mirror of
https://codeberg.org/forgejo/forgejo
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404 lines
9.8 KiB
Go
404 lines
9.8 KiB
Go
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// Copyright 2015 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 ast
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import (
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"bytes"
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"fmt"
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"strings"
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"github.com/juju/errors"
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"github.com/pingcap/tidb/model"
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"github.com/pingcap/tidb/util/distinct"
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"github.com/pingcap/tidb/util/types"
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)
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var (
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_ FuncNode = &AggregateFuncExpr{}
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_ FuncNode = &FuncCallExpr{}
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_ FuncNode = &FuncCastExpr{}
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)
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// UnquoteString is not quoted when printed.
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type UnquoteString string
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// FuncCallExpr is for function expression.
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type FuncCallExpr struct {
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funcNode
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// FnName is the function name.
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FnName model.CIStr
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// Args is the function args.
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Args []ExprNode
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}
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// Accept implements Node interface.
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func (n *FuncCallExpr) Accept(v Visitor) (Node, bool) {
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newNode, skipChildren := v.Enter(n)
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if skipChildren {
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return v.Leave(newNode)
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}
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n = newNode.(*FuncCallExpr)
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for i, val := range n.Args {
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node, ok := val.Accept(v)
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if !ok {
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return n, false
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}
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n.Args[i] = node.(ExprNode)
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}
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return v.Leave(n)
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}
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// CastFunctionType is the type for cast function.
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type CastFunctionType int
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// CastFunction types
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const (
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CastFunction CastFunctionType = iota + 1
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CastConvertFunction
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CastBinaryOperator
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)
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// FuncCastExpr is the cast function converting value to another type, e.g, cast(expr AS signed).
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// See https://dev.mysql.com/doc/refman/5.7/en/cast-functions.html
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type FuncCastExpr struct {
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funcNode
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// Expr is the expression to be converted.
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Expr ExprNode
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// Tp is the conversion type.
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Tp *types.FieldType
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// Cast, Convert and Binary share this struct.
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FunctionType CastFunctionType
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}
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// Accept implements Node Accept interface.
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func (n *FuncCastExpr) Accept(v Visitor) (Node, bool) {
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newNode, skipChildren := v.Enter(n)
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if skipChildren {
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return v.Leave(newNode)
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}
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n = newNode.(*FuncCastExpr)
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node, ok := n.Expr.Accept(v)
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if !ok {
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return n, false
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}
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n.Expr = node.(ExprNode)
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return v.Leave(n)
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}
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// TrimDirectionType is the type for trim direction.
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type TrimDirectionType int
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const (
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// TrimBothDefault trims from both direction by default.
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TrimBothDefault TrimDirectionType = iota
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// TrimBoth trims from both direction with explicit notation.
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TrimBoth
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// TrimLeading trims from left.
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TrimLeading
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// TrimTrailing trims from right.
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TrimTrailing
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)
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// DateArithType is type for DateArith type.
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type DateArithType byte
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const (
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// DateAdd is to run adddate or date_add function option.
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// See: https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_adddate
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// See: https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_date-add
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DateAdd DateArithType = iota + 1
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// DateSub is to run subdate or date_sub function option.
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// See: https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_subdate
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// See: https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_date-sub
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DateSub
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)
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// DateArithInterval is the struct of DateArith interval part.
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type DateArithInterval struct {
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Unit string
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Interval ExprNode
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}
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const (
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// AggFuncCount is the name of Count function.
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AggFuncCount = "count"
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// AggFuncSum is the name of Sum function.
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AggFuncSum = "sum"
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// AggFuncAvg is the name of Avg function.
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AggFuncAvg = "avg"
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// AggFuncFirstRow is the name of FirstRowColumn function.
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AggFuncFirstRow = "firstrow"
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// AggFuncMax is the name of max function.
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AggFuncMax = "max"
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// AggFuncMin is the name of min function.
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AggFuncMin = "min"
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// AggFuncGroupConcat is the name of group_concat function.
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AggFuncGroupConcat = "group_concat"
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)
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// AggregateFuncExpr represents aggregate function expression.
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type AggregateFuncExpr struct {
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funcNode
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// F is the function name.
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F string
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// Args is the function args.
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Args []ExprNode
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// If distinct is true, the function only aggregate distinct values.
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// For example, column c1 values are "1", "2", "2", "sum(c1)" is "5",
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// but "sum(distinct c1)" is "3".
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Distinct bool
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CurrentGroup string
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// contextPerGroupMap is used to store aggregate evaluation context.
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// Each entry for a group.
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contextPerGroupMap map[string](*AggEvaluateContext)
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}
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// Accept implements Node Accept interface.
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func (n *AggregateFuncExpr) Accept(v Visitor) (Node, bool) {
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newNode, skipChildren := v.Enter(n)
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if skipChildren {
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return v.Leave(newNode)
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}
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n = newNode.(*AggregateFuncExpr)
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for i, val := range n.Args {
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node, ok := val.Accept(v)
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if !ok {
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return n, false
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}
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n.Args[i] = node.(ExprNode)
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}
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return v.Leave(n)
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}
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// Clear clears aggregate computing context.
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func (n *AggregateFuncExpr) Clear() {
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n.CurrentGroup = ""
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n.contextPerGroupMap = nil
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}
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// Update is used for update aggregate context.
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func (n *AggregateFuncExpr) Update() error {
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name := strings.ToLower(n.F)
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switch name {
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case AggFuncCount:
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return n.updateCount()
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case AggFuncFirstRow:
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return n.updateFirstRow()
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case AggFuncGroupConcat:
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return n.updateGroupConcat()
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case AggFuncMax:
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return n.updateMaxMin(true)
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case AggFuncMin:
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return n.updateMaxMin(false)
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case AggFuncSum, AggFuncAvg:
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return n.updateSum()
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}
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return nil
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}
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// GetContext gets aggregate evaluation context for the current group.
