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forgejo/modules/markup/markdown/goldmark.go
zeripath 88c2e24360
Add KaTeX rendering to Markdown. (#20571)
This PR adds mathematical rendering with KaTeX.

The first step is to add a Goldmark extension that detects the latex
(and tex) mathematics delimiters.

The second step to make this extension only run if math support is
enabled.

The second step is to then add KaTeX CSS and JS to the head which will
load after the dom is rendered.

Fix #3445

Signed-off-by: Andrew Thornton <art27@cantab.net>

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
2022-09-14 00:33:37 +08:00

398 lines
10 KiB
Go

// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package markdown
import (
"bytes"
"fmt"
"regexp"
"strings"
"code.gitea.io/gitea/modules/markup"
"code.gitea.io/gitea/modules/markup/common"
"code.gitea.io/gitea/modules/setting"
giteautil "code.gitea.io/gitea/modules/util"
"github.com/yuin/goldmark/ast"
east "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 byteMailto = []byte("mailto:")
// ASTTransformer is a default transformer of the goldmark tree.
type ASTTransformer struct{}
// Transform transforms the given AST tree.
func (g *ASTTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
firstChild := node.FirstChild()
createTOC := false
ctx := pc.Get(renderContextKey).(*markup.RenderContext)
rc := pc.Get(renderConfigKey).(*RenderConfig)
if rc.yamlNode != nil {
metaNode := rc.toMetaNode()
if metaNode != nil {
node.InsertBefore(node, firstChild, metaNode)
}
createTOC = rc.TOC
ctx.TableOfContents = make([]markup.Header, 0, 100)
}
_ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
switch v := n.(type) {
case *ast.Heading:
for _, attr := range v.Attributes() {
if _, ok := attr.Value.([]byte); !ok {
v.SetAttribute(attr.Name, []byte(fmt.Sprintf("%v", attr.Value)))
}
}
text := n.Text(reader.Source())
header := markup.Header{
Text: util.BytesToReadOnlyString(text),
Level: v.Level,
}
if id, found := v.AttributeString("id"); found {
header.ID = util.BytesToReadOnlyString(id.([]byte))
}
ctx.TableOfContents = append(ctx.TableOfContents, header)
case *ast.Image:
// Images need two things:
//
// 1. Their src needs to munged to be a real value
// 2. If they're not wrapped with a link they need a link wrapper
// Check if the destination is a real link
link := v.Destination
if len(link) > 0 && !markup.IsLink(link) {
prefix := pc.Get(urlPrefixKey).(string)
if pc.Get(isWikiKey).(bool) {
prefix = giteautil.URLJoin(prefix, "wiki", "raw")
}
prefix = strings.Replace(prefix, "/src/", "/media/", 1)
lnk := strings.TrimLeft(string(link), "/")
lnk = giteautil.URLJoin(prefix, lnk)
link = []byte(lnk)
}
v.Destination = link
parent := n.Parent()
// Create a link around image only if parent is not already a link
if _, ok := parent.(*ast.Link); !ok && parent != nil {
next := n.NextSibling()
// Create a link wrapper
wrap := ast.NewLink()
wrap.Destination = link
wrap.Title = v.Title
wrap.SetAttributeString("target", []byte("_blank"))
// Duplicate the current image node
image := ast.NewImage(ast.NewLink())
image.Destination = link
image.Title = v.Title
for _, attr := range v.Attributes() {
image.SetAttribute(attr.Name, attr.Value)
}
for child := v.FirstChild(); child != nil; {
next := child.NextSibling()
image.AppendChild(image, child)
child = next
}
// Append our duplicate image to the wrapper link
wrap.AppendChild(wrap, image)
// Wire in the next sibling
wrap.SetNextSibling(next)
// Replace the current node with the wrapper link
parent.ReplaceChild(parent, n, wrap)
// But most importantly ensure the next sibling is still on the old image too
v.SetNextSibling(next)
}
case *ast.Link:
// Links need their href to munged to be a real value
link := v.Destination
if len(link) > 0 && !markup.IsLink(link) &&
link[0] != '#' && !bytes.HasPrefix(link, byteMailto) {
// special case: this is not a link, a hash link or a mailto:, so it's a
// relative URL
lnk := string(link)
if pc.Get(isWikiKey).(bool) {
lnk = giteautil.URLJoin("wiki", lnk)
}
link = []byte(giteautil.URLJoin(pc.Get(urlPrefixKey).(string), lnk))
}
if len(link) > 0 && link[0] == '#' {
link = []byte("#user-content-" + string(link)[1:])
}
v.Destination = link
case *ast.List:
if v.HasChildren() {
children := make([]ast.Node, 0, v.ChildCount())
child := v.FirstChild()
for child != nil {
children = append(children, child)
child = child.NextSibling()
}
v.RemoveChildren(v)
for _, child := range children {
listItem := child.(*ast.ListItem)
if !child.HasChildren() || !child.FirstChild().HasChildren() {
v.AppendChild(v, child)
continue
}
taskCheckBox, ok := child.FirstChild().FirstChild().(*east.TaskCheckBox)
if !ok {
v.AppendChild(v, child)
continue
}
newChild := NewTaskCheckBoxListItem(listItem)
newChild.IsChecked = taskCheckBox.IsChecked
newChild.SetAttributeString("class", []byte("task-list-item"))
v.AppendChild(v, newChild)
}
}
case *ast.Text:
if v.SoftLineBreak() && !v.HardLineBreak() {
renderMetas := pc.Get(renderMetasKey).(map[string]string)
