Method Eval

pkg/sql/sem/tree/eval.go:4011–4049

Eval implements the TypedExpr interface.

(ctx *EvalContext)

// Eval implements the TypedExpr interface.
func (expr *ComparisonExpr) Eval(ctx *EvalContext) (Datum, error) {
	left, err := expr.Left.(TypedExpr).Eval(ctx)
	if err != nil {
		return nil, err
	}
	right, err := expr.Right.(TypedExpr).Eval(ctx)
	if err != nil {
		return nil, err
	}

	op := expr.Operator
	if op.hasSubOperator() {
		var datums Datums
		// Right is either a tuple or an array of Datums.
		if !expr.fn.NullableArgs && right == DNull {
			return DNull, nil
		} else if tuple, ok := AsDTuple(right); ok {
			datums = tuple.D
		} else if array, ok := AsDArray(right); ok {
			datums = array.Array
		} else {
			return nil, errors.AssertionFailedf("unhandled right expression %s", right)
		}
		return evalDatumsCmp(ctx, op, expr.SubOperator, expr.fn, left, datums)
	}

	_, newLeft, newRight, _, not := foldComparisonExpr(op, left, right)
	if !expr.fn.NullableArgs && (newLeft == DNull || newRight == DNull) {
		return DNull, nil
	}
	d, err := expr.fn.Fn(ctx, newLeft.(Datum), newRight.(Datum))
	if err != nil {
		return nil, err
	}
	if b, ok := d.(*DBool); ok {
		return MakeDBool(*b != DBool(not)), nil
	}
	return d, nil
}

//// EvalArgsAndGetGenerator evaluates the arguments and instanciates a
//// ValueGenerator for use by set projections.