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feat: create napi-go/js helper library
Create `js/` wrapper around `napi`. Add `js.Value`, `js.Callback`, `js.Func`, and `js.Promise` implementations. Add `js.AsCallback` to provide `napi.Callback` values, generally to `entry.Export`.
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5 files changed

+365
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lines changed

‎js/callback.go‎

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package js
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import (
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"github.com/akshayganeshen/napi-go"
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)
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type Callback = func(env Env, this Value, args []Value) any
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func AsCallback(fn Callback) napi.Callback {
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return func(env napi.Env, info napi.CallbackInfo) napi.Value {
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cbInfo, st := napi.GetCbInfo(env, info)
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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jsEnv := AsEnv(env)
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this := Value{
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Env: jsEnv,
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Value: cbInfo.This,
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}
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args := make([]Value, len(cbInfo.Args))
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for i, cbArg := range cbInfo.Args {
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args[i] = Value{
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Env: jsEnv,
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Value: cbArg,
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}
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}
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result := fn(jsEnv, this, args)
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return jsEnv.ValueOf(result).Value
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}
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}

‎js/env.go‎

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package js
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import (
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"fmt"
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"unsafe"
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"github.com/akshayganeshen/napi-go"
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)
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type Env struct {
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Env napi.Env
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}
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type InvalidValueTypeError struct {
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Value any
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}
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var _ error = InvalidValueTypeError{}
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func AsEnv(env napi.Env) Env {
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return Env{
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Env: env,
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}
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}
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func (e Env) Global() Value {
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v, st := napi.GetGlobal(e.Env)
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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return Value{
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Env: e,
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Value: v,
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}
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}
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func (e Env) Null() Value {
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v, st := napi.GetNull(e.Env)
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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return Value{
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Env: e,
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Value: v,
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}
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}
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func (e Env) Undefined() Value {
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v, st := napi.GetUndefined(e.Env)
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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return Value{
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Env: e,
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Value: v,
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}
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}
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func (e Env) ValueOf(x any) Value {
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var (
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v napi.Value
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st napi.Status
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)
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switch xt := x.(type) {
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case Value:
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return xt
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case []Value:
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l := len(xt)
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v, st = napi.CreateArrayWithLength(e.Env, l)
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if st != napi.StatusOK {
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break
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}
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for i, xti := range xt {
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// TODO: Use Value.SetIndex helper
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st = napi.SetElement(e.Env, v, i, xti.Value)
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if st != napi.StatusOK {
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break
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}
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}
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case Func:
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return xt.Value
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case Callback:
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return e.FuncOf(xt).Value
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case *Promise:
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v, st = xt.Promise.Value, napi.StatusOK
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case napi.Value:
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v, st = xt, napi.StatusOK
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case nil:
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v, st = napi.GetNull(e.Env)
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case bool:
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v, st = napi.GetBoolean(e.Env, xt)
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case int:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case int8:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case int16:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case int64:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case uint:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case uint8:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case uint16:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case uint64:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case uintptr:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case unsafe.Pointer:
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v, st = napi.CreateDouble(e.Env, float64(uintptr(xt)))
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case float32:
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v, st = napi.CreateDouble(e.Env, float64(xt))
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case float64:
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v, st = napi.CreateDouble(e.Env, xt)
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case string:
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v, st = napi.CreateStringUtf8(e.Env, xt)
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case error:
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msg := e.ValueOf(xt.Error())
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v, st = napi.CreateError(e.Env, nil, msg.Value)
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case []any:
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l := len(xt)
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v, st = napi.CreateArrayWithLength(e.Env, l)
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if st != napi.StatusOK {
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break
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}
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for i, xti := range xt {
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// TODO: Use Value.SetIndex helper
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vti := e.ValueOf(xti)
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st = napi.SetElement(e.Env, v, i, vti.Value)
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if st != napi.StatusOK {
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break
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}
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}
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case map[string]any:
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v, st = napi.CreateObject(e.Env)
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if st != napi.StatusOK {
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break
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}
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for xtk, xtv := range xt {
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// TODO: Use Value.Set helper
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vtk, vtv := e.ValueOf(xtk), e.ValueOf(xtv)
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st = napi.SetProperty(e.Env, v, vtk.Value, vtv.Value)
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if st != napi.StatusOK {
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break
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}
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}
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default:
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panic(InvalidValueTypeError{x})
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}
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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return Value{
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Env: e,
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Value: v,
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}
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}
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func (e Env) FuncOf(fn Callback) Func {
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// TODO: Add CreateReference to FuncOf to keep value alive
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v, st := napi.CreateFunction(
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e.Env,
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"",
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AsCallback(fn),
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)
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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return Func{
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Value: Value{
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Env: e,
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Value: v,
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},
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}
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}
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func (e Env) NewPromise() *Promise {
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var result Promise
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result.reset(e)
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return &result
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}
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func (err InvalidValueTypeError) Error() string {
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return fmt.Sprintf("Value cannot be represented in JS: %T", err.Value)
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}

