Remove stringutil

Go has generics now, so such utilities are not generally useful.
Libraries should have generic utilities instead.

validator/stringutil.go

@@ -0,0 +1,18 @@
+package validator
+
+func mapString(in []string, f func(string) string) []string {
+	res := make([]string, 0, len(in))
+	for _, s := range in {
+		res = append(res, f(s))
+	}
+	return res
+}
+
+func containsString(in []string, element string) bool {
+	for _, a := range in {
+		if a == element {
+			return true
+		}
+	}
+	return false
+}

validator/validators.go

@@ -3,7 +3,6 @@ package validator
 import (
 	"errors"
 	"github.com/lithictech/go-aperitif/kronos"
-	"github.com/lithictech/go-aperitif/stringutil"
 	"github.com/rgalanakis/validator"
 	"net/url"
 	"regexp"
@@ -92,7 +91,7 @@ func validateEnumImpl(v interface{}, param string, mapper func(string) string) e
 		return err
 	}
 	if mapper != nil {
-		choices = stringutil.Map(choices, mapper)
+		choices = mapString(choices, mapper)
 	}
 
 	if s, ok := v.(string); ok {
@@ -110,7 +109,7 @@ func validateEnumImpl(v interface{}, param string, mapper func(string) string) e
 			return validator.ErrBadParameter
 		}
 		if mapper != nil {
-			ss = stringutil.Map(ss, mapper)
+			ss = mapString(ss, mapper)
 		}
 		return validateEnumImplSlice(ss, choices)
 	}
@@ -139,7 +138,7 @@ func validateEnumImplStr(s string, choices []string, optional bool) error {
 
 func validateEnumImplSlice(ss []string, choices []string) error {
 	for _, s := range ss {
-		if !stringutil.Contains(choices, s) {
+		if !containsString(choices, s) {
 			return newError("element not one of " + strings.Join(choices, "|"))
 		}
 	}