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305 lines
7.5 KiB
305 lines
7.5 KiB
/*
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* MinIO Cloud Storage, (C) 2019 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 sql
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import (
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"errors"
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"fmt"
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)
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// Query analysis - The query is analyzed to determine if it involves
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// aggregation.
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//
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// Aggregation functions - An expression that involves aggregation of
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// rows in some manner. Requires all input rows to be processed,
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// before a result is returned.
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//
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// Row function - An expression that depends on a value in the
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// row. They have an output for each input row.
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//
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// Some types of a queries are not valid. For example, an aggregation
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// function combined with a row function is meaningless ("AVG(s.Age) +
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// s.Salary"). Analysis determines if such a scenario exists so an
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// error can be returned.
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var (
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// Fatal error for query processing.
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errNestedAggregation = errors.New("Cannot nest aggregations")
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errFunctionNotImplemented = errors.New("Function is not yet implemented")
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errUnexpectedInvalidNode = errors.New("Unexpected node value")
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errInvalidKeypath = errors.New("A provided keypath is invalid")
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)
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// qProp contains analysis info about an SQL term.
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type qProp struct {
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isAggregation, isRowFunc bool
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err error
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}
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// `combine` combines a pair of `qProp`s, so that errors are
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// propagated correctly, and checks that an aggregation is not being
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// combined with a row-function term.
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func (p *qProp) combine(q qProp) {
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switch {
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case p.err != nil:
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// Do nothing
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case q.err != nil:
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p.err = q.err
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default:
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p.isAggregation = p.isAggregation || q.isAggregation
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p.isRowFunc = p.isRowFunc || q.isRowFunc
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if p.isAggregation && p.isRowFunc {
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p.err = errNestedAggregation
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}
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}
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}
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func (e *SelectExpression) analyze(s *Select) (result qProp) {
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if e.All {
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return qProp{isRowFunc: true}
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}
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for _, ex := range e.Expressions {
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result.combine(ex.analyze(s))
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}
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return
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}
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func (e *AliasedExpression) analyze(s *Select) qProp {
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return e.Expression.analyze(s)
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}
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func (e *Expression) analyze(s *Select) (result qProp) {
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for _, ac := range e.And {
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result.combine(ac.analyze(s))
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}
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return
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}
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func (e *AndCondition) analyze(s *Select) (result qProp) {
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for _, ac := range e.Condition {
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result.combine(ac.analyze(s))
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}
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return
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}
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func (e *Condition) analyze(s *Select) (result qProp) {
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if e.Operand != nil {
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result = e.Operand.analyze(s)
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} else {
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result = e.Not.analyze(s)
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}
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return
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}
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func (e *ConditionOperand) analyze(s *Select) (result qProp) {
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if e.ConditionRHS == nil {
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result = e.Operand.analyze(s)
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} else {
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result.combine(e.Operand.analyze(s))
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result.combine(e.ConditionRHS.analyze(s))
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}
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return
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}
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func (e *ConditionRHS) analyze(s *Select) (result qProp) {
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switch {
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case e.Compare != nil:
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result = e.Compare.Operand.analyze(s)
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case e.Between != nil:
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result.combine(e.Between.Start.analyze(s))
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result.combine(e.Between.End.analyze(s))
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case e.In != nil:
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for _, elt := range e.In.Expressions {
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result.combine(elt.analyze(s))
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}
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case e.Like != nil:
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result.combine(e.Like.Pattern.analyze(s))
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if e.Like.EscapeChar != nil {
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result.combine(e.Like.EscapeChar.analyze(s))
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}
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default:
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result = qProp{err: errUnexpectedInvalidNode}
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}
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return
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}
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func (e *Operand) analyze(s *Select) (result qProp) {
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result.combine(e.Left.analyze(s))
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for _, r := range e.Right {
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result.combine(r.Right.analyze(s))
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}
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return
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}
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func (e *MultOp) analyze(s *Select) (result qProp) {
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result.combine(e.Left.analyze(s))
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for _, r := range e.Right {
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result.combine(r.Right.analyze(s))
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}
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return
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}
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func (e *UnaryTerm) analyze(s *Select) (result qProp) {
