sdks/go/pkg/beam/core/runtime/exec/optimized/inputs.tmpl

// 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 {{.Package}}

import (
    "io"
    "fmt"
    "reflect"

    "github.com/apache/beam/sdks/v2/go/pkg/beam/core/runtime/exec"
  	"github.com/apache/beam/sdks/v2/go/pkg/beam/core/typex"
{{- range $import := .Imports}}
    "{{$import}}"
{{- end}}
)

func init() {
{{- range $x := .X}}
    exec.RegisterInput(reflect.TypeOf((*func (*{{$x.Type}})bool)(nil)).Elem(), iterMaker{{$x.Name}})
    exec.RegisterInput(reflect.TypeOf((*func (*typex.EventTime, *{{$x.Type}})bool)(nil)).Elem(), iterMakerET{{$x.Name}})
{{- range $y := .Y}}
    exec.RegisterInput(reflect.TypeOf((*func (*{{$x.Type}}, *{{$y.Type}})bool)(nil)).Elem(), iterMaker{{$x.Name}}{{$y.Name}})
    exec.RegisterInput(reflect.TypeOf((*func (*typex.EventTime, *{{$x.Type}}, *{{$y.Type}})bool)(nil)).Elem(), iterMakerET{{$x.Name}}{{$y.Name}})
{{- end}}
{{- end}}
}

type iterNative struct {
	s     exec.ReStream
	fn    interface{}

	// cur is the "current" stream, if any.
	cur exec.Stream
}

func (v *iterNative) Init() error {
    cur, err := v.s.Open()
    if err != nil {
       return err
    }
	v.cur = cur
	return nil
}

func (v *iterNative) Value() interface{} {
	return v.fn
}

func (v *iterNative) Reset() error {
	if err := v.cur.Close(); err != nil {
		return err
	}
	v.cur = nil
	return nil
}

{{range $x := .X}}
func (v *iterNative) read{{$x.Name}}(val *{{$x.Type}}) bool {
	elm, err := v.cur.Read()
	if err != nil {
		if err == io.EOF {
			return false
		}
		panic(fmt.Sprintf("broken stream: %v", err))
	}
    *val = elm.Elm.({{$x.Type}})
    return true
}

func iterMaker{{$x.Name}}(s exec.ReStream) exec.ReusableInput {
	ret := &iterNative{s: s}
	ret.fn = ret.read{{$x.Name}}
	return ret
}

func (v *iterNative) readET{{$x.Name}}(et *typex.EventTime, val *{{$x.Type}}) bool {
	elm, err := v.cur.Read()
	if err != nil {
		if err == io.EOF {
			return false
		}
		panic(fmt.Sprintf("broken stream: %v", err))
	}

    *et = elm.Timestamp
    *val = elm.Elm.({{$x.Type}})
    return true
}

func iterMakerET{{$x.Name}}(s exec.ReStream) exec.ReusableInput {
	ret := &iterNative{s: s}
	ret.fn = ret.readET{{$x.Name}}
	return ret
}

{{range $y := .Y}}
func (v *iterNative) read{{$x.Name}}{{$y.Name}}(key *{{$x.Type}}, value *{{$y.Type}}) bool {
	elm, err := v.cur.Read()
	if err != nil {
		if err == io.EOF {
			return false
		}
		panic(fmt.Sprintf("broken stream: %v", err))
	}
    *key = elm.Elm.({{$x.Type}})
    *value = elm.Elm2.({{$y.Type}})
    return true
}

func iterMaker{{$x.Name}}{{$y.Name}}(s exec.ReStream) exec.ReusableInput {
	ret := &iterNative{s: s}
	ret.fn = ret.read{{$x.Name}}{{$y.Name}}
	return ret
}

func (v *iterNative) readET{{$x.Name}}{{$y.Name}}(et *typex.EventTime, key *{{$x.Type}}, value *{{$y.Type}}) bool {
	elm, err := v.cur.Read()
	if err != nil {
		if err == io.EOF {
			return false
		}
		panic(fmt.Sprintf("broken stream: %v", err))
	}

    *et = elm.Timestamp
    *key = elm.Elm.({{$x.Type}})
    *value = elm.Elm2.({{$y.Type}})
    return true
}

func iterMakerET{{$x.Name}}{{$y.Name}}(s exec.ReStream) exec.ReusableInput {
	ret := &iterNative{s: s}
	ret.fn = ret.readET{{$x.Name}}{{$y.Name}}
	return ret
}
{{end}}
{{end}}