Description

Implementation of the state machine transitions.

One instance of this class implements state machine transitions of all machines of this type. When a transition is invoked a Reference object is passed as the first parameter of the transition method (a protected method of the same name as transition). The Reference provides ID of the state machine instance and may contain cached state data.

Configuration Schema

The state machine is configured using JSON object passed to the constructor (the $config parameter). The object must match the following JSON schema (JSON format):

Smalldb Abstract State Machine [object]
- _: [string] Token to stop PHP from interpreting the rest of the file. Ignored by Smalldb.
  
  Pattern: ^<\?php printf$'_%c%c}%c',34,10,10$;__halt_compiler;\?>$
- access_policies: [object] Access policies
  - *: [object] Access policy
    
    arrow_tail: [string] Shape of arrow tail in the state diagram. Visual effect only. See http://www.graphviz.org/content/arrow-shapes.
    
    Pattern: ^((|l|r|o|ol|or)box|(|l|r)crow|(l|r|o|ol|or)diamond|(|o)dot|(|l|r|o|ol|or)inv|none|(|l|r|o|ol|or)normal|(|l|r)tee|(|l|e)vee|(|l|r|i|li|ri)curve){1,4}$
- actions: [object] State machine actions (groups of transitions of the same name).
  - *: [object] State machine action.
    
    access_policy: [string] Name of required access policy, see access_policies.
    
    args: [array] Additional arguments prefixed to transition arguments when calling the method.
    
    color: [string] Color of the arrow in the state diagram.
    
    Pattern: ^#[0-9A-Fa-f]{6}$
    
    method: [string] Name of PHP method which implements the transition.
    
    Pattern: ^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$
    
    post_transition_methods: [array] Methods to call after the transition is invoked.
    
    *: [string]
    
    Pattern: ^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$
    
    pre_check_methods: [array] Methods to call before the transition is invoked. All of these methods must not return false otherwise the transition is aborted.
    
    *: [string]
    
    Pattern: ^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$
    
    returns: [string, null] Semantics of return value of the method.
    
    transitions: [object] Transitions of the action
    
    *: [object] Starting state of the transition.
    
    targets: [array] List of possible target states of the transition starting from this state.
    
    *: [string]
    
    *: [object] All properties are merged with action's properties; transition's properties have precedence.
    
    weight: [number] Weight of the arrow in the state diagram (heavier arrows are rendered shorter).
- class: [JsonDirBackend] [string] [required] Interpreted by JsonDirBackend. PHP class name of transitions implementation.
  
  Pattern: ^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*(\\[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)*$
- include: [JsonDirBackend] [array] Interpreted by JsonDirBackend only. List of files to include and merge with this JSON file.
  - *: [JsonDirBackend] [string, object] File name of the file to include or object containing the filename and additional options.
    
    file: [JsonDirBackend] [string] File name of the file to include.
    
    *: [JsonDirBackend] Options passed to dedicated reader.
- properties: [object] State machine properties.
  - *: [object] State machine property definition
- state_diagram_extras: [array] List of additional fragments of state diagram.
  - *: [string] Dot source code to be added just before the end of the state diagram..
- state_groups: [object] Groups of states in the state machine diagram. Visual effect only.
  - *: [object] Group of states in the state machine diagram.
    
    color: [string] Color of the group (border and label).
    
    Pattern: ^#[0-9A-Fa-f]{6}$
    
    label: [string] [required] Label of the group.
    
    state_groups: [object] Recursively nested state groups (same as parent state_groups).
    
    *: [not allowed]
- states: [object] State machine states
  - *: [object] State of the state machine
    
    color: [string] Color of the state in the state diagram (fillcolor). Visual effect only.
    
    Pattern: ^#[0-9A-Fa-f]{6}$
    
    group: [string] Name of a group (subgraph) in the state diagram to which the state belongs. Visual effect only. See state_groups.

