Option to add a ToString interface where numeric-based strings are generated

README.md

@@ -26,6 +26,8 @@ Flags:
         if true, json marshaling methods will be generated. Default: false
   -linecomment
         use line comment text as printed text when present
+  -tostring
+        if true, ToString function that returns an number-based string will be generated. Default: false
   -output string
         output file name; default srcdir/<type>_string.go
   -sql
@@ -71,6 +73,9 @@ When Enumer is applied to a type, it will generate:
   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.
   Useful when storing the enum in a database.
+- When the flag `tostring` is provided, the methods for implementing the `ToString` interfaces.
+  the `ToString` interface, Instead of an enumerated string, get a defined number-based string.
+
 
 
 For example, if we have an enum type called `Pill`,

golden_test.go

@@ -33,6 +33,15 @@ var golden = []Golden{
 	{"prime", primeIn},
 }
 
+var goldenToString = []Golden{
+	{"tostring_day", dayIn},
+	{"tostring_offset", offsetIn},
+	{"tostring_gap", gapIn},
+	{"tostring_num", numIn},
+	{"tostring_unum", unumIn},
+	{"tostring_prime", primeIn},
+}
+
 var goldenJSON = []Golden{
 	{"primeJson", primeJsonIn},
 }
@@ -315,45 +324,48 @@ const (
 
 func TestGolden(t *testing.T) {
 	for _, test := range golden {
-		runGoldenTest(t, test, false, false, false, false, false, false, true, "", "")
+		runGoldenTest(t, test, false, false, false, false, false, false, true, false, "", "")
+	}
+	for _, test := range goldenToString {
+		runGoldenTest(t, test, false, false, false, false, false, false, false, true, "", "")
 	}
 	for _, test := range goldenJSON {
-		runGoldenTest(t, test, true, false, false, false, false, false, false, "", "")
+		runGoldenTest(t, test, true, false, false, false, false, false, false, false, "", "")
 	}
 	for _, test := range goldenText {
-		runGoldenTest(t, test, false, false, false, true, false, false, false, "", "")
+		runGoldenTest(t, test, false, false, false, true, false, false, false, false, "", "")
 	}
 	for _, test := range goldenYAML {
-		runGoldenTest(t, test, false, true, false, false, false, false, false, "", "")
+		runGoldenTest(t, test, false, true, false, false, false, false, false, false, "", "")
 	}
 	for _, test := range goldenSQL {
-		runGoldenTest(t, test, false, false, true, false, false, false, false, "", "")
+		runGoldenTest(t, test, false, false, true, false, false, false, false, false, "", "")
 	}
 	for _, test := range goldenJSONAndSQL {
-		runGoldenTest(t, test, true, false, true, false, false, false, false, "", "")
+		runGoldenTest(t, test, true, false, true, false, false, false, false, false, "", "")
 	}
 	for _, test := range goldenGQLGen {
-		runGoldenTest(t, test, false, false, false, false, false, true, false, "", "")
+		runGoldenTest(t, test, false, false, false, false, false, true, false, false, "", "")
 	}
 	for _, test := range goldenTrimPrefix {
-		runGoldenTest(t, test, false, false, false, false, false, false, false, "Day", "")
+		runGoldenTest(t, test, false, false, false, false, false, false, false, false, "Day", "")
 	}
 	for _, test := range goldenTrimPrefixMultiple {
-		runGoldenTest(t, test, false, false, false, false, false, false, false, "Day,Night", "")
+		runGoldenTest(t, test, false, false, false, false, false, false, false, false, "Day,Night", "")
 	}
 	for _, test := range goldenWithPrefix {
-		runGoldenTest(t, test, false, false, false, false, false, false, false, "", "Day")
+		runGoldenTest(t, test, false, false, false, false, false, false, false, false, "", "Day")
 	}
 	for _, test := range goldenTrimAndAddPrefix {
-		runGoldenTest(t, test, false, false, false, false, false, false, false, "Day", "Night")
+		runGoldenTest(t, test, false, false, false, false, false, false, false, false, "Day", "Night")
 	}
 	for _, test := range goldenLinecomment {
-		runGoldenTest(t, test, false, false, false, false, true, false, false, "", "")
+		runGoldenTest(t, test, false, false, false, false, true, false, false, false, "", "")
 	}
 }
 
