refactor(parser): simplify DocumentFragment rule (bytesparadise#1038)

also, refactor block delimiter tracking in preprocessing

Signed-off-by: Xavier Coulon <xcoulon@redhat.com>

pkg/parser/document_preprocessing.go

@@ -60,8 +60,8 @@ func preprocess(ctx *ParseContext, source io.Reader) (string, error) {
 				}
 				b.WriteString(f)
 			case *types.BlockDelimiter:
-				t.push(e.Kind, e.Length)
-				ctx.opts = append(ctx.opts, withinDelimitedBlock(t.withinDelimitedBlock()))
+				t.track(e.Kind, e.Length)
+				ctx.opts = append(ctx.opts, t.withinDelimitedBlock())
 				b.WriteString(e.RawText())
 			case types.ConditionalInclusion:
 				if content, ok := e.SingleLineContent(); ok {
@@ -81,6 +81,39 @@ func preprocess(ctx *ParseContext, source io.Reader) (string, error) {
 	return b.String(), nil
 }
 
+type blockDelimiterTracker struct {
+	stack []blockDelimiter
+}
+
+type blockDelimiter struct {
+	kind   string
+	length int
+}
+
+func newBlockDelimiterTracker() *blockDelimiterTracker {
+	return &blockDelimiterTracker{
+		stack: []blockDelimiter{},
+	}
+}
+
+func (t *blockDelimiterTracker) track(kind string, length int) {
+	switch {
+	case len(t.stack) > 0 && t.stack[len(t.stack)-1].kind == kind && t.stack[len(t.stack)-1].length == length:
+		// pop
+		t.stack = t.stack[:len(t.stack)-1]
+	default:
+		// push
+		t.stack = append(t.stack, blockDelimiter{
+			kind:   kind,
+			length: length,
+		})
+	}
+}
+
+func (t *blockDelimiterTracker) withinDelimitedBlock() Option {
+	return GlobalStore(withinDelimitedBlockKey, len(t.stack) > 0)
+}
+
 // replace the content of this FileInclusion element the content of the target file
 // note: there is a trade-off here: we include the whole content of the file in the current
 // fragment, making it potentially big, but at the same time we ensure that the context

pkg/parser/document_processing_parse_fragments.go

@@ -160,7 +160,7 @@ func reparseDelimitedBlock(ctx *ParseContext, b *types.DelimitedBlock) error {
 	switch b.Kind {
 	case types.Example, types.Quote, types.Sidebar, types.Open:
 		log.Debugf("parsing elements of delimited block of kind '%s'", b.Kind)
-		opts := append(ctx.opts, Entrypoint("DelimitedBlockElements"), withinDelimitedBlock(true))
+		opts := append(ctx.opts, Entrypoint("DelimitedBlockElements"))
 		elements, err := reparseElements(b.Elements, opts...)
 		if err != nil {
 			return err
@@ -238,6 +238,6 @@ func (c *current) isWithinLiteralParagraph() bool {
 		log.Debugf("within literal paragraph: %t", attrs[types.AttrStyle] == types.Literal)
 		return attrs[types.AttrPositional1] == types.Literal || attrs[types.AttrStyle] == types.Literal
 	}
-	log.Debug("not within literal paragraph")
+	// log.Debug("not within literal paragraph")
 	return false
 }