Using Calends in PHP

Calends exposes a very small handful of things for use outside the library itself. One is the Calends class, documented here, which should be the only interface users of the library ever need to touch.

Another thing Calends exposes is the TAITime class, used to store and manipulate the instants of time which make up a Calends instance. The rest are interfaces for extending the library’s functionality. These are covered in the Custom Calendars in PHP section.

Note

Calends objects are immutable - all methods return a new Calends object where they might otherwise alter the current one. This has the side effect of using more memory to perform manipulations than updating values on an existing object would. It makes many operations safer, though, than mutable objects would allow.

class Calends\Calends

The main entry point to Calends and its functionality. Calends objects can only be created with the Calends\Calends::create function, and not directly. Calends does implement the Serializable interface, though, so it’s safe to serialize/unserialize instances if you want.

Create

static Calends\Calends::create($value, $calendar, $format)
Parameters

  • $value (mixed) – The value to parse the date(s)/time(s) from.

  • $calendar (string) – The calendar system to parse the date(s)/time(s) with.

  • $format (string) – The format the date(s)/time(s) is/are expected to use.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Creates a new Calends object, using $calendar to select a calendar system, and $format to parse the contents of $value into the Calends object’s internal instants. The type of $value can vary based on the calendar system itself, but generally speaking can always be a string.

In any case, the value can always be an associative array, where the keys are any two of start, end, and duration. If all three are provided, duration is ignored in favor of calculating it directly.

The calendar system then converts $value to a TAITime instant, which the Calends object sets to the appropriate internal value.

Read

Calends\Calends::date($calendar, $format)
Parameters

  • $calendar (string) – The calendar system to format the date/time with.

  • $format (string) – The format the date/time is expected to be in.

Returns

The start date of the Calends object

Return type

string

Throws

CalendsException – when an error occurs

Retrieves the start date of the Calends object as a string. The value is generated by the calendar system given in $calendar, according to the format string in $format.

Calends\Calends::endDate($calendar, $format)
Parameters

  • $calendar (string) – The calendar system to format the date/time with.

  • $format (string) – The format the date/time is expected to be in.

Returns

The end date of the Calends object

Return type

string

Throws

CalendsException – when an error occurs

Retrieves the end date of the Calends object as a string. The value is generated by the calendar system given in $calendar, according to the format string in $format.

Calends\Calends::duration()
Returns

The duration of the Calends object

Return type

string

Retrieves the duration of the Calends object as a decimal string. This value will be 0 if the Calends object is an instant.

Update

Calends\Calends::withDate($value, $calendar, $format)
Parameters

  • $value (mixed) – The value to parse the date/time from.

  • $calendar (string) – The calendar system to parse the date/time with.

  • $format (string) – The format the date/time is expected to use.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object with a start date based on the current Calends object’s value. The inputs are the same as for Calends\Calends::create, above, except the string → value map option isn’t available, since you’re already specifically setting the start value explicitly.

Calends\Calends::withEndDate($value, $calendar, $format)
Parameters

  • $value (mixed) – The value to parse the date/time from.

  • $calendar (string) – The calendar system to parse the date/time with.

  • $format (string) – The format the date/time is expected to use.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object with an end date based on the current Calends object’s value. The inputs are the same as for Calends\Calends::create, above, except the string → value map option isn’t available, since you’re already specifically setting the end value explicitly.

Calends\Calends::withDuration($duration, $calendar)
Parameters

  • $duration (string) – The value to parse the new duration from.

  • $calendar (string) – The calendar system to parse the date/time with.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object with a duration set by adjusting the current Calends object’s end point, and using its start point as an anchor. The $duration value is interpreted by the calendar system given in $calendar, so is subject to any of its rules.

Calends\Calends::withDurationFromEnd($duration, $calendar)
Parameters

  • $duration (string) – The value to parse the new duration from.

  • $calendar (string) – The calendar system to parse the date/time with.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object with a duration set by adjusting the current Calends object’s start point, and using its end point as an anchor. The $duration value is interpreted by the calendar system given in $calendar, so is subject to any of its rules.

Manipulate

Calends\Calends::add($offset, $calendar)
Parameters

  • $offset (string) – The value to parse the offset from.

  • $calendar (string) – The calendar system to parse the date/time with.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Increases the end date of the Calends object’s current value by $offset, as interpreted by the calendar system given in $calendar, and returns a new Calends object with the result.

Calends\Calends::addFromEnd($offset, $calendar)
Parameters

  • $offset (string) – The value to parse the offset from.

  • $calendar (string) – The calendar system to parse the date/time with.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Increases the start date of the Calends object’s current value by $offset, as interpreted by the calendar system given in $calendar, and returns a new Calends object with the result.

