Rule syntax
The decision logic is specified in multiple rules.
A rule consists of a list of one or more statements.
A statement always ends with a ‘;’ semi-colon. Multiple statements can be combined.
Example:
<statement> ; <statement> ;
or:
<statement> ;
<statement> ;
There are 2 kinds of statements:
- if-statement
- assignment
An “if” statement can have the following forms ;
if( <expression> ) { <statements> } else { <statements> };
if( <expression> ) { <statements> } ;
The else part is optional.
If the expression evaluates to non-zero the first statements will be executed.
If the expression evaluates to zero the next list of statements will be executed. The ‘else’ part of the if statement.
For example:
if( temp > 10 ) {
fan = 1 ;
} else {
fan = 0 ;
}
An expression can be a single item or a combination of expressions.
Constants, for example:
10
12345
Variables, for example:
temp
fan
Operator expressions are formed as:
<expression> <operator> <expression>
For example, arithmetic expressions:
a + z
b / c
d * e
f - g
Boolean expressions:
a < 10
b < c
c > d
e == f
e <= f
e >= f
A assignment consists of a left part and a right part combined with an ‘=’ (equal) sign. The left part should always be a variable reference. The right part is an expression.
<variable> = <expression> ;
For example:
temp = temp2 - 10 ;