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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 utils
import (
"math"
"reflect"
)
// IndexType is the type we're going to use for Dictionary indexes, currently
// an alias to int32
type IndexType = int32
// Max and Min constants for the IndexType
const (
MaxIndexType = math.MaxInt32
MinIndexType = math.MinInt32
)
// DictionaryConverter is an interface used for dealing with RLE decoding and encoding
// when working with dictionaries to get values from indexes.
type DictionaryConverter interface {
// Copy takes an interface{} which must be a slice of the appropriate type, and will be populated
// by the dictionary values at the indexes from the IndexType slice
Copy(interface{}, []IndexType) error
// Fill fills interface{} which must be a slice of the appropriate type, with the value
// specified by the dictionary index passed in.
Fill(interface{}, IndexType) error
// FillZero fills interface{}, which must be a slice of the appropriate type, with the zero value
// for the given type.
FillZero(interface{})
// IsValid validates that all of the indexes passed in are valid indexes for the dictionary
IsValid(...IndexType) bool
}
// converter for getspaced that handles runs that get returned directly
// as output, rather than using a dictionary
type plainConverter struct{}
func (plainConverter) IsValid(...IndexType) bool { return true }
func (plainConverter) Fill(values interface{}, val IndexType) error {
v := reflect.ValueOf(values)
switch v.Type().Elem().Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
v.Index(0).SetInt(int64(val))
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
v.Index(0).SetUint(uint64(val))
}
for i := 1; i < v.Len(); i *= 2 {
reflect.Copy(v.Slice(i, v.Len()), v.Slice(0, i))
}
return nil
}
func (plainConverter) FillZero(values interface{}) {
v := reflect.ValueOf(values)
zeroVal := reflect.New(v.Type().Elem()).Elem()
v.Index(0).Set(zeroVal)
for i := 1; i < v.Len(); i *= 2 {
reflect.Copy(v.Slice(i, v.Len()), v.Slice(0, i))
}
}
func (plainConverter) Copy(out interface{}, values []IndexType) error {
vout := reflect.ValueOf(out)
vin := reflect.ValueOf(values)
for i := 0; i < vin.Len(); i++ {
vout.Index(i).Set(vin.Index(i).Convert(vout.Type().Elem()))
}
return nil
}
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