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types.go
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types.go
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// Copyright 2017 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 ranger
import (
"fmt"
"math"
"strings"
"github.com/juju/errors"
"github.com/pingcap/tidb/sessionctx/stmtctx"
"github.com/pingcap/tidb/types"
)
// Range represents a range generated in physical plan building phase.
type Range struct {
LowVal []types.Datum
HighVal []types.Datum
LowExclude bool // Low value is exclusive.
HighExclude bool // High value is exclusive.
}
// Clone clones a Range.
func (ran *Range) Clone() *Range {
newRange := &Range{
LowVal: make([]types.Datum, 0, len(ran.LowVal)),
HighVal: make([]types.Datum, 0, len(ran.HighVal)),
LowExclude: ran.LowExclude,
HighExclude: ran.HighExclude,
}
for i, length := 0, len(ran.LowVal); i < length; i++ {
newRange.LowVal = append(newRange.LowVal, ran.LowVal[i])
}
for i, length := 0, len(ran.HighVal); i < length; i++ {
newRange.HighVal = append(newRange.HighVal, ran.HighVal[i])
}
return newRange
}
// IsPoint returns if the range is a point.
func (ran *Range) IsPoint(sc *stmtctx.StatementContext) bool {
if len(ran.LowVal) != len(ran.HighVal) {
return false
}
for i := range ran.LowVal {
a := ran.LowVal[i]
b := ran.HighVal[i]
if a.Kind() == types.KindMinNotNull || b.Kind() == types.KindMaxValue {
return false
}
cmp, err := a.CompareDatum(sc, &b)
if err != nil {
return false
}
if cmp != 0 {
return false
}
}
return !ran.LowExclude && !ran.HighExclude
}
// String implements the Stringer interface.
func (ran *Range) String() string {
lowStrs := make([]string, 0, len(ran.LowVal))
for _, d := range ran.LowVal {
lowStrs = append(lowStrs, formatDatum(d, true))
}
highStrs := make([]string, 0, len(ran.LowVal))
for _, d := range ran.HighVal {
highStrs = append(highStrs, formatDatum(d, false))
}
l, r := "[", "]"
if ran.LowExclude {
l = "("
}
if ran.HighExclude {
r = ")"
}
return l + strings.Join(lowStrs, " ") + "," + strings.Join(highStrs, " ") + r
}
// PrefixEqualLen tells you how long the prefix of the range is a point.
// e.g. If this range is (1 2 3, 1 2 +inf), then the return value is 2.
func (ran *Range) PrefixEqualLen(sc *stmtctx.StatementContext) (int, error) {
// Here, len(ran.LowVal) always equal to len(ran.HighVal)
for i := 0; i < len(ran.LowVal); i++ {
cmp, err := ran.LowVal[i].CompareDatum(sc, &ran.HighVal[i])
if err != nil {
return 0, errors.Trace(err)
}
if cmp != 0 {
return i, nil
}
}
return len(ran.LowVal), nil
}
func formatDatum(d types.Datum, isLeftSide bool) string {
switch d.Kind() {
case types.KindNull:
return "<nil>"
case types.KindMinNotNull:
return "-inf"
case types.KindMaxValue:
return "+inf"
case types.KindInt64:
switch d.GetInt64() {
case math.MinInt64:
if isLeftSide {
return "-inf"
}
case math.MaxInt64:
if !isLeftSide {
return "+inf"
}
}
case types.KindUint64:
if d.GetUint64() == math.MaxUint64 && !isLeftSide {
return "+inf"
}
}
return fmt.Sprintf("%v", d.GetValue())
}