Expressions — Advanced topics

Expressions are evaluated as follows:

1. PRPC evaluates expressions from left to right.
2. The target property reference (the destination for a value) is evaluated completely before the expression (the source of the value) is evaluated.
3. Evaluation reflects nesting within parentheses, and operator precedence.
4. Partial expressions combined by an operator are evaluated before the operation, with a few exceptions: For the logical functions @if(), @and(), and @or(), and the conditional operators (&&, || and ?:) only those operands needed to determine the true or false result are evaluated.
5. Argument lists for functions are evaluated left to right.

This table shows the valid combinations of types when the operator is + or -. To understand the calculation of the expression A + B, find the type of A in the Left Hand Side (rows) of each table. Find the type of B in the Right Hand Side (columns) if the table. Consult the numbered notes for the details of casting or conversion.

Right Hand Side	DateTime	Date	Time of Day	Integer	Decimal	Double	True or False	Other (text)
Left Hand Side
DateTime	3	3	3	5	5	5	X	1
Date	X	3	4	5	5	5	X	1
Time of Day	X	4	3	X	5	5	X	1
Integer	5	5	X	2	2	2	X	1
Decimal	5	5	5	2	2	2	X	1
Double	5	5	5	2	2	2	X	1
True or False	X	X	X	X	X	X	X	1
Other (text)	1	1	1	1	1	1	1	1

X indicates that a casting, promotion or conversion is not supported. PRPC reports an error.

1. For +, performs Java String concatenation (result is of mode Single Value). The minus operator (-) is not permitted.
2. Converts Integer > Double > Decimal until both operands have same type, then perform operation. Result is of the promoted type. (Converts directly to the target type without performing intermediate conversions.)
3. The + operator is not permitted. The - operator converts operands to Decimal and performs the operation, yielding Decimal number of days and fraction of day.
4. The + operator converts operands to Decimal and performs the operation, yielding a DateTime with GMT assumed. The - operator is not permitted.
5. Converts operands to Decimal and performs the operation, yielding a Date (rounded), Time of Day or DateTime (depending upon type of original non-numeric operand)

This table shows the valid combinations of types when the operator is *, / or %. To understand the calculation of the expression A * B, find the type of A in the Left Hand Side (rows) of each table. Find the type of B in the Right Hand Side (columns) if the table. Consult the numbered notes for the details of casting or conversion.

Notes for multiplication, division, and remainder operations:

1. Convert Integer > Double > BigDecimal until both operands have same type, then perform operation. The result is of the promoted type. (Conversion is directly to target type without performing additional intermediate conversions.)
2. Integer divide operations with the / operator provide no rounding. For example, 10/6 = 1. You can use the built-in function @divide(dividend, divisor, mode) with Integer or Decimal operations to compute a result that contains at least two decimal places and rounds half values up: @divide(10, 6) = 1.67. Rounding modes are the same as for the BigDecimal class:
   • ceiling — round to a more positive integer
   • down — round towards zero
   • floor — round to a more negative number
   • half_down — round to the nearest neighbor, where an equidistant value is rounded down
   • half_even — round to the nearest neighbor, where an equidistant value is rounded to an even value
   • half_up — round to the nearest neighbor, where an equidistant value is rounded up
   • unnecessary — assert that no rounding is necessary
   • up — round away from zero

This table shows the valid combinations of types for comparison operators. To understand the calculation of the expression A > B, find the type of A in the Left Hand Side (rows) of each table. Find the type of B in the Right Hand Side (columns) if the table. Consult the numbered notes for the details of casting or conversion.

The operator ~= evaluates using equalsIgnoreCase().

Legend: