Fix shortcode detection in RenderString

Fixes #10654

4 files changed, 78 insertions, 2 deletions

diff --git a/hugolib/page__per_output.go b/hugolib/page__per_output.go
index 60e3a7f59..97e9cc465 100644
--- a/hugolib/page__per_output.go
+++ b/hugolib/page__per_output.go
@@ -384,8 +384,8 @@ func (p *pageContentOutput) RenderString(args ...any) (template.HTML, error) {
 
 	var rendered []byte
 
-	if strings.Contains(contentToRender, "{{") {
-		// Probably a shortcode.
+	if pageparser.HasShortcode(contentToRender) {
+		// String contains a shortcode.
 		parsed, err := pageparser.ParseMain(strings.NewReader(contentToRender), pageparser.Config{})
 		if err != nil {
 			return "", err
diff --git a/hugolib/renderstring_test.go b/hugolib/renderstring_test.go
index 1be0cdffb..af66156e6 100644
--- a/hugolib/renderstring_test.go
+++ b/hugolib/renderstring_test.go
@@ -190,3 +190,39 @@ Has other: false
 `)
 
 }
+
+func TestRenderStringWithShortcodeIssue10654(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+timeout = '300ms'
+-- content/p1.md --
+---
+title: "P1"
+---
+{{< toc >}}
+
+## Heading 1
+
+{{< noop >}}
+     {{ not a shortcode
+{{< /noop >}}
+}
+-- layouts/shortcodes/noop.html --
+{{ .Inner | $.Page.RenderString }}
+-- layouts/shortcodes/toc.html --
+{{ .Page.TableOfContents }}
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	b := NewIntegrationTestBuilder(
+		IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+		},
+	).Build()
+
+	b.AssertFileContent("public/p1/index.html", `TableOfContents`)
+}
diff --git a/parser/pageparser/pageparser.go b/parser/pageparser/pageparser.go
index 0a9fc61af..768747907 100644
--- a/parser/pageparser/pageparser.go
+++ b/parser/pageparser/pageparser.go
@@ -19,6 +19,8 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"regexp"
+	"strings"
 
 	"github.com/gohugoio/hugo/parser/metadecoders"
 )
@@ -234,3 +236,14 @@ func IsProbablySourceOfItems(source []byte, items Items) bool {
 
 	return true
 }
+
+var hasShortcodeRe = regexp.MustCompile(`{{[%,<][^\/]`)
+
+// HasShortcode returns true if the given string contains a shortcode.
+func HasShortcode(s string) bool {
+	// Fast path for the common case.
+	if !strings.Contains(s, "{{") {
+		return false
+	}
+	return hasShortcodeRe.MatchString(s)
+}
diff --git a/parser/pageparser/pageparser_test.go b/parser/pageparser/pageparser_test.go
index a21b97970..de817d1fb 100644
--- a/parser/pageparser/pageparser_test.go
+++ b/parser/pageparser/pageparser_test.go
@@ -101,3 +101,30 @@ func TestIsProbablyItemsSource(t *testing.T) {
 	c.Assert(IsProbablySourceOfItems([]byte(`{{< foo >}}  `), items), qt.IsFalse)
 	c.Assert(IsProbablySourceOfItems([]byte(``), items), qt.IsFalse)
 }
+
+func TestHasShortcode(t *testing.T) {
+	c := qt.New(t)
+
+	c.Assert(HasShortcode("{{< foo >}}"), qt.IsTrue)
+	c.Assert(HasShortcode("aSDasd  SDasd aSD\n\nasdfadf{{% foo %}}\nasdf"), qt.IsTrue)
+	c.Assert(HasShortcode("{{</* foo */>}}"), qt.IsFalse)
+	c.Assert(HasShortcode("{{%/* foo */%}}"), qt.IsFalse)
+
+}
+
+func BenchmarkHasShortcode(b *testing.B) {
+	withShortcode := strings.Repeat("this is text", 30) + "{{< myshortcode >}}This is some inner content.{{< /myshortcode >}}" + strings.Repeat("this is text", 30)
+	withoutShortcode := strings.Repeat("this is text", 30) + "This is some inner content." + strings.Repeat("this is text", 30)
+	b.Run("Match", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			HasShortcode(withShortcode)
+		}
+	})
+
+	b.Run("NoMatch", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			HasShortcode(withoutShortcode)
+		}
+	})
+
+}