Add KaTeX rendering to Markdown.

custom/conf/app.example.ini

@@ -1262,6 +1262,12 @@ ROUTER = console
 ;; List of file extensions that should be rendered/edited as Markdown
 ;; Separate the extensions with a comma. To render files without any extension as markdown, just put a comma
 ;FILE_EXTENSIONS = .md,.markdown,.mdown,.mkd
+;;
+;; Enables math inline and block detection
+;ENABLE_MATH = true
+;;
+;; Enables in addition inline block detection using single dollars
+;ENABLE_INLINE_DOLLAR_MATH = true
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -236,6 +236,8 @@ The following configuration set `Content-Type: application/vnd.android.package-a
 - `CUSTOM_URL_SCHEMES`: Use a comma separated list (ftp,git,svn) to indicate additional
   URL hyperlinks to be rendered in Markdown. URLs beginning in http and https are
   always displayed
+- `ENABLE_MATH`: **true**: Enables detection of `\(...\)`, `\[...\]` and `$$...$$` blocks as math blocks.
+- `ENABLE_INLINE_DOLLAR_MATH`: **true**: In addition enables detection of `$...$` as inline math.
 
 ## Server (`server`)
 

docs/content/doc/advanced/external-renderers.en-us.md

@@ -74,12 +74,13 @@ RENDER_COMMAND = "timeout 30s pandoc +RTS -M512M -RTS -f rst"
 IS_INPUT_FILE = false
 ```
 
-If your external markup relies on additional classes and attributes on the generated HTML elements, you might need to enable custom sanitizer policies. Gitea uses the [`bluemonday`](https://godoc.org/github.com/microcosm-cc/bluemonday) package as our HTML sanitizier. The example below will support [KaTeX](https://katex.org/) output from [`pandoc`](https://pandoc.org/).
+If your external markup relies on additional classes and attributes on the generated HTML elements, you might need to enable custom sanitizer policies. Gitea uses the [`bluemonday`](https://godoc.org/github.com/microcosm-cc/bluemonday) package as our HTML sanitizier. The example below could be used to support server-side [KaTeX](https://katex.org/) rendering output from [`pandoc`](https://pandoc.org/).
 
 ```ini
 [markup.sanitizer.TeX]
 ; Pandoc renders TeX segments as <span>s with the "math" class, optionally
 ; with "inline" or "display" classes depending on context.
+; - note this is different from the built-in math support in our markdown parser which uses <code>
 ELEMENT = span
 ALLOW_ATTR = class
 REGEXP = ^\s*((math(\s+|$)|inline(\s+|$)|display(\s+|$)))+

go.mod

@@ -103,6 +103,7 @@ require (
 	gopkg.in/gomail.v2 v2.0.0-20160411212932-81ebce5c23df
 	gopkg.in/ini.v1 v1.67.0
 	gopkg.in/yaml.v2 v2.4.0
+	gopkg.in/yaml.v3 v3.0.1
 	mvdan.cc/xurls/v2 v2.4.0
 	strk.kbt.io/projects/go/libravatar v0.0.0-20191008002943-06d1c002b251
 	xorm.io/builder v0.3.11
@@ -290,7 +291,6 @@ require (
 	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect
 	gopkg.in/cheggaaa/pb.v1 v1.0.28 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 	sigs.k8s.io/yaml v1.2.0 // indirect
 )
 

modules/markup/markdown/convertyaml.go

@@ -0,0 +1,84 @@
+// Copyright 2022 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 (
+	"github.com/yuin/goldmark/ast"
+	east "github.com/yuin/goldmark/extension/ast"
+	"gopkg.in/yaml.v3"
+)
+
+func nodeToTable(meta *yaml.Node) ast.Node {
+	for {
+		if meta == nil {
+			return nil
+		}
+		switch meta.Kind {
+		case yaml.DocumentNode:
+			meta = meta.Content[0]
+			continue
+		default:
+		}
+		break
+	}
+	switch meta.Kind {
+	case yaml.MappingNode:
+		return mappingNodeToTable(meta)
+	case yaml.SequenceNode:
+		return sequenceNodeToTable(meta)
+	default:
+		return ast.NewString([]byte(meta.Value))
+	}
+}
+
+func mappingNodeToTable(meta *yaml.Node) ast.Node {
+	table := east.NewTable()
+	alignments := []east.Alignment{}
+	for i := 0; i < len(meta.Content); i += 2 {
+		alignments = append(alignments, east.AlignNone)
+	}
+
+	headerRow := east.NewTableRow(alignments)
+	valueRow := east.NewTableRow(alignments)
+	for i := 0; i < len(meta.Content); i += 2 {
+		cell := east.NewTableCell()
+
+		cell.AppendChild(cell, nodeToTable(meta.Content[i]))
+		headerRow.AppendChild(headerRow, cell)
+
+		if i+1 < len(meta.Content) {
+			cell = east.NewTableCell()
+			cell.AppendChild(cell, nodeToTable(meta.Content[i+1]))
+			valueRow.AppendChild(valueRow, cell)
+		}
+	}
+
+	table.AppendChild(table, east.NewTableHeader(headerRow))
+	table.AppendChild(table, valueRow)
+	return table
+}
+
+func sequenceNodeToTable(meta *yaml.Node) ast.Node {
+	table := east.NewTable()
+	alignments := []east.Alignment{east.AlignNone}
+	for _, item := range meta.Content {
+		row := east.NewTableRow(alignments)
+		cell := east.NewTableCell()
+		cell.AppendChild(cell, nodeToTable(item))
+		row.AppendChild(row, cell)
+		table.AppendChild(table, row)
+	}
+	return table
+}
+
+func nodeToDetails(meta *yaml.Node, icon string) ast.Node {
+	details := NewDetails()
+	summary := NewSummary()
+	summary.AppendChild(summary, NewIcon(icon))
+	details.AppendChild(details, summary)
+	details.AppendChild(details, nodeToTable(meta))
+
+	return details
+}

