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//go:build wasm
// Package main is an experimental WASM library intended for TinyGO.
package main
import (
"strings"
"syscall/js"
"github.com/alecthomas/chroma/v2"
"github.com/alecthomas/chroma/v2/formatters/html"
"github.com/alecthomas/chroma/v2/lexers"
"github.com/alecthomas/chroma/v2/styles"
)
func main() {
// Register the highlight function with the JavaScript global object
js.Global().Set("highlight", js.FuncOf(highlight))
// Keep the program running
select {}
}
// Highlight source code using Chroma.
//
// Equivalent to the JS function:
//
// function highlight(source, lexer, styleName, classes)
//
// If the "lexer" is unknown, this will attempt to autodetect the language type.
func highlight(this js.Value, args []js.Value) any {
source := args[0].String()
lexer := args[1].String()
styleName := args[2].String()
classes := args[3].Bool()
language := lexers.Get(lexer)
if language == nil {
language = lexers.Analyse(source)
if language != nil {
lexer = language.Config().Name
}
}
if language == nil {
language = lexers.Fallback
}
tokens, err := chroma.Coalesce(language).Tokenise(nil, source)
if err != nil {
panic(err)
}
style := styles.Get(styleName)
if style == nil {
style = styles.Fallback
}
buf := &strings.Builder{}
options := []html.Option{}
if classes {
options = append(options, html.WithClasses(true), html.Standalone(true))
}
formatter := html.New(options...)
err = formatter.Format(buf, style, tokens)
if err != nil {
panic(err)
}
lang := language.Config().Name
if language == lexers.Fallback {
lang = ""
}
return js.ValueOf(map[string]any{
"html": buf.String(),
"language": lang,
"background": html.StyleEntryToCSS(style.Get(chroma.Background)),
})
}
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