add typst export

pkg/cat/entry.go

@@ -0,0 +1,32 @@
+package cat
+
+type entry struct {
+	name     string
+	fqname   string
+	content  string
+	children []entry
+}
+
+func (e entry) filter(ok func(e entry) bool) entry {
+	children := make([]entry, 0, len(e.children))
+	for _, entry := range e.children {
+		if !ok(entry) {
+			continue
+		}
+		children = append(children, entry.filter(ok))
+	}
+
+	return entry{
+		name:     e.name,
+		fqname:   e.fqname,
+		content:  e.content,
+		children: children,
+	}
+}
+
+func (e entry) traverse(lvl int, do func(e entry, lvl int)) {
+	do(e, lvl)
+	for _, entry := range e.children {
+		entry.traverse(lvl+1, do)
+	}
+}