gitroast/vendor/github.com/pingcap/tidb/optimizer/plan/stringer.go

90 lines
2.1 KiB
Go
Raw Normal View History

// 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 plan
import (
"fmt"
"math"
"strings"
)
// ToString explains a Plan, returns description string.
func ToString(p Plan) string {
var e stringer
p.Accept(&e)
return strings.Join(e.strs, "->")
}
type stringer struct {
strs []string
idxs []int
}
func (e *stringer) Enter(in Plan) (Plan, bool) {
switch in.(type) {
case *JoinOuter, *JoinInner:
e.idxs = append(e.idxs, len(e.strs))
}
return in, false
}
func (e *stringer) Leave(in Plan) (Plan, bool) {
var str string
switch x := in.(type) {
case *CheckTable:
str = "CheckTable"
case *IndexScan:
str = fmt.Sprintf("Index(%s.%s)", x.Table.Name.L, x.Index.Name.L)
case *Limit:
str = "Limit"
case *SelectFields:
str = "Fields"
case *SelectLock:
str = "Lock"
case *ShowDDL:
str = "ShowDDL"
case *Sort:
str = "Sort"
case *TableScan:
if len(x.Ranges) > 0 {
ran := x.Ranges[0]
if ran.LowVal != math.MinInt64 || ran.HighVal != math.MaxInt64 {
str = fmt.Sprintf("Range(%s)", x.Table.Name.L)
} else {
str = fmt.Sprintf("Table(%s)", x.Table.Name.L)
}
} else {
str = fmt.Sprintf("Table(%s)", x.Table.Name.L)
}
case *JoinOuter:
last := len(e.idxs) - 1
idx := e.idxs[last]
chilrden := e.strs[idx:]
e.strs = e.strs[:idx]
str = "OuterJoin{" + strings.Join(chilrden, "->") + "}"
e.idxs = e.idxs[:last]
case *JoinInner:
last := len(e.idxs) - 1
idx := e.idxs[last]
chilrden := e.strs[idx:]
e.strs = e.strs[:idx]
str = "InnerJoin{" + strings.Join(chilrden, "->") + "}"
e.idxs = e.idxs[:last]
default:
str = fmt.Sprintf("%T", in)
}
e.strs = append(e.strs, str)
return in, true
}