Inheritance diagram for AbstractMachine

Public Member Functions
	__construct (AbstractBackend $backend, $type, $config, $context)
	Constructor. More...

	getState ($id)
	Get current state of state machine. More...

	getProperties ($id, &$state_cache=null)
	Get properties of state machine, including it's state. More...

	getView ($id, $view, &$properties_cache=null, &$view_cache=null, &$persistent_view_cache=null)
	Get properties in given view. More...

	isTransitionAllowed (Reference $ref, $transition_name, $state=null)
	Returns true if transition can be invoked right now. More...

	getAvailableTransitions (Reference $ref, $state=null)
	Get list of all available actions for state machine instance identified by $id. More...

	invokeTransition (Reference $ref, $transition_name, $args, &$returns, callable $new_id_callback=null)
	Invoke state machine transition. More...

	getMachineType ()
	Get type of this machine. More...

	getBackend ()
	Get backend which owns this machine. More...

	ref ($id)
	Helper to create Reference to this machine. More...

	nullRef ()
	Helper to create null Reference to this machine. More...

	hotRef ($properties)
	Create pre-heated reference using properties loaded from elsewhere. More...

	performSelfCheck ()
	Perform self-check. More...

Public Attributes
const	RETURNS_VALUE = null
	Return value of invoked transition is just some value. More...

const	RETURNS_NEW_ID = 'new_id'
	Return value of invoked transition is new ID of the state machine. More...

Protected Member Functions
	initializeMachine ($config)
	Define state machine used by all instances of this type. More...

	setupDefaultMachine ($config)
	Setup default machine when initializeMachine is finished. More...

	initializeMachineConfig ($config, $keys)
	Merge $config into state machine member variables. More...

	checkAccessPolicy ($access_policy, Reference $ref)
	Returns true if user has required access_policy to invoke a transition, which requires given access_policy. More...

	getContext ($resource_name=null)
	Get context object (whatever it is). More...

	urlFormat ($id, $url_fmt, $properties_cache)
	Create URL using properties and given format. More...

	resolveMachineReference ($reference_name, $properties_cache)
	Helper function to resolve reference to another machine. More...

	onStateChanged (Reference $ref, $old_state, $transition_name, $new_state)
	Called when state is changed, when transition invocation is completed. More...

Protected Attributes
	$backend
	Backend, where all machines are stored. More...

	$context
	Global context passed from backend. More...

	$machine_type
	Identification within $backend. More...

	$state_diagram_extras = []
	List of additional diagram parts in Dot language provided by backend (and its readers). More...

	$url_fmt
	URL format string where machine is located, usualy only the path part, e.g. More...

	$parent_url_fmt
	URL format string where parent of this machine is located, usualy only the path part, e.g. More...

	$post_action_url_fmt
	URL format string for redirect-after-post. More...

	$states
	Descriptions of all known states – key is state id, value is * description. More...

	$state_groups
	State groups. More...

	$actions
	Description of all known actions – key is action name. More...

	$default_access_policy = null
	Default access policy. More...

	$read_access_policy = null
	Read access policy. More...

	$listing_access_policy = null
	Listing access policy. More...

	$access_policies
	Access policies. More...

	$properties
	Description of machine properties – key is property name. More...

	$views
	Description of machine views – key is view name. More...

	$references
	Description of machine references. More...

Reflection API
	describeId ()
	Reflection: Describe ID (primary key). More...

	getUrlFormat ()
	Get URL format. More...

	getParentUrlFormat ()
	Get prent URL format. More...

	getPostActionUrlFormat ()
	Get URL for redirect-after-post. More...

	getMachineImplementationMTime ()
	Get mtime of machine implementation. More...

	getAllMachineStates ($having_section=null)
	Reflection: Get all states. More...

	describeMachineState ($state, $field=null)
	Reflection: Describe given machine state. More...

	describeAllMachineStates ($having_section=null)
	Reflection: Describe all states. More...

	getAllMachineActions ($having_section=null)
	Reflection: Get all actions (transitions) More...

	describeMachineAction ($action, $field=null)
	Reflection: Describe given machine action (transition) More...

	describeAllMachineActions ($having_section=null)
	Reflection: Describe all actions (transitions) More...

