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main.go
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main.go
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/*
* Copyright (C) 2017 Dgraph Labs, Inc. and Contributors
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package main
import (
"encoding/binary"
"fmt"
)
func Tokenizer() interface{} { return FactorTokenizer{} }
type FactorTokenizer struct{}
func (FactorTokenizer) Name() string { return "factor" }
func (FactorTokenizer) Type() string { return "int" }
func (FactorTokenizer) Identifier() byte { return 0xfe }
func (FactorTokenizer) Tokens(value interface{}) ([]string, error) {
x := value.(int64)
if x <= 1 {
return nil, fmt.Errorf("cannot factor int <= 1: %d", x)
}
var toks []string
for p := int64(2); x > 1; p++ {
if x%p == 0 {
toks = append(toks, encodeInt(p))
for x%p == 0 {
x /= p
}
}
}
return toks, nil
}
func encodeInt(x int64) string {
var buf [binary.MaxVarintLen64]byte
n := binary.PutVarint(buf[:], x)
return string(buf[:n])
}