *trimPrefix)
 	}
 
 	// Format the output.
@@ -315,7 +316,7 @@ func (g *Generator) trimValueNames(values []Value, prefix string) {
 }
 
 // generate produces the String method for the named type.
-func (g *Generator) generate(typeName string, includeJSON, includeYAML, includeSQL bool, transformMethod string, trimPrefix string) {
+func (g *Generator) generate(typeName string, includeJSON, includeYAML, includeSQL, includeText bool, transformMethod string, trimPrefix string) {
 	values := make([]Value, 0, 100)
 	for _, file := range g.pkg.files {
 		// Set the state for this run of the walker.
@@ -362,6 +363,9 @@ func (g *Generator) generate(typeName string, includeJSON, includeYAML, includeS
 	if includeJSON {
 		g.buildJSONMethods(runs, typeName, runsThreshold)
 	}
+	if includeText {
+		g.buildTextMethods(runs, typeName, runsThreshold)
+	}
 	if includeYAML {
 		g.buildYAMLMethods(runs, typeName, runsThreshold)
 	}