support multi language

.gitignore

@@ -4,3 +4,4 @@
 !test/golden/**/*.png
 !examples/*.svg
 /result
+freeze

README.md

@@ -96,7 +96,7 @@ Screenshots can be customized with `--flags` or [Configuration](#configuration)
 - [`-o`](#output), [`--output`](#output): Output location for .svg, .png, .jpg.
 - [`-c`](#configuration), [`--config`](#configuration): Base configuration file or template.
 - [`-t`](#theme), [`--theme`](#theme): Theme to use for syntax highlighting.
-- [`-l`](#language), [`--language`](#language): Language to apply to code
+- [`-l`](#language), [`--language`](#language): Languages to apply to code
 - [`-w`](#window), [`--window`](#window): Display window controls.
 - [`-m`](#margin), [`--margin`](#margin): Apply margin to the window.
 - [`-p`](#padding), [`--padding`](#padding): Apply padding to the code.
@@ -126,6 +126,12 @@ cat artichoke.hs | freeze --language haskell
   <img alt="output of freeze command, Haskell code block" src="./test/golden/svg/haskell.svg" width="600" />
 </a>
 
+`freeze` also allows multi-language highlighting. Only two languages are supported.
+
+```bash
+freeze main.go --language go,c
+```
+
 ### Theme
 
 Change the color theme.

config.go

@@ -26,10 +26,10 @@ type Config struct {
 	Height     float64   `json:"height" help:"Height of terminal window." short:"H" group:"Window"`
 
 	// Settings
-	Config      string `json:"config,omitempty" help:"Base configuration file or template." short:"c" group:"Settings" default:"default" placeholder:"base"`
-	Interactive bool   `hidden:"" json:",omitempty" help:"Use an interactive form for configuration options." short:"i" group:"Settings"`
-	Language    string `json:"language,omitempty" help:"Language of code file." short:"l" group:"Settings" placeholder:"go"`
-	Theme       string `json:"theme" help:"Theme to use for syntax highlighting." short:"t" group:"Settings" placeholder:"charm"`
+	Config      string   `json:"config,omitempty" help:"Base configuration file or template." short:"c" group:"Settings" default:"default" placeholder:"base"`
+	Interactive bool     `hidden:"" json:",omitempty" help:"Use an interactive form for configuration options." short:"i" group:"Settings"`
+	Language    []string `json:"language,omitempty" help:"Languages of code file. Allows upto two languages." short:"l" group:"Settings" placeholder:"go"`
+	Theme       string   `json:"theme" help:"Theme to use for syntax highlighting." short:"t" group:"Settings" placeholder:"charm"`
 
 	Output         string        `json:"output,omitempty" help:"Output location for {{.svg}}, {{.png}}, or {{.webp}}." short:"o" group:"Settings" default:"" placeholder:"freeze.svg"`
 	Execute        string        `json:"-" help:"Capture output of command execution." short:"x" group:"Settings" default:""`

main.go

@@ -150,7 +150,7 @@ func main() {
 		input, err = in.ReadInput(os.Stdin)
 		lexer = lexers.Analyse(input)
 	} else if config.Execute != "" {
-		config.Language = "ansi"
+		config.Language[0] = "ansi"
 	} else {
 		input, err = in.ReadFile(config.Input)
 		if err != nil {
@@ -159,8 +159,16 @@ func main() {
 		lexer = lexers.Get(config.Input)
 	}
 
-	if config.Language != "" {
-		lexer = lexers.Get(config.Language)
+	if len(config.Language) > 2 {
+		printErrorFatal("languages can only be two", errors.New("--language can have only two inputs"))
+	}
+
+	if config.Language[0] != "" && len(config.Language) == 1 {
+		lexer = lexers.Get(config.Language[0])
+	} else {
+		language := lexers.Get(config.Language[0])
+		root := lexers.Get(config.Language[1])
+		lexer = chroma.DelegatingLexer(root, language)
 	}
 
 	// adjust for 1-indexing
@@ -169,7 +177,7 @@ func main() {
 	}
 
 	var strippedInput string = ansi.Strip(input)
-	isAnsi := strings.ToLower(config.Language) == "ansi" || strippedInput != input
+	isAnsi := strings.ToLower(config.Language[0]) == "ansi" || strippedInput != input
 	strippedInput = cut(strippedInput, config.Lines)
 
 	if !isAnsi && lexer == nil {