forgejo/vendor/github.com/pingcap/tidb/util/distinct/distinct.go

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// Copyright 2015 PingCAP, Inc.
//
// Licensed 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package distinct
import (
"github.com/juju/errors"
"github.com/pingcap/tidb/util/codec"
"github.com/pingcap/tidb/util/types"
)
// CreateDistinctChecker creates a new distinct checker.
func CreateDistinctChecker() *Checker {
return &Checker{
existingKeys: make(map[string]bool),
}
}
// Checker stores existing keys and checks if given data is distinct.
type Checker struct {
existingKeys map[string]bool
}
// Check checks if values is distinct.
func (d *Checker) Check(values []interface{}) (bool, error) {
bs, err := codec.EncodeValue([]byte{}, types.MakeDatums(values...)...)
if err != nil {
return false, errors.Trace(err)
}
key := string(bs)
_, ok := d.existingKeys[key]
if ok {
return false, nil
}
d.existingKeys[key] = true
return true, nil
}