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forked from apache/beam
/
coder.go
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/
coder.go
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// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package exec
import (
"fmt"
"io"
"reflect"
"strings"
"bytes"
"github.com/apache/beam/sdks/go/pkg/beam/core/graph/coder"
"github.com/apache/beam/sdks/go/pkg/beam/core/graph/mtime"
"github.com/apache/beam/sdks/go/pkg/beam/core/graph/window"
"github.com/apache/beam/sdks/go/pkg/beam/core/typex"
"github.com/apache/beam/sdks/go/pkg/beam/core/util/ioutilx"
"github.com/apache/beam/sdks/go/pkg/beam/internal/errors"
)
// NOTE(herohde) 4/30/2017: The main complication is CoGBK results, which have
// nested streams. Hence, a simple read-one-element-at-a-time approach doesn't
// work, because each "element" can be too large to fit into memory. Instead,
// we handle the top GBK/CoGBK layer in the processing node directly.
// ElementEncoder handles FullValue serialization to a byte stream. The encoder
// can be reused, even if an error is encountered.
type ElementEncoder interface {
// Encode serializes the given value to the writer.
Encode(*FullValue, io.Writer) error
}
// EncodeElement is a convenience function for encoding a single element into a
// byte slice.
func EncodeElement(c ElementEncoder, val interface{}) ([]byte, error) {
var buf bytes.Buffer
if err := c.Encode(&FullValue{Elm: val}, &buf); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// ElementDecoder handles FullValue deserialization from a byte stream. The decoder
// can be reused, even if an error is encountered.
type ElementDecoder interface {
// Decode deserializes a value from the given reader.
Decode(io.Reader) (*FullValue, error)
// DecodeTo deserializes a value from the given reader into the provided FullValue.
DecodeTo(io.Reader, *FullValue) error
}
// MakeElementEncoder returns a ElementCoder for the given coder.
// It panics if given an unknown coder, or a coder with stream types, such as GBK.
func MakeElementEncoder(c *coder.Coder) ElementEncoder {
switch c.Kind {
case coder.Bytes:
return &bytesEncoder{}
case coder.Bool:
return &boolEncoder{}
case coder.VarInt:
return &varIntEncoder{}
case coder.Double:
return &doubleEncoder{}
case coder.String:
return &stringEncoder{}
case coder.Custom:
enc := &customEncoder{
t: c.Custom.Type,
enc: makeEncoder(c.Custom.Enc.Fn),
}
if c.Custom.Name != "schema" {
return enc
}
// Custom schema coding uses the beam row coder, but wraps it in a
// length prefix and treats it as an opaque coder.
// Specialization to handle slice and array types.
switch c.T.Type().Kind() {
case reflect.Slice, reflect.Array:
// We don't permit registering custom coders for slice types
// so we must length prefix the entire iterable.
return &lpEncoder{
enc: &iterableEncoder{
t: c.Custom.Type,
enc: enc,
},
}
}
return enc
case coder.LP:
return &lpEncoder{
enc: MakeElementEncoder(c.Components[0]),
}
case coder.KV:
return &kvEncoder{
fst: MakeElementEncoder(c.Components[0]),
snd: MakeElementEncoder(c.Components[1]),
}
case coder.Window:
return &wrappedWindowEncoder{
enc: MakeWindowEncoder(c.Window),
}
case coder.Iterable:
return &iterableEncoder{
enc: MakeElementEncoder(c.Components[0]),
}
case coder.WindowedValue:
return &windowedValueEncoder{
elm: MakeElementEncoder(c.Components[0]),
win: MakeWindowEncoder(c.Window),
}
case coder.ParamWindowedValue:
return ¶mWindowedValueEncoder{
elm: MakeElementEncoder(c.Components[0]),
win: MakeWindowEncoder(c.Window),
}
case coder.Timer:
return &timerEncoder{
elm: MakeElementEncoder(c.Components[0]),
}
case coder.Row:
enc, err := coder.RowEncoderForStruct(c.T.Type())
if err != nil {
panic(err)
}
return &rowEncoder{
enc: enc,
}
default:
panic(fmt.Sprintf("Unexpected coder: %v", c))
}
}
// MakeElementDecoder returns a ElementDecoder for the given coder.
// It panics if given an unknown coder, or a coder with stream types, such as GBK.
func MakeElementDecoder(c *coder.Coder) ElementDecoder {
switch c.Kind {
case coder.Bytes:
return &bytesDecoder{}
case coder.Bool:
return &boolDecoder{}
case coder.VarInt:
return &varIntDecoder{}
case coder.Double:
return &doubleDecoder{}
case coder.String:
return &stringDecoder{}
case coder.Custom:
dec := &customDecoder{
t: c.Custom.Type,
dec: makeDecoder(c.Custom.Dec.Fn),
}
if c.Custom.Name != "schema" {
return dec
}
// Custom schema coding uses the beam row coder, but wraps it in a
// length prefix and treats it as an opaque coder.
