/**********************************************************************************
    queryByFormula

    $inTable        ->  Table pointer   Table to apply query
    $inExpression   ->  Text            Expression to execute for each record,
                                        should evaluate to a boolean
    $context        ->  Collection      Values for use in the expression

    Allows you to execute a QUERY BY FORMULA using Active4D variables
    and methods. This is the functional equivalent of the QUERY BY FORMULA
    command from v4.5.

    If $inExpression is empty, the current selection of $inTable will be empty.
**********************************************************************************/

method "queryByFormula"($inTable; $inExpression; $context = 0)

    if (length($inExpression) # 0)
        $inExpression := "return ({0})" %% ($inExpression)
        all records($inTable->)
        $set := "a4d.utils.queryByFormula"
        create empty set($inTable->; $set)

        for each($inTable->)
            if (execute($inExpression))
                add to set($inTable->; $set)
            end if
        end for each

        use set($set)
        clear set($set)
        first record($inTable->)
    else
        reduce selection($inTable->; 0)
    end if

end method