	getAllMachineProperties ($having_section=null)
	Reflection: Get all properties. More...

	describeMachineProperty ($property, $field=null)
	Reflection: Describe given property. More...

	describeAllMachineProperties ($having_section=null)
	Reflection: Describe all properties. More...

	getAllMachineViews ($having_section=null)
	Reflection: Get all views. More...

	describeMachineView ($view, $field=null)
	Reflection: Describe given view. More...

	describeAllMachineViews ($having_section=null)
	Reflection: Describe all views. More...

	getAllMachineReferences ($having_section=null)
	Reflection: Get all references. More...

	describeMachineReference ($reference, $field=null)
	Reflection: Describe given reference. More...

	describeAllMachineReferences ($having_section=null)
	Reflection: Describe all references. More...

	exportDot ($debug_opts=false)
	Export state machine to Graphviz source code. More...

	exportDotRenderExtras ($debug_opts)
	Render extra diagram features. More...

static	exportDotIdentifier ($str, $prefix= 's_')
	Convert state machine state name or group name to a safe dot identifier. More...

Constructor & Destructor Documentation

__construct	(	AbstractBackend	$backend,
			$type,
			$config,
			$context
	)

Constructor.

Machine gets reference to owning backend, name of its type (under which is this machine registered in backend) and optional array of additional configuration (passed directly to initializeMachine method).

Member Function Documentation

initializeMachine ( $config )

protected

Define state machine used by all instances of this type.

Warning: Derived classes always must call parent's implementation.

setupDefaultMachine ( $config )

protected

Setup default machine when initializeMachine is finished.

This method should check what is already defined to not overwrite provided definitions.

Note: This method is not called is $config['no_default_machine'] is set.

Warning: Derived classes may not call parent's implementation.

initializeMachineConfig	(	$config,
		$keys
	)

protected

Merge $config into state machine member variables.

Already set member variables are not overwriten. If the member variable is an array, the $config array is merged with the config, overwriting only matching keys (using array_replace_recursive).

Parameters

$config	Configuration passed to state machine
$keys	List of feys from $config to load into member variables of the same name.

checkAccessPolicy	(		$access_policy,
		Reference	$ref
	)

abstractprotected

Returns true if user has required access_policy to invoke a transition, which requires given access_policy.

getState ( $id )

abstract

Get current state of state machine.

Note: getState() does not check read access policy.

getProperties	(		$id,
		&	$state_cache = `null`
	)

abstract

Get properties of state machine, including it's state.

If state machine uses property views, not all properties may be returned by this method. Some of them may be computed or too big.

Some implementations may store current state to $state_cache, so it does not have to be retireved in the second query.

Note: getProperties() does not check read access policy.

getView	(		$id,
			$view,
		&	$properties_cache = `null`,
		&	$view_cache = `null`,
		&	$persistent_view_cache = `null`
	)

Get properties in given view.

Just like SQL view, the property view is transformed set of properties. These views are useful when some properties require heavy calculations.

Keep in mind, that view name must not interfere with Reference properties, otherwise the view is inaccessible directly.

Array $properties_cache is supplied by Reference class to make some calculations faster and without duplicate database queries. Make sure these cached properties are up to date or null.

Array $view_cache is writable cache inside the Reference class, flushed together with $properties_cache. If cache is empty, but available, an empty array is supplied.

Array $persistent_view_cache is kept untouched for entire Reference lifetime. If cache is empty, but available, an empty array is supplied.

Todo:: Override or call handlers?

getContext ( $resource_name = null )

protected

Get context object (whatever it is).

Parameters

$resource_name Resource of the context to return.

Returns: Return whole context if $resource is null, otherwise returns requested resource from the context.

See also: AbstractBackend::getContext()

urlFormat	(	$id,
		$url_fmt,
		$properties_cache
	)

protected

Create URL using properties and given format.

resolveMachineReference	(	$reference_name,
		$properties_cache
	)

protected

Helper function to resolve reference to another machine.

Parameters

$reference_name	Name of the reference in AbstractMachine::references.
$properties_cache	Properties of referencing machine.