// Specialization to handle slice and array types.
switch c.T.Type().Kind() {
case reflect.Slice:
return &lpDecoder{
dec: &iterableDecoder{
t: c.Custom.Type,
dec: dec,
},
}
case reflect.Array:
return &lpDecoder{
dec: &arrayDecoder{
t: c.Custom.Type,
dec: dec,
},
}
}
return dec
case coder.LP:
return &lpDecoder{
dec: MakeElementDecoder(c.Components[0]),
}
case coder.KV:
return &kvDecoder{
fst: MakeElementDecoder(c.Components[0]),
snd: MakeElementDecoder(c.Components[1]),
}
// The following cases are not expected to be executed in the normal
// course of a pipeline, however including them here enables simpler
// end to end validation of standard coders against
// the standard_coders.yaml specs.
case coder.Window:
return &wrappedWindowDecoder{
dec: MakeWindowDecoder(c.Window),
}
// Note: Iterables in CoGBK are handled in datasource.go instead.
case coder.Iterable:
return &iterableDecoder{
t: c.T.Type(),
dec: MakeElementDecoder(c.Components[0]),
}
case coder.WindowedValue:
return &windowedValueDecoder{
elm: MakeElementDecoder(c.Components[0]),
win: MakeWindowDecoder(c.Window),
}
case coder.ParamWindowedValue:
return ¶mWindowedValueDecoder{
elm: MakeElementDecoder(c.Components[0]),
win: MakeWindowDecoder(c.Window),
}
case coder.Timer:
return &timerDecoder{
elm: MakeElementDecoder(c.Components[0]),
}
case coder.Row:
dec, err := coder.RowDecoderForStruct(c.T.Type())
if err != nil {
panic(err)
}
return &rowDecoder{
dec: dec,
}
default:
panic(fmt.Sprintf("Unexpected coder: %v", c))
}
}
type bytesEncoder struct{}
func (*bytesEncoder) Encode(val *FullValue, w io.Writer) error {
// Encoding: size (varint) + raw data
var data []byte
data, ok := val.Elm.([]byte)
if !ok {
return errors.Errorf("received unknown value type: want []byte, got %T", val.Elm)
}
return coder.EncodeBytes(data, w)
}
type bytesDecoder struct{}
func (*bytesDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// Encoding: size (varint) + raw data
data, err := coder.DecodeBytes(r)
if err != nil {
return err
}
*fv = FullValue{Elm: data}
return nil
}
func (d *bytesDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type boolEncoder struct{}
func (*boolEncoder) Encode(val *FullValue, w io.Writer) error {
// Encoding: false = 0, true = 1
var err error
if val.Elm.(bool) {
_, err = ioutilx.WriteUnsafe(w, []byte{1})
} else {
_, err = ioutilx.WriteUnsafe(w, []byte{0})
}
if err != nil {
return fmt.Errorf("error encoding bool: %v", err)
}
return nil
}
type boolDecoder struct{}
func (*boolDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// Encoding: false = 0, true = 1
b := make([]byte, 1, 1)
if err := ioutilx.ReadNBufUnsafe(r, b); err != nil {
if err == io.EOF {
return err
}
return fmt.Errorf("error decoding bool: %v", err)
}
switch b[0] {
case 0:
*fv = FullValue{Elm: false}
return nil
case 1:
*fv = FullValue{Elm: true}
return nil
}
return fmt.Errorf("error decoding bool: received invalid value %v", b)
}
func (d *boolDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type varIntEncoder struct{}
func (*varIntEncoder) Encode(val *FullValue, w io.Writer) error {
// Encoding: beam varint
return coder.EncodeVarInt(val.Elm.(int64), w)
}
type varIntDecoder struct{}
func (*varIntDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// Encoding: beam varint
n, err := coder.DecodeVarInt(r)
if err != nil {
return err
}
*fv = FullValue{Elm: n}
return nil
}
func (d *varIntDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type doubleEncoder struct{}
func (*doubleEncoder) Encode(val *FullValue, w io.Writer) error {
// Encoding: beam double (big-endian 64-bit IEEE 754 double)
return coder.EncodeDouble(val.Elm.(float64), w)
}
type doubleDecoder struct{}
func (*doubleDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// Encoding: beam double (big-endian 64-bit IEEE 754 double)
f, err := coder.DecodeDouble(r)
if err != nil {
return err
}
*fv = FullValue{Elm: f}
return nil
}
func (d *doubleDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type stringEncoder struct{}
func (*stringEncoder) Encode(val *FullValue, w io.Writer) error {
// Encoding: beam utf8 string (length prefix + run of bytes)
