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161 lines
4.6 KiB
161 lines
4.6 KiB
// Copyright 2017 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expression
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import (
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"bytes"
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"fmt"
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"sort"
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"strings"
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"github.com/pingcap/tidb/types"
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"github.com/pingcap/tidb/util/chunk"
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)
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// ExplainInfo implements the Expression interface.
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func (expr *ScalarFunction) ExplainInfo() string {
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return expr.explainInfo(false)
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}
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func (expr *ScalarFunction) explainInfo(normalized bool) string {
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var buffer bytes.Buffer
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fmt.Fprintf(&buffer, "%s(", expr.FuncName.L)
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for i, arg := range expr.GetArgs() {
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if normalized {
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buffer.WriteString(arg.ExplainNormalizedInfo())
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} else {
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buffer.WriteString(arg.ExplainInfo())
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}
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if i+1 < len(expr.GetArgs()) {
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buffer.WriteString(", ")
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}
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}
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buffer.WriteString(")")
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return buffer.String()
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}
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// ExplainNormalizedInfo implements the Expression interface.
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func (expr *ScalarFunction) ExplainNormalizedInfo() string {
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return expr.explainInfo(true)
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}
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// ExplainInfo implements the Expression interface.
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func (col *Column) ExplainInfo() string {
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return col.String()
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}
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// ExplainNormalizedInfo implements the Expression interface.
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func (col *Column) ExplainNormalizedInfo() string {
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if col.OrigName != "" {
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return col.OrigName
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}
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return "?"
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}
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// ExplainInfo implements the Expression interface.
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func (expr *Constant) ExplainInfo() string {
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dt, err := expr.Eval(chunk.Row{})
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if err != nil {
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return "not recognized const vanue"
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}
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return expr.format(dt)
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}
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// ExplainNormalizedInfo implements the Expression interface.
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func (expr *Constant) ExplainNormalizedInfo() string {
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return "?"
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}
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func (expr *Constant) format(dt types.Datum) string {
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switch dt.Kind() {
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case types.KindNull:
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return "NULL"
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case types.KindString, types.KindBytes, types.KindMysqlEnum, types.KindMysqlSet,
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types.KindMysqlJSON, types.KindBinaryLiteral, types.KindMysqlBit:
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return fmt.Sprintf("\"%v\"", dt.GetValue())
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}
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return fmt.Sprintf("%v", dt.GetValue())
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}
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// ExplainExpressionList generates explain information for a list of expressions.
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func ExplainExpressionList(exprs []Expression, schema *Schema) string {
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builder := &strings.Builder{}
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for i, expr := range exprs {
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switch expr.(type) {
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case *Column, *CorrelatedColumn:
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builder.WriteString(expr.String())
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default:
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builder.WriteString(expr.String())
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builder.WriteString("->")
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builder.WriteString(schema.Columns[i].String())
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}
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if i+1 < len(exprs) {
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builder.WriteString(", ")
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}
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}
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return builder.String()
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}
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// SortedExplainExpressionList generates explain information for a list of expressions in order.
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// In some scenarios, the expr's order may not be stable when executing multiple times.
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// So we add a sort to make its explain result stable.
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func SortedExplainExpressionList(exprs []Expression) []byte {
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return sortedExplainExpressionList(exprs, false)
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}
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func sortedExplainExpressionList(exprs []Expression, normalized bool) []byte {
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buffer := bytes.NewBufferString("")
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exprInfos := make([]string, 0, len(exprs))
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for _, expr := range exprs {
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if normalized {
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exprInfos = append(exprInfos, expr.ExplainNormalizedInfo())
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} else {
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exprInfos = append(exprInfos, expr.ExplainInfo())
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}
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}
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sort.Strings(exprInfos)
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for i, info := range exprInfos {
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buffer.WriteString(info)
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if i+1 < len(exprInfos) {
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buffer.WriteString(", ")
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}
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}
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return buffer.Bytes()
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}
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// SortedExplainNormalizedExpressionList is same like SortedExplainExpressionList, but use for generating normalized information.
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func SortedExplainNormalizedExpressionList(exprs []Expression) []byte {
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return sortedExplainExpressionList(exprs, true)
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}
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// SortedExplainNormalizedScalarFuncList is same like SortedExplainExpressionList, but use for generating normalized information.
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func SortedExplainNormalizedScalarFuncList(exprs []*ScalarFunction) []byte {
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expressions := make([]Expression, len(exprs))
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for i := range exprs {
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expressions[i] = exprs[i]
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}
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return sortedExplainExpressionList(expressions, true)
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}
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// ExplainColumnList generates explain information for a list of columns.
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func ExplainColumnList(cols []*Column) []byte {
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buffer := bytes.NewBufferString("")
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for i, col := range cols {
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buffer.WriteString(col.ExplainInfo())
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if i+1 < len(cols) {
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buffer.WriteString(", ")
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}
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}
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return buffer.Bytes()
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}
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