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if e.Negated != nil {
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result = e.Negated.Term.analyze(s)
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} else {
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result = e.Primary.analyze(s)
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}
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return
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}
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func (e *PrimaryTerm) analyze(s *Select) (result qProp) {
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switch {
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case e.Value != nil:
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result = qProp{}
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case e.JPathExpr != nil:
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// Check if the path expression is valid
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if len(e.JPathExpr.PathExpr) > 0 {
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if e.JPathExpr.BaseKey.String() != s.From.As {
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result = qProp{err: errInvalidKeypath}
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return
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}
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}
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result = qProp{isRowFunc: true}
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case e.SubExpression != nil:
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result = e.SubExpression.analyze(s)
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case e.FuncCall != nil:
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result = e.FuncCall.analyze(s)
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default:
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result = qProp{err: errUnexpectedInvalidNode}
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}
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return
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}
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func (e *FuncExpr) analyze(s *Select) (result qProp) {
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funcName := e.getFunctionName()
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switch funcName {
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case sqlFnCast:
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return e.Cast.Expr.analyze(s)
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case sqlFnExtract:
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return e.Extract.From.analyze(s)
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case sqlFnDateAdd:
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result.combine(e.DateAdd.Quantity.analyze(s))
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result.combine(e.DateAdd.Timestamp.analyze(s))
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return result
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case sqlFnDateDiff:
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result.combine(e.DateDiff.Timestamp1.analyze(s))
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result.combine(e.DateDiff.Timestamp2.analyze(s))
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return result
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// Handle aggregation function calls
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case aggFnAvg, aggFnMax, aggFnMin, aggFnSum, aggFnCount:
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// Initialize accumulator
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e.aggregate = newAggVal(funcName)
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var exprA qProp
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if funcName == aggFnCount {
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if e.Count.StarArg {
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return qProp{isAggregation: true}
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}
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exprA = e.Count.ExprArg.analyze(s)
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} else {
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if len(e.SFunc.ArgsList) != 1 {
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return qProp{err: fmt.Errorf("%s takes exactly one argument", funcName)}
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}
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exprA = e.SFunc.ArgsList[0].analyze(s)
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}
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if exprA.err != nil {
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return exprA
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}
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if exprA.isAggregation {
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return qProp{err: errNestedAggregation}
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}
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return qProp{isAggregation: true}
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case sqlFnCoalesce:
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if len(e.SFunc.ArgsList) == 0 {
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return qProp{err: fmt.Errorf("%s needs at least one argument", string(funcName))}
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}
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for _, arg := range e.SFunc.ArgsList {
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result.combine(arg.analyze(s))
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}
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return result
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case sqlFnNullIf:
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if len(e.SFunc.ArgsList) != 2 {
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return qProp{err: fmt.Errorf("%s needs exactly 2 arguments", string(funcName))}
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}
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for _, arg := range e.SFunc.ArgsList {
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result.combine(arg.analyze(s))
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}
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return result
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case sqlFnCharLength, sqlFnCharacterLength:
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if len(e.SFunc.ArgsList) != 1 {
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return qProp{err: fmt.Errorf("%s needs exactly 2 arguments", string(funcName))}
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}
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for _, arg := range e.SFunc.ArgsList {
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result.combine(arg.analyze(s))
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}
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return result
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case sqlFnLower, sqlFnUpper:
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if len(e.SFunc.ArgsList) != 1 {
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return qProp{err: fmt.Errorf("%s needs exactly 2 arguments", string(funcName))}
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}
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for _, arg := range e.SFunc.ArgsList {
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result.combine(arg.analyze(s))
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}
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return result
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case sqlFnSubstring:
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errVal := fmt.Errorf("Invalid argument(s) to %s", string(funcName))
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result.combine(e.Substring.Expr.analyze(s))
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switch {
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case e.Substring.From != nil:
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result.combine(e.Substring.From.analyze(s))
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if e.Substring.For != nil {
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result.combine(e.Substring.Expr.analyze(s))
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}
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case e.Substring.Arg2 != nil:
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result.combine(e.Substring.Arg2.analyze(s))
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if e.Substring.Arg3 != nil {
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result.combine(e.Substring.Arg3.analyze(s))
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}
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default:
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result.err = errVal
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}
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return result
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case sqlFnUTCNow:
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if len(e.SFunc.ArgsList) != 0 {
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result.err = fmt.Errorf("%s() takes no arguments", string(funcName))
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}
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return result
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}
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// TODO: implement other functions
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return qProp{err: errFunctionNotImplemented}
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}
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