Refactor markdown math render (#32831)

Add more tests

10 files changed, 137 insertions, 151 deletions

diff --git a/modules/markup/markdown/markdown.go b/modules/markup/markdown/markdown.go
index f77db9eb38..a14c0cad59 100644
--- a/modules/markup/markdown/markdown.go
+++ b/modules/markup/markdown/markdown.go
@@ -78,26 +78,23 @@ func (r *GlodmarkRender) Renderer() renderer.Renderer {
 
 func (r *GlodmarkRender) highlightingRenderer(w util.BufWriter, c highlighting.CodeBlockContext, entering bool) {
 	if entering {
-		language, _ := c.Language()
-		if language == nil {
-			language = []byte("text")
-		}
-
-		languageStr := string(language)
+		languageBytes, _ := c.Language()
+		languageStr := giteautil.IfZero(string(languageBytes), "text")
 
-		preClasses := []string{"code-block"}
+		preClasses := "code-block"
 		if languageStr == "mermaid" || languageStr == "math" {
-			preClasses = append(preClasses, "is-loading")
+			preClasses += " is-loading"
 		}
 
-		err := r.ctx.RenderInternal.FormatWithSafeAttrs(w, `<pre class="%s">`, strings.Join(preClasses, " "))
+		err := r.ctx.RenderInternal.FormatWithSafeAttrs(w, `<pre class="%s">`, preClasses)
 		if err != nil {
 			return
 		}
 
-		// include language-x class as part of commonmark spec
-		// the "display" class is used by "js/markup/math.js" to render the code element as a block
-		err = r.ctx.RenderInternal.FormatWithSafeAttrs(w, `<code class="chroma language-%s display">`, string(language))
+		// include language-x class as part of commonmark spec, "chroma" class is used to highlight the code
+		// the "display" class is used by "js/markup/math.ts" to render the code element as a block
+		// the "math.ts" strictly depends on the structure: <pre class="code-block is-loading"><code class="language-math display">...</code></pre>
+		err = r.ctx.RenderInternal.FormatWithSafeAttrs(w, `<code class="chroma language-%s display">`, languageStr)
 		if err != nil {
 			return
 		}
@@ -128,7 +125,12 @@ func SpecializedMarkdown(ctx *markup.RenderContext) *GlodmarkRender {
 				),
 				highlighting.WithWrapperRenderer(r.highlightingRenderer),
 			),
-			math.NewExtension(&ctx.RenderInternal, math.Enabled(setting.Markdown.EnableMath)),
+			math.NewExtension(&ctx.RenderInternal, math.Options{
+				Enabled:           setting.Markdown.EnableMath,
+				ParseDollarInline: true,
+				ParseDollarBlock:  true,
+				ParseSquareBlock:  true, // TODO: this is a bad syntax, it should be deprecated in the future (by some config options)
+			}),
 			meta.Meta,
 		),
 		goldmark.WithParserOptions(
diff --git a/modules/markup/markdown/markdown_math_test.go b/modules/markup/markdown/markdown_math_test.go
index a2213b2ce7..813f050965 100644
--- a/modules/markup/markdown/markdown_math_test.go
+++ b/modules/markup/markdown/markdown_math_test.go
@@ -12,8 +12,9 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+const nl = "\n"
+
 func TestMathRender(t *testing.T) {
-	const nl = "\n"
 	testcases := []struct {
 		testcase string
 		expected string
@@ -86,6 +87,18 @@ func TestMathRender(t *testing.T) {
 			`$\text{$b$}$`,
 			`<p><code class="language-math">\text{$b$}</code></p>` + nl,
 		},
+		{
+			"a$`b`$c",
+			`<p>a<code class="language-math">b</code>c</p>` + nl,
+		},
+		{
+			"a $`b`$ c",
+			`<p>a <code class="language-math">b</code> c</p>` + nl,
+		},
+		{
+			"a$``b``$c x$```y```$z",
+			`<p>a<code class="language-math">b</code>c x<code class="language-math">y</code>z</p>` + nl,
+		},
 	}
 
 	for _, test := range testcases {
@@ -215,6 +228,11 @@ x
 </ol>
 `,
 		},
+		{
+			"inline-non-math",
+			`\[x]`,
+			`<p>[x]</p>` + nl,
+		},
 	}
 
 	for _, test := range testcases {
diff --git a/modules/markup/markdown/math/block_parser.go b/modules/markup/markdown/math/block_parser.go
index 3f37ce8333..2c5553550a 100644
--- a/modules/markup/markdown/math/block_parser.go
+++ b/modules/markup/markdown/math/block_parser.go
@@ -16,16 +16,18 @@ import (
 
 type blockParser struct {
 	parseDollars    bool
+	parseSquare     bool
 	endBytesDollars []byte
-	endBytesBracket []byte
+	endBytesSquare  []byte
 }
 
