package extension import ( "regexp" "github.com/yuin/goldmark" gast "github.com/yuin/goldmark/ast" "github.com/yuin/goldmark/extension/ast" "github.com/yuin/goldmark/parser" "github.com/yuin/goldmark/renderer" "github.com/yuin/goldmark/renderer/html" "github.com/yuin/goldmark/text" "github.com/yuin/goldmark/util" ) var taskListRegexp = regexp.MustCompile(`^\[([\sxX])\]\s*`) type taskCheckBoxParser struct { } var defaultTaskCheckBoxParser = &taskCheckBoxParser{} // NewTaskCheckBoxParser returns a new InlineParser that can parse // checkboxes in list items. // This parser must take precedence over the parser.LinkParser. func NewTaskCheckBoxParser() parser.InlineParser { return defaultTaskCheckBoxParser } func (s *taskCheckBoxParser) Trigger() []byte { return []byte{'['} } func (s *taskCheckBoxParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node { // Given AST structure must be like // - List // - ListItem : parent.Parent // - TextBlock : parent // (current line) if parent.Parent() == nil || parent.Parent().FirstChild() != parent { return nil } if parent.HasChildren() { return nil } if _, ok := parent.Parent().(*gast.ListItem); !ok { return nil } line, _ := block.PeekLine() m := taskListRegexp.FindSubmatchIndex(line) if m == nil { return nil } value := line[m[2]:m[3]][0] block.Advance(m[1]) checked := value == 'x' || value == 'X' return ast.NewTaskCheckBox(checked) } func (s *taskCheckBoxParser) CloseBlock(parent gast.Node, pc parser.Context) { // nothing to do } // TaskCheckBoxHTMLRenderer is a renderer.NodeRenderer implementation that // renders checkboxes in list items. type TaskCheckBoxHTMLRenderer struct { html.Config } // NewTaskCheckBoxHTMLRenderer returns a new TaskCheckBoxHTMLRenderer. func NewTaskCheckBoxHTMLRenderer(opts ...html.Option) renderer.NodeRenderer { r := &TaskCheckBoxHTMLRenderer{ Config: html.NewConfig(), } for _, opt := range opts { opt.SetHTMLOption(&r.Config) } return r } // RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs. func (r *TaskCheckBoxHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) { reg.Register(ast.KindTaskCheckBox, r.renderTaskCheckBox) } func (r *TaskCheckBoxHTMLRenderer) renderTaskCheckBox( w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) { if !entering { return gast.WalkContinue, nil } n := node.(*ast.TaskCheckBox) if n.IsChecked { _, _ = w.WriteString(` ") } else { _, _ = w.WriteString("> ") } return gast.WalkContinue, nil } type taskList struct { } // TaskList is an extension that allow you to use GFM task lists. var TaskList = &taskList{} func (e *taskList) Extend(m goldmark.Markdown) { m.Parser().AddOptions(parser.WithInlineParsers( util.Prioritized(NewTaskCheckBoxParser(), 0), )) m.Renderer().AddOptions(renderer.WithNodeRenderers( util.Prioritized(NewTaskCheckBoxHTMLRenderer(), 500), )) }