github.com/insionng/yougam@v0.0.0-20170714101924-2bc18d833463/libraries/pingcap/tidb/util/distinct/distinct.go (about)

     1  // Copyright 2015 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package distinct
    15  
    16  import (
    17  	"github.com/insionng/yougam/libraries/juju/errors"
    18  	"github.com/insionng/yougam/libraries/pingcap/tidb/util/codec"
    19  	"github.com/insionng/yougam/libraries/pingcap/tidb/util/types"
    20  )
    21  
    22  // CreateDistinctChecker creates a new distinct checker.
    23  func CreateDistinctChecker() *Checker {
    24  	return &Checker{
    25  		existingKeys: make(map[string]bool),
    26  	}
    27  }
    28  
    29  // Checker stores existing keys and checks if given data is distinct.
    30  type Checker struct {
    31  	existingKeys map[string]bool
    32  }
    33  
    34  // Check checks if values is distinct.
    35  func (d *Checker) Check(values []interface{}) (bool, error) {
    36  	bs, err := codec.EncodeValue([]byte{}, types.MakeDatums(values...)...)
    37  	if err != nil {
    38  		return false, errors.Trace(err)
    39  	}
    40  	key := string(bs)
    41  	_, ok := d.existingKeys[key]
    42  	if ok {
    43  		return false, nil
    44  	}
    45  	d.existingKeys[key] = true
    46  	return true, nil
    47  }