return coder.EncodeStringUTF8(val.Elm.(string), w)
}
type stringDecoder struct{}
func (*stringDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// Encoding: beam utf8 string (length prefix + run of bytes)
f, err := coder.DecodeStringUTF8(r)
if err != nil {
return err
}
*fv = FullValue{Elm: f}
return nil
}
func (d *stringDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type customEncoder struct {
t reflect.Type
enc Encoder
}
func (c *customEncoder) Encode(val *FullValue, w io.Writer) error {
// (1) Call encode
data, err := c.enc.Encode(c.t, val.Elm)
if err != nil {
return err
}
// (2) Add length prefix
size := len(data)
if err := coder.EncodeVarInt((int64)(size), w); err != nil {
return err
}
_, err = w.Write(data)
return err
}
type customDecoder struct {
t reflect.Type
dec Decoder
}
func (c *customDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// (1) Read length-prefixed encoded data
size, err := coder.DecodeVarInt(r)
if err != nil {
return err
}
data, err := ioutilx.ReadN(r, (int)(size))
if err != nil {
return err
}
// (2) Call decode
val, err := c.dec.Decode(c.t, data)
if err != nil {
return err
}
*fv = FullValue{Elm: val}
return nil
}
func (c *customDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := c.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type lpEncoder struct {
enc ElementEncoder
buf bytes.Buffer
}
func (c *lpEncoder) Encode(val *FullValue, w io.Writer) error {
// (1) Call encode
if err := c.enc.Encode(val, &c.buf); err != nil {
return err
}
// (2) Add length prefix
data := c.buf.Bytes()
size := len(data)
if err := coder.EncodeVarInt((int64)(size), w); err != nil {
return err
}
_, err := w.Write(data)
c.buf.Reset()
return err
}
type lpDecoder struct {
dec ElementDecoder
r io.LimitedReader
}
func (c *lpDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// (1) Read length-prefixed encoded data
size, err := coder.DecodeVarInt(r)
if err != nil {
return err
}
c.r = io.LimitedReader{R: r, N: size}
// (2) Call decode
return c.dec.DecodeTo(&c.r, fv)
}
func (c *lpDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := c.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type kvEncoder struct {
fst, snd ElementEncoder
cached FullValue
}
func (c *kvEncoder) Encode(val *FullValue, w io.Writer) error {
defer func() {
// clear the cached FullValue after use to avoid leaks.
c.cached = FullValue{}
}()
if err := c.fst.Encode(convertIfNeeded(val.Elm, &c.cached), w); err != nil {
return err
}
return c.snd.Encode(convertIfNeeded(val.Elm2, &c.cached), w)
}
type kvDecoder struct {
fst, snd ElementDecoder
}
func (c *kvDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
var key FullValue
if err := c.fst.DecodeTo(r, &key); err != nil {
return err
}
var value FullValue
if err := c.snd.DecodeTo(r, &value); err != nil {
return err
}
*fv = FullValue{Elm: elideSingleElmFV(&key), Elm2: elideSingleElmFV(&value)}
return nil
}
// Decode returns a *FullValue containing the contents of the decoded KV. If
// one of the elements of the KV is a nested KV, then the corresponding Elm
// field in the returned value will be another *FullValue. Otherwise, the
// Elm will be the decoded type.
//
// Example:
// KV<int, KV<...>> decodes to *FullValue{Elm: int, Elm2: *FullValue{...}}
func (c *kvDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := c.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
// elideSingleElmFV elides a FullValue if it has only one element, returning
// the contents of the first element, but returning the FullValue unchanged
// if it has two elements.
//
// Technically drops window and timestamp info, so only use when those are
// expected to be empty.
func elideSingleElmFV(fv *FullValue) interface{} {
if fv.Elm2 == nil {
return fv.Elm
}
return fv
}
// convertIfNeeded reuses Wrapped KVs if needed, but accepts pointer
// to a pre-allocated non-nil *FullValue for overwriting and use.
func convertIfNeeded(v interface{}, allocated *FullValue) *FullValue {
if fv, ok := v.(*FullValue); ok {
return fv
} else if _, ok := v.(FullValue); ok {
panic("Nested FullValues must be nested as pointers.")
