Description
Expressions describe a sequence of operations to be performed on one or more operands that result in a single value of a particular type. The operations to be performed are specified by operators.
Example
Here are some examples of expressions:
3+5 which results in the integer value 8
3+5.0 which results in the real value 8.0
1+2*3 which results in the integer value 7
(1+2)*3 which results in the integer value 9Syntax
(NOTE: for clarity some parts of the syntax are omitted, see Irie Pascal Grammar for the full syntax):
expression = shift-expression [ relational-operator shift-expression ]
adding-operator = '+' | '-' | 'or' | 'or_else' | 'xor'
factor = [ sign ] unsigned-constant |
[ sign ] variable-access |
[ sign ] '(' expression ')' |
[ sign ] function-designator |
[ sign ] function-method-designator |
[ sign ] 'not' factor |
set-constructor
multiplying-operator = '*' | '/' | 'div' | 'mod' | 'and' | 'and_then'
relational-operator = '=' | '<>' | '<' | '<=' | '>' | '>=' | 'in'
shift-expression = simple-expression [ shift-operator simple-expression ]
shift-operator = 'shl' | 'shr'
sign = '-' | '+'
simple-expression = term { adding-operator term }
term = factor { multiplying-operator factor }