Returns: Reference to referred machine.

isTransitionAllowed	(	Reference	$ref,
			$transition_name,
			$state = `null`
	)

Returns true if transition can be invoked right now.

Todo:: Transition should not have full definition of the policy, only its name. Definitions should be in common place.

getAvailableTransitions	(	Reference	$ref,
			$state = `null`
	)

Get list of all available actions for state machine instance identified by $id.

invokeTransition	(	Reference	$ref,
			$transition_name,
			$args,
		&	$returns,
		callable	$new_id_callback = `null`
	)

Invoke state machine transition.

State machine is not instance of this class, but it is represented by record in database.

onStateChanged	(	Reference	$ref,
			$old_state,
			$transition_name,
			$new_state
	)

protected

Called when state is changed, when transition invocation is completed.

getMachineType ( )

Get type of this machine.

getBackend ( )

Get backend which owns this machine.

ref ( $id )

Helper to create Reference to this machine.

See also: AbstractBackend::ref

nullRef ( )

Helper to create null Reference to this machine.

See also: AbstractBackend::nullRef

hotRef ( $properties )

Create pre-heated reference using properties loaded from elsewhere.

Warning: This may break things a lot. Be careful.

performSelfCheck ( )

Perform self-check.

Todo:: Extend this method with more checks.

See also: AbstractBackend::performSelfCheck()

describeId ( )

abstract

Reflection: Describe ID (primary key).

Returns array of all parts of the primary key and its types (as strings). If primary key is not compound, something like array('id' => 'string') is returned.

Order of the parts may be mandatory.

getUrlFormat ( )

Get URL format.

Format string for Utils::filename_format().

getParentUrlFormat ( )

Get prent URL format.

Parent URL is URL of collection or something of which is this machine part of.

Format string for Utils::filename_format().

getPostActionUrlFormat ( )

Get URL for redirect-after-post.

Format string for Utils::filename_format().

getMachineImplementationMTime ( )

Get mtime of machine implementation.

Useful to detect outdated cache entry in generated documentation.

No need to override this method, it handles inherited classes correctly. However if machine is loaded from database, a new implementation is needed.

This does not include filemtime(FILE) intentionaly.

getAllMachineStates ( $having_section = null )

Reflection: Get all states.

List of can be filtered by section, just like getAllMachineActions method does.

describeMachineState	(	$state,
		$field = `null`
	)

Reflection: Describe given machine state.

Returns state description in array or null. If field is specified, only given field is returned.

describeAllMachineStates ( $having_section = null )

Reflection: Describe all states.

getAllMachineActions ( $having_section = null )

Reflection: Get all actions (transitions)

List of actions can be filtered by section defined in action configuration. For example $this->getAllMachineStates('block') will return only actions which have 'block' configuration defined. Requested section must contain non-empty() value.

describeMachineAction	(	$action,
		$field = `null`
	)

Reflection: Describe given machine action (transition)

Returns action description in array or null. If field is specified, only given field is returned.

describeAllMachineActions ( $having_section = null )

Reflection: Describe all actions (transitions)

getAllMachineProperties ( $having_section = null )

Reflection: Get all properties.

List of can be filtered by section, just like getAllMachineActions method does.

describeMachineProperty	(	$property,
		$field = `null`
	)

Reflection: Describe given property.

Returns property description in array or null. If field is specified, only given field is returned.

describeAllMachineProperties ( $having_section = null )

Reflection: Describe all properties.

Returns array of all properties and their descriptions. See describeMachineProperty and getAllMachineProperties.

getAllMachineViews ( $having_section = null )

Reflection: Get all views.

List of can be filtered by section, just like getAllMachineActions method does.

describeMachineView	(	$view,
		$field = `null`
	)

Reflection: Describe given view.

Returns view description in array or null. If field is specified, only given field is returned.

describeAllMachineViews ( $having_section = null )

Reflection: Describe all views.

getAllMachineReferences ( $having_section = null )

Reflection: Get all references.