}
*allocated = FullValue{Elm: v}
return allocated
}
type iterableEncoder struct {
t reflect.Type
enc ElementEncoder
}
func (c *iterableEncoder) Encode(val *FullValue, w io.Writer) error {
// Do a reflect, get the length.
rv := reflect.ValueOf(val.Elm)
size := rv.Len()
if err := coder.EncodeInt32((int32)(size), w); err != nil {
return err
}
var e FullValue
for i := 0; i < size; i++ {
e.Elm = rv.Index(i).Interface()
err := c.enc.Encode(&e, w)
if err != nil {
return err
}
}
return nil
}
type iterableDecoder struct {
t reflect.Type
dec ElementDecoder
}
func (c *iterableDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// (1) Read count prefixed encoded data
size, err := coder.DecodeInt32(r)
if err != nil {
return err
}
n := int(size)
switch {
case n >= 0:
rv, err := c.decodeToSlice(n, r)
if err != nil {
return err
}
*fv = FullValue{Elm: rv.Interface()}
return nil
case n == -1:
rv := reflect.MakeSlice(c.t, 0, 0)
chunk, err := coder.DecodeVarInt(r)
if err != nil {
return err
}
for chunk != 0 {
rvi, err := c.decodeToSlice(int(chunk), r)
if err != nil {
return err
}
rv = reflect.AppendSlice(rv, rvi)
chunk, err = coder.DecodeVarInt(r)
if err != nil {
return err
}
}
*fv = FullValue{Elm: rv.Interface()}
}
return nil
}
func (c *iterableDecoder) decodeToSlice(n int, r io.Reader) (reflect.Value, error) {
var e FullValue
rv := reflect.MakeSlice(c.t, n, n)
for i := 0; i < n; i++ {
err := c.dec.DecodeTo(r, &e)
if err != nil {
return reflect.Value{}, err
}
if e.Elm != nil {
rv.Index(i).Set(reflect.ValueOf(e.Elm))
} else {
// Hack to support testing the standard window coders
// against standard_coders.yaml.
// It is not supported for BeamGo pipelines to treat windows
// as elements natively.
rv.Index(i).Set(reflect.ValueOf(e.Windows[0]))
}
}
return rv, nil
}
func (c *iterableDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := c.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
// arrayDecoder reads the same format as iterableDecoder but
// produces arrays instead of slices, taking the encoded length
// as the length of the array.
type arrayDecoder struct {
t reflect.Type // array type
dec ElementDecoder
}
func (c *arrayDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// (1) Read count prefixed encoded data
size, err := coder.DecodeInt32(r)
if err != nil {
return err
}
n := int(size)
if n != c.t.Len() {
return errors.Errorf("array len mismatch. decoding %v but only have %v elements.", c.t, n)
}
switch {
case n >= 0:
rv := reflect.New(c.t).Elem()
var e FullValue
for i := 0; i < int(n); i++ {
err := c.dec.DecodeTo(r, &e)
if err != nil {
return err
}
if e.Elm != nil {
rv.Index(i).Set(reflect.ValueOf(e.Elm))
}
}
*fv = FullValue{Elm: rv.Interface()}
return nil
default:
return errors.Errorf("unable to decode array with iterable marker %v", n)
}
}
func (c *arrayDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := c.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type windowedValueEncoder struct {
elm ElementEncoder
win WindowEncoder
}
func (e *windowedValueEncoder) Encode(val *FullValue, w io.Writer) error {
if err := EncodeWindowedValueHeader(e.win, val.Windows, val.Timestamp, w); err != nil {
return err
}
return e.elm.Encode(val, w)
}
type windowedValueDecoder struct {
elm ElementDecoder
win WindowDecoder
}
func (d *windowedValueDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// Encoding: beam utf8 string (length prefix + run of bytes)
w, et, err := DecodeWindowedValueHeader(d.win, r)
if err != nil {
return err
}
if err := d.elm.DecodeTo(r, fv); err != nil {
return err
}
fv.Windows = w
fv.Timestamp = et
return nil
}
func (d *windowedValueDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type paramWindowedValueEncoder struct {
elm ElementEncoder
win WindowEncoder
}
func (*paramWindowedValueEncoder) Encode(val *FullValue, w io.Writer) error {
// Encoding: beam utf8 string (length prefix + run of bytes)
return coder.EncodeStringUTF8(val.Elm.(string), w)
}
type paramWindowedValueDecoder struct {
elm ElementDecoder
win WindowDecoder
}
func (*paramWindowedValueDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
// Encoding: beam utf8 string (length prefix + run of bytes)
f, err := coder.DecodeStringUTF8(r)
if err != nil {
return err
}
*fv = FullValue{Elm: f}
return nil
}
func (d *paramWindowedValueDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type timerEncoder struct {
elm ElementEncoder
}
func (e *timerEncoder) Encode(val *FullValue, w io.Writer) error {
return e.elm.Encode(val, w)
}
type timerDecoder struct {
elm ElementDecoder
}
func (d *timerDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
return d.elm.DecodeTo(r, fv)
}
func (d *timerDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type rowEncoder struct {
enc func(interface{}, io.Writer) error
}
func (e *rowEncoder) Encode(val *FullValue, w io.Writer) error {
return e.enc(val.Elm, w)
}
type rowDecoder struct {
dec func(r io.Reader) (interface{}, error)
}
func (d *rowDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
v, err := d.dec(r)
if err != nil {
return err
}
*fv = FullValue{Elm: v}
return nil
}
func (d *rowDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
// WindowEncoder handles Window serialization to a byte stream. The encoder
// can be reused, even if an error is encountered. Concurrency-safe.