modules/markup/markdown/goldmark.go

@@ -15,7 +15,6 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	giteautil "code.gitea.io/gitea/modules/util"
 
-	meta "github.com/yuin/goldmark-meta"
 	"github.com/yuin/goldmark/ast"
 	east "github.com/yuin/goldmark/extension/ast"
 	"github.com/yuin/goldmark/parser"
@@ -32,20 +31,12 @@ type ASTTransformer struct{}
 
 // Transform transforms the given AST tree.
 func (g *ASTTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
-	metaData := meta.GetItems(pc)
 	firstChild := node.FirstChild()
 	createTOC := false
 	ctx := pc.Get(renderContextKey).(*markup.RenderContext)
-	rc := &RenderConfig{
-		Meta: "table",
-		Icon: "table",
-		Lang: "",
-	}
-
-	if metaData != nil {
-		rc.ToRenderConfig(metaData)
-
-		metaNode := rc.toMetaNode(metaData)
+	rc := pc.Get(renderConfigKey).(*RenderConfig)
+	if rc.yamlNode != nil {
+		metaNode := rc.toMetaNode()
 		if metaNode != nil {
 			node.InsertBefore(node, firstChild, metaNode)
 		}

modules/markup/markdown/markdown.go

@@ -14,6 +14,7 @@ import (
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/markup/common"
+	"code.gitea.io/gitea/modules/markup/markdown/math"
 	"code.gitea.io/gitea/modules/setting"
 	giteautil "code.gitea.io/gitea/modules/util"
 
@@ -38,6 +39,7 @@ var (
 	isWikiKey        = parser.NewContextKey()
 	renderMetasKey   = parser.NewContextKey()
 	renderContextKey = parser.NewContextKey()
+	renderConfigKey  = parser.NewContextKey()
 )
 
 type limitWriter struct {
@@ -98,7 +100,7 @@ func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer)
 							languageStr := string(language)
 
 							preClasses := []string{"code-block"}
-							if languageStr == "mermaid" {
+							if languageStr == "mermaid" || languageStr == "math" {
 								preClasses = append(preClasses, "is-loading")
 							}
 
@@ -120,6 +122,10 @@ func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer)
 						}
 					}),
 				),
+				math.NewExtension(
+					math.Enabled(setting.Markdown.EnableMath),
+					math.WithInlineDollarParser(setting.Markdown.EnableInlineDollarMath),
+				),
 				meta.Meta,
 			),
 			goldmark.WithParserOptions(
@@ -167,7 +173,18 @@ func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer)
 		log.Error("Unable to ReadAll: %v", err)
 		return err
 	}
-	if err := converter.Convert(giteautil.NormalizeEOL(buf), lw, parser.WithContext(pc)); err != nil {
+	buf = giteautil.NormalizeEOL(buf)
+
+	rc := &RenderConfig{
+		Meta: "table",
+		Icon: "table",
+		Lang: "",
+	}
+	buf, _ = ExtractMetadataBytes(buf, rc)
+
+	pc.Set(renderConfigKey, rc)
+
+	if err := converter.Convert(buf, lw, parser.WithContext(pc)); err != nil {
 		log.Error("Unable to render: %v", err)
 		return err
 	}

