From 3158a512835bc6a417f9b253a772ab921d26583d Mon Sep 17 00:00:00 2001
From: Joe Mooring <joe.mooring@veriphor.com>
Date: Tue, 22 Apr 2025 19:42:04 -0700
Subject: [PATCH] markup/highlight: Allow lineNos to be true, false, "inline",
 or "table"

Closes #13481
---
 markup/highlight/config.go                    | 40 ++++++++--
 markup/highlight/highlight.go                 |  6 +-
 .../highlight/highlight_integration_test.go   | 73 +++++++++++++++++++
 3 files changed, 112 insertions(+), 7 deletions(-)

diff --git a/markup/highlight/config.go b/markup/highlight/config.go
index fff9bfeca..6407cdff6 100644
--- a/markup/highlight/config.go
+++ b/markup/highlight/config.go
@@ -60,7 +60,7 @@ type Config struct {
 	NoClasses bool
 
 	// When set, line numbers will be printed.
-	LineNos            bool
+	LineNos            any
 	LineNumbersInTable bool
 
 	// When set, add links to line numbers
@@ -85,16 +85,44 @@ type Config struct {
 	GuessSyntax bool
 }
 
-func (cfg Config) toHTMLOptions() []html.Option {
-	var lineAnchors string
+const errLineNosMsg = `lineNos must be one of true, false, "inline", or "table"; got %[1]v (%[1]T)`
+
+func (cfg Config) toHTMLOptions() ([]html.Option, error) {
+	var (
+		lineAnchors string
+		lineNos     bool
+		inTable     = cfg.LineNumbersInTable
+	)
+
 	if cfg.LineAnchors != "" {
 		lineAnchors = cfg.LineAnchors + "-"
 	}
+
+	switch v := cfg.LineNos.(type) {
+	case string:
+		switch v {
+		case "inline":
+			lineNos = true
+			inTable = false
+		case "table":
+			lineNos = true
+			inTable = true
+		default:
+			return nil, fmt.Errorf(errLineNosMsg, v)
+		}
+	case bool:
+		lineNos = v
+	case nil:
+		lineNos = false
+	default:
+		return nil, fmt.Errorf(errLineNosMsg, v)
+	}
+
 	options := []html.Option{
 		html.TabWidth(cfg.TabWidth),
-		html.WithLineNumbers(cfg.LineNos),
+		html.WithLineNumbers(lineNos),
 		html.BaseLineNumber(cfg.LineNoStart),
-		html.LineNumbersInTable(cfg.LineNumbersInTable),
+		html.LineNumbersInTable(inTable),
 		html.WithClasses(!cfg.NoClasses),
 		html.WithLinkableLineNumbers(cfg.AnchorLineNos, lineAnchors),
 		html.InlineCode(cfg.Hl_inline),
@@ -117,7 +145,7 @@ func (cfg Config) toHTMLOptions() []html.Option {
 		}
 	}
 
-	return options
+	return options, nil
 }
 
 func applyOptions(opts any, cfg *Config) error {
diff --git a/markup/highlight/highlight.go b/markup/highlight/highlight.go
index ee07fb9ad..8fe304254 100644
--- a/markup/highlight/highlight.go
+++ b/markup/highlight/highlight.go
@@ -205,7 +205,11 @@ func highlight(fw hugio.FlexiWriter, code, lang string, attributes []attributes.
 		writeDivStart(w, attributes, cfg.WrapperClass)
 	}
 
-	options := cfg.toHTMLOptions()
+	options, err := cfg.toHTMLOptions()
+	if err != nil {
+		return 0, 0, err
+	}
+
 	var wrapper html.PreWrapper
 
 	if cfg.Hl_inline {
diff --git a/markup/highlight/highlight_integration_test.go b/markup/highlight/highlight_integration_test.go
index a737d9a6a..19779fd2f 100644
--- a/markup/highlight/highlight_integration_test.go
+++ b/markup/highlight/highlight_integration_test.go
@@ -14,8 +14,10 @@
 package highlight_test
 
 import (
+	"strings"
 	"testing"
 
+	qt "github.com/frankban/quicktest"
 	"github.com/gohugoio/hugo/hugolib"
 )
 
@@ -129,3 +131,74 @@ xəx := 0
 		 <div class="highlight no-prose"><pre
 	`)
 }
+
+func TestHighlightLineNos(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+disableKinds = ['page','rss','section','sitemap','taxonomy','term']
+[markup.highlight]
+noClasses = false
+lineNoStart = 42
+#LINENOS
+-- content/_index.md --
+---
+title: home
+---
+§§§go
+aaa
+§§§
+-- layouts/index.html --
+{{ .Content }}
+`
+
+	b := hugolib.Test(t, files)
+	b.AssertFileContent("public/index.html",
+		`<span class="nx">aaa</span>`,
+		`! <table class="lntable">`,
+		`! 42`,
+	)
+
+	f := strings.ReplaceAll(files, "#LINENOS", `linenos = false`)
+	b = hugolib.Test(t, f)
+	b.AssertFileContent("public/index.html",
+		`<span class="nx">aaa</span>`,
+		`! <table class="lntable">`,
+		`! 42`,
+	)
+
+	f = strings.ReplaceAll(files, "#LINENOS", `linenos = true`)
+	b = hugolib.Test(t, f)
+	b.AssertFileContent("public/index.html",
+		`<span class="nx">aaa</span>`,
+		`<table class="lntable">`,
+		`42`,
+	)
+
+	f = strings.ReplaceAll(files, "#LINENOS", `linenos = "table"`)
+	b = hugolib.Test(t, f)
+	b.AssertFileContent("public/index.html",
+		`<span class="nx">aaa</span>`,
+		`<table class="lntable">`,
+		`42`,
+	)
+
+	f = strings.ReplaceAll(files, "#LINENOS", `linenos = "inline"`)
+	b = hugolib.Test(t, f)
+	b.AssertFileContent("public/index.html",
+		`<span class="nx">aaa</span>`,
+		`! <table class="lntable">`,
+		`42`,
+	)
+
+	want := `.* lineNos must be one of .*`
+
+	f = strings.ReplaceAll(files, "#LINENOS", `linenos = "foo"`)
+	b, err := hugolib.TestE(t, f)
+	b.Assert(err, qt.ErrorMatches, want)
+
+	f = strings.ReplaceAll(files, "#LINENOS", `linenos = 123`)
+	b, err = hugolib.TestE(t, f)
+	b.Assert(err, qt.ErrorMatches, want)
+}
-- 
2.39.5