type WindowEncoder interface {
// Encode serializes the given value to the writer.
Encode([]typex.Window, io.Writer) error
EncodeSingle(typex.Window, io.Writer) error
}
// EncodeWindow is a convenience function for encoding a single window into a
// byte slice.
func EncodeWindow(c WindowEncoder, w typex.Window) ([]byte, error) {
var buf bytes.Buffer
if err := c.EncodeSingle(w, &buf); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// WindowDecoder handles Window deserialization from a byte stream. The decoder
// can be reused, even if an error is encountered. Concurrency-safe.
type WindowDecoder interface {
// Decode deserializes a value from the given reader.
Decode(io.Reader) ([]typex.Window, error)
// DecodeSingle decodes a single window from the given reader.
DecodeSingle(io.Reader) (typex.Window, error)
}
// MakeWindowEncoder returns a WindowEncoder for the given window coder.
func MakeWindowEncoder(c *coder.WindowCoder) WindowEncoder {
if c.Payload != "" {
return &payloadWindowEncoder{payload: []byte(c.Payload)}
}
switch c.Kind {
case coder.GlobalWindow:
return &globalWindowEncoder{}
case coder.IntervalWindow:
return &intervalWindowEncoder{}
default:
panic(fmt.Sprintf("Unexpected window coder: %v", c))
}
}
// MakeWindowDecoder returns a WindowDecoder for the given window coder.
func MakeWindowDecoder(c *coder.WindowCoder) WindowDecoder {
var w WindowDecoder
switch c.Kind {
case coder.GlobalWindow:
w = &globalWindowDecoder{}
case coder.IntervalWindow:
w = &intervalWindowDecoder{}
default:
panic(fmt.Sprintf("Unexpected window coder: %v", c))
}
if c.Payload != "" {
w = &payloadWindowDecoder{dec: w, payload: c.Payload, payloadR: strings.NewReader(c.Payload)}
}
return w
}
// wrappedWindowEncoder wraps a WindowEncoder for the ElementEncoder interface.
type wrappedWindowEncoder struct {
enc WindowEncoder
}
func (e *wrappedWindowEncoder) Encode(val *FullValue, w io.Writer) error {
if len(val.Windows) == 0 {
return nil
}
return e.enc.EncodeSingle(val.Windows[0], w)
}
// wrappedWindowDecoder wraps a WindowDecoder for the ElementDecoder interface.
type wrappedWindowDecoder struct {
dec WindowDecoder
}
func (d *wrappedWindowDecoder) DecodeTo(r io.Reader, fv *FullValue) error {
ws, err := d.dec.DecodeSingle(r)
if err != nil {
return err
}
fv.Windows = []typex.Window{ws}
return nil
}
func (d *wrappedWindowDecoder) Decode(r io.Reader) (*FullValue, error) {
fv := &FullValue{}
if err := d.DecodeTo(r, fv); err != nil {
return nil, err
}
return fv, nil
}
type payloadWindowEncoder struct {
payload []byte
}
func (e *payloadWindowEncoder) Encode(ws []typex.Window, w io.Writer) error {
_, err := w.Write(e.payload)
return err
}
func (e *payloadWindowEncoder) EncodeSingle(ws typex.Window, w io.Writer) error {
_, err := w.Write(e.payload)
return err
}
type payloadWindowDecoder struct {
dec WindowDecoder
payload string
payloadR *strings.Reader
}
func (d *payloadWindowDecoder) Decode(r io.Reader) ([]typex.Window, error) {
d.payloadR.Reset(d.payload)
return d.dec.Decode(d.payloadR)
}
func (d *payloadWindowDecoder) DecodeSingle(r io.Reader) (typex.Window, error) {
d.payloadR.Reset(d.payload)
return d.dec.DecodeSingle(d.payloadR)
}