interval
A set of numbers between two endpoints., (*1)
use Jstewmc\Interval;
// create an interval between 2 (exclusive) and 4 (inclusive)
$interval = new Interval('(2, 4]');
// compare values
$interval->compare(1); // returns -1
$interval->compare(2); // returns -1
$interval->compare(3); // returns 0
$interval->compare(4); // returns 0
$interval->compare(5); // returns 1
// echo the interval
echo $interval; // returns "(2, 4]"
Syntax
This library supports standard US interval syntax requiring (in order):, (*2)
- an open-bracket (
[) or open-parentheses (();
- a number, positive infinity (
INF), or negative infinity (-INF);
- a comma-space (
,);
- a number, positive infinity (
INF), or negative infinity (-INF); and,
- a close-bracket (
]) or close-parentheses ()).
Positive or negative floats, integers, and infinity are accepted., (*3)
For example:, (*4)
-
(2, 4] represents 2 < x <= 4
-
(-10.5, 10.5) represents -10.5 < x < 10.5
-
[0, INF) represents 0 <= x < ∞
-
(-INF, INF) represents -∞ < x < ∞
Keep in mind, this library does not support reverse-bracket syntax (e.g., ]2, 4]) or semi-colon separated syntax (e.g., [2; 4])., (*5)
Usage
You can instantiate an interval from a string or create it manually using the set methods:, (*6)
use Jstewmc\Interval;
$a = new Interval('(2, 4]');
$b = (new Interval())
->setLowerExclusive()
->setLower(2)
->setUpper(4)
->setUpperInclusive();
$a == $b; // returns true
Keep in mind, when instantiating an interval from a string, an InvalidArgumentException will be thrown if the interval's syntax is invalid:, (*7)
use Jstewmc\Interval;
new Interval('[0; 0]'); // throws exception (semicolon syntax not supported)
new Interval(']0, 2]'); // throws exception (reverse brackets not supported)
new Interval('[foo, bar]'); // throws exception (use numbers or INF)
new Interval('[0, 0)'); // throws exception (same endpoint, different boundary)
new Interval('[1, -1]'); // throws exception (upper- is less than lower-bound)
Infinity is supported as the string 'INF' or the INF predefined constant:, (*8)
use Jstewmc\Interval;
$a = new Interval('(-INF, 0]');
$b = (new Interval())
->setLowerExclusive()
->setLower(-INF)
->setUpper(0)
->setUpperInclusive(true);
$a == $b; // returns true
You can compare a value to the interval using the compare() method. The compare() method will return -1, 0, or 1 if the value is below, inside, or above the interval, respectively:, (*9)
use Jstewmc\Interval;
$interval = new Interval('(2, 4]');
$interval->compare(1); // returns -1
$interval->compare(2); // returns -1
$interval->compare(3); // returns 0
$interval->compare(4); // returns 0
$interval->compare(5); // returns 1
You can get any of the interval's settings with the get methods:, (*10)
use Jstewmc\Interval;
$interval = new Interval('(2, 4]');
$interval->getIsLowerInclusive(); // returns false
$interval->getLower(); // returns 2
$interval->getUpper(); // returns 4
$interval->getIsUpperInclusive(); // returns true
There are a few convenience methods to make getting and setting the boundaries eaiser:, (*11)
use Jstewmc\Interval;
$interval = new Interval('(2, 4]');
$interval->isLowerInclusive(); // returns false
$interval->isLowerExclusive(); // returns true
$interval->isUpperInclusive(); // returns true
$interval->isUpperExclusive(); // returns false
echo $interval->setLowerInclusive(); // prints "[2, 4]"
echo $interval->setLowerExclusive(); // prints "(2, 4]"
echo $interval->setUpperInclusive(); // prints "(2, 4]"
echo $interval->setUpperExclusive(); // prints "(2, 4)"
That's about it!, (*12)
License
MIT, (*13)
Author
Jack Clayton, (*14)
Version
1.0.0, August 13, 2016
- Major release
- Update
composer.json
0.2.0, August 7, 2016
- Add support for infinity (e.g.,
'(-INF, 0]').
- Update error messages to be a little more informative.
- Update README examples.
0.1.0, August 6, 2016
Wallogit.com
