visitor

type BetweenAndElement struct {
	Not   bool
	Left  interface{}
	Right interface{}
}

type Filter struct {
	Left   string
	Op     opcode.Op
	Right  interface{}
	ColPos int // 字段所在的位置
}

type InElement struct {
	KeyType int
	Not     bool
	Data    map[interface{}]struct{}
}

type MatchTable struct {
	SchemaName        string
	TableName         string
	ColumnNames       []string
	AllColumn         bool
	StartLogFile      string
	StartLogPos       uint64
	EndLogFile        string
	EndLogPos         uint64
	StartRollBackTime string
	EndRollBackTime   string
	ThreadId          uint32
	CalcOp            []interface{}
}

type SelectVisitor struct {
	CurrentNodeLevel int
	TableCnt         int
	Err              error
	MTable           *MatchTable
	PosInfoColCnt    int // 记录 where 位点字段出现的次数
	EliminateOpCnt   int // 还有几个操作符需要消除
}