 // NewBlockParser creates a new math BlockParser
-func NewBlockParser(parseDollarBlocks bool) parser.BlockParser {
+func NewBlockParser(parseDollars, parseSquare bool) parser.BlockParser {
 	return &blockParser{
-		parseDollars:    parseDollarBlocks,
+		parseDollars:    parseDollars,
+		parseSquare:     parseSquare,
 		endBytesDollars: []byte{'$', '$'},
-		endBytesBracket: []byte{'\\', ']'},
+		endBytesSquare:  []byte{'\\', ']'},
 	}
 }
 
@@ -40,7 +42,7 @@ func (b *blockParser) Open(parent ast.Node, reader text.Reader, pc parser.Contex
 	var dollars bool
 	if b.parseDollars && line[pos] == '$' && line[pos+1] == '$' {
 		dollars = true
-	} else if line[pos] == '\\' && line[pos+1] == '[' {
+	} else if b.parseSquare && line[pos] == '\\' && line[pos+1] == '[' {
 		if len(line[pos:]) >= 3 && line[pos+2] == '!' && bytes.Contains(line[pos:], []byte(`\]`)) {
 			// do not process escaped attention block: "> \[!NOTE\]"
 			return nil, parser.NoChildren
@@ -53,10 +55,10 @@ func (b *blockParser) Open(parent ast.Node, reader text.Reader, pc parser.Contex
 	node := NewBlock(dollars, pos)
 
 	// Now we need to check if the ending block is on the segment...
-	endBytes := giteaUtil.Iif(dollars, b.endBytesDollars, b.endBytesBracket)
+	endBytes := giteaUtil.Iif(dollars, b.endBytesDollars, b.endBytesSquare)
 	idx := bytes.Index(line[pos+2:], endBytes)
 	if idx >= 0 {
-		// for case $$ ... $$ any other text
+		// for case: "$$ ... $$ any other text" (this case will be handled by the inline parser)
 		for i := pos + 2 + idx + 2; i < len(line); i++ {
 			if line[i] != ' ' && line[i] != '\n' {
 				return nil, parser.NoChildren
@@ -70,6 +72,13 @@ func (b *blockParser) Open(parent ast.Node, reader text.Reader, pc parser.Contex
 		return node, parser.Close | parser.NoChildren
 	}
 
+	// for case "\[ ... ]" (no close marker on the same line)
+	for i := pos + 2 + idx + 2; i < len(line); i++ {
+		if line[i] != ' ' && line[i] != '\n' {
+			return nil, parser.NoChildren
+		}
+	}
+
 	segment.Start += pos + 2
 	node.Lines().Append(segment)
 	return node, parser.NoChildren
@@ -85,7 +94,7 @@ func (b *blockParser) Continue(node ast.Node, reader text.Reader, pc parser.Cont
 	line, segment := reader.PeekLine()
 	w, pos := util.IndentWidth(line, reader.LineOffset())
 	if w < 4 {
-		endBytes := giteaUtil.Iif(block.Dollars, b.endBytesDollars, b.endBytesBracket)
+		endBytes := giteaUtil.Iif(block.Dollars, b.endBytesDollars, b.endBytesSquare)
 		if bytes.HasPrefix(line[pos:], endBytes) && util.IsBlank(line[pos+len(endBytes):]) {
 			if util.IsBlank(line[pos+len(endBytes):]) {
 				newline := giteaUtil.Iif(line[len(line)-1] != '\n', 0, 1)
diff --git a/modules/markup/markdown/math/inline_block_node.go b/modules/markup/markdown/math/inline_block_node.go
deleted file mode 100644
index c92d0c8d84..0000000000
--- a/modules/markup/markdown/math/inline_block_node.go
+++ /dev/null
@@ -1,31 +0,0 @@
-// Copyright 2024 The Gitea Authors. All rights reserved.
-// SPDX-License-Identifier: MIT
-
-package math
-
-import (
-	"github.com/yuin/goldmark/ast"
-)
-
-// InlineBlock represents inline math e.g. $$...$$
-type InlineBlock struct {
-	Inline
-}
-
-// InlineBlock implements InlineBlock.
-func (n *InlineBlock) InlineBlock() {}
-
-// KindInlineBlock is the kind for math inline block
-var KindInlineBlock = ast.NewNodeKind("MathInlineBlock")
-
-// Kind returns KindInlineBlock
-func (n *InlineBlock) Kind() ast.NodeKind {
-	return KindInlineBlock
-}
-
-// NewInlineBlock creates a new ast math inline block node
-func NewInlineBlock() *InlineBlock {
-	return &InlineBlock{
-		Inline{},
-	}
-}
diff --git a/modules/markup/markdown/math/inline_node.go b/modules/markup/markdown/math/inline_node.go
index 2221a251bf..1e4034d54b 100644
--- a/modules/markup/markdown/math/inline_node.go
+++ b/modules/markup/markdown/math/inline_node.go
@@ -8,7 +8,7 @@ import (
 	"github.com/yuin/goldmark/util"
 )
 
