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float.go
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float.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 coderx
import (
"fmt"
"math"
"math/bits"
"reflect"
"github.com/apache/beam/sdks/go/pkg/beam/core/graph/coder"
"github.com/apache/beam/sdks/go/pkg/beam/core/runtime"
"github.com/apache/beam/sdks/go/pkg/beam/core/typex"
"github.com/apache/beam/sdks/go/pkg/beam/core/util/reflectx"
)
func init() {
runtime.RegisterFunction(encFloat)
runtime.RegisterFunction(decFloat)
}
func encFloat(v typex.T) []byte {
var val float64
switch n := v.(type) {
case float32:
val = float64(n)
case float64:
val = n
default:
panic(fmt.Sprintf("received unknown value type: want a float, got %T", n))
}
return encVarUintZ(bits.ReverseBytes64(math.Float64bits(val)))
}
func decFloat(t reflect.Type, data []byte) (typex.T, error) {
uval, err := decVarUintZ(reflectx.Uint64, data)
if err != nil {
return nil, fmt.Errorf("invalid float encoding for: %v", data)
}
n := math.Float64frombits(bits.ReverseBytes64(uval.(uint64)))
switch t.Kind() {
case reflect.Float64:
return n, nil
case reflect.Float32:
return float32(n), nil
default:
panic(fmt.Sprintf("unreachable statement: expected a float, got %v", t))
}
}
// NewFloat returns a coder for the given float type. It uses the same
// encoding scheme as the gob package.
func NewFloat(t reflect.Type) (*coder.CustomCoder, error) {
switch t.Kind() {
case reflect.Float32, reflect.Float64:
return coder.NewCustomCoder("float", t, encFloat, decFloat)
default:
return nil, fmt.Errorf("not a float type: %v", t)
}
}