Class that holds a tree of availability conditions. More...

Inheritance diagram for core_availability\tree:

Public Member Functions
	__construct ($structure, $lax=false, $root=true)
	Decodes availability structure.

	__toString ()
	Display a representation of this tree (used for debugging).

	check_available ($not, info $info, $grabthelot, $userid)

	check_available ($not, core_availability\info $info, $grabthelot, $userid)
	Determines whether this particular item is currently available according to the availability criteria.

	filter_user_list (array $users, $not, info $info, capability_checker $checker)
	Tests against a user list.

	filter_user_list (array $users, $not, core_availability\info $info, capability_checker $checker)
	Tests this condition against a user list.

	get_all_children ($classname)
	Recursively gets all children of a particular class (you can use a base class to get all conditions, or a specific class).

	get_full_information (info $info)
	Gets full information about this tree (including all children) as HTML for display to staff.

	get_logic_flags ($not)
	Converts the operator for the tree into two flags used for computing the result.

	get_result_information (info $info, result $result)
	Gets information about this tree corresponding to the given result object.

	get_user_list_sql ($not, info $info, $onlyactive)

	get_user_list_sql ($not, core_availability\info $info, $onlyactive)
	Obtains SQL that returns a list of enrolled users that has been filtered by the conditions applied in the availability API, similar to calling get_enrolled_users and then filter_user_list.

	include_after_restore ($restoreid, $courseid, base_logger $logger, $name, base_task $task)
	Checks whether this node should be included after restore or not.

	is_applied_to_user_lists ()
	Checks whether this condition applies to user lists.

	is_available_for_all ($not=false)
	Checks whether this condition is actually going to be available for all users under normal circumstances.

	is_empty ()
	Checks whether this tree is empty (contains no children).

	save ()
	Saves tree data back to a structure object.

	update_after_restore ($restoreid, $courseid, base_logger $logger, $name)
	Updates this node after restore, returning true if anything changed.

	update_dependency_id ($table, $oldid, $newid)
	Updates this node if it contains any references (dependencies) to the given table and id.

Static Public Member Functions
static	get_nested_json (array $children, $op=self::OP_AND)
	Returns a JSON object which corresponds to a tree.

static	get_root_json (array $children, $op=self::OP_AND, $show=true)
	Returns a JSON object which corresponds to a tree at root level.

Public Attributes
int const	OP_AND = '&'
	Operator: AND.

int const	OP_NOT_AND = '!&'
	Operator: NOT(AND)

int const	OP_NOT_OR = '!\|'
	Operator: NOT(OR)

int const	OP_OR = '\|'
	Operator: OR.

Protected Member Functions
	get_full_information_recursive ( $not, info $info, ?result $result, $root, $hidden=false)
	Gets information about this tree (including all or selected children) as HTML for display to staff or student.

	recursive_get_all_children ($classname, array &$result)
	Internal function that implements get_all_children efficiently.

Static Protected Member Functions
static	unique_sql_parameter (array &$params, $value)
	Utility function for generating SQL parameters (because we can't use ? parameters because get_enrolled_sql has infected us with horrible named parameters).

Protected Attributes
tree_node[]	$children
	Children in this branch (may be empty array if needed)

string	$op
	Operator type (OP_xx constant)

bool	$root
	True if this tree is at root level.

bool	$show
	Single 'show information or hide completely' option for tree.

bool[]	$showchildren
	Array of 'show information or hide completely' options for each child.

Static Protected Attributes
static int	$uniquesqlparametercounter = 1
	Counter to be used in tree_node::unique_sql_parameter().

Detailed Description

Class that holds a tree of availability conditions.

The structure of this tree in JSON input data is:

{ op:'&', c:[] }

where 'op' is one of the OP_xx constants and 'c' is an array of children.

At the root level one of the following additional values must be included:

op '|' or '!&' show:true Boolean value controlling whether a failed match causes the item to display to students with information, or be completely hidden. op '&' or '!|' showc:[] Array of same length as c with booleans corresponding to each child; you can make it be hidden or shown depending on which one they fail. (Anything with false takes precedence.)

Copyright: 2014 The Open University

License: http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

Constructor & Destructor Documentation

◆ __construct()

core_availability\tree::__construct	(	$structure,
		$lax = false,
		$root = true )

Decodes availability structure.

