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Copy pathfuncEval.go
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231 lines (215 loc) · 7.34 KB
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/*
* Minio Cloud Storage, (C) 2018 Minio, 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,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package s3select
import (
"strings"
"github.com/xwb1989/sqlparser"
)
// stringOps is a function which handles the case in a clause if there is a need
// to perform a string function
func stringOps(myFunc *sqlparser.FuncExpr, record []string, myReturnVal string, columnsMap map[string]int) string {
var value string
funcName := myFunc.Name.CompliantName()
switch tempArg := myFunc.Exprs[0].(type) {
case *sqlparser.AliasedExpr:
switch col := tempArg.Expr.(type) {
case *sqlparser.FuncExpr:
// myReturnVal is actually the tail recursive value being used in the eval func.
return applyStrFunc(myReturnVal, funcName)
case *sqlparser.ColName:
value = applyStrFunc(record[columnsMap[col.Name.CompliantName()]], funcName)
case *sqlparser.SQLVal:
value = applyStrFunc(string(col.Val), funcName)
}
}
return value
}
// coalOps is a function which decomposes a COALESCE func expr into its struct.
func coalOps(myFunc *sqlparser.FuncExpr, record []string, myReturnVal string, columnsMap map[string]int) string {
myArgs := make([]string, len(myFunc.Exprs))
for i := 0; i < len(myFunc.Exprs); i++ {
switch tempArg := myFunc.Exprs[i].(type) {
case *sqlparser.AliasedExpr:
switch col := tempArg.Expr.(type) {
case *sqlparser.FuncExpr:
// myReturnVal is actually the tail recursive value being used in the eval func.
return myReturnVal
case *sqlparser.ColName:
myArgs[i] = record[columnsMap[col.Name.CompliantName()]]
case *sqlparser.SQLVal:
myArgs[i] = string(col.Val)
}
}
}
return processCoalNoIndex(myArgs)
}
// nullOps is a function which decomposes a NullIf func expr into its struct.
func nullOps(myFunc *sqlparser.FuncExpr, record []string, myReturnVal string, columnsMap map[string]int) string {
myArgs := make([]string, 2)
for i := 0; i < len(myFunc.Exprs); i++ {
switch tempArg := myFunc.Exprs[i].(type) {
case *sqlparser.AliasedExpr:
switch col := tempArg.Expr.(type) {
case *sqlparser.FuncExpr:
return myReturnVal
case *sqlparser.ColName:
myArgs[i] = record[columnsMap[col.Name.CompliantName()]]
case *sqlparser.SQLVal:
myArgs[i] = string(col.Val)
}
}
}
return processNullIf(myArgs)
}
// isValidString is a function that ensures the current index is one with a
// StrFunc
func isValidFunc(myList []int, index int) bool {
if myList == nil {
return false
}
for i := 0; i < len(myList); i++ {
if myList[i] == index {
return true
}
}
return false
}
// processNullIf is a function that evaluates a given NULLIF clause.
func processNullIf(nullStore []string) string {
nullValOne := nullStore[0]
nullValTwo := nullStore[1]
if nullValOne == nullValTwo {
return ""
}
return nullValOne
}
// processCoalNoIndex is a function which evaluates a given COALESCE clause.
func processCoalNoIndex(coalStore []string) string {
for i := 0; i < len(coalStore); i++ {
if coalStore[i] != "null" && coalStore[i] != "missing" && coalStore[i] != "" {
return coalStore[i]
}
}
return "null"
}
// evaluateFuncExpr is a function that allows for tail recursive evaluation of
// nested function expressions.