modules/markup/markdown/math/block_node.go

@@ -0,0 +1,42 @@
+// Copyright 2022 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 math
+
+import "github.com/yuin/goldmark/ast"
+
+// Block represents a math Block
+type Block struct {
+	ast.BaseBlock
+	Dollars bool
+	Indent  int
+	Closed  bool
+}
+
+// KindBlock is the node kind for math blocks
+var KindBlock = ast.NewNodeKind("MathBlock")
+
+// NewBlock creates a new math Block
+func NewBlock(dollars bool, indent int) *Block {
+	return &Block{
+		Dollars: dollars,
+		Indent:  indent,
+	}
+}
+
+// Dump dumps the block to a string
+func (n *Block) Dump(source []byte, level int) {
+	m := map[string]string{}
+	ast.DumpHelper(n, source, level, m, nil)
+}
+
+// Kind returns KindBlock for math Blocks
+func (n *Block) Kind() ast.NodeKind {
+	return KindBlock
+}
+
+// IsRaw returns true as this block should not be processed further
+func (n *Block) IsRaw() bool {
+	return true
+}

modules/markup/markdown/math/block_parser.go

@@ -0,0 +1,123 @@
+// Copyright 2022 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 math
+
+import (
+	"bytes"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type blockParser struct {
+	parseDollars bool
+}
+
+// NewBlockParser creates a new math BlockParser
+func NewBlockParser(parseDollarBlocks bool) parser.BlockParser {
+	return &blockParser{
+		parseDollars: parseDollarBlocks,
+	}
+}
+
+// Open parses the current line and returns a result of parsing.
+func (b *blockParser) Open(parent ast.Node, reader text.Reader, pc parser.Context) (ast.Node, parser.State) {
+	line, segment := reader.PeekLine()
+	pos := pc.BlockOffset()
+	if pos == -1 || len(line[pos:]) < 2 {
+		return nil, parser.NoChildren
+	}
+
+	dollars := false
+	if b.parseDollars && line[pos] == '$' && line[pos+1] == '$' {
+		dollars = true
+	} else if line[pos] != '\\' || line[pos+1] != '[' {
+		return nil, parser.NoChildren
+	}
+
+	node := NewBlock(dollars, pos)
+
+	// Now we need to check if the ending block is on the segment...
+	endBytes := []byte{'\\', ']'}
+	if dollars {
+		endBytes = []byte{'$', '$'}
+	}
+	idx := bytes.Index(line[pos+2:], endBytes)
+	if idx >= 0 {
+		segment.Stop = segment.Start + idx + 2
+		reader.Advance(segment.Len() - 1)
+		segment.Start += 2
+		node.Lines().Append(segment)
+		node.Closed = true
+		return node, parser.Close | parser.NoChildren
+	}
+
+	reader.Advance(segment.Len() - 1)
+	segment.Start += 2
+	node.Lines().Append(segment)
+	return node, parser.NoChildren
+}
+
+// Continue parses the current line and returns a result of parsing.
+func (b *blockParser) Continue(node ast.Node, reader text.Reader, pc parser.Context) parser.State {
+	block := node.(*Block)
+	if block.Closed {
+		return parser.Close
+	}
+
+	line, segment := reader.PeekLine()
+	w, pos := util.IndentWidth(line, 0)
+	if w < 4 {
+		if block.Dollars {
+			i := pos
+			for ; i < len(line) && line[i] == '$'; i++ {
+			}
+			length := i - pos
+			if length >= 2 && util.IsBlank(line[i:]) {
+				reader.Advance(segment.Stop - segment.Start - segment.Padding)
+				block.Closed = true
+				return parser.Close
+			}
+		} else if len(line[pos:]) > 1 && line[pos] == '\\' && line[pos+1] == ']' && util.IsBlank(line[pos+2:]) {
+			reader.Advance(segment.Stop - segment.Start - segment.Padding)
+			block.Closed = true
+			return parser.Close
+		}
+	}
+
+	pos, padding := util.IndentPosition(line, 0, block.Indent)
+	seg := text.NewSegmentPadding(segment.Start+pos, segment.Stop, padding)
+	node.Lines().Append(seg)
+	reader.AdvanceAndSetPadding(segment.Stop-segment.Start-pos-1, padding)
+	return parser.Continue | parser.NoChildren
+}
+
+// Close will be called when the parser returns Close.
+func (b *blockParser) Close(node ast.Node, reader text.Reader, pc parser.Context) {
+	// noop
+}
+
+// CanInterruptParagraph returns true if the parser can interrupt paragraphs,
+// otherwise false.
+func (b *blockParser) CanInterruptParagraph() bool {
+	return true
+}
+
+// CanAcceptIndentedLine returns true if the parser can open new node when
+// the given line is being indented more than 3 spaces.
+func (b *blockParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+// Trigger returns a list of characters that triggers Parse method of
+// this parser.
+// If Trigger returns a nil, Open will be called with any lines.
+//
+// We leave this as nil as our parse method is quick enough
+func (b *blockParser) Trigger() []byte {
+	return nil
+}