fix: take care of nil handlers, fixes #1

Author: CoolSpring8

.idea/watcherTasks.xml

@@ -42,9 +42,7 @@ func main() {
 			return lolhtml.Continue
 		},
 		nil,
-		func(*lolhtml.TextChunk) lolhtml.RewriterDirective {
-			return lolhtml.Continue
-		},
+		nil,
 	)
 	r, _ := rb.Build(
 		lolhtml.Config{

README.md

@@ -130,19 +130,32 @@ func (rb *RewriterBuilder) AddDocumentContentHandlers(
 	textChunkHandler TextChunkHandler,
 	docEndHandler DocEndHandler,
 ) {
+	var cCallbackDoctypePointer, cCallbackCommentPointer, cCallbackTextChunkPointer, cCallbackDocEndPointer *[0]byte
+	if doctypeHandler != nil {
+		cCallbackDoctypePointer = (*[0]byte)(C.callback_doctype)
+	}
+	if commentHandler != nil {
+		cCallbackCommentPointer = (*[0]byte)(C.callback_comment)
+	}
+	if textChunkHandler != nil {
+		cCallbackTextChunkPointer = (*[0]byte)(C.callback_text_chunk)
+	}
+	if docEndHandler != nil {
+		cCallbackDocEndPointer = (*[0]byte)(C.callback_doc_end)
+	}
 	doctypeHandlerPointer := pointer.Save(doctypeHandler)
 	commentHandlerPointer := pointer.Save(commentHandler)
 	textChunkHandlerPointer := pointer.Save(textChunkHandler)
 	docEndHandlerPointer := pointer.Save(docEndHandler)
 	C.lol_html_rewriter_builder_add_document_content_handlers(
 		(*C.lol_html_rewriter_builder_t)(rb),
-		(*[0]byte)(C.callback_doctype),
+		cCallbackDoctypePointer,
 		doctypeHandlerPointer,
-		(*[0]byte)(C.callback_comment),
+		cCallbackCommentPointer,
 		commentHandlerPointer,
-		(*[0]byte)(C.callback_text_chunk),
+		cCallbackTextChunkPointer,
 		textChunkHandlerPointer,
-		(*[0]byte)(C.callback_doc_end),
+		cCallbackDocEndPointer,
 		docEndHandlerPointer,
 	)
 }
@@ -153,17 +166,27 @@ func (rb *RewriterBuilder) AddElementContentHandlers(
 	commentHandler CommentHandler,
 	textChunkHandler TextChunkHandler,
 ) {
-	commentHandlerPointer := pointer.Save(commentHandler)
+	var cCallbackElementPointer, cCallbackCommentPointer, cCallbackTextChunkPointer *[0]byte
+	if elementHandler != nil {
+		cCallbackElementPointer = (*[0]byte)(C.callback_element)
+	}
+	if commentHandler != nil {
+		cCallbackCommentPointer = (*[0]byte)(C.callback_comment)
+	}
+	if textChunkHandler != nil {
+		cCallbackTextChunkPointer = (*[0]byte)(C.callback_text_chunk)
+	}
 	elementHandlerPointer := pointer.Save(elementHandler)
+	commentHandlerPointer := pointer.Save(commentHandler)
 	textChunkHandlerPointer := pointer.Save(textChunkHandler)
 	C.lol_html_rewriter_builder_add_element_content_handlers(
 		(*C.lol_html_rewriter_builder_t)(rb),
 		(*C.lol_html_selector_t)(selector),
-		(*[0]byte)(C.callback_element),
+		cCallbackElementPointer,
 		elementHandlerPointer,
-		(*[0]byte)(C.callback_comment),
+		cCallbackCommentPointer,
 		commentHandlerPointer,
-		(*[0]byte)(C.callback_text_chunk),
+		cCallbackTextChunkPointer,
 		textChunkHandlerPointer,
 	)
 }

lolhtml.go

@@ -126,7 +126,7 @@ func TestDoctypeApi(t *testing.T) {
 		},
 		nil,
 		nil,
-		func(*lolhtml.DocEnd) lolhtml.RewriterDirective { return lolhtml.Continue },
+		nil,
 	)
 	r, err := rb.Build(lolhtml.NewDefaultConfig())
 	if err != nil {
@@ -160,7 +160,7 @@ func TestCommentApi(t *testing.T) {
 			return lolhtml.Continue
 		},
 		nil,
-		func(*lolhtml.DocEnd) lolhtml.RewriterDirective { return lolhtml.Continue },
+		nil,
 	)
 	var finalText string
 	r, err := rb.Build(lolhtml.Config{
@@ -221,7 +221,7 @@ func TestTextChunkApi(t *testing.T) {
 			}
 			return lolhtml.Continue
 		},
-		func(*lolhtml.DocEnd) lolhtml.RewriterDirective { return lolhtml.Continue },
+		nil,
 	)
 	var finalText string
 	r, err := rb.Build(lolhtml.Config{