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232 lines
7.3 KiB
Go
232 lines
7.3 KiB
Go
/*
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* Minio Cloud Storage, (C) 2018 Minio, 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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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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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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*/
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package s3select
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import (
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"strings"
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"github.com/xwb1989/sqlparser"
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)
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// stringOps is a function which handles the case in a clause if there is a need
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// to perform a string function
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func stringOps(myFunc *sqlparser.FuncExpr, record []string, myReturnVal string, columnsMap map[string]int) string {
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var value string
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funcName := myFunc.Name.CompliantName()
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switch tempArg := myFunc.Exprs[0].(type) {
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case *sqlparser.AliasedExpr:
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switch col := tempArg.Expr.(type) {
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case *sqlparser.FuncExpr:
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// myReturnVal is actually the tail recursive value being used in the eval func.
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return applyStrFunc(myReturnVal, funcName)
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case *sqlparser.ColName:
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value = applyStrFunc(record[columnsMap[col.Name.CompliantName()]], funcName)
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case *sqlparser.SQLVal:
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value = applyStrFunc(string(col.Val), funcName)
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}
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}
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return value
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}
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// coalOps is a function which decomposes a COALESCE func expr into its struct.
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func coalOps(myFunc *sqlparser.FuncExpr, record []string, myReturnVal string, columnsMap map[string]int) string {
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myArgs := make([]string, len(myFunc.Exprs))
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for i := 0; i < len(myFunc.Exprs); i++ {
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switch tempArg := myFunc.Exprs[i].(type) {
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case *sqlparser.AliasedExpr:
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switch col := tempArg.Expr.(type) {
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case *sqlparser.FuncExpr:
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// myReturnVal is actually the tail recursive value being used in the eval func.
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return myReturnVal
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case *sqlparser.ColName:
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myArgs[i] = record[columnsMap[col.Name.CompliantName()]]
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case *sqlparser.SQLVal:
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myArgs[i] = string(col.Val)
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}
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}
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}
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return processCoalNoIndex(myArgs)
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}
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// nullOps is a function which decomposes a NullIf func expr into its struct.
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func nullOps(myFunc *sqlparser.FuncExpr, record []string, myReturnVal string, columnsMap map[string]int) string {
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myArgs := make([]string, 2)
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for i := 0; i < len(myFunc.Exprs); i++ {
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switch tempArg := myFunc.Exprs[i].(type) {
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case *sqlparser.AliasedExpr:
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switch col := tempArg.Expr.(type) {
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case *sqlparser.FuncExpr:
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return myReturnVal
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case *sqlparser.ColName:
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myArgs[i] = record[columnsMap[col.Name.CompliantName()]]
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case *sqlparser.SQLVal:
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myArgs[i] = string(col.Val)
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}
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}
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}
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return processNullIf(myArgs)
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}
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// isValidString is a function that ensures the current index is one with a
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// StrFunc
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func isValidFunc(myList []int, index int) bool {
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if myList == nil {
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return false
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}
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for i := 0; i < len(myList); i++ {
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if myList[i] == index {
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return true
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}
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}
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return false
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}
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// processNullIf is a function that evaluates a given NULLIF clause.
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func processNullIf(nullStore []string) string {
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nullValOne := nullStore[0]
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nullValTwo := nullStore[1]
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if nullValOne == nullValTwo {
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return ""
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}
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return nullValOne
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}
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// processCoalNoIndex is a function which evaluates a given COALESCE clause.
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func processCoalNoIndex(coalStore []string) string {
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for i := 0; i < len(coalStore); i++ {
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if coalStore[i] != "null" && coalStore[i] != "missing" && coalStore[i] != "" {
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return coalStore[i]
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}
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}
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return "null"
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}
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// evaluateFuncExpr is a function that allows for tail recursive evaluation of
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// nested function expressions.
