Spent way too much time building a playground for.. reasons

cmd/playwasm/jsiter.go

@@ -0,0 +1,73 @@
+//go:build js && wasm
+
+package main
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"github.com/alecthomas/participle/v2"
+	"github.com/lmika/cmdlang-proto/cmdlang"
+	"strings"
+	"syscall/js"
+)
+
+func invokeUCLCallback(name string, args ...any) {
+	if onLine := js.Global().Get("ucl").Get(name); !onLine.IsNull() {
+		onLine.Invoke(args...)
+	}
+}
+
+func initJS(ctx context.Context) {
+	ucl := make(map[string]any)
+
+	inst := cmdlang.New(cmdlang.WithOut(&uclOut{
+		lineBuffer: new(bytes.Buffer),
+		writeLine: func(line string) {
+			invokeUCLCallback("onOutLine", line)
+		},
+	}))
+
+	ucl["eval"] = js.FuncOf(func(this js.Value, args []js.Value) any {
+		if len(args) != 2 {
+			return nil
+		}
+
+		cmdLine := args[0].String()
+		if strings.TrimSpace(cmdLine) == "" {
+			invokeUCLCallback("onNewCommand")
+			return nil
+		}
+
+		wantContinue := args[1].Bool()
+		if err := inst.EvalAndDisplay(ctx, cmdLine); err != nil {
+			var p participle.Error
+			if errors.As(err, &p) && wantContinue {
+				invokeUCLCallback("onContinue")
+				return nil
+			}
+
+			invokeUCLCallback("onError", err.Error())
+		}
+		invokeUCLCallback("onNewCommand")
+		return nil
+	})
+	js.Global().Set("ucl", ucl)
+}
+
+type uclOut struct {
+	lineBuffer *bytes.Buffer
+	writeLine  func(line string)
+}
+
+func (uo *uclOut) Write(p []byte) (n int, err error) {
+	for _, b := range p {
+		if b == '\n' {
+			uo.writeLine(uo.lineBuffer.String())
+			uo.lineBuffer.Reset()
+		} else {
+			uo.lineBuffer.WriteByte(b)
+		}
+	}
+	return len(p), nil
+}

cmd/playwasm/main.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"context"
+)
+
+func main() {
+	initJS(context.Background())
+
+	<-make(chan struct{})
+}