func evaluateFuncExpr(myVal *sqlparser.FuncExpr, myReturnVal string, myRecord []string, columnsMap map[string]int) string {
if myVal == nil {
return myReturnVal
}
// retrieve all the relevant arguments of the function
var mySubFunc []*sqlparser.FuncExpr
mySubFunc = make([]*sqlparser.FuncExpr, len(myVal.Exprs))
for i := 0; i < len(myVal.Exprs); i++ {
switch col := myVal.Exprs[i].(type) {
case *sqlparser.AliasedExpr:
switch temp := col.Expr.(type) {
case *sqlparser.FuncExpr:
mySubFunc[i] = temp
}
}
}
// Need to do tree recursion so as to explore all possible directions of the
// nested function recursion
for i := 0; i < len(mySubFunc); i++ {
if supportedString(myVal.Name.CompliantName()) {
if mySubFunc != nil {
return stringOps(myVal, myRecord, evaluateFuncExpr(mySubFunc[i], myReturnVal, myRecord, columnsMap), columnsMap)
}
return stringOps(myVal, myRecord, myReturnVal, columnsMap)
} else if strings.ToUpper(myVal.Name.CompliantName()) == "NULLIF" {
if mySubFunc != nil
825A
{
return nullOps(myVal, myRecord, evaluateFuncExpr(mySubFunc[i], myReturnVal, myRecord, columnsMap), columnsMap)
}
return nullOps(myVal, myRecord, myReturnVal, columnsMap)
} else if strings.ToUpper(myVal.Name.CompliantName()) == "COALESCE" {
if mySubFunc != nil {
return coalOps(myVal, myRecord, evaluateFuncExpr(mySubFunc[i], myReturnVal, myRecord, columnsMap), columnsMap)
}
return coalOps(myVal, myRecord, myReturnVal, columnsMap)
}
}
return ""
}
// evaluateFuncErr is a function that flags errors in nested functions.
func (reader *Input) evaluateFuncErr(myVal *sqlparser.FuncExpr) error {
if myVal == nil {
return nil
}
if !supportedFunc(myVal.Name.CompliantName()) {
return ErrUnsupportedSQLOperation
}
for i := 0; i < len(myVal.Exprs); i++ {
switch tempArg := myVal.Exprs[i].(type) {
case *sqlparser.StarExpr:
return ErrParseUnsupportedCallWithStar
case *sqlparser.AliasedExpr:
switch col := tempArg.Expr.(type) {
case *sqlparser.FuncExpr:
if err := reader.evaluateFuncErr(col); err != nil {
return err
}
case *sqlparser.ColName:
if err := reader.colNameErrs([]string{col.Name.CompliantName()}); err != nil {
return err
}
}
}
}
return nil
}
// evaluateIsExpr is a function for evaluating expressions of the form "column
// is ...."
func evaluateIsExpr(myFunc *sqlparser.IsExpr, row []string, columnNames map[string]int, alias string) (bool, error) {
operator := myFunc.Operator
var colName string
var myVal string
switch myIs := myFunc.Expr.(type) {
// case for literal val
case *sqlparser.SQLVal:
myVal = string(myIs.Val)
// case for nested func val
case *sqlparser.FuncExpr:
myVal = evaluateFuncExpr(myIs, "", row, columnNames)
// case for col val
case *sqlparser.ColName:
colName = cleanCol(myIs.Name.CompliantName(), alias)
}
// case if it is a col val
if colName != "" {
myVal = row[columnNames[colName]]
}
// case to evaluate is null
if strings.ToLower(operator) == "is null" {
return myVal == "", nil
}
// case to evaluate is not null
if strings.ToLower(operator) == "is not null" {
return myVal != "", nil
}
return false, ErrUnsupportedSQLOperation
}
// supportedString is a function that checks whether the function is a supported
// string one
func supportedString(strFunc string) bool {
return stringInSlice(strings.ToUpper(strFunc), []string{"TRIM", "SUBSTRING", "CHAR_LENGTH", "CHARACTER_LENGTH", "LOWER", "UPPER"})
}
// supportedFunc is a function that checks whether the function is a supported
// S3 one.
func supportedFunc(strFunc string) bool {
return stringInSlice(strings.ToUpper(strFunc), []string{"TRIM", "SUBSTRING", "CHAR_LENGTH", "CHARACTER_LENGTH", "LOWER", "UPPER", "COALESCE", "NULLIF"})
}