Add withprefix flag

README.md

@@ -158,6 +158,9 @@ The default value for `transform` flag is `noop` which means no transformation w
 If a prefix is provided via the `trimprefix` flag, it will be trimmed from the start of each name (before
 it is transformed). If a name doesn't have the prefix it will be passed unchanged.
 
+If a prefix is provided via the `addprefix` flag, it will be added to the start of each name (before
+it is transformed and after trimming).
+
 ## Inspiring projects
 
 - [Stringer](https://godoc.org/golang.org/x/tools/cmd/stringer)

golden_test.go

@@ -49,8 +49,12 @@ var goldenJSONAndSQL = []Golden{
 	{"prime", primeJsonAndSqlIn, primeJsonAndSqlOut},
 }
 
-var goldenPrefix = []Golden{
-	{"prefix", prefixIn, dayOut},
+var goldenTrimPrefix = []Golden{
+	{"trimprefix", trimPrefixIn, dayOut},
+}
+
+var goldenWithPrefix = []Golden{
+	{"withprefix", dayIn, prefixedDayOut},
 }
 
 // Each example starts with "type XXX [u]int", with a single space separating them.
@@ -117,6 +121,55 @@ func (i Day) IsADay() bool {
 }
 `
 
+const prefixedDayOut = `
+const _DayName = "DayMondayDayTuesdayDayWednesdayDayThursdayDayFridayDaySaturdayDaySunday"
+
+var _DayIndex = [...]uint8{0, 9, 19, 31, 42, 51, 62, 71}
+
+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]]
+}
+
+var _DayValues = []Day{0, 1, 2, 3, 4, 5, 6}
+
+var _DayNameToValueMap = map[string]Day{
+	_DayName[0:9]:   0,
+	_DayName[9:19]:  1,
+	_DayName[19:31]: 2,
+	_DayName[31:42]: 3,
+	_DayName[42:51]: 4,
+	_DayName[51:62]: 5,
+	_DayName[62:71]: 6,
+}
+
+// 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
+	}
+	return 0, fmt.Errorf("%s does not belong to Day values", s)
+}
+
+// DayValues returns all values of the enum
+func DayValues() []Day {
+	return _DayValues
+}
+
+// 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
+}
+`
+
 // Enumeration with an offset.
 // Also includes a duplicate.
 const offsetIn = `type Number int
@@ -1010,7 +1063,7 @@ func (i *Prime) Scan(value interface{}) error {
 }
 `
 
-const prefixIn = `type Day int
+const trimPrefixIn = `type Day int
 const (
 	DayMonday Day = iota
 	DayTuesday
@@ -1024,29 +1077,32 @@ const (
 
 func TestGolden(t *testing.T) {
 	for _, test := range golden {
-		runGoldenTest(t, test, false, false, false, false, "")
+		runGoldenTest(t, test, false, false, false, false, "", "")
 	}
 	for _, test := range goldenJSON {
-		runGoldenTest(t, test, true, false, false, false, "")
+		runGoldenTest(t, test, true, false, false, false, "", "")
 	}
 	for _, test := range goldenText {
-		runGoldenTest(t, test, false, false, false, true, "")
+		runGoldenTest(t, test, false, false, false, true, "", "")
 	}
 	for _, test := range goldenYAML {
-		runGoldenTest(t, test, false, true, false, false, "")
+		runGoldenTest(t, test, false, true, false, false, "", "")
 	}
 	for _, test := range goldenSQL {
-		runGoldenTest(t, test, false, false, true, false, "")
+		runGoldenTest(t, test, false, false, true, false, "", "")
 	}
 	for _, test := range goldenJSONAndSQL {
-		runGoldenTest(t, test, true, false, true, false, "")
+		runGoldenTest(t, test, true, false, true, false, "", "")
 	}
-	for _, test := range goldenPrefix {
-		runGoldenTest(t, test, false, false, false, false, "Day")
+	for _, test := range goldenTrimPrefix {
+		runGoldenTest(t, test, false, false, false, false, "Day", "")
+	}
+	for _, test := range goldenWithPrefix {
+		runGoldenTest(t, test, false, false, false, false, "", "Day")
 	}
 }
 
-func runGoldenTest(t *testing.T, test Golden, generateJSON, generateYAML, generateSQL, generateText bool, prefix string) {
+func runGoldenTest(t *testing.T, test Golden, generateJSON, generateYAML, generateSQL, generateText bool, trimPrefix string, prefix string) {
 	var g Generator
 	input := "package test\n" + test.input
 	file := test.name + ".go"
@@ -1056,7 +1112,7 @@ 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, generateText, "noop", prefix)
+	g.generate(tokens[1], generateJSON, generateYAML, generateSQL, generateText, "noop", trimPrefix, 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

@@ -41,6 +41,7 @@ var (
 	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: \"\"")
+	addPrefix       = flag.String("addprefix", "", "transform each item name by adding a prefix. Default: \"\"")
 )
 
 // Usage is a replacement usage function for the flags package.
@@ -103,7 +104,7 @@ func main() {
 
 	// Run generate for each type.
 	for _, typeName := range types {
-		g.generate(typeName, *json, *yaml, *sql, *text, *transformMethod, *trimPrefix)
+		g.generate(typeName, *json, *yaml, *sql, *text, *transformMethod, *trimPrefix, *addPrefix)
 	}
 
 	// Format the output.
@@ -302,8 +303,16 @@ func (g *Generator) trimValueNames(values []Value, prefix string) {
 	}
 }
 
+// prefixValueNames adds a prefix to each name
+func (g *Generator) prefixValueNames(values []Value, prefix string) {
+	for i := range values {
+		values[i].name = prefix + values[i].name
+	}
+}
+
 // generate produces the String method for the named type.
-func (g *Generator) generate(typeName string, includeJSON, includeYAML, includeSQL, includeText bool, transformMethod string, trimPrefix string) {
+func (g *Generator) generate(typeName string, includeJSON, includeYAML, includeSQL, includeText bool,
+	transformMethod string, trimPrefix string, addPrefix string) {
 	values := make([]Value, 0, 100)
 	for _, file := range g.pkg.files {
 		// Set the state for this run of the walker.
@@ -321,6 +330,8 @@ func (g *Generator) generate(typeName string, includeJSON, includeYAML, includeS
 
 	g.trimValueNames(values, trimPrefix)
 
+	g.prefixValueNames(values, addPrefix)
+
 	g.transformValueNames(values, transformMethod)
 
 	runs := splitIntoRuns(values)