Merge pull request #9 from m-mizutani/enhance/mask-string

enhance(filter): Update MaskWithSymbol

redactor.go

@@ -1,6 +1,7 @@
 package masq
 
 import (
+	"fmt"
 	"reflect"
 	"strings"
 )
@@ -31,9 +32,12 @@ func RedactString(redact func(s string) string) Redactor {
 	}
 }
 
-// MaskString is a redactor to redact string value with masked string that have the same length as the source string value. It can help the developer to know the length of the string value. The returned Redact function always returns true if the source value is string. Otherwise, it returns false.
-func MaskString(masking rune) Redactor {
+// MaskWithSymbol is a redactor to redact string value with masked string that have the same length as the source string value. It can help the developer to know the length of the string value. The returned Redact function always returns true if the source value is string. Otherwise, it returns false.
+func MaskWithSymbol(symbol rune, max int) Redactor {
 	return RedactString(func(s string) string {
-		return strings.Repeat(string(masking), len(s))
+		if len(s) > max {
+			return strings.Repeat(string(symbol), max) + fmt.Sprintf(" (remained %d chars)", len(s)-max)
+		}
+		return strings.Repeat(string(symbol), len(s))
 	})
 }

redactor_test.go

@@ -4,24 +4,27 @@ import (
 	"github.com/m-mizutani/masq"
 )
 
-func ExampleMaskString() {
+func ExampleMaskWithSymbol() {
 	out := &fixedTimeWriter{}
 
 	type myRecord struct {
 		ID    string
 		Phone string
+		Email string
 	}
 	record := myRecord{
 		ID:    "m-mizutani",
 		Phone: "090-0000-0000",
+		// too long email address
+		Email: "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx@example.com",
 	}
 
 	logger := newLogger(out, masq.New(
-		// custom redactor
-		masq.WithFieldName("Phone", masq.MaskString('*')),
+		masq.WithFieldName("Phone", masq.MaskWithSymbol('*', 32)),
+		masq.WithFieldName("Email", masq.MaskWithSymbol('*', 12)),
 	))
 	logger.With("record", record).Info("Got record")
 	out.Flush()
 	// Output:
-	// {"level":"INFO","msg":"Got record","record":{"ID":"m-mizutani","Phone":"*************"},"time":"2022-12-25T09:00:00.123456789"}
+	// {"level":"INFO","msg":"Got record","record":{"Email":"************ (remained 36 chars)","ID":"m-mizutani","Phone":"*************"},"time":"2022-12-25T09:00:00.123456789"}
 }