Operators and Constants in Function Library |
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The Function Library in the rule creator provides a set of functions and operators that can be used for framing simple as well as complex rules. The following sections describe the operators and constants that are provided by the function library.
Arithmetic Operators
Arithmetic operators allow you to define mathematical operations in rule expressions.
The following table describes the arithmetic operators you can select from the function library area while creating a rule.
Table 1. Arithmetic Operators
| Operator | Description | Syntax |
|---|---|---|
| + | Adds e1 and e2 | e1 + e2 |
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Subtracts e2 from e1 | e1 - e2 |
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Multiplies e1 and e2 | e1 * e2 |
| div | Divides e1 and e2 (If e2 is 0, then the expression evaluates to 0.) | e1 div e2 |
| mod | Gives the modulus(division remainder) of e1 and e2 | e1 mod e2 |
Boolean Operators
Boolean operators evaluate expressions to true or false. The resulttruetakes the integer value 1 whilefalsetakes the value 0.
Table 2. Boolean Operators
| Operator | Description | Syntax |
|---|---|---|
| and | Logical and operator | e1 and e2 |
| or | Logical or operator | e1 or e2 |
| = | Equality operator | e1 = e2 |
| != | Inequality operator | e1 != e2 |
| < | Less than operator | e1 < e2 |
| <= | Less than or equal to operator | e1 <= e2 |
| > | Greater than operator | e1 > e2 |
| >= | Greater than or equal to operator | e1 >= e2 |
Boolean Functions
The rule engine provides a set of boolean functions that can be used directly in a rule.
Table 3. Boolean Functions
| Constant | Description | Value |
|---|---|---|
| true() | function call for returning true | 1 |
| false() | function call for returning false | 0 |
Operator Precedence and Associativity
Operator precedence describes the order in which the rule engine reads expressions. Operators are arranged in descending order of precedence, that is, from the highest to the lowest. More than one operator appearing in a single row has the same precedence.
The following table lists the operators in the order in which the rule engine reads them. The associativity column specifies the direction in which each operator is read.
Table 4. Operator Precedence and Associativity
| Operator | Description | Associativity |
|---|---|---|
| in | Logical in operator | Left to right |
| + - | Unary plus/minus operators | Right to left |
| ^ | Power operator | Left to right |
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Multiplication, division, modulus operators | Left to right |
| + - | Addition/subtraction operators | Left to right |
| < <= | Relational less than/less than or equal to operators | No Associativity |
| > >= | Relational greater than/greater than or equal to operators | |
| = != | Relational is equal to/is not equal to operators | |
| and | Logical and operator | Left to right |
| or | Logical or operator | Left to right |