-// Inline represents inline math e.g. $...$ or \(...\)
+// Inline struct represents inline math e.g. $...$ or \(...\)
 type Inline struct {
 	ast.BaseInline
 }
diff --git a/modules/markup/markdown/math/inline_parser.go b/modules/markup/markdown/math/inline_parser.go
index 191d1e5a31..a57abe9f9b 100644
--- a/modules/markup/markdown/math/inline_parser.go
+++ b/modules/markup/markdown/math/inline_parser.go
@@ -12,31 +12,25 @@ import (
 )
 
 type inlineParser struct {
-	start []byte
-	end   []byte
+	trigger              []byte
+	endBytesSingleDollar []byte
+	endBytesDoubleDollar []byte
+	endBytesBracket      []byte
 }
 
 var defaultInlineDollarParser = &inlineParser{
-	start: []byte{'$'},
-	end:   []byte{'$'},
-}
-
-var defaultDualDollarParser = &inlineParser{
-	start: []byte{'$', '$'},
-	end:   []byte{'$', '$'},
+	trigger:              []byte{'$'},
+	endBytesSingleDollar: []byte{'$'},
+	endBytesDoubleDollar: []byte{'$', '$'},
 }
 
 func NewInlineDollarParser() parser.InlineParser {
 	return defaultInlineDollarParser
 }
 
-func NewInlineDualDollarParser() parser.InlineParser {
-	return defaultDualDollarParser
-}
-
 var defaultInlineBracketParser = &inlineParser{
-	start: []byte{'\\', '('},
-	end:   []byte{'\\', ')'},
+	trigger:         []byte{'\\', '('},
+	endBytesBracket: []byte{'\\', ')'},
 }
 
 func NewInlineBracketParser() parser.InlineParser {
@@ -45,7 +39,7 @@ func NewInlineBracketParser() parser.InlineParser {
 
 // Trigger triggers this parser on $ or \
 func (parser *inlineParser) Trigger() []byte {
-	return parser.start
+	return parser.trigger
 }
 
 func isPunctuation(b byte) bool {
@@ -64,33 +58,60 @@ func isAlphanumeric(b byte) bool {
 func (parser *inlineParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
 	line, _ := block.PeekLine()
 
-	if !bytes.HasPrefix(line, parser.start) {
+	if !bytes.HasPrefix(line, parser.trigger) {
 		// We'll catch this one on the next time round
 		return nil
 	}
 
-	precedingCharacter := block.PrecendingCharacter()
-	if precedingCharacter < 256 && (isAlphanumeric(byte(precedingCharacter)) || isPunctuation(byte(precedingCharacter))) {
-		// need to exclude things like `a$` from being considered a start
-		return nil
+	var startMarkLen int
+	var stopMark []byte
+	checkSurrounding := true
+	if line[0] == '$' {
+		startMarkLen = 1
+		stopMark = parser.endBytesSingleDollar
+		if len(line) > 1 {
+			if line[1] == '$' {
+				startMarkLen = 2
+				stopMark = parser.endBytesDoubleDollar
+			} else if line[1] == '`' {
+				pos := 1
+				for ; pos < len(line) && line[pos] == '`'; pos++ {
+				}
+				startMarkLen = pos
+				stopMark = bytes.Repeat([]byte{'`'}, pos)
+				stopMark[len(stopMark)-1] = '$'
+				checkSurrounding = false
+			}
+		}
+	} else {
+		startMarkLen = 2
+		stopMark = parser.endBytesBracket
+	}
+
+	if checkSurrounding {
+		precedingCharacter := block.PrecendingCharacter()
+		if precedingCharacter < 256 && (isAlphanumeric(byte(precedingCharacter)) || isPunctuation(byte(precedingCharacter))) {
+			// need to exclude things like `a$` from being considered a start
+			return nil
+		}
 	}
 
