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option.go
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option.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 beam
import (
"fmt"
"reflect"
)
// Option is an optional value or context to a transformation, used at pipeline
// construction time. The primary use case is providing side inputs.
type Option interface {
private()
}
// SideInput provides a view of the given PCollection to the transformation.
type SideInput struct {
Input PCollection
// WindowFn interface{}
// ViewFn interface{}
}
func (s SideInput) private() {}
// TypeDefinition provides construction-time type information that the platform
// cannot infer, such as structured storage sources. These types are universal types
// that appear as output only. Types that are inferrable should not be conveyed via
// this mechanism.
type TypeDefinition struct {
// Var is the universal type defined.
Var reflect.Type
// T is the type it is bound to.
T reflect.Type
}
func (s TypeDefinition) private() {}
func parseOpts(opts []Option) ([]SideInput, []TypeDefinition) {
var side []SideInput
var infer []TypeDefinition
for _, opt := range opts {
switch opt.(type) {
case SideInput:
side = append(side, opt.(SideInput))
case TypeDefinition:
infer = append(infer, opt.(TypeDefinition))
default:
panic(fmt.Sprintf("Unexpected opt: %v", opt))
}
}
return side, infer
}