Expressions: Range Operations
A range operation is a way to create a range of integer values. There are six different types of range operations: from, to, to inclusive, between, between inclusive, and full.
The range operation is way of constructing a Psl\Range\RangeInterface object, according to the following table:
| Syntax | Type | Range |
|---|---|---|
start.. | Psl\Range\FromRange | start ≤ x |
..end | Psl\Range\ToRange | x < end |
..=end | Psl\Range\ToRange | x ≤ end |
start..end | Psl\Range\BetweenRange | start ≤ x < end |
start..=end | Psl\Range\BetweenRange | start ≤ x ≤ end |
.. | Psl\Range\FullRange | - |
The following operations are equivalent:
$a = new Psl\Range\between(1, 10, false);
$b = 1..10;
Psl\invariant($a == $b);
Ranges can be iterated over as long as the range has a starting point:
foreach 1..100 as $value {
// $value is 1, 2, 3, ..., 99
}
From
A from range operation can be used to create a range from a starting point to infinity. This is done using the .. operator following the starting point.
$a = 1..;
To
A to range operation can be used to create a range to an ending point. This is done using the .. operator preceding the ending point.
$a = ..10;
To Inclusive
A to inclusive range operation can be used to create a range to an ending point, inclusive. This is done using the ..= operator preceding the ending point.
$a = ..=10;
Between
A between range operation can be used to create a range from a starting point to an ending point. This is done using the .. operator between the starting and ending points.
$a = 1..10;
Between Inclusive
A between inclusive range operation can be used to create a range from a starting point to an ending point, inclusive. This is done using the ..= operator between the starting and ending points.
$a = 1..=10;
Full
A full range operation can be used to create a range to infinity. This is done using the .. operator.
$a = ..;