66 lines
1.3 KiB
Go
66 lines
1.3 KiB
Go
// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
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// All rights reserved.
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// operator-join.go
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package expr
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import (
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"fmt"
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"io"
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)
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//-------- join term
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func newJoinTerm(tk *Token) (inst *term) {
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return &term{
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tk: *tk,
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children: make([]*term, 0, 2),
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position: posInfix,
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priority: priIterOp,
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evalFunc: evalJoin,
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}
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}
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func evalJoin(ctx ExprContext, opTerm *term) (v any, err error) {
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var leftValue, rightValue any
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var itLeft, itRight Iterator
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var item any
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if err = opTerm.checkOperands(); err != nil {
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return
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}
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if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
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return
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}
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if rightValue, err = opTerm.children[1].compute(ctx); err != nil {
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return
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}
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if itLeft, err = NewIterator(leftValue); err != nil {
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return nil, fmt.Errorf("left operand of JOIN must be an iterable data-source; got %s", TypeName(leftValue))
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}
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if itRight, err = NewIterator(rightValue); err != nil {
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return nil, fmt.Errorf("right operand of JOIN must be an iterable data-source; got %s", TypeName(rightValue))
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}
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values := newListA()
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for _, it := range []Iterator{itLeft, itRight} {
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for item, err = it.Next(); err == nil; item, err = it.Next() {
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values.appendItem(item)
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}
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}
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if err == io.EOF {
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err = nil
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}
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v = values
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return
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}
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// init
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func init() {
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registerTermConstructor(SymKwJoin, newJoinTerm)
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}
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