 func runGoldenTest(t *testing.T, test Golden,
-	generateJSON, generateYAML, generateSQL, generateText, linecomment, generateGQLGen, generateValuesMethod bool,
+	generateJSON, generateYAML, generateSQL, generateText, linecomment, generateGQLGen, generateValuesMethod, toString bool,
 	trimPrefix string, prefix string) {
 
 	var g Generator
@@ -382,7 +394,7 @@ func runGoldenTest(t *testing.T, test Golden,
 	if len(tokens) != 3 {
 		t.Fatalf("%s: need type declaration on first line", test.name)
 	}
-	g.generate(tokens[1], generateJSON, generateYAML, generateSQL, generateText, generateGQLGen, "noop", trimPrefix, prefix, linecomment, generateValuesMethod)
+	g.generate(tokens[1], generateJSON, generateYAML, generateSQL, generateText, generateGQLGen, "noop", trimPrefix, prefix, linecomment, generateValuesMethod, toString)
 	got := string(g.format())
 	if got != loadGolden(test.name) {
 		// Use this to help build a golden text when changes are needed

stringer.go

@@ -56,6 +56,7 @@ var (
 	trimPrefix      = flag.String("trimprefix", "", "transform each item name by removing a prefix. Default: \"\"")
 	addPrefix       = flag.String("addprefix", "", "transform each item name by adding a prefix. Default: \"\"")
 	linecomment     = flag.Bool("linecomment", false, "use line comment text as printed text when present")
+	tostring        = flag.Bool("tostring", false, "if true, ToString function that returns an number-based string will be generated. Default: false")
 )
 
 var comments arrayFlags
@@ -135,7 +136,7 @@ func main() {
 
 	// Run generate for each type.
 	for _, typeName := range typs {
-		g.generate(typeName, *json, *yaml, *sql, *text, *gqlgen, *transformMethod, *trimPrefix, *addPrefix, *linecomment, *altValuesFunc)
+		g.generate(typeName, *json, *yaml, *sql, *text, *gqlgen, *transformMethod, *trimPrefix, *addPrefix, *linecomment, *altValuesFunc, *tostring)
 	}
 
 	// Format the output.
@@ -415,7 +416,8 @@ func (g *Generator) prefixValueNames(values []Value, prefix string) {
 // generate produces the String method for the named type.
 func (g *Generator) generate(typeName string,
 	includeJSON, includeYAML, includeSQL, includeText, includeGQLGen bool,
-	transformMethod string, trimPrefix string, addPrefix string, lineComment bool, includeValuesMethod bool) {
+	transformMethod string, trimPrefix string, addPrefix string, lineComment bool, includeValuesMethod bool,
+	toString bool) {
 	values := make([]Value, 0, 100)
 	for _, file := range g.pkg.files {
 		file.lineComment = lineComment
@@ -465,6 +467,9 @@ func (g *Generator) generate(typeName string,
 	if includeValuesMethod {
 		g.buildAltStringValuesMethod(typeName)
 	}
+	if toString {
+		g.buildToStringMethod(typeName)
+	}
 
 	g.buildNoOpOrderChangeDetect(runs, typeName)
 
@@ -774,9 +779,10 @@ func (g *Generator) buildOneRun(runs [][]Value, typeName string) {
 }
 
 // Arguments to format are:
-// 	[1]: type name
-// 	[2]: size of index element (8 for uint8 etc.)
-// 	[3]: less than zero check (for signed types)
+//
+//	[1]: type name
+//	[2]: size of index element (8 for uint8 etc.)
+//	[3]: less than zero check (for signed types)
 const stringOneRun = `func (i %[1]s) String() string {
 	if %[3]si >= %[1]s(len(_%[1]sIndex)-1) {
 		return fmt.Sprintf("%[1]s(%%d)", i)
@@ -786,10 +792,11 @@ const stringOneRun = `func (i %[1]s) String() string {
 `
 