This function also validates the retrieved data as follows:

Data that does not meet the API-defined structure causes a coding_exception (this should be impossible unless there is a system bug or somebody manually hacks the database).
Data that meets the structure but cannot be implemented (e.g. reference to missing plugin or to module that doesn't exist) is either silently discarded (if $lax is true) or causes a coding_exception (if $lax is false).

See also: decode_availability

Parameters

stdClass	$structure	Structure (decoded from JSON)
boolean	$lax	If true, throw exceptions only for invalid structure
boolean	$root	If true, this is the root tree

Return values

tree	Availability tree

Exceptions

coding_exception If data is not valid structure

Member Function Documentation

◆ __toString()

core_availability\tree::__toString ( )

Display a representation of this tree (used for debugging).

Return values

string Text representation of tree

◆ check_available()

core_availability\tree_node::check_available	(		$not,
		core_availability\info	$info,
			$grabthelot,
			$userid )

abstractinherited

Determines whether this particular item is currently available according to the availability criteria.

This does not include the 'visible' setting (i.e. this might return true even if visible is false); visible is handled independently.
This does not take account of the viewhiddenactivities capability. That should apply later.

The $not option is potentially confusing. This option always indicates the 'real' value of NOT. For example, a condition inside a 'NOT AND' group will get this called with $not = true, but if you put another 'NOT OR' group inside the first group, then a condition inside that will be called with $not = false. We need to use the real values, rather than the more natural use of the current value at this point inside the tree, so that the information displayed to users makes sense.

Parameters

bool	$not	Set true if we are inverting the condition
core_availability\info	$info	Item we're checking
bool	$grabthelot	Performance hint: if true, caches information required for all course-modules, to make the front page and similar pages work more quickly (works only for current user)
int	$userid	User ID to check availability for

Return values

result Availability check result

◆ filter_user_list() [1/2]

core_availability\tree::filter_user_list	(	array	$users,
			$not,
		info	$info,
		capability_checker	$checker )

Tests against a user list.

Users who cannot access the activity due to availability restrictions will be removed from the list.

This test ONLY includes conditions which are marked as being applied to user lists. For example, group conditions are included but date conditions are not included.

The function operates reasonably efficiently i.e. should not do per-user database queries. It is however likely to be fairly slow.

Parameters

array	$users	Array of userid => object
bool	$not	If tree's parent indicates it's being checked negatively
info	$info	Info about current context
capability_checker	$checker	Capability checker

Return values

array Filtered version of input array

◆ filter_user_list() [2/2]

core_availability\tree_node::filter_user_list	(	array	$users,
			$not,
		core_availability\info	$info,
		capability_checker	$checker )

inherited

Tests this condition against a user list.

Users who do not meet the condition will be removed from the list, unless they have the ability to view hidden activities/sections.

This function must be implemented if is_applied_to_user_lists returns true. Otherwise it will not be called.

The function must operate efficiently, e.g. by using a fixed number of database queries regardless of how many users are in the list.

Within this function, if you need to check capabilities, please use the provided checker which caches results where possible.

Conditions do not need to check the viewhiddenactivities or viewhiddensections capabilities. These are handled by core_availability\info\filter_user_list.

Parameters

array	$users	Array of userid => object
bool	$not	True if this condition is applying in negative mode
core_availability\info	$info	Item we're checking
capability_checker	$checker

Return values

array Filtered version of input array

Exceptions

coding_exception If called on a condition that doesn't apply to user lists

◆ get_all_children()

core_availability\tree::get_all_children ( $classname )

Recursively gets all children of a particular class (you can use a base class to get all conditions, or a specific class).

Parameters

string $classname Full class name e.g. core_availability\condition

Return values

array Array of nodes of that type (flattened, not a tree any more)

◆ get_full_information()

core_availability\tree::get_full_information ( info $info )

Gets full information about this tree (including all children) as HTML for display to staff.

Parameters

info $info Information about location of condition tree

Exceptions

coding_exception If you call on a non-root tree

Return values

string HTML data (empty string if none)

◆ get_full_information_recursive()

core_availability\tree::get_full_information_recursive	(		$not,
		info	$info,
		?result	$result,
			$root,
			$hidden = false )

protected

Gets information about this tree (including all or selected children) as HTML for display to staff or student.

