84 lines
2.3 KiB
Go
84 lines
2.3 KiB
Go
package jsStreams
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"sync"
|
|
|
|
"syscall/js"
|
|
)
|
|
|
|
// ReadableStream implements io.ReaderCloser for a JavaScript ReadableStream.
|
|
type ReadableStream struct {
|
|
stream js.Value
|
|
reader js.Value
|
|
lock sync.Mutex
|
|
}
|
|
|
|
// Read reads up to len(p) bytes into p. It returns the number of bytes read (0 <= n <= len(p)) and any error encountered.
|
|
// This implementation of Read does not use scratch space if n < len(p). If some data is available but not len(p) bytes,
|
|
// Read conventionally returns what is available instead of waiting for more. Note: Read will block until data is available,
|
|
// meaning in a WASM environment, you **must** use a goroutine to call Read.
|
|
func (r *ReadableStream) Read(inputBytes []byte) (n int, err error) {
|
|
defer func() {
|
|
recovered := recover()
|
|
if recovered != nil {
|
|
err = fmt.Errorf("panic: %v", recovered)
|
|
}
|
|
}()
|
|
|
|
r.lock.Lock()
|
|
var waitGroup sync.WaitGroup
|
|
waitGroup.Add(1)
|
|
|
|
if r.reader.IsUndefined() {
|
|
r.reader = r.stream.Call("getReader", map[string]interface{}{"mode": "byob"})
|
|
}
|
|
|
|
resultBuffer := js.Global().Get("Uint8Array").New(len(inputBytes))
|
|
readResult := r.reader.Call("read", resultBuffer)
|
|
|
|
readResult.Call("then", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
|
|
defer waitGroup.Done()
|
|
data := args[0].Get("value")
|
|
js.CopyBytesToGo(inputBytes, data)
|
|
if args[0].Get("done").Bool() {
|
|
err = errors.New("EOF")
|
|
}
|
|
n = data.Length()
|
|
return nil
|
|
}))
|
|
|
|
readResult.Call("catch", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
|
|
defer waitGroup.Done()
|
|
err = errors.New(args[0].Get("message").String())
|
|
return nil
|
|
}))
|
|
|
|
waitGroup.Wait()
|
|
|
|
return n, err
|
|
}
|
|
|
|
// Close closes the ReadableStream. If the stream is already closed, Close does nothing.
|
|
// If the stream is not yet closed, it is canceled. The reader is closed and the underlying source or pipeline is terminated.
|
|
// This method is idempotent, meaning that it can be called multiple times without causing an error.
|
|
func (r *ReadableStream) Close() (err error) {
|
|
defer func() {
|
|
recovered := recover()
|
|
if recovered != nil {
|
|
err = fmt.Errorf("panic: %v", recovered)
|
|
}
|
|
}()
|
|
|
|
if !r.reader.IsUndefined() {
|
|
r.reader.Call("cancel")
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func NewReadableStream(stream js.Value) *ReadableStream {
|
|
return &ReadableStream{stream: stream}
|
|
}
|