mode := renderMetas["mode"]
if mode != "document" {
v.SetHardLineBreak(setting.Markdown.EnableHardLineBreakInComments)
} else {
v.SetHardLineBreak(setting.Markdown.EnableHardLineBreakInDocuments)
}
}
}
return ast.WalkContinue, nil
})
if createTOC && len(ctx.TableOfContents) > 0 {
lang := rc.Lang
if len(lang) == 0 {
lang = setting.Langs[0]
}
tocNode := createTOCNode(ctx.TableOfContents, lang)
if tocNode != nil {
node.InsertBefore(node, firstChild, tocNode)
}
}
if len(rc.Lang) > 0 {
node.SetAttributeString("lang", []byte(rc.Lang))
}
}
type prefixedIDs struct {
values map[string]bool
}
// Generate generates a new element id.
func (p *prefixedIDs) Generate(value []byte, kind ast.NodeKind) []byte {
dft := []byte("id")
if kind == ast.KindHeading {
dft = []byte("heading")
}
return p.GenerateWithDefault(value, dft)
}
// Generate generates a new element id.
func (p *prefixedIDs) GenerateWithDefault(value, dft []byte) []byte {
result := common.CleanValue(value)
if len(result) == 0 {
result = dft
}
if !bytes.HasPrefix(result, []byte("user-content-")) {
result = append([]byte("user-content-"), result...)
}
if _, ok := p.values[util.BytesToReadOnlyString(result)]; !ok {
p.values[util.BytesToReadOnlyString(result)] = true
return result
}
for i := 1; ; i++ {
newResult := fmt.Sprintf("%s-%d", result, i)
if _, ok := p.values[newResult]; !ok {
p.values[newResult] = true
return []byte(newResult)
}
}
}
// Put puts a given element id to the used ids table.
func (p *prefixedIDs) Put(value []byte) {
p.values[util.BytesToReadOnlyString(value)] = true
}
func newPrefixedIDs() *prefixedIDs {
return &prefixedIDs{
values: map[string]bool{},
}
}
// NewHTMLRenderer creates a HTMLRenderer to render
// in the gitea form.
func NewHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
r := &HTMLRenderer{
Config: html.NewConfig(),
}
for _, opt := range opts {
opt.SetHTMLOption(&r.Config)
}
return r
}
// HTMLRenderer is a renderer.NodeRenderer implementation that
// renders gitea specific features.
type HTMLRenderer struct {
html.Config
}
// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
func (r *HTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
reg.Register(ast.KindDocument, r.renderDocument)
reg.Register(KindDetails, r.renderDetails)
reg.Register(KindSummary, r.renderSummary)
reg.Register(KindIcon, r.renderIcon)
reg.Register(KindTaskCheckBoxListItem, r.renderTaskCheckBoxListItem)
reg.Register(east.KindTaskCheckBox, r.renderTaskCheckBox)
}
func (r *HTMLRenderer) renderDocument(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*ast.Document)
if val, has := n.AttributeString("lang"); has {
var err error
if entering {
_, err = w.WriteString("<div")
if err == nil {
_, err = w.WriteString(fmt.Sprintf(` lang=%q`, val))
}
if err == nil {
_, err = w.WriteRune('>')
}
} else {
_, err = w.WriteString("</div>")
}
if err != nil {
return ast.WalkStop, err
}
}
return ast.WalkContinue, nil
}
func (r *HTMLRenderer) renderDetails(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
var err error
if entering {
_, err = w.WriteString("<details>")
} else {
_, err = w.WriteString("</details>")
}
if err != nil {
return ast.WalkStop, err
}
return ast.WalkContinue, nil
}
func (r *HTMLRenderer) renderSummary(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
var err error
if entering {
_, err = w.WriteString("<summary>")
} else {
_, err = w.WriteString("</summary>")
}
if err != nil {
return ast.WalkStop, err
}
return ast.WalkContinue, nil
}
var validNameRE = regexp.MustCompile("^[a-z ]+$")
func (r *HTMLRenderer) renderIcon(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
n := node.(*Icon)
name := strings.TrimSpace(strings.ToLower(string(n.Name)))
if len(name) == 0 {
// skip this
return ast.WalkContinue, nil
}
if !validNameRE.MatchString(name) {
// skip this
return ast.WalkContinue, nil
}
var err error
_, err = w.WriteString(fmt.Sprintf(`<i class="icon %s"></i>`, name))
if err != nil {
return ast.WalkStop, err
}
return ast.WalkContinue, nil
}
func (r *HTMLRenderer) renderTaskCheckBoxListItem(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*TaskCheckBoxListItem)
if entering {
if n.Attributes() != nil {
_, _ = w.WriteString("<li")
html.RenderAttributes(w, n, html.ListItemAttributeFilter)
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString("<li>")
}
_, _ = w.WriteString(`<input type="checkbox" disabled=""`)
segments := node.FirstChild().Lines()
if segments.Len() > 0 {
segment := segments.At(0)
_, _ = w.WriteString(fmt.Sprintf(` data-source-position="%d"`, segment.Start))
}
if n.IsChecked {
_, _ = w.WriteString(` checked=""`)
}
if r.XHTML {
_, _ = w.WriteString(` />`)
} else {
_ = w.WriteByte('>')
}
fc := n.FirstChild()
if fc != nil {
if _, ok := fc.(*ast.TextBlock); !ok {
_ = w.WriteByte('\n')
}
}
} else {
_, _ = w.WriteString("</li>\n")
}
return ast.WalkContinue, nil
}
func (r *HTMLRenderer) renderTaskCheckBox(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
return ast.WalkContinue, nil
}