markup/goldmark: Support passthrough extension

Fixes #10894

3 files changed, 158 insertions, 0 deletions

diff --git a/markup/goldmark/convert.go b/markup/goldmark/convert.go
index 6ebcd8a77..56cc56fcd 100644
--- a/markup/goldmark/convert.go
+++ b/markup/goldmark/convert.go
@@ -19,6 +19,7 @@ import (
 
 	"github.com/gohugoio/hugo/identity"
 
+	"github.com/gohugoio/hugo-goldmark-extensions/passthrough"
 	"github.com/gohugoio/hugo/markup/goldmark/codeblocks"
 	"github.com/gohugoio/hugo/markup/goldmark/goldmark_config"
 	"github.com/gohugoio/hugo/markup/goldmark/images"
@@ -154,6 +155,33 @@ func newMarkdown(pcfg converter.ProviderConfig) goldmark.Markdown {
 		extensions = append(extensions, c)
 	}
 
+	if cfg.Extensions.Passthrough.Enable {
+		configuredInlines := cfg.Extensions.Passthrough.Delimiters.Inline
+		configuredBlocks := cfg.Extensions.Passthrough.Delimiters.Block
+
+		inlineDelimiters := make([]passthrough.Delimiters, len(configuredInlines))
+		blockDelimiters := make([]passthrough.Delimiters, len(configuredBlocks))
+
+		for i, d := range configuredInlines {
+			inlineDelimiters[i] = passthrough.Delimiters{
+				Open:  d[0],
+				Close: d[1],
+			}
+		}
+
+		for i, d := range configuredBlocks {
+			blockDelimiters[i] = passthrough.Delimiters{
+				Open:  d[0],
+				Close: d[1],
+			}
+		}
+
+		extensions = append(extensions, passthrough.NewPassthroughWithDelimiters(
+			inlineDelimiters,
+			blockDelimiters,
+		))
+	}
+
 	if pcfg.Conf.EnableEmoji() {
 		extensions = append(extensions, emoji.Emoji)
 	}
diff --git a/markup/goldmark/goldmark_config/config.go b/markup/goldmark/goldmark_config/config.go
index cdfb4e7cc..ba1874a18 100644
--- a/markup/goldmark/goldmark_config/config.go
+++ b/markup/goldmark/goldmark_config/config.go
@@ -49,6 +49,13 @@ var Default = Config{
 			EastAsianLineBreaksStyle: "simple",
 			EscapedSpace:             false,
 		},
+		Passthrough: Passthrough{
+			Enable: false,
+			Delimiters: DelimitersConfig{
+				Inline: [][]string{},
+				Block:  [][]string{},
+			},
+		},
 	},
 	Renderer: Renderer{
 		Unsafe: false,
@@ -75,6 +82,7 @@ type Extensions struct {
 	Typographer    Typographer
 	Footnote       bool
 	DefinitionList bool
+	Passthrough    Passthrough
 
 	// GitHub flavored markdown
 	Table           bool
@@ -112,6 +120,28 @@ type Typographer struct {
 	Apostrophe string
 }
 
+// Passthrough hold passthrough configuration.
+// github.com/hugoio/hugo-goldmark-extensions/passthrough
+type Passthrough struct {
+	// Whether to enable the extension
+	Enable bool
+
+	// The delimiters to use for inline and block passthroughs.
+	Delimiters DelimitersConfig
+}
+
+type DelimitersConfig struct {
+	// The delimiters to use for inline passthroughs. Each entry in the list
+	// is a size-2 list of strings, where the first string is the opening delimiter
+	// and the second string is the closing delimiter, e.g.,
+	//
+	// [["$", "$"], ["\\(", "\\)"]]
+	Inline [][]string
+
+	// The delimiters to use for block passthroughs. Same format as Inline.
+	Block [][]string
+}
+
 type CJK struct {
 	// Whether to enable CJK support.
 	Enable bool
diff --git a/markup/goldmark/integration_test.go b/markup/goldmark/integration_test.go
index a2bf16374..c9c6ef338 100644
--- a/markup/goldmark/integration_test.go
+++ b/markup/goldmark/integration_test.go
@@ -711,3 +711,103 @@ echo "hello";
 	b := hugolib.Test(t, files)
 	b.AssertFileContent("public/index.html", "<div class=foo><?php\necho \"hello\";\n?>\n</div>")
 }
+
+// Issue #10894
+func TestPassthroughInlineFences(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+[markup.goldmark.extensions.passthrough]
+enable = true
+[markup.goldmark.extensions.passthrough.delimiters]
+inline = [['$', '$'], ['\(', '\)']]
+-- content/p1.md --
+---
+title: "p1"
+---
+## LaTeX test
+
+Inline equation that would be mangled by default parser: $a^*=x-b^*$
+
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	b := hugolib.Test(t, files)
+	b.AssertFileContent("public/p1/index.html", `
+		$a^*=x-b^*$
+	`)
+}
+
+func TestPassthroughBlockFences(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+[markup.goldmark.extensions.passthrough]
+enable = true
+[markup.goldmark.extensions.passthrough.delimiters]
+block = [['$$', '$$']]
+-- content/p1.md --
+---
+title: "p1"
+---
+## LaTeX test
+
+Block equation that would be mangled by default parser:
+
+$$a^*=x-b^*$$
+
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	b := hugolib.Test(t, files)
+	b.AssertFileContent("public/p1/index.html", `
+		$$a^*=x-b^*$$
+	`)
+}
+
+func TestPassthroughWithAlternativeFences(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+[markup.goldmark.extensions.passthrough]
+enable = true
+[markup.goldmark.extensions.passthrough.delimiters]
+inline = [['(((', ')))']]
+block = [['%!%', '%!%']]
+-- content/p1.md --
+---
+title: "p1"
+---
+## LaTeX test
+
+Inline equation that would be mangled by default parser: (((a^*=x-b^*)))
+Inline equation that should be mangled by default parser: $a^*=x-b^*$
+
+Block equation that would be mangled by default parser:
+
+%!%
+a^*=x-b^*
+%!%
+
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	b := hugolib.Test(t, files)
+	b.AssertFileContent("public/p1/index.html", `
+		(((a^*=x-b^*)))
+	`)
+	b.AssertFileContent("public/p1/index.html", `
+		$a^<em>=x-b^</em>$
+	`)
+	b.AssertFileContent("public/p1/index.html", `
+%!%
+a^*=x-b^*
+%!%
+	`)
+}