ucl/cmd/playwasm/jsiter.go

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//go:build js && wasm
package main
import (
"bytes"
"context"
"errors"
"github.com/alecthomas/participle/v2"
"strings"
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"syscall/js"
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"ucl.lmika.dev/ucl"
)
func invokeUCLCallback(name string, args ...any) {
if onLine := js.Global().Get("ucl").Get(name); !onLine.IsNull() {
onLine.Invoke(args...)
}
}
func initJS(ctx context.Context) {
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uclObj := make(map[string]any)
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inst := ucl.New(ucl.WithOut(&uclOut{
lineBuffer: new(bytes.Buffer),
writeLine: func(line string) {
invokeUCLCallback("onOutLine", line)
},
}))
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uclObj["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()
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if err := ucl.EvalAndDisplay(ctx, inst, 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
})
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js.Global().Set("ucl", uclObj)
}
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
}