Add go dependencies for mdtoc

vendor/github.com/mmarkdown/mmark/mast/index.go

@@ -0,0 +1,34 @@
+package mast
+
+import "github.com/gomarkdown/markdown/ast"
+
+// DocumentIndex represents markdown document index node.
+type DocumentIndex struct {
+	ast.Container
+}
+
+// IndexItem contains an index for the indices section.
+type IndexItem struct {
+	ast.Container
+
+	*ast.Index
+}
+
+// IndexSubItem contains an sub item index for the indices section.
+type IndexSubItem struct {
+	ast.Container
+
+	*ast.Index
+}
+
+// IndexLetter has the Letter of this index item.
+type IndexLetter struct {
+	ast.Container
+}
+
+// IndexLink links to the index in the document.
+type IndexLink struct {
+	*ast.Link
+
+	Primary bool
+}