 	// move the opener marker point at the start of the text
-	opener := len(parser.start)
+	opener := startMarkLen
 
 	// Now look for an ending line
 	depth := 0
 	ender := -1
 	for i := opener; i < len(line); i++ {
-		if depth == 0 && bytes.HasPrefix(line[i:], parser.end) {
+		if depth == 0 && bytes.HasPrefix(line[i:], stopMark) {
 			succeedingCharacter := byte(0)
-			if i+len(parser.end) < len(line) {
-				succeedingCharacter = line[i+len(parser.end)]
+			if i+len(stopMark) < len(line) {
+				succeedingCharacter = line[i+len(stopMark)]
 			}
 			// check valid ending character
 			isValidEndingChar := isPunctuation(succeedingCharacter) || isBracket(succeedingCharacter) ||
 				succeedingCharacter == ' ' || succeedingCharacter == '\n' || succeedingCharacter == 0
-			if !isValidEndingChar {
+			if checkSurrounding && !isValidEndingChar {
 				break
 			}
 			ender = i
@@ -112,21 +133,12 @@ func (parser *inlineParser) Parse(parent ast.Node, block text.Reader, pc parser.
 
 	block.Advance(opener)
 	_, pos := block.Position()
-	var node ast.Node
-	if parser == defaultDualDollarParser {
-		node = NewInlineBlock()
-	} else {
-		node = NewInline()
-	}
+	node := NewInline()
+
 	segment := pos.WithStop(pos.Start + ender - opener)
 	node.AppendChild(node, ast.NewRawTextSegment(segment))
-	block.Advance(ender - opener + len(parser.end))
-
-	if parser == defaultDualDollarParser {
-		trimBlock(&(node.(*InlineBlock)).Inline, block)
-	} else {
-		trimBlock(node.(*Inline), block)
-	}
+	block.Advance(ender - opener + len(stopMark))
+	trimBlock(node, block)
 	return node
 }
 
diff --git a/modules/markup/markdown/math/inline_renderer.go b/modules/markup/markdown/math/inline_renderer.go
index 4e0531cf40..d000a7b317 100644
--- a/modules/markup/markdown/math/inline_renderer.go
+++ b/modules/markup/markdown/math/inline_renderer.go
@@ -50,5 +50,4 @@ func (r *InlineRenderer) renderInline(w util.BufWriter, source []byte, n ast.Nod
 // RegisterFuncs registers the renderer for inline math nodes
 func (r *InlineRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
 	reg.Register(KindInline, r.renderInline)
-	reg.Register(KindInlineBlock, r.renderInline)
 }
diff --git a/modules/markup/markdown/math/math.go b/modules/markup/markdown/math/math.go
index 7e8defcd4a..a6ff593d62 100644
--- a/modules/markup/markdown/math/math.go
+++ b/modules/markup/markdown/math/math.go
@@ -5,6 +5,7 @@ package math
 
 import (
 	"code.gitea.io/gitea/modules/markup/internal"
+	giteaUtil "code.gitea.io/gitea/modules/util"
 
 	"github.com/yuin/goldmark"
 	"github.com/yuin/goldmark/parser"
@@ -12,70 +13,45 @@ import (
 	"github.com/yuin/goldmark/util"
 )
 
-// Extension is a math extension
-type Extension struct {
-	renderInternal    *internal.RenderInternal
-	enabled           bool
-	parseDollarInline bool
-	parseDollarBlock  bool
-}
-
-// Option is the interface Options should implement
-type Option interface {
-	SetOption(e *Extension)
-}
-
-type extensionFunc func(e *Extension)
-
-func (fn extensionFunc) SetOption(e *Extension) {
-	fn(e)
+type Options struct {
+	Enabled           bool
+	ParseDollarInline bool
+	ParseDollarBlock  bool
+	ParseSquareBlock  bool
 }
 
-// Enabled enables or disables this extension
-func Enabled(enable ...bool) Option {
-	value := true
-	if len(enable) > 0 {
-		value = enable[0]
-	}
-	return extensionFunc(func(e *Extension) {
-		e.enabled = value
-	})
+// Extension is a math extension
+type Extension struct {
+	renderInternal *internal.RenderInternal
+	options        Options
 }
 
 // NewExtension creates a new math extension with the provided options
-func NewExtension(renderInternal *internal.RenderInternal, opts ...Option) *Extension {
+func NewExtension(renderInternal *internal.RenderInternal, opts ...Options) *Extension {
+	opt := giteaUtil.OptionalArg(opts)
 	r := &Extension{
-		renderInternal:    renderInternal,
-		enabled:           true,
-		parseDollarBlock:  true,
-		parseDollarInline: true,
-	}
-
-	for _, o := range opts {
-		o.SetOption(r)
+		renderInternal: renderInternal,
+		options:        opt,
 	}
 	return r
 }
 
