- add ReplaceRawByCallback

docx.go

@@ -93,6 +93,10 @@ func (d *Docx) ReplaceRaw(oldString string, newString string, num int) {
 	d.content = strings.Replace(d.content, oldString, newString, num)
 }
 
+func (d *Docx) ReplaceRawByCallback(callback func(content string) string) {
+	d.content = callback(d.content)
+}
+
 func (d *Docx) Replace(oldString string, newString string, num int) (err error) {
 	oldString, err = encode(oldString)
 	if err != nil {

docx_test.go

@@ -5,6 +5,7 @@ import (
 	"embed"
 	"fmt"
 	"io/ioutil"
+	"regexp"
 	"strings"
 	"testing"
 )
@@ -104,6 +105,24 @@ func TestReplace(t *testing.T) {
 	}
 }
 
+func TestReplaceRawByCallback(t *testing.T) {
+	d := loadFile(testFile)
+
+	d.ReplaceRawByCallback(func(oldContent string) string {
+		return regexp.
+			MustCompile(`document\.`).
+			ReplaceAllStringFunc(oldContent, func(src string) string {
+				return "line1\r\nline2"
+			})
+	})
+
+	d.WriteToFile(testFileResult)
+	d = loadFile(testFileResult)
+	if strings.Contains(d.content, "word document.") {
+		t.Error("Should not contain 'word document.' after replacement, got ", d.content)
+	}
+}
+
 // To make test failure messages easier to read, trim off the beginning and end of the document to focus on the part expected
 // to have changed
 func extractMiddle(start, end int, content string) string {