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108 lines
2.9 KiB
Go
108 lines
2.9 KiB
Go
package planner
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import (
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"strconv"
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"github.com/molecula/featurebase/v3/sql3"
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"github.com/molecula/featurebase/v3/sql3/parser"
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)
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func (p *ExecutionPlanner) analyseFunctionReverse(call *parser.Call, scope parser.Statement) (parser.Expr, error) {
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//one argument
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if len(call.Args) != 1 {
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return nil, sql3.NewErrCallParameterCountMismatch(call.Rparen.Line, call.Rparen.Column, call.Name.Name, 1, len(call.Args))
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}
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if !typeIsString(call.Args[0].DataType()) {
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return nil, sql3.NewErrStringExpressionExpected(call.Args[0].Pos().Line, call.Args[0].Pos().Column)
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}
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call.ResultDataType = parser.NewDataTypeString()
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return call, nil
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}
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func (p *ExecutionPlanner) analyseFunctionSubstring(call *parser.Call, scope parser.Statement) (parser.Expr, error) {
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if len(call.Args) <= 1 || len(call.Args) > 3 {
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return nil, sql3.NewErrCallParameterCountMismatch(call.Rparen.Line, call.Rparen.Column, call.Name.Name, 2, len(call.Args))
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}
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if !typeIsString(call.Args[0].DataType()) {
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return nil, sql3.NewErrStringExpressionExpected(call.Args[0].Pos().Line, call.Args[0].Pos().Column)
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}
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// the third parameter is optional
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for i := 1; i < len(call.Args); i++ {
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if !typeIsInteger(call.Args[i].DataType()) {
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return nil, sql3.NewErrIntExpressionExpected(call.Args[i].Pos().Line, call.Args[i].Pos().Column)
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}
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}
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call.ResultDataType = parser.NewDataTypeString()
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return call, nil
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}
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// reverses the string
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func (n *callPlanExpression) EvaluateReverse(currentRow []interface{}) (interface{}, error) {
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argOneEval, err := n.args[0].Evaluate(currentRow)
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if err != nil {
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return nil, err
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}
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stringArgOne, ok := argOneEval.(string)
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if !ok {
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return nil, sql3.NewErrInternalf("unexpected type converion %T", argOneEval)
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}
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// reverse the string
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runes := []rune(stringArgOne)
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for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
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runes[i], runes[j] = runes[j], runes[i]
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}
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return string(runes), nil
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}
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// Takes string, startIndex and length and returns the substring.
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func (n *callPlanExpression) EvaluateSubstring(currentRow []interface{}) (interface{}, error) {
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argOneEval, err := n.args[0].Evaluate(currentRow)
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if err != nil {
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return nil, err
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}
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stringArgOne, ok := argOneEval.(string)
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if !ok {
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return nil, sql3.NewErrInternalf("unexpected type converion %T", argOneEval)
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}
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// this takes a sliding window approach to evaluate substring.
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startIndex, err := strconv.Atoi(n.args[1].String())
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if err != nil {
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return nil, sql3.NewErrInternalf("unexpected type converion %T", n.args[1])
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}
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if startIndex >= len(stringArgOne) {
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return "", nil
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}
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endIndex := len(stringArgOne)
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if len(n.args) > 2 {
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ln, err := strconv.Atoi(n.args[2].String())
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if err != nil {
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return nil, sql3.NewErrInternalf("unexpected type converion %T", n.args[1])
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}
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endIndex = startIndex + ln
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}
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if endIndex < 0 {
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return "", nil
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}
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if startIndex < 0 {
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startIndex = 0
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}
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if endIndex > len(stringArgOne) {
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return stringArgOne[startIndex:], nil
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}
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return stringArgOne[startIndex:endIndex], nil
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}
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