Function liftFilterOps

compiler/optimizer/optimizer.go:606–652

(seq dag.Seq)

}

func liftFilterOps(seq dag.Seq) dag.Seq {
	walkT(reflect.ValueOf(&seq), func(seq dag.Seq) dag.Seq {
		for i := len(seq) - 2; i >= 0; i-- {
			y, ok := seq[i].(*dag.ValuesOp)
			if !ok || len(y.Exprs) != 1 {
				continue
			}
			re, ok1 := y.Exprs[0].(*dag.RecordExpr)
			f, ok2 := seq[i+1].(*dag.FilterOp)
			if !ok1 || !ok2 || hasThisWithEmptyPath(f) {
				continue
			}
			fields, spread, ok := recordElemsFieldsAndSpread(re.Elems)
			if !ok {
				continue
			}
			f = dag.CopyOp(f).(*dag.FilterOp)
			liftOK := true
			walkT(reflect.ValueOf(f), func(e dag.Expr) dag.Expr {
				if !liftOK {
					return e
				}
				this, ok := e.(*dag.ThisExpr)
				if !ok {
					return e
				}
				e1, ok := fields[this.Path[0]]
				if !ok {
					if spread == nil {
						return newErrorMissing()
					}
					// Copy spread so f and y don't share dag.Exprs.
					e, liftOK = addPathToExpr(dag.CopyExpr(spread), this.Path)
					return e
				}
				// Copy e1 so f and y don't share dag.Exprs.
				e, liftOK = addPathToExpr(dag.CopyExpr(e1), this.Path[1:])
				return e
			})
			if liftOK {
				seq[i], seq[i+1] = f, y
			}
		}
		return seq
	})
	return seq
}

func mergeValuesOps(seq dag.Seq) dag.Seq {
	return Walk(seq, func(seq dag.Seq) dag.Seq {