‎js/func.go‎

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package js
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type Func struct {
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Value
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}

‎js/promise.go‎

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package js
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import (
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"errors"
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"github.com/akshayganeshen/napi-go"
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)
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type Promise struct {
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Promise napi.Promise
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ThreadsafeFunction napi.ThreadsafeFunction
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Result any
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ResultType PromiseResultType
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}
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type PromiseResultType string
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type PromiseProvider interface {
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Resolve(resolution any)
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Reject(rejection any)
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}
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var _ PromiseProvider = &Promise{}
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const (
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PromiseResultTypeResolved PromiseResultType = "resolved"
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PromiseResultTypeRejected PromiseResultType = "rejected"
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)
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var ErrPromiseSettled = errors.New(
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"Promise: Cannot resolve/reject a settled promise",
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)
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func (p *Promise) Resolve(resolution any) {
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p.ensurePending()
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p.Result = resolution
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p.ResultType = PromiseResultTypeResolved
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// function has already been acquired during reset
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defer p.release()
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p.settle()
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}
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func (p *Promise) Reject(rejection any) {
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p.ensurePending()
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p.Result = rejection
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p.ResultType = PromiseResultTypeRejected
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// function has already been acquired during reset
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defer p.release()
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p.settle()
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}
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func (p *Promise) reset(e Env) {
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np, st := napi.CreatePromise(e.Env)
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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asyncResourceName := e.ValueOf("napi-go/js-promise")
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fn := e.FuncOf(func(env Env, this Value, args []Value) any {
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value := env.ValueOf(p.Result)
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st := napi.StatusOK
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switch p.ResultType {
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case PromiseResultTypeResolved:
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st = napi.ResolveDeferred(env.Env, p.Promise.Deferred, value.Value)
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case PromiseResultTypeRejected:
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st = napi.RejectDeferred(env.Env, p.Promise.Deferred, value.Value)
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}
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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return nil
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})
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tsFn, st := napi.CreateThreadsafeFunction(
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e.Env,
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fn.Value.Value,
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nil, asyncResourceName.Value,
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0,
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1, // initialize with 1 acquisition
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)
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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*p = Promise{
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Promise: np,
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ThreadsafeFunction: tsFn,
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}
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}
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func (p *Promise) ensurePending() {
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if p.ResultType != "" {
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panic(ErrPromiseSettled)
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}
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}
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func (p *Promise) settle() {
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st := napi.CallThreadsafeFunction(p.ThreadsafeFunction)
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if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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}
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func (p *Promise) release() {
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st := napi.ReleaseThreadsafeFunction(p.ThreadsafeFunction)
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if st == napi.StatusClosing {
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p.ThreadsafeFunction = nil
115+
} else if st != napi.StatusOK {
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panic(napi.StatusError(st))
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}
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}

‎js/value.go‎

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package js
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import (
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"github.com/akshayganeshen/napi-go"
5+
)
6+
7+
type Value struct {
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Env Env
9+
Value napi.Value
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}
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func (v Value) GetEnv() Env {
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return v.Env
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}

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