Parameters

bool	$not	True if there is a NOT in effect
info	$info	Information about location of condition tree
result \| null	$result	Result object if this is a student display, else null
bool	$root	True if this is the root item
bool	$hidden	Staff display; true if this tree has show=false (from parent)

Return values

string|renderable Information to render

◆ get_logic_flags()

core_availability\tree::get_logic_flags ( $not )

Converts the operator for the tree into two flags used for computing the result.

The 2 flags are $innernot (whether to set $not when calling for children) and $andoperator (whether to use AND or OR operator to combine children).

Parameters

bool $not Not flag passed to this tree

Return values

array Array of the 2 flags ($innernot, $andoperator)

◆ get_nested_json()

static core_availability\tree::get_nested_json	(	array	$children,
			$op = self::OP_AND )

static

Returns a JSON object which corresponds to a tree.

Intended for unit testing, as normally the JSON values are constructed by JavaScript code.

This function generates 'nested' (i.e. not root-level) trees.

Parameters

array	$children	Array of JSON objects from component children
string	$op	Operator (tree\OP_xx)

Return values

stdClass JSON object

Exceptions

coding_exception If you get parameters wrong

◆ get_result_information()

core_availability\tree::get_result_information	(	info	$info,
		result	$result )

Gets information about this tree corresponding to the given result object.

(In other words, only conditions which the student actually fails will be shown - and nothing if display is turned off.)

Parameters

info	$info	Information about location of condition tree
result	$result	Result object

Exceptions

coding_exception If you call on a non-root tree

Return values

string HTML data (empty string if none)

◆ get_root_json()

static core_availability\tree::get_root_json	(	array	$children,
			$op = self::OP_AND,
			$show = true )

static

Returns a JSON object which corresponds to a tree at root level.

Intended for unit testing, as normally the JSON values are constructed by JavaScript code.

The $show parameter can be a boolean for all OP_xx options. For OP_AND and OP_NOT_OR where you have individual show options, you can specify a boolean (same for all) or an array.

Parameters

array	$children	Array of JSON objects from component children
string	$op	Operator (tree\OP_xx)
bool \| array	$show	Whether 'show' option is turned on (see above)

Return values

stdClass JSON object ready for encoding

Exceptions

coding_exception If you get parameters wrong

◆ get_user_list_sql()

core_availability\tree_node::get_user_list_sql	(		$not,
		core_availability\info	$info,
			$onlyactive )

inherited

Obtains SQL that returns a list of enrolled users that has been filtered by the conditions applied in the availability API, similar to calling get_enrolled_users and then filter_user_list.

As for filter_user_list, this ONLY filters out users with conditions that are marked as applying to user lists. For example, group conditions are included but date conditions are not included.

The returned SQL is a query that returns a list of user IDs. It does not include brackets, so you neeed to add these to make it into a subquery. You would normally use it in an SQL phrase like "WHERE u.id IN ($sql)".

The SQL will be complex and may be slow. It uses named parameters (sorry, I know they are annoying, but it was unavoidable here).

If there are no conditions, the returned result is array('', array()).

Conditions do not need to check the viewhiddenactivities or viewhiddensections capabilities. These are handled by core_availability\info\get_user_list_sql.

Parameters

bool	$not	True if this condition is applying in negative mode
core_availability\info	$info	Item we're checking
bool	$onlyactive	If true, only returns active enrolments

Return values

array Array with two elements: SQL subquery and parameters array

Exceptions

coding_exception If called on a condition that doesn't apply to user lists

◆ include_after_restore()

core_availability\tree_node::include_after_restore	(		$restoreid,
			$courseid,
		base_logger	$logger,
			$name,
		base_task	$task )

inherited

Checks whether this node should be included after restore or not.

The node may be removed depending on restore settings, which you can get from the $task object.

By default nodes are still included after restore.

Parameters

string	$restoreid	Restore ID
int	$courseid	ID of target course
base_logger	$logger	Logger for any warnings
string	$name	Name of this item (for use in warning messages)
base_task	$task	Current restore task

Return values

bool	True if there was any change

Reimplemented in availability_group\condition, and availability_grouping\condition.

◆ is_applied_to_user_lists()

core_availability\tree::is_applied_to_user_lists ( )

Checks whether this condition applies to user lists.

The default is false (the condition is used to control access, but does not prevent the student from appearing in lists).

