markup/highlight: Allow cfg.LineNos to be true, false, "inline", or "table"

Closes gohugoio#13481

Author: jmooring

markup/highlight/config.go

@@ -15,6 +15,7 @@
 package highlight
 
 import (
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -60,7 +61,7 @@ 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
@@ -85,14 +86,37 @@ type Config struct {
 	GuessSyntax bool
 }
 
-func (cfg Config) toHTMLOptions() []html.Option {
+func (cfg Config) toHTMLOptions() ([]html.Option, error) {
 	var lineAnchors string
 	if cfg.LineAnchors != "" {
 		lineAnchors = cfg.LineAnchors + "-"
 	}
+
+	var lineNos bool
+	err := errors.New(`lineNos must be one of true, false, "inline", or "table"`)
+	switch v := cfg.LineNos.(type) {
+	case string:
+		switch v {
+		case "inline":
+			lineNos = true
+			cfg.LineNumbersInTable = false
+		case "table":
+			lineNos = true
+			cfg.LineNumbersInTable = true
+		default:
+			return nil, err
+		}
+	case bool:
+		lineNos = v
+	case nil:
+		lineNos = false
+	default:
+		return nil, err
+	}
+
 	options := []html.Option{
 		html.TabWidth(cfg.TabWidth),
-		html.WithLineNumbers(cfg.LineNos),
+		html.WithLineNumbers(lineNos),
 		html.BaseLineNumber(cfg.LineNoStart),
 		html.LineNumbersInTable(cfg.LineNumbersInTable),
 		html.WithClasses(!cfg.NoClasses),
@@ -117,7 +141,7 @@ func (cfg Config) toHTMLOptions() []html.Option {
 		}
 	}
 
-	return options
+	return options, nil
 }
 
 func applyOptions(opts any, cfg *Config) error {

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 {

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 +131,75 @@ xəx := 0
 		 <div class="highlight no-prose"><pre
 	`)
 }
+
+func TestHighlightLineNos(t *testing.T) {
+	t.Parallel()
+	c := qt.New(t)
+
+	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(c, f)
+	b.Assert(err, qt.ErrorMatches, want)
+
+	f = strings.ReplaceAll(files, "#LINENOS", `linenos = 123`)
+	b, err = hugolib.TestE(c, f)
+	b.Assert(err, qt.ErrorMatches, want)
+}