Calends\Calends::subtract($offset, $calendar)
Parameters

  • $offset (string) – The value to parse the offset from.

  • $calendar (string) – The calendar system to parse the date/time with.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Works the same as add, except it decreases the start date, rather than increasing it.

Calends\Calends::subtractFromEnd($offset, $calendar)
Parameters

  • $offset (string) – The value to parse the offset from.

  • $calendar (string) – The calendar system to parse the date/time with.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Works the same as addFromEnd, except it decreases the end date, rather than increasing it.

Calends\Calends::next($offset, $calendar)
Parameters

  • $offset (string) – The value to parse the offset from.

  • $calendar (string) – The calendar system to parse the date/time with.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object of $offset duration (as interpreted by the calendar system given in $calendar), which abuts the current Calends object’s value. If $offset is empty, $calendar is ignored, and the current object’s duration is used instead.

Calends\Calends::previous($offset, $calendar)
Parameters

  • $offset (string) – The value to parse the offset from.

  • $calendar (string) – The calendar system to parse the date/time with.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object of $offset duration (as interpreted by the calendar system given in $calendar), which abuts the current Calends object’s value. If $offset is empty, $calendar is ignored, and the current object’s duration is used instead.

Combine

Calends\Calends::merge($c2)
Parameters
Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object spanning from the earliest start date to the latest end date between the current Calends object and $c2.

Calends\Calends::intersect($c2)
Parameters
Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object spanning the overlap between the current Calends object and $c2. If the current object and $c2 don’t overlap, throws an error.

Calends\Calends::gap($c2)
Parameters
Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Returns a Calends object spanning the gap between the current Calends object and $c2. If the current object and $c2 overlap (and there is, therefore, no gap to return), throws an error.

Compare

Calends\Calends::difference($c2, $mode)
Parameters
Returns

The difference, as a decimal string

Return type

string

Returns the difference of the current Calends object minus $c2, using $mode to select which values to use in the calculation. Valid $modes include:

  • start - use the start date of both the current object and $c2

  • duration - use the duration of both the current object and $c2

  • end - use the end date of both the current object and $c2

  • start-end - use the start of the current object, and the end of $c2

  • end-start - use the end of the current object, and the start of $c2

Calends\Calends::compare($c2, $mode)
Parameters
Returns

A standard comparison result

Return type

int

Returns -1 if the current Calends object is less than $c2, 0 if they are equal, and 1 if the current object is greater than $c2, using $mode to select which values to use in the comparison. Valid $modes are the same as for Calends\Calends::difference, above.

Calends\Calends::contains($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Checks whether the current Calends object contains all of $c2.

Calends\Calends::overlaps($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Checks whether the current Calends object overlaps with $c2.

Calends\Calends::abuts($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Checks whether the current Calends object abuts $c2 (that is, whether one begins at the same instant the other ends).

Calends\Calends::isSame($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Checks whether the current Calends object covers the same span of time as $c2.

Calends\Calends::isShorter($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the duration of the current Calends object and $c2.

Calends\Calends::isSameDuration($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the duration of the current Calends object and $c2.

Calends\Calends::isLonger($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the duration of the current Calends object and $c2.

Calends\Calends::isBefore($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the entirety of the current Calends object with the start date of $c2.

Calends\Calends::startsBefore($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the start date of the current Calends object with the start date of $c2.

Calends\Calends::endsBefore($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the end date of the current Calends object with the start date of $c2.

Calends\Calends::isDuring($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Checks whether the entirety of the current Calends object lies between the start and end dates of $c2.

Calends\Calends::startsDuring($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Checks whether the start date of the current Calends object lies between the start and end dates of $c2.

Calends\Calends::endsDuring($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Checks whether the end date of the current Calends object lies between the start and end dates of $c2.

Calends\Calends::isAfter($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the entirety of the current Calends object with the end date of $c2.

Calends\Calends::startsAfter($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the start date of the current Calends object with the end date of $c2.

Calends\Calends::endsAfter($c2)
Parameters
Returns

The result of the comparison

Return type

bool

Compares the end date of the current Calends object with the end date of $c2.

Export

It’s possible to export Calends values in a couple of ways. It implements Serializable and JsonSerializable, as well as the __toString method, so the regular mechanisms for each of those are readily available and usable. In addition, it also offers support for JSON-decoding values directly:

static Calends\Calends::jsonUnserialize($encoded)
Parameters

  • $encoded (string) – The JSON-encoded value to import.

Returns

A new Calends object

Return type

Calends

Throws

CalendsException – when an error occurs

Error Handling

class Calends\CalendsException

A very simple exception class, directly extending Exception. It is thrown by the library for all encountered errors.