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func evaluateFuncExpr(myVal *sqlparser.FuncExpr, myReturnVal string, myRecord []string, columnsMap map[string]int) string {
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if myVal == nil {
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return myReturnVal
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}
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// retrieve all the relevant arguments of the function
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var mySubFunc []*sqlparser.FuncExpr
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mySubFunc = make([]*sqlparser.FuncExpr, len(myVal.Exprs))
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for i := 0; i < len(myVal.Exprs); i++ {
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switch col := myVal.Exprs[i].(type) {
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case *sqlparser.AliasedExpr:
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switch temp := col.Expr.(type) {
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case *sqlparser.FuncExpr:
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mySubFunc[i] = temp
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}
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}
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}
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// Need to do tree recursion so as to explore all possible directions of the
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// nested function recursion
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for i := 0; i < len(mySubFunc); i++ {
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if supportedString(myVal.Name.CompliantName()) {
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if mySubFunc != nil {
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return stringOps(myVal, myRecord, evaluateFuncExpr(mySubFunc[i], myReturnVal, myRecord, columnsMap), columnsMap)
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}
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return stringOps(myVal, myRecord, myReturnVal, columnsMap)
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} else if strings.ToUpper(myVal.Name.CompliantName()) == "NULLIF" {
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if mySubFunc != nil {
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return nullOps(myVal, myRecord, evaluateFuncExpr(mySubFunc[i], myReturnVal, myRecord, columnsMap), columnsMap)
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}
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return nullOps(myVal, myRecord, myReturnVal, columnsMap)
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} else if strings.ToUpper(myVal.Name.CompliantName()) == "COALESCE" {
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if mySubFunc != nil {
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return coalOps(myVal, myRecord, evaluateFuncExpr(mySubFunc[i], myReturnVal, myRecord, columnsMap), columnsMap)
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}
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return coalOps(myVal, myRecord, myReturnVal, columnsMap)
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}
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}
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return ""
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}
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// evaluateFuncErr is a function that flags errors in nested functions.
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func (reader *Input) evaluateFuncErr(myVal *sqlparser.FuncExpr) error {
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if myVal == nil {
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return nil
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}
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if !supportedFunc(myVal.Name.CompliantName()) {
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return ErrUnsupportedSQLOperation
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}
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for i := 0; i < len(myVal.Exprs); i++ {
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switch tempArg := myVal.Exprs[i].(type) {
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case *sqlparser.StarExpr:
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return ErrParseUnsupportedCallWithStar
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case *sqlparser.AliasedExpr:
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switch col := tempArg.Expr.(type) {
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case *sqlparser.FuncExpr:
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if err := reader.evaluateFuncErr(col); err != nil {
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return err
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}
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case *sqlparser.ColName:
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if err := reader.colNameErrs([]string{col.Name.CompliantName()}); err != nil {
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return err
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}
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}
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}
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}
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return nil
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}
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// evaluateIsExpr is a function for evaluating expressions of the form "column
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// is ...."
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func evaluateIsExpr(myFunc *sqlparser.IsExpr, row []string, columnNames map[string]int, alias string) (bool, error) {
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operator := myFunc.Operator
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var colName string
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var myVal string
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switch myIs := myFunc.Expr.(type) {
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// case for literal val
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case *sqlparser.SQLVal:
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myVal = string(myIs.Val)
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// case for nested func val
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case *sqlparser.FuncExpr:
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myVal = evaluateFuncExpr(myIs, "", row, columnNames)
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// case for col val
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case *sqlparser.ColName:
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colName = cleanCol(myIs.Name.CompliantName(), alias)
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}
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// case if it is a col val
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if colName != "" {
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myVal = row[columnNames[colName]]
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}
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// case to evaluate is null
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if strings.ToLower(operator) == "is null" {
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return myVal == "", nil
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}
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// case to evaluate is not null
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if strings.ToLower(operator) == "is not null" {
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return myVal != "", nil
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}
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return false, ErrUnsupportedSQLOperation
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}
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// supportedString is a function that checks whether the function is a supported
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// string one
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func supportedString(strFunc string) bool {
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return stringInSlice(strings.ToUpper(strFunc), []string{"TRIM", "SUBSTRING", "CHAR_LENGTH", "CHARACTER_LENGTH", "LOWER", "UPPER"})
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}
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// supportedFunc is a function that checks whether the function is a supported
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// S3 one.
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func supportedFunc(strFunc string) bool {
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return stringInSlice(strings.ToUpper(strFunc), []string{"TRIM", "SUBSTRING", "CHAR_LENGTH", "CHARACTER_LENGTH", "LOWER", "UPPER", "COALESCE", "NULLIF"})
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}
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