For example, group conditions apply to user lists: we do not want to include a student in a list of users if they are prohibited from accessing the activity because they don't belong to a relevant group. However, date conditions do not apply - we still want to show users in a list of people who might have submitted an assignment, even if they are no longer able to access the assignment in question because there is a date restriction.

The general idea is that conditions which are likely to be permanent (group membership, user profile) apply to user lists. Conditions which are likely to be temporary (date, grade requirement) do not.

Conditions which do apply to user lists must implement the filter_user_list function.

Return values

bool	True if this condition applies to user lists

Reimplemented from core_availability\tree_node.

◆ is_available_for_all()

core_availability\tree::is_available_for_all ( $not = false )

Checks whether this condition is actually going to be available for all users under normal circumstances.

Normally, if there are any conditions, then it may be hidden. However in the case of date conditions there are some conditions which will definitely not result in it being hidden for anyone.

Parameters

bool $not Set true if we are inverting the condition

Return values

bool	True if condition will return available for everyone

Reimplemented from core_availability\tree_node.

◆ is_empty()

core_availability\tree::is_empty ( )

Checks whether this tree is empty (contains no children).

Return values

boolean True if empty

◆ recursive_get_all_children()

core_availability\tree::recursive_get_all_children	(		$classname,
		array &	$result )

protected

Internal function that implements get_all_children efficiently.

Parameters

string	$classname	Full class name e.g. core_availability\condition
array	$result	Output array of nodes

◆ save()

core_availability\tree::save ( )

Saves tree data back to a structure object.

Return values

stdClass Structure object (ready to be made into JSON format)

Reimplemented from core_availability\tree_node.

◆ unique_sql_parameter()

static core_availability\tree_node::unique_sql_parameter	(	array &	$params,
			$value )

staticprotectedinherited

Utility function for generating SQL parameters (because we can't use ? parameters because get_enrolled_sql has infected us with horrible named parameters).

Parameters

array	$params	Params array (value will be added to this array)
string \| int	$value	Value

Return values

SQL	code for the parameter, e.g. ':pr1234'

◆ update_after_restore()

core_availability\tree::update_after_restore	(		$restoreid,
			$courseid,
		base_logger	$logger,
			$name )

Updates this node after restore, returning true if anything changed.

The default behaviour is simply to return false. If there is a problem with the update, $logger can be used to output a warning.

Note: If you need information about the date offset, call core_availability\info\get_restore_date_offset($restoreid). For information on the restoring task and its settings, call core_availability\info\get_restore_task($restoreid).

Parameters

string	$restoreid	Restore ID
int	$courseid	ID of target course
base_logger	$logger	Logger for any warnings
string	$name	Name of this item (for use in warning messages)

Return values

bool	True if there was any change

Reimplemented from core_availability\tree_node.

◆ update_dependency_id()

core_availability\tree::update_dependency_id	(	$table,
		$oldid,
		$newid )

Updates this node if it contains any references (dependencies) to the given table and id.

Parameters

string	$table	Table name e.g. 'course_modules'
int	$oldid	Previous ID
int	$newid	New ID

Return values

bool	True if it changed, otherwise false

Reimplemented from core_availability\tree_node.

Member Data Documentation

◆ $show

bool core_availability\tree::$show

protected

Single 'show information or hide completely' option for tree.

This option is only set for the root tree if it is in OR or NOT AND mode, otherwise it is true.

◆ $showchildren

bool [] core_availability\tree::$showchildren

protected

Array of 'show information or hide completely' options for each child.

This array is only set for the root tree if it is in AND or NOT OR mode, otherwise it is null.

The documentation for this class was generated from the following file:

availability/classes/tree.php

Public Member Functions

Static Public Member Functions

Public Attributes

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ __construct()

Member Function Documentation

◆ __toString()

◆ check_available()

◆ filter_user_list() [1/2]

◆ filter_user_list() [2/2]

◆ get_all_children()

◆ get_full_information()

◆ get_full_information_recursive()

◆ get_logic_flags()

◆ get_nested_json()

◆ get_result_information()

◆ get_root_json()

◆ get_user_list_sql()

◆ include_after_restore()

◆ is_applied_to_user_lists()

◆ is_available_for_all()

◆ is_empty()

◆ recursive_get_all_children()

◆ save()

◆ unique_sql_parameter()

◆ update_after_restore()

◆ update_dependency_id()

Member Data Documentation

◆ $show

◆ $showchildren