 // Extend extends goldmark with our parsers and renderers
 func (e *Extension) Extend(m goldmark.Markdown) {
-	if !e.enabled {
+	if !e.options.Enabled {
 		return
 	}
 
-	m.Parser().AddOptions(parser.WithBlockParsers(
-		util.Prioritized(NewBlockParser(e.parseDollarBlock), 701),
-	))
-
-	inlines := []util.PrioritizedValue{
-		util.Prioritized(NewInlineBracketParser(), 501),
-	}
-	if e.parseDollarInline {
-		inlines = append(inlines, util.Prioritized(NewInlineDollarParser(), 503),
-			util.Prioritized(NewInlineDualDollarParser(), 502))
+	inlines := []util.PrioritizedValue{util.Prioritized(NewInlineBracketParser(), 501)}
+	if e.options.ParseDollarInline {
+		inlines = append(inlines, util.Prioritized(NewInlineDollarParser(), 502))
 	}
 	m.Parser().AddOptions(parser.WithInlineParsers(inlines...))
 
+	m.Parser().AddOptions(parser.WithBlockParsers(
+		util.Prioritized(NewBlockParser(e.options.ParseDollarBlock, e.options.ParseSquareBlock), 701),
+	))
+
 	m.Renderer().AddOptions(renderer.WithNodeRenderers(
 		util.Prioritized(NewBlockRenderer(e.renderInternal), 501),
 		util.Prioritized(NewInlineRenderer(e.renderInternal), 502),
diff --git a/web_src/css/repo/home-file-list.css b/web_src/css/repo/home-file-list.css
index ecb26fa662..285b823d57 100644
--- a/web_src/css/repo/home-file-list.css
+++ b/web_src/css/repo/home-file-list.css
@@ -29,7 +29,7 @@
 #repo-files-table .repo-file-line,
 #repo-files-table .repo-file-cell {
   border-top: 1px solid var(--color-light-border);
-  padding: 6px 10px;
+  padding: 8px 10px;
 }
 
 #repo-files-table .repo-file-line:first-child {
@@ -41,7 +41,6 @@
   display: flex;
   align-items: center;
   gap: 0.5em;
-  padding: 6px 10px;
 }
 
 #repo-files-table .repo-file-last-commit {
diff --git a/web_src/js/markup/math.ts b/web_src/js/markup/math.ts
index 22a4de38e9..4777805e3c 100644
--- a/web_src/js/markup/math.ts
+++ b/web_src/js/markup/math.ts
@@ -1,8 +1,14 @@
 import {displayError} from './common.ts';
 
-function targetElement(el: Element) {
+function targetElement(el: Element): {target: Element, displayAsBlock: boolean} {
   // The target element is either the parent "code block with loading indicator", or itself
-  return el.closest('.code-block.is-loading') ?? el;
+  // It is designed to work for 2 cases (guaranteed by backend code):
+  // * <pre class="code-block is-loading"><code class="language-math display">...</code></pre>
+  // * <code class="language-math">...</code>
+  return {
+    target: el.closest('.code-block.is-loading') ?? el,
+    displayAsBlock: el.classList.contains('display'),
+  };
 }
 
 export async function renderMath(): Promise<void> {
@@ -19,7 +25,7 @@ export async function renderMath(): Promise<void> {
   const MAX_EXPAND = 1000;
 
   for (const el of els) {
-    const target = targetElement(el);
+    const {target, displayAsBlock} = targetElement(el);
     if (target.hasAttribute('data-render-done')) continue;
     const source = el.textContent;
 
@@ -27,16 +33,12 @@ export async function renderMath(): Promise<void> {
       displayError(target, new Error(`Math source of ${source.length} characters exceeds the maximum allowed length of ${MAX_CHARS}.`));
       continue;
     }
-
-    const displayMode = el.classList.contains('display');
-    const nodeName = displayMode ? 'p' : 'span';
-
     try {
-      const tempEl = document.createElement(nodeName);
+      const tempEl = document.createElement(displayAsBlock ? 'p' : 'span');
       katex.render(source, tempEl, {
         maxSize: MAX_SIZE,
         maxExpand: MAX_EXPAND,
-        displayMode,
+        displayMode: displayAsBlock, // katex: true for display (block) mode, false for inline mode
       });
       target.replaceWith(tempEl);
     } catch (error) {