1package extension
  2
  3import (
  4	"github.com/yuin/goldmark"
  5	gast "github.com/yuin/goldmark/ast"
  6	"github.com/yuin/goldmark/extension/ast"
  7	"github.com/yuin/goldmark/parser"
  8	"github.com/yuin/goldmark/renderer"
  9	"github.com/yuin/goldmark/renderer/html"
 10	"github.com/yuin/goldmark/text"
 11	"github.com/yuin/goldmark/util"
 12	"regexp"
 13)
 14
 15var taskListRegexp = regexp.MustCompile(`^\[([\sxX])\]\s*`)
 16
 17type taskCheckBoxParser struct {
 18}
 19
 20var defaultTaskCheckBoxParser = &taskCheckBoxParser{}
 21
 22// NewTaskCheckBoxParser returns a new  InlineParser that can parse
 23// checkboxes in list items.
 24// This parser must take precedence over the parser.LinkParser.
 25func NewTaskCheckBoxParser() parser.InlineParser {
 26	return defaultTaskCheckBoxParser
 27}
 28
 29func (s *taskCheckBoxParser) Trigger() []byte {
 30	return []byte{'['}
 31}
 32
 33func (s *taskCheckBoxParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
 34	// Given AST structure must be like
 35	// - List
 36	//   - ListItem         : parent.Parent
 37	//     - TextBlock      : parent
 38	//       (current line)
 39	if parent.Parent() == nil || parent.Parent().FirstChild() != parent {
 40		return nil
 41	}
 42
 43	if _, ok := parent.Parent().(*gast.ListItem); !ok {
 44		return nil
 45	}
 46	line, _ := block.PeekLine()
 47	m := taskListRegexp.FindSubmatchIndex(line)
 48	if m == nil {
 49		return nil
 50	}
 51	value := line[m[2]:m[3]][0]
 52	block.Advance(m[1])
 53	checked := value == 'x' || value == 'X'
 54	return ast.NewTaskCheckBox(checked)
 55}
 56
 57func (s *taskCheckBoxParser) CloseBlock(parent gast.Node, pc parser.Context) {
 58	// nothing to do
 59}
 60
 61// TaskCheckBoxHTMLRenderer is a renderer.NodeRenderer implementation that
 62// renders checkboxes in list items.
 63type TaskCheckBoxHTMLRenderer struct {
 64	html.Config
 65}
 66
 67// NewTaskCheckBoxHTMLRenderer returns a new TaskCheckBoxHTMLRenderer.
 68func NewTaskCheckBoxHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
 69	r := &TaskCheckBoxHTMLRenderer{
 70		Config: html.NewConfig(),
 71	}
 72	for _, opt := range opts {
 73		opt.SetHTMLOption(&r.Config)
 74	}
 75	return r
 76}
 77
 78// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
 79func (r *TaskCheckBoxHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
 80	reg.Register(ast.KindTaskCheckBox, r.renderTaskCheckBox)
 81}
 82
 83func (r *TaskCheckBoxHTMLRenderer) renderTaskCheckBox(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
 84	if !entering {
 85		return gast.WalkContinue, nil
 86	}
 87	n := node.(*ast.TaskCheckBox)
 88
 89	if n.IsChecked {
 90		w.WriteString(`<input checked="" disabled="" type="checkbox"`)
 91	} else {
 92		w.WriteString(`<input disabled="" type="checkbox"`)
 93	}
 94	if r.XHTML {
 95		w.WriteString(" /> ")
 96	} else {
 97		w.WriteString("> ")
 98	}
 99	return gast.WalkContinue, nil
100}
101
102type taskList struct {
103}
104
105// TaskList is an extension that allow you to use GFM task lists.
106var TaskList = &taskList{}
107
108func (e *taskList) Extend(m goldmark.Markdown) {
109	m.Parser().AddOptions(parser.WithInlineParsers(
110		util.Prioritized(NewTaskCheckBoxParser(), 0),
111	))
112	m.Renderer().AddOptions(renderer.WithNodeRenderers(
113		util.Prioritized(NewTaskCheckBoxHTMLRenderer(), 500),
114	))
115}