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// If it is nil, add a new context into contextPerGroupMap.
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func (n *AggregateFuncExpr) GetContext() *AggEvaluateContext {
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if n.contextPerGroupMap == nil {
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n.contextPerGroupMap = make(map[string](*AggEvaluateContext))
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}
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if _, ok := n.contextPerGroupMap[n.CurrentGroup]; !ok {
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c := &AggEvaluateContext{}
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if n.Distinct {
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c.distinctChecker = distinct.CreateDistinctChecker()
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}
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n.contextPerGroupMap[n.CurrentGroup] = c
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}
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return n.contextPerGroupMap[n.CurrentGroup]
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}
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func (n *AggregateFuncExpr) updateCount() error {
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ctx := n.GetContext()
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vals := make([]interface{}, 0, len(n.Args))
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for _, a := range n.Args {
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value := a.GetValue()
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if value == nil {
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return nil
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}
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vals = append(vals, value)
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}
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if n.Distinct {
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d, err := ctx.distinctChecker.Check(vals)
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if err != nil {
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return errors.Trace(err)
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}
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if !d {
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return nil
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}
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}
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ctx.Count++
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return nil
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}
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func (n *AggregateFuncExpr) updateFirstRow() error {
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ctx := n.GetContext()
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if ctx.evaluated {
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return nil
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}
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if len(n.Args) != 1 {
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return errors.New("Wrong number of args for AggFuncFirstRow")
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}
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ctx.Value = n.Args[0].GetValue()
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ctx.evaluated = true
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return nil
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}
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func (n *AggregateFuncExpr) updateMaxMin(max bool) error {
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ctx := n.GetContext()
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if len(n.Args) != 1 {
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return errors.New("Wrong number of args for AggFuncFirstRow")
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}
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v := n.Args[0].GetValue()
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if !ctx.evaluated {
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ctx.Value = v
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ctx.evaluated = true
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return nil
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}
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c, err := types.Compare(ctx.Value, v)
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if err != nil {
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return errors.Trace(err)
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}
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if max {
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if c == -1 {
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ctx.Value = v
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}
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} else {
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if c == 1 {
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ctx.Value = v
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}
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}
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return nil
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}
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func (n *AggregateFuncExpr) updateSum() error {
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ctx := n.GetContext()
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a := n.Args[0]
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value := a.GetValue()
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if value == nil {
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return nil
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}
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if n.Distinct {
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d, err := ctx.distinctChecker.Check([]interface{}{value})
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if err != nil {
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return errors.Trace(err)
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}
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if !d {
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return nil
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}
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}
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var err error
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ctx.Value, err = types.CalculateSum(ctx.Value, value)
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if err != nil {
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return errors.Trace(err)
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}
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ctx.Count++
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return nil
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}
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func (n *AggregateFuncExpr) updateGroupConcat() error {
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ctx := n.GetContext()
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vals := make([]interface{}, 0, len(n.Args))
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for _, a := range n.Args {
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value := a.GetValue()
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if value == nil {
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return nil
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}
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vals = append(vals, value)
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}
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if n.Distinct {
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d, err := ctx.distinctChecker.Check(vals)
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if err != nil {
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return errors.Trace(err)
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}
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if !d {
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return nil
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}
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}
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if ctx.Buffer == nil {
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ctx.Buffer = &bytes.Buffer{}
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} else {
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// now use comma separator
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ctx.Buffer.WriteString(",")
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}
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for _, val := range vals {
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ctx.Buffer.WriteString(fmt.Sprintf("%v", val))
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}
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// TODO: if total length is greater than global var group_concat_max_len, truncate it.
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return nil
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}
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// AggregateFuncExtractor visits Expr tree.
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// It converts ColunmNameExpr to AggregateFuncExpr and collects AggregateFuncExpr.
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type AggregateFuncExtractor struct {
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inAggregateFuncExpr bool
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// AggFuncs is the collected AggregateFuncExprs.
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AggFuncs []*AggregateFuncExpr
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extracting bool
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}
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// Enter implements Visitor interface.
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func (a *AggregateFuncExtractor) Enter(n Node) (node Node, skipChildren bool) {
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switch n.(type) {
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case *AggregateFuncExpr:
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a.inAggregateFuncExpr = true
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case *SelectStmt, *InsertStmt, *DeleteStmt, *UpdateStmt:
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// Enter a new context, skip it.
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// For example: select sum(c) + c + exists(select c from t) from t;
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if a.extracting {
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return n, true
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}
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}
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a.extracting = true
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return n, false
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}
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// Leave implements Visitor interface.
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func (a *AggregateFuncExtractor) Leave(n Node) (node Node, ok bool) {
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switch v := n.(type) {
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case *AggregateFuncExpr:
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a.inAggregateFuncExpr = false
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a.AggFuncs = append(a.AggFuncs, v)
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case *ColumnNameExpr:
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// compose new AggregateFuncExpr
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if !a.inAggregateFuncExpr {
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// For example: select sum(c) + c from t;
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// The c in sum() should be evaluated for each row.
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// The c after plus should be evaluated only once.
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agg := &AggregateFuncExpr{
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F: AggFuncFirstRow,
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Args: []ExprNode{v},
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}
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a.AggFuncs = append(a.AggFuncs, agg)
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return agg, true
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}
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}
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return n, true
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}
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// AggEvaluateContext is used to store intermediate result when caculation aggregate functions.
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type AggEvaluateContext struct {
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distinctChecker *distinct.Checker
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Count int64
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Value interface{}
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Buffer *bytes.Buffer // Buffer is used for group_concat.
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evaluated bool
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}
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