✨ Add IncrementalStep* Generators

generators.go

@@ -2,6 +2,7 @@ package nomino
 
 import (
 	"errors"
+	"fmt"
 	"strconv"
 	"time"
 
@@ -105,26 +106,56 @@ func Incremental() Generator {
 	return IncrementalWithStartAndStep(0, 1)
 }
 
+// IncrementalFormat generates a name that is a series of integers starting at 0, formatted with Printf
+// This is mostly likely useful with a format like "%02d"
+func IncrementalFormat(format string) Generator {
+	return IncrementalFormatWithStartAndStep(0, 1, format)
+}
+
 // IncrementalWithStart generates a name that is a series of integers starting at the specified number
 func IncrementalWithStart(start int) Generator {
 	return IncrementalWithStartAndStep(start, 1)
 }
 
+// IncrementalFormatWithStart generates a name that is a series of integers starting at the specified number, formatted with Printf
+func IncrementalFormatWithStart(start int, format string) Generator {
+	return IncrementalFormatWithStartAndStep(start, 1, format)
+}
+
 // IncrementalWithStep generates a name that is a series of integers, starting at 0, and increasing the specified number each time
 func IncrementalWithStep(step int) Generator {
 	return IncrementalWithStartAndStep(0, step)
 }
 
-// InrementalWithStartAndStep generates a name that is a series of integers, starting at the specified number, and increasing the specified step each time
-func IncrementalWithStartAndStep(start, step int) Generator {
+// IncrementalFormatWithStep generates a name that is a series of integers, starting at 0, and increasing the specified number each time,
+// formatted with Printf
+func IncrementalFormatWithStep(step int, format string) Generator {
+	return IncrementalFormatWithStartAndStep(0, step, format)
+}
+
+func incrementalHelper(start, step int, cb func(int) string) Generator {
 	next := start
 	return func(*Config) (string, error) {
-		out := strconv.Itoa(next)
+		out := cb(next)
 		next += step
 		return out, nil
 	}
 }
 
+// InrementalWithStartAndStep generates a name that is a series of integers, starting at the specified number,
+// and increasing the specified step each time
+func IncrementalWithStartAndStep(start, step int) Generator {
+	return incrementalHelper(start, step, strconv.Itoa)
+}
+
+// IncrementalFormatWithStartAndStep generates a name that is a series of integers, starting at the specified number,
+// and increasing the specified step each time, formatted with Printf
+func IncrementalFormatWithStartAndStep(start, step int, format string) Generator {
+	return incrementalHelper(start, step, func(i int) string {
+		return fmt.Sprintf(format, i)
+	})
+}
+
 // ErrMissingOriginal is the error returned by Slug if there is no filename
 var ErrMissingOriginal = errors.New("missing original filename")
 

generators_examples_test.go

@@ -91,6 +91,61 @@ func ExampleIncrementalWithStartAndStep() {
 	// foo_46.txt
 }
 
+func ExampleIncrementalFormat() {
+	conf := NewConfig(
+		WithPrefix("foo"),
+		WithGenerator(IncrementalFormat("%03d")),
+	)
+
+	str, _ := Make(conf)
+	fmt.Println(str)
+
+	str, _ = Make(conf)
+	fmt.Println(str)
+
+	str, _ = Make(conf)
+	fmt.Println(str)
+
+	// Output:
+	// foo_000.txt
+	// foo_001.txt
+	// foo_002.txt
+}
+
+func ExampleIncrementalFormatWithStart() {
+	conf := NewConfig(
+		WithPrefix("foo"),
+		WithGenerator(IncrementalFormatWithStart(9, "%02d")),
+	)
+
+	str, _ := Make(conf)
+	fmt.Println(str)
+
+	str, _ = Make(conf)
+	fmt.Println(str)
+
+	// Output:
+	// foo_09.txt
+	// foo_10.txt
+}
+
+func ExampleIncrementalFormatWithStep() {
+	conf := NewConfig(
+		WithPrefix("foo"),
+		WithGenerator(IncrementalFormatWithStep(10, "%02d")),
+	)
+
+	str, _ := Make(conf)
+	fmt.Println(str)
+
+	str, _ = Make(conf)
+	fmt.Println(str)
+
+	// Output:
+	// foo_00.txt
+	// foo_10.txt
+}
+
 func ExampleSlug() {
 	conf := NewConfig(WithGenerator(Slug()), WithOriginal("My name is Jimmy"))
 	str, _ := Make(conf)