 // Arguments to format are:
-// 	[1]: type name
-// 	[2]: lowest defined value for type, as a string
-// 	[3]: size of index element (8 for uint8 etc.)
-// 	[4]: less than zero check (for signed types)
+//
+//	[1]: type name
+//	[2]: lowest defined value for type, as a string
+//	[3]: size of index element (8 for uint8 etc.)
+//	[4]: less than zero check (for signed types)
 const stringOneRunWithOffset = `func (i %[1]s) String() string {
 	i -= %[2]s
 	if %[4]si >= %[1]s(len(_%[1]sIndex)-1) {
@@ -868,3 +875,18 @@ const stringMap = `func (i %[1]s) String() string {
 	return fmt.Sprintf("%[1]s(%%d)", i)
 }
 `
+
+func (g *Generator) buildToStringMethod(typeName string) {
+	g.Printf(toStringFromInt, typeName)
+}
+
+// Arguments to format are:
+//
+//	[1]: type name
+//	[2]: size of index element (8 for uint8 etc.)
+//	[3]: less than zero check (for signed types)
+const toStringFromInt = `// ToString converts %[1]s to an int-based string and returns it.
+func (i %[1]s) ToString() string {
+	return strconv.Itoa(int(i))
+}
+`

testdata/tostring_day.golden

@@ -0,0 +1,95 @@
+
+const _DayName = "MondayTuesdayWednesdayThursdayFridaySaturdaySunday"
+
+var _DayIndex = [...]uint8{0, 6, 13, 22, 30, 36, 44, 50}
+
+const _DayLowerName = "mondaytuesdaywednesdaythursdayfridaysaturdaysunday"
+
+func (i Day) String() string {
+	if i < 0 || i >= Day(len(_DayIndex)-1) {
+		return fmt.Sprintf("Day(%d)", i)
+	}
+	return _DayName[_DayIndex[i]:_DayIndex[i+1]]
+}
+
+// ToString converts Day to an int-based string and returns it.
+func (i Day) ToString() string {
+	return strconv.Itoa(int(i))
+}
+
+// An "invalid array index" compiler error signifies that the constant values have changed.
+// Re-run the stringer command to generate them again.
+func _DayNoOp() {
+	var x [1]struct{}
+	_ = x[Monday-(0)]
+	_ = x[Tuesday-(1)]
+	_ = x[Wednesday-(2)]
+	_ = x[Thursday-(3)]
+	_ = x[Friday-(4)]
+	_ = x[Saturday-(5)]
+	_ = x[Sunday-(6)]
+}
+
+var _DayValues = []Day{Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday}
+
+var _DayNameToValueMap = map[string]Day{
+	_DayName[0:6]:        Monday,
+	_DayLowerName[0:6]:   Monday,
+	_DayName[6:13]:       Tuesday,
+	_DayLowerName[6:13]:  Tuesday,
+	_DayName[13:22]:      Wednesday,
+	_DayLowerName[13:22]: Wednesday,
+	_DayName[22:30]:      Thursday,
+	_DayLowerName[22:30]: Thursday,
+	_DayName[30:36]:      Friday,
+	_DayLowerName[30:36]: Friday,
+	_DayName[36:44]:      Saturday,
+	_DayLowerName[36:44]: Saturday,
+	_DayName[44:50]:      Sunday,
+	_DayLowerName[44:50]: Sunday,
+}
+
+var _DayNames = []string{
+	_DayName[0:6],
+	_DayName[6:13],
+	_DayName[13:22],
+	_DayName[22:30],
+	_DayName[30:36],
+	_DayName[36:44],
+	_DayName[44:50],
+}
+
+// DayString retrieves an enum value from the enum constants string name.
+// Throws an error if the param is not part of the enum.
+func DayString(s string) (Day, error) {
+	if val, ok := _DayNameToValueMap[s]; ok {
+		return val, nil
+	}
+
+	if val, ok := _DayNameToValueMap[strings.ToLower(s)]; ok {
+		return val, nil
+	}
+	return 0, fmt.Errorf("%s does not belong to Day values", s)
+}
+
+// DayValues returns all values of the enum
+func DayValues() []Day {
+	return _DayValues
+}
+
+// DayStrings returns a slice of all String values of the enum
+func DayStrings() []string {
+	strs := make([]string, len(_DayNames))
+	copy(strs, _DayNames)
+	return strs
+}
+
+// IsADay returns "true" if the value is listed in the enum definition. "false" otherwise
+func (i Day) IsADay() bool {
+	for _, v := range _DayValues {
+		if i == v {
+			return true
+		}
+	}
+	return false
+}