List of can be filtered by section, just like getAllMachineActions method does.

describeMachineReference	(	$reference,
		$field = `null`
	)

Reflection: Describe given reference.

Returns reference description in array or null. If field is specified, only given field is returned.

describeAllMachineReferences ( $having_section = null )

Reflection: Describe all references.

exportDot ( $debug_opts = false )

Export state machine to Graphviz source code.

Parameters

$debug_opts Machine-specific debugging options - passed to exportDotRenderDebugData(). If empty/false, no debug data are added to the diagram.

static exportDotIdentifier	(	$str,
		$prefix = `'s_'`
	)

static

Convert state machine state name or group name to a safe dot identifier.

Todo:: Extract Graphviz library to keep graphs and parts of the graphs contained.

exportDotRenderExtras ( $debug_opts )

protected

Render extra diagram features.

Writes Graphviz dot syntax to stdout (echo), output is placed just before digraph's closing bracket.

Parameters

$debug_opts Machine-specific Options to configure visible debug data.

Member Data Documentation

const RETURNS_VALUE = null

Return value of invoked transition is just some value.

const RETURNS_NEW_ID = 'new_id'

Return value of invoked transition is new ID of the state machine.

$backend

protected

Backend, where all machines are stored.

See also: AbstractBackend

$context

protected

Global context passed from backend.

$machine_type

protected

Identification within $backend.

$state_diagram_extras = []

protected

List of additional diagram parts in Dot language provided by backend (and its readers).

See also: BpmnReader, GraphMLReader

$url_fmt

protected

URL format string where machine is located, usualy only the path part, e.g.

"/machine-type/{id}".

To make reverse routes work, only entire path fragment can be replaced by symbol:

Good: /machine-type/foo/{id}/bar
Bad: /machine-type/foo-{id}/bar

This is limitation of default router, not this class.

If URL does not start with slash, router will ignore it.

$parent_url_fmt

protected

URL format string where parent of this machine is located, usualy only the path part, e.g.

"/parent-type/{id}/machine-type".

See also: $url_fmt

$post_action_url_fmt

protected

URL format string for redirect-after-post.

When machine is part of another entity, it may be reasonable to redirect to such entity instead of showing this machine alone. If not set, url_fmt is used.

See also: $url_fmt

$states

protected

Descriptions of all known states – key is state id, value is * description.

Fill these data in self::initializeMachine().

$state_groups

protected

State groups.

This state machine is flat – no sub-states. To make diagrams easier to read, this allows to group relevant states together. This has no influence on the behaviour.

Fill these data in self::initializeMachine().

$actions

protected

Description of all known actions – key is action name.

Each action has transitions (transition function) and each transition can end in various different states (assertion function).

Fill these data in self::initializeMachine().

$default_access_policy = null

protected

Default access policy.

When transition nor action has policy specified, this one is used.

Note: This does not affect read_access_policy.

$read_access_policy = null

protected

Read access policy.

Policy applied when reading machine state.

Note: Not affected by default_access_policy.

$listing_access_policy = null

protected

Listing access policy.

Policy applied when creating machine listing (read_access_policy is also applied).

Note: Not affected by default_access_policy.

$access_policies

protected

Access policies.

Description of all access policies available to this state machine type.

$properties

protected

Description of machine properties – key is property name.

Each property has some metadata available, so it is possible to generate simple forms or present data to user without writing per-machine specific templates. These metadata should be as little implementation specific as possible.

$views

protected

Description of machine views – key is view name.

Some properties may require heavy computations and may not be used as often as other properties, so it is reasonable to put them into separate view instead.

These views are just like SQL views. They are somehow transformed view on the machine and its properties. There is no explicit definition of structure of the view – it can be single value, subset of properties, or something completely different.

View names must not collide with reference names, since references are special cases of views.

$references

protected

Description of machine references.

Often it is useful to reference one state machine from another, just like foreign keys in SQL.

Smalldb is limited to reference using primary keys only.

References are added to views.

Description

Configuration Schema

Inheritance diagram for AbstractMachine

Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Reflection API

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation