Acceleo Query Language

Query and navigate in EMF models

Overview

The Acceleo Query Language (AQL) is a language used to navigate and query an EMF model. In this document, you will find the description of all the services of the standard library of AQL.

Introduction

The Acceleo Query Language (AQL) is a language used to navigate and query an EMF model. In this document, you will find the description of the syntax, all the services and the standard library of AQL.
AQL as a query engine is small, simple, fast, extensible and it brings a richer validation than the MTL interpreter.

For those looking for a simple and fast interpreters for your EMF models, AQL can provide you with a lot of features, including:

The AQL interpreter is used in Sirius with the prefix «aql:».

Syntax

Basics

The syntax is very similar to the OCL syntax. An expression always starts with a variable
aVariable

The variable named self represent the current object (think of it as the this in Java).

Let’s consider the following metamodel :

From a variable one can access field or reference values using the . separator.
With self being an instance of Person, self.name returns the value of the attribute name and self.father return the father of the person.

If the attribute or the reference is multi-valued, then self.parents will return a collection.

Calls can be chained, as such self.parents.name will return a collection containing the names of the parents.

If one want to access the collection itself, then the separator -> must be used, as such self.parents.name->size() will return the number of elements in the collection whereas self.parents.name.size() will return a collection containing
the sizes of each name.

AQL can also call methods modeled as EOperations or defined through Java services. The syntax denoting such a call is . for instance self.someCall() will call the someCall method and return the result.

Working with collections

Filtering a collection is generaly done using either ->filter(..) to keep elements of a given type or ->select(..) to keep elements which are validating a given condition.

With self being an instance of Family, self.members->filter(family::Man) will return all the members of the family which are mens and self.members->select( p | p.name.startsWith('A')) will return all the members of the family which have a name starting by the letter ‹A›.

To access an element at a particular index you can use the operation ->at(..) ; self.members->at(1) will return the first person which is a member of the family (in that specific case it is probably better to use self.members->first()

AQL has two kinds of collections, a Sequence which is a list, or an OrderedSet which does not allow doubles. You can convert a Sequence to an OrderedSet by as such : self.members->asSet()

You can also define a collection by extension using the following syntax:

AQL provides operations out of the box to browse the model. Most notably :

Conditions

AQL provides an If but it has to be an expression and not a statement. As such one has to define the else. Here is the syntax

if self.name.startsWith('a') then self else self.eContainer() endif

Walkthrough using an UML example

Let’s move to a slightly more complex example to learn how to navigate through a model. We will work with a model instance from the following metamodel: a simplified view of the UML2 metamodel with Package, UseCase, Model or Component instances.

The following illustration demonstrate the result of the just typing self as a query. At the bottom every instance of the UML model is represented by a node with containment relationships from top to bottom and displaying the non-contained references in between those nodes through horizontal edges. The result of the query is highlighted in blue.

The variable self here is the Class named «Invoice» in the model, as such the query self hightlight this instance.

eContainer()

When using the query self.eContainer() the cursor move from the self variable to its most direct parent, here the Component instance named «Accounting».

Such calls can be chained and as such self.eContainer().eContainer() return the Component parents: the Package named «Components».

The eContainer() call can also be used with a type parameter, in that case it will be transitively executed up to the point where an instance of the given type is found.

In this case then self.eContainer(uml::Model) goes up to the root of the graph. If no instance of the given type is found in the parents then the query returns an empty result.

eContainer() or any other service using types as parameters will match both the given types or its subtypes. The only exception to this rule is the oclIsTypeOf(..) service which is intended to check only for the given type and not its subtypes.

When using the query self.eContainer(uml::Class) the result is an instance of Component as the Component type extends Class in the metamodel.

A variant of eContainer(..) named eContainerOrSelf(..) is provided it will first check the type of the current instance. As such the query self.eContainerOrSelf(uml::Class) when self is the «Invoice» class returns this instance.

eContents()

One use eContainer() to go up in the parent. The eContents() axes is its counterpart and returns the direct children of the element.

select()

The select(...) service can be used to filter elements from a list by veryfing a predicate. In the query self.eContents()->select(p | p.name = 'id') the query only returns the elements which have a name equal to "id", in this case a single element.

Equality is checked with a single = , inequality is expressed with the operator <> .

Comparing values with an enumeration is slightly different as the enumeration value should be explicitely qualified. In the self.eContents()->select(p | p.visibility = uml::VisibilityKind::private ) query the expression uml::VisibilityKind::private denotes the enumeration literal named private which is contained in the VisibilityKind enumeration of the uml metamodel.

eAllContents()

The eAllContents() axe is used to browse direct and indirect children. It goes from the starting point to the leafs of the model. Here the expression starts with self.eContainer(uml::Model) which has we’ve seen before goes up until an instance of Model is found. From here eAllContents is executed returning all the direct and indirect childrens of the «Travel Agency» model instance.

Just like any other collection it can be filtered to retrieve, for instace, the elements whose name is starting by the letter «I».

A type parameter can be used to retrieve the direct or indirect children of a specific type: here components.

Or use case instances.

It is interesting to note that the parameter can also be a collection of types, enabling the retrieval of many elements through a single pass.

eInverse()

Queries using eAllContents must be designed with care as they tend to lead to an intense browsing of the model. In many cases they can be replaced with eInverse() calls to retrieve elements of interests.

eInverse() returns any element which as a relationship with the current one. This relationship can be indifferently a containment one or not.

It is often of interest to restrict the type of elements we expect out of the eInverse() call. With the query self.eContainer().eInverse(uml::UseCase) only use cases instances will be returned, here the UseCase named «to Invoice» which refers to the «Accounting» Component through the reference named subject

One can also be even more explicit and query for a specific reference name, here packagedElement : only the Package named «Components» refers to the «Accounting» Component through the reference named «packagedElement».

Language Reference

These sections are listing all the services of the standard library of AQL.

Services available for all types

String + Object : String

Returns the concatenation of the current string and the given object "any" (as a String).

Expression Result
'times ' + 42 'times 42'

Object + String : String

Returns the concatenation of self (as a String) and the given string "s".

Expression Result
42 + ' times' '42 times'

Object <> Object : Boolean

Indicates whether the object "o1" is a different object from the object "o2".

Expression Result
'Hello' <> 'World' true
'Hello' <> 'Hello' false

Object = Object : Boolean

Indicates whether the object "o1" i"the same as the object "o2". For more information refer to the Object#equals(Object) method.

Expression Result
'Hello' = 'World' false
'Hello' = 'Hello' true

Object.oclAsType(Object) : Object

Casts the current object to the given type.

Expression Result
anEPackage.oclAsType(ecore::EPackage) anEPackage
anEPackage.oclAsType(ecore::EClass) anEPackage

Contrary to Acceleo 3, the type is ignored, the given object will be returned directly.

In other languages

Language Expression Result
Acceleo 3 (MTL) anEPackage.oclAsType(ecore::EPackage) anEPackage
Acceleo 3 (MTL) anEPackage.oclAsType(ecore::EClass) oclInvalid

Object.oclIsKindOf(Object) : Boolean

Evaluates to "true" if the type of the object o1 conforms to the type "classifier". That is, o1 is of type "classifier" or a subtype of "classifier".

Expression Result
anEPackage.oclIsKindOf(ecore::EPackage) true
anEPackage.oclIsKindOf(ecore::ENamedElement) true

Object.oclIsTypeOf(Object) : Boolean

Evaluates to "true" if the object o1 if of the type "classifier" but not a subtype of the "classifier".

Expression Result
anEPackage.oclIsKindOf(ecore::EPackage) true
anEPackage.oclIsKindOf(ecore::ENamedElement) false

Object.toString() : String

Returns a string representation of the current object.

Expression Result
42.toString() '42'

Object.trace() : String

Returns a string representation of the current environment.

Expression Result
42.trace() 'Metamodels: http://www.eclipse.org/emf/2002/Ecore Services: org.eclipse.acceleo.query.services.AnyServices public java.lang.String org.eclipse.acceleo.query.services.AnyServices.add(java.lang.Object,java.lang.String) ... receiver: 42 '

Services available for Booleans

Boolean.and(Boolean) : Boolean

Logical and.

Expression Result
true and false false
false and true false
true and true true
false and false false

Boolean.implies(Boolean) : Boolean

Logical implies.

Expression Result
true implies true true
true implies false false
false implies true true
false implies false true

Boolean.not() : Boolean

Logical negation.

Expression Result
not true false
not false true

Boolean.or(Boolean) : Boolean

Logical or.

Expression Result
true or false true
false or true true
true or true true
false or false false

Boolean.xor(Boolean) : Boolean

Logical xor.

Expression Result
true xor true false
true xor false true
false xor true true
false xor false false

Services available for Collections

OrderedSet + Collection : OrderedSet

Returns the concatenation of the given collection into the current set.

Expression Result
OrderedSet{'a', 'b', 'c'} + OrderedSet{'c', 'b', 'f'} OrderedSet{'a', 'b', 'c', 'c', 'b', 'f'}

The service addAll has been replaced by "add" in order to have access to the operator "+" between to sets

In other languages

Language Expression Result
Acceleo 3 (MTL) OrderedSet{'a', 'b', 'c'}.addAll(OrderedSet{'c', 'b', 'f'}) OrderedSet{'a', 'b', 'c', 'c', 'b', 'f'}

Sequence + Collection : Sequence

Returns the concatenation of the given collection into the given sequence.

Expression Result
Sequence{'a', 'b', 'c'}.add(Sequence{'d', 'e'}) Sequence{'a', 'b', 'c', 'd', 'e'}
Sequence{'a', 'b', 'c'} + OrderedSet{'c', 'e'} Sequence{'a', 'b', 'c', 'c', 'e'}

The service addAll has been replaced by "add" in order to have access to the operator "+" between to sequences

In other languages

Language Expression Result
Acceleo 3 (MTL) Sequence{'a', 'b', 'c'} + Sequence{'d', 'e'} Sequence{'a', 'b', 'c', 'd', 'e'}
Acceleo 3 (MTL) Sequence{'a', 'b', 'c'}.addAll(OrderedSet{'c', 'e'}) Sequence{'a', 'b', 'c', 'c', 'e'}

Collection->any( x | ... ) : Object

Gets the first element in the current collection for which the value returned by the lambda evaluates to "true".

Expression Result
Sequence{'a', 'b', 'c'}->any(str | str.size() = 1) 'a'

Collection->asOrderedSet() : OrderedSet

Returns a set representation of the specified collection. Returns the same object if it is a set already. This operation has the same behavior as "asSet()"

Expression Result
OrderedSet{'a', 'b', 'c'}->asOrderedSet() OrderedSet{'a', 'b', 'c'}
Sequence{'a', 'b', 'c'}->asOrderedSet() OrderedSet{'a', 'b', 'c'}

Collection->asSequence() : Sequence

Returns a sequence representation of the specified collection. Returns the same object if it is already a sequence.

Expression Result
OrderedSet{'a', 'b', 'c'}->asSequence() Sequence{'a', 'b', 'c'}
Sequence{'a', 'b', 'c'}->asSequence() Sequence{'a', 'b', 'c'}

Collection->asSet() : OrderedSet

Returns a set representation of the specified collection. Returns the same object if it is already a set.

Expression Result
OrderedSet{'a', 'b', 'c'}->asSet() OrderedSet{'a', 'b', 'c'}
Sequence{'a', 'b', 'c', 'c', 'a'}->asSet() OrderedSet{'a', 'b', 'c'}

Sequence->at(Integer) : Object

Returns the element at the specified position in the sequence.

Expression Result
Sequence{'a', 'b', 'c'}->at(1) 'a'
Sequence{'a', 'b', 'c'}->at(2) 'b'

Sequence->collect( x | ... ) : Sequence{Object}

Returns a sequence containing the result of applying "lambda" on all elements contained in the current sequence, maintaining order.

Expression Result
Sequence{'a', 'b', 'c'}->collect(str | str.toUpper()) Sequence{'A', 'B', 'C'}

OrderedSet->collect( x | ... ) : OrderedSet{Object}

Returns a set containing the result of applying "lambda" on all elements contained in the current set, maintaining order.

Expression Result
OrderedSet{'a', 'b', 'c'}->collect(str | str.toUpper()) OrderedSet{'A', 'B', 'C'}

OrderedSet->concat(Collection) : OrderedSet

Returns the concatenation of the current set with the given collection.

Expression Result
OrderedSet{'a', 'b', 'c'}.concat(Sequence{'d', 'e'}) OrderedSet{'a', 'b', 'c', 'd', 'e'}

In other languages

Language Expression Result
Acceleo 3 (MTL) OrderedSet{'a', 'b', 'c'}.addAll(Sequence{'d', 'e'}) OrderedSet{'a', 'b', 'c', 'd', 'e'}

Sequence->concat(Collection) : Sequence

Returns the concatenation of the current sequence with the given collection.

Expression Result
Sequence{'a', 'b', 'c'}.concat(Sequence{'d', 'e'}) Sequence{'a', 'b', 'c', 'd', 'e'}

In other languages

Language Expression Result
Acceleo 3 (MTL) Sequence{'a', 'b', 'c'}.addAll(Sequence{'d', 'e'}) Sequence{'a', 'b', 'c', 'd', 'e'}

OrderedSet->count(Object) : Integer

Returns "1" if the current set contains the given object, "0" otherwise.

Expression Result
OrderedSet{'a', 'b', 'c'}->count('d') 0
OrderedSet{'a', 'b', 'c'}->count('a') 1

Sequence{Object}->count(Object) : Integer

Counts the number of occurrences of the given object in the given sequence

Expression Result
Sequence{'a', 'b', 'c'}->count('d') 0
Sequence{'a', 'b', 'c'}->count('a') 1

Collection->excludes(Object) : Boolean

Indicates if the given collection doesn't contain the given object.

Expression Result
Sequence{'a', 'b', 'c'}->excludes('a') false
Sequence{'a', 'b', 'c'}->excludes('d') true

Collection->excludesAll(Collection) : Boolean

Indicates if no elements from the second collection are contained in the first collection

Expression Result
Sequence{'a', 'b'}->excludesAll(OrderedSet{'f'}) true
Sequence{'a', 'b'}->excludesAll(OrderedSet{'a', 'f'}) false

OrderedSet->excluding(Object) : OrderedSet

Removes the given object from the current set.

Expression Result
OrderedSet{'a', 'b', 'c'}->excluding('c') OrderedSet{'a', 'b'}

Sequence->excluding(Object) : Sequence

Removes the given object from the current sequence.

Expression Result
Sequence{'a', 'b', 'c'}->excluding('c') Sequence{'a', 'b'}

Collection->exists( x | ... ) : Boolean

Indicates if it exists an object from the given collection for which the given lambda evaluates to "true"

Expression Result
Sequence{'a', 'b', 'c'}->exists(str | str.size() > 5) false

OrderedSet->filter(EClassifier) : OrderedSet

Keeps only instances of the given EClassifier from the given set.

Expression Result
OrderedSet{anEClass, anEAttribute, anEReference}->filter(ecore::EClass) OrederedSet{anEClass}
OrderedSet{anEClass, anEAttribute}->filter(ecore::EStructuralFeature) OrederedSet{anEAttribute}

Sequence->filter(OrderedSet{EClassifier}) : Sequence

Keeps only instances of the given EClassifier in the given sequence.

Expression Result
Sequence{anEClass, anEAttribute, anEReference}->filter({ecore::EClass | ecore::EReference}) Sequence{anEClass, anEReference}
Sequence{anEClass, anEAttribute, anEPackage}->filter({ecore::EStructuralFeature | ecore::EPacakge}) Sequence{anEAttribute, anEPackage}

OrderedSet->filter(OrderedSet{EClassifier}) : OrderedSet

Keeps only instances of the given set of EClassifier from the given set.

Expression Result
OrderedSet{anEClass, anEAttribute, anEReference}->filter({ecore::EClass | ecore::EReference}) OrderedSet{anEClass, anEReference}
OrderedSet{anEClass, anEAttribute, anEPackage}->filter({ecore::EStructuralFeature | ecore::EPacakge}) OrderedSet{anEAttribute, anEPackage}

Sequence->filter(EClassifier) : Sequence

Keeps only instances of the given EClassifier in the given sequence.

Expression Result
Sequence{anEClass, anEAttribute, anEReference}->filter(ecore::EClass) Sequence{anEClass}
Sequence{anEClass, anEAttribute}->filter(ecore::EStructuralFeature) Sequence{anEAttribute}

Collection->first() : Object

Returns the first element of the specified Collection.

Expression Result
Sequence{'a', 'b', 'c'}->first() 'a'

Collection->forAll( x | ... ) : Boolean

Indicates if all the objects from the given collection validate the given lamba

Expression Result
Sequence{'a', 'b', 'ccc'}->forAll(str | str.size() = 1) false
Sequence{'a', 'b', 'c'}->forAll(str | str.size() = 1) false

Collection->includes(Object) : Boolean

Indicates if the given collection contains the given object.

Expression Result
Sequence{'a', 'b', 'c'}->includes('a') true
Sequence{'a', 'b', 'c'}->includes('d') false

Collection->includesAll(Collection) : Boolean

Indicates if all elements from the second collection are contained in the first collection

Expression Result
Sequence{'a', 'b', 'c'}->includesAll(OrderedSet{'a'}) true
Sequence{'a', 'b', 'c'}->includesAll(OrderedSet{'a', 'f'}) false

OrderedSet->including(Object) : OrderedSet

Adds the given object to the current set.

Expression Result
OrderedSet{'a', 'b', 'c'}->including('d') OrderedSet{'a', 'b', 'c', 'd'}

Sequence->including(Object) : Sequence

Adds the given object to the current sequence.

Expression Result
Sequence{'a', 'b', 'c'}->including('d') Sequence{'a', 'b', 'c', 'd'}

OrderedSet->indexOf(Object) : Integer

Returns the index of the given object in the given set ([1..size]).

Expression Result
OrderedSet{1, 2, 3, 4}->indexOf(3) 3

Sequence->indexOf(Object) : Integer

Returns the index of the given object in the given sequence ([1..size]).

Expression Result
Sequence{1, 2, 3, 4}->indexOf(3) 3

OrderedSet->insertAt(Integer, Object) : OrderedSet

Inserts the given object in a copy of the given set at the given position ([1..size]). If the given set already contains this object, it will be moved to the accurate position.

Expression Result
OrderedSet{'a', 'b', 'c'}->insertAt(2, 'f') Sequence{'a', 'f', 'b', 'c'}

Sequence->insertAt(Integer, Object) : Sequence

Inserts the given object in a copy of the given sequence at the given position ([1..size]).

Expression Result
Sequence{'a', 'b', 'c'}->insertAt(2, 'f') Sequence{'a', 'f', 'b', 'c'}

OrderedSet->intersection(Collection) : OrderedSet

Creates a set with the elements from the given set that are also present in the given collection.

Expression Result
OrderedSet{'a', 'b', 'c'}->intersection(OrderedSet{'a', 'f'}) OrderedSet{'a'}

Sequence->intersection(Collection) : Sequence

Creates a sequence with elements from the given sequence that are present in both the current sequence and the given other {@code Collection}. Iteration order will match that of the current sequence. Duplicates from the first list will all be kept in the result if they also are in the second one, but duplicates from the second list will be dumped even if they are present in the first.

Expression Result
Sequence{'a', 'b', 'c'}->intersection(OrderedSet{'a', 'f'}) Sequence{'a'}

Collection->isEmpty() : Boolean

Returns "true" when the input collection is empty.

Expression Result
OrderedSet{'a', 'b', 'c'}->isEmpty() false
Sequence{}->isEmpty() true

Collection->isUnique( x | ... ) : Boolean

Indicates if the evaluation of the given lambda gives a different value for all elements of the given collection.

Expression Result
Sequence{'a', 'b', 'c'}->isUnique(str | str.size()) false
Sequence{'a', 'bb', 'ccc'}->isUnique(str | str.size()) true

Sequence->last() : Object

Returns the last element of the given sequence.

Expression Result
Sequence{'a', 'b', 'c'}->last() 'c'

OrderedSet->last() : Object

Returns the last element of the given set.

Expression Result
OrderedSet{'a', 'b', 'c'}->last() 'c'

Collection->notEmpty() : Boolean

Returns "true" when the input collection is not empty.

Expression Result
OrderedSet{'a', 'b', 'c'}->notEmpty() true
Sequence{}->notEmpty() false

Collection->one( x | ... ) : Boolean

Indicates if one and only one element of the given collection validates the given lambda.

Expression Result
Sequence{'a', 'b', 'c'}->one(str | str.equals('a')) true
Sequence{'a', 'a', 'c'}->one(str | str.equals('a')) false

OrderedSet->prepend(Object) : OrderedSet

Inserts the given object in a copy of the given set at the first position. If the set already contained the given object, it is moved to the first position.

Expression Result
OrderedSet{'a', 'b', 'c'}->prepend('f') OrderedSet{'f', 'a', 'b', 'c'}

Sequence->prepend(Object) : Sequence

Inserts the given object in a copy of the given sequence at the first position.

Expression Result
Sequence{'a', 'b', 'c'}->prepend('f') Sequence{'f', 'a', 'b', 'c'}

OrderedSet->reject( x | ... ) : OrderedSet

Reject returns a filtered version of the specified set. Only elements for which the given "lambda" evaluates to false will be present in the returned set

Expression Result
OrderedSet{'a', 'b', 'c'}->reject(str | str.equals('a')) OrderedSet{'b', 'c'}

Sequence->reject( x | ... ) : Sequence

Reject returns a filtered version of the specified sequence. Only elements for which the given "lambda" evaluates to false will be present in the returned sequence

Expression Result
Sequence{'a', 'b', 'c'}->reject(str | str.equals('a')) Sequence{'b', 'c'}

OrderedSet->reverse() : OrderedSet

Returns the given set in reversed order.

Expression Result
OrderedSet{'a', 'b', 'c'}->reverse() OrderedSet{'c', 'b', 'a'}

Sequence->reverse() : Sequence

Returns the given sequence in reversed order.

Expression Result
Sequence{'a', 'b', 'c'}->reverse() Sequence{'c', 'b', 'a'}

Sequence->select( x | ... ) : Sequence

Select returns a filtered version of the specified sequence. Only elements for which the given "lambda" evaluates to true will be present in the returned sequence.

Expression Result
Sequence{'a', 'b', 'c'}->select(str | str.equals('a')) Sequence{'a'}

OrderedSet->select( x | ... ) : OrderedSet

Select returns a filtered version of the specified set. Only elements for which the given "lambda" evaluates to true will be present in the returned set.

Expression Result
OrderedSet{'a', 'b', 'c'}->select(str | str.equals('a')) OrderedSet{'a'}

Collection->sep(Object, Object, Object) : Sequence{Object}

Inserts the given separator between each elements of the given collection, the given prefix before the first element, and the given suffix after the last element.

Expression Result
Sequence{'a', 'b', 'c'}->sep('[', '-', ']') Sequence{'[', 'a', '-', 'b', '-', 'c', ']'}

Collection->sep(Object) : Sequence{Object}

Inserts the given separator between each elements of the given collection.

Expression Result
Sequence{'a', 'b', 'c'}->sep('-') Sequence{'a', '-', 'b', '-', 'c'}
OrderedSet{'a', 'b', 'c'}->sep('-') Sequence{'a', '-', 'b', '-', 'c'}

Collection->size() : Integer

Returns the size of the specified collection

Expression Result
Sequence{'a', 'b', 'c'}->size() 3
OrderedSet{'a', 'b', 'c', 'd'}->size() 4

Sequence->sortedBy( x | ... ) : Sequence

Returns a sequence containing the elements of the original sequence ordered by the result of the given lamba

Expression Result
Sequence{'aa', 'bbb', 'c'}->sortedBy(str | str.size()) Sequence{'c', 'aa', 'bbb'}

OrderedSet->sortedBy( x | ... ) : OrderedSet

Returns a set containing the elements of the original set ordered by the result of the given lamba

Expression Result
OrderedSet{'aa', 'bbb', 'c'}->sortedBy(str | str.size()) OrderedSet{'c', 'aa', 'bbb'}

Sequence - Collection : Sequence

Returns the difference of the current sequence and the given collection.

Expression Result
Sequence{'a', 'b', 'c'} - Sequence{'c', 'b', 'f'} Sequence{'a'}
Sequence{'a', 'b', 'c'} - OrderedSet{'c', 'b', 'f'} Sequence{'a'}

The service removeAll has been replaced by "sub" in order to have access to the operator "-" between to sequences

In other languages

Language Expression Result
Acceleo 3 (MTL) Sequence{'a', 'b', 'c'}.removeAll(Sequence{'c', 'b', 'f'}) Sequence{'a'}
Acceleo 3 (MTL) Sequence{'a', 'b', 'c'}.removeAll(OrderedSet{'c', 'b', 'f'}) Sequence{'a'}

OrderedSet - Collection : OrderedSet

Returns the difference of the current set and the given collection.

Expression Result
OrderedSet{'a', 'b', 'c'} - OrderedSet{'c', 'b', 'f'} OrderedSet{'a'}

The service removeAll has been replaced by "sub" in order to have access to the operator "-" between to sets

In other languages

Language Expression Result
Acceleo 3 (MTL) OrderedSet{'a', 'b', 'c'}.removeAll(OrderedSet{'c', 'b', 'f'}) OrderedSet{'a'}

OrderedSet->subOrderedSet(Integer, Integer) : OrderedSet

Returns a subset of the given set

Expression Result
OrderedSet{'a', 'b', 'c'}->subOrderedSet(1, 2) OrderedSet{'a', 'b'}

Sequence->subSequence(Integer, Integer) : Sequence

Returns a subset of the given sequence

Expression Result
Sequence{'a', 'b', 'c'}->subSequence(1, 2) Sequence{'a', 'b'}

Collection->sum() : Number

Sums elements of the given collection if possible.

Expression Result
Sequence{1, 2, 3, 4}->sum() 10

Sequence->union(Sequence) : Sequence

Returns a sequence containing all the elements of the first and second sequences

Expression Result
Sequence{'a', 'b', 'c'}->union(Sequence{'d', 'c'}) Sequence{'a', 'b', 'c', 'd'}

OrderedSet->union(OrderedSet) : OrderedSet

Returns a set containing all the elements of the first and second sets

Expression Result
OrderedSet{'a', 'b', 'c'}->union(OrderedSet{'d', 'c'}) OrderedSet{'a', 'b', 'c', 'd'}

Services available for Comparables

Comparable > Comparable : Boolean

Compares "a" to "b" and return "true" if "a" is greater than "b".

Expression Result
'Hello' > 'Abc' true
'Hello' > 'Hello' false

Comparable >= Comparable : Boolean

Compares "a" to "b" and return "true" if "a" is greater than or equal to "b".

Expression Result
'Hello' >= 'Abc' true
'Hello' >= 'Hello' true

Comparable < Comparable : Boolean

Compares "a" to "b" and return "true" if "a" is less than "b".

Expression Result
'Hello' < 'Hello' false
'Hello' < 'World' true

Comparable <= Comparable : Boolean

Compares "a" to "b" and return "true" if "a" is less than or equal to "b".

Expression Result
'Hello' <='Hello' true
'Hello' <='World' true

Services available for EObjects

EClass.allInstances() : Sequence{EObject}

Returns all instances of the EClass

OrderedSet{EClass}->allInstances() : Sequence{EObject}

Returns all instances of any EClass from the OrderedSet

EObject.eAllContents() : Sequence{EObject}

Returns a sequence of the EObjects recursively contained in the specified root eObject.

Expression Result
anEPackage.eAllContents() Sequence{firstEClass, firstEAttribute, secondEClass, firstDataType}

EObject.eAllContents(OrderedSet{EClass}) : Sequence{EObject}

Returns a sequence of the EObjects recursively contained in the specified root eObject and that are instances of the specified EClass

Expression Result
anEPackage.eAllContents({ecore::EPackage | ecore::EClass}) Sequence{ePackage, eClass, ...}

EObject.eAllContents(EClass) : Sequence{EObject}

Returns a sequence of the EObjects recursively contained in the specified root eObject and that are instances of the specified EClass

Expression Result
anEPackage.eAllContents(ecore::EClass) Sequence{firstEClass, secondEClass}

EObject.eClass() : EClass

Returns the EClass of the specified EObject

EObject.eContainer() : EObject

Returns the container of the specified EObject

Expression Result
firstEAttribute.eContainer() firstEClass

EObject.eContainer(EClass) : EObject

Returns the first container of the specified EObject that matches the given type

Expression Result
firstEAttribute.eContainer(ecore::EPackage) anEPackage

EObject.eContainerOrSelf(EClass) : EObject

Returns self or the first container of the specified EObject that matches the given type

Expression Result
firstEAttribute.eContainerOrSelf(ecore::EAttribute) firstEAttribute

EObject.eContainingFeature() : EStructuralFeature

Returns the containing feature of the specified EObject

EObject.eContainmentFeature() : EReference

Returns the containment feature of the specified EObject

EObject.eContents() : Sequence{EObject}

Returns the contents of the specified EObject instance.

Expression Result
anEPackage.eContents() Sequence{firstEClass, secondEClass, firstDataType}

EObject.eContents(EClass) : Sequence{EObject}

Returns a sequence made of the instances of the specified type in the contents of the specified eObject.

Expression Result
anEPackage.eContents(ecore::EDataType) Sequence{firstDataType}

EObject.eContents(OrderedSet{EClass}) : Sequence{EObject}

Returns a sequence made of the instances of the specified types in the contents of the specified eObject.

Expression Result
anEPackage.eContents({ecore::EPackage | ecore::EClass}) Sequence{SubEPackage, eClass, ... }

EObject.eCrossReferences() : Object

Returns the list of all EObjects cross-referenced from the receiver.

EObject.eGet(String) : Object

Handles calls to the operation "eGet". This will fetch the value of the feature named "featureName" on "source"

EObject.eInverse() : OrderedSet{EObject}

Returns the set containing the inverse references.

EObject.eInverse(EClassifier) : OrderedSet{EObject}

Returns the elements of the given type from the set of the inverse references of the receiver.

EObject.eInverse(String) : OrderedSet{EObject}

Returns the elements from the set of the inverse references of the receiver that are referencing the receiver using a feature with the given name.

Services available for Resources and URIs

EObject.eResource() : Resource

Returns the Resource containing the given EObject. This service is equivalent to a direct call to EObject#eResource().

URI.fileExtension() : String

Returns the extension of the file referred to by the given URI. This service is equivalent to a direct call to URI#fileExtension()

Resource.getContents() : Sequence{EObject}

Returns the direct content of the given Resource. This service is equivalent to a direct call to Resource#getContents()

Resource.getContents(EClass) : Sequence{EObject}

Returns the EObjects of the given type from the direct content of the given Resource.

Resource.getURI() : URI

Returns the URI of the given Resource. This service is equivalent to a direct call to Resource#getURI()

URI.isPlatformPlugin() : Boolean

Returns "true" if the given URI is a platform plugin URI. This service is equivalent to a direct call to URI#isPlatformPlugin()

URI.isPlatformResource() : Boolean

Returns "true" if the given URI is a platform resource URI. This service is equivalent to a direct call to URI#isPlatformResource()

URI.lastSegment() : String

Returns the last segment of the given URI. This service is equivalent to a direct call to URI#lastSegment()

Services available for Strings

String + String : String

Returns a string that is the result of the concatenation of the current string and the string "b".

Expression Result
'Hello' + 'World' HelloWorld

This operation behaves like '+' between two strings.

String.concat(String) : String

Returns a string that is the result of the concatenation of the current string and the string "b".

Expression Result
'Hello'.concat('World') HelloWorld

This operation behaves like '+' between two strings.

String.contains(String) : Boolean

Returns "true" if the current String contains the String "b"

Expression Result
'Hello'.contains('llo') true

String.endsWith(String) : Boolean

Returns true if the current String ends with the string "b".

Expression Result
'Hello'.endsWidth('llo') true

String.equalsIgnoreCase(String) : Boolean

Returns true if the current String is equals to the String "b" without considering case in the comparison.

Expression Result
'Hello'.equalsIgnoreCase('hello') true

String.first(Integer) : String

Returns the "n" first characters of the current String, or the current String itself if its size is less than "n".

Expression Result
'HelloWorld'.first(5) 'Hello'

String.index(String) : Integer

Returns the index of the first occurrence "subString" in the current String, or -1 if "subString" is not in the current String. The index referential is 1 as in OCL and not 0.

Expression Result
'HelloHello'.index('Hello') 1

String.index(String, Integer) : Integer

Returns the index of the first occurrence "subString" in the current String from the given index, or -1 if "subString" is not in the current String. The index referential is 1 as in OCL and not 0.

Expression Result
'HelloHello'.index('Hello', 2) 6

String.isAlpha() : Boolean

Returns "true" if self consists only of alphabetical characters, "false" otherwise.

Expression Result
'abc123'.isAlpha() false
'abcdef'.isAlpha() true

String.isAlphaNum() : Boolean

Returns "true" if self consists only of alphanumeric characters, "false" otherwise.

Expression Result
'abc123'.isAlphaNum() true
'abcdef'.isAlphaNum() true

String.last(Integer) : String

Returns the "n" last characters of the current String, or the current String if its size is less than "n".

Expression Result
'HelloWorld'.last(5) 'World'

String.lastIndex(String, Integer) : Integer

Returns the index of the last occurrence "subString" in the current String searching backward from the given index, or -1 if "subString" is not in the current String. The index referential is 1 as in OCL and not 0.

Expression Result
'HelloHello'.lastIndex('Hello', 7) 1

String.lastIndex(String) : Integer

Returns the index of the last occurrence of "subString" in the current String, "-1" if the current String doesn't contain this particular substring. The index referential is 1 as in OCL and not 0.

Expression Result
'HelloHello'.lastIndex('World') 6

String.matches(String) : Boolean

Returns "true" if the current String matches the given "regex".

Expression Result
'Hello'.matches('*llo') true

String.prefix(String) : String

Returns the current String prefixed with the given "prefix".

Expression Result
'World'.prefix('Hello') 'HelloWorld'

String.replace(String, String) : String

Replaces the first substring of the current String that matches the regular expression "regex" with the String "replacement".

Expression Result
'Hello'.replace('(.*)ll', 'Wh') 'Who'

String.replaceAll(String, String) : String

Replaces each substring of the current String that matches the given regular expression "regex" with the String "replacement".

Expression Result
'TestTest'.replace('.st', 'erminated') 'TerminatedTerminated'

String.size() : Integer

Return the length of the current String.

Expression Result
'HelloWorld'.size() 10

String.startsWith(String) : Boolean

Returns true if the current String starts with the string "b".

Expression Result
'Hello'.startsWith('Hell') true

String.strcmp(String) : Integer

Returns an integer that is either negative, zero or positive depending on whether s1 is alphabetically less than, equal to or greater than self. Note that upper case letters come before lower case ones, so that 'AA' is closer to 'AC' than it is to 'Ab'.

Expression Result
'strcmp operation'.strcmp('strcmp') 10
'strcmp operation'.strcmp('strcmp operation') 0
'strcmp operation'.strcmp('strtok') -17

String.strstr(String) : Boolean

Searches r in self.

Expression Result
'HelloWorld'.strstr('World') true

String.substitute(String, String) : String

Substitutes the first occurrence of the substring "r" in self by "t" and returns the resulting string. Will return self if it contains no occurrence of the substring r.

Expression Result
'WorldWorld'.substitute('World', 'Hello') 'HelloWorld'

String.substituteAll(String, String) : String

Substitutes all occurences of the substring "r" in self by "t" and returns the resulting string. Will return self if it contains no occurrence of the substring r.

Expression Result
'WorldWorld'.substituteAll('World', 'Hello') 'HelloHello'

String.substring(Integer, Integer) : String

Returns a string containing all characters from self starting from index lower up to index upper included. Both lower and upper parameters should be contained between 1 and self.size() included. Lower cannot be greater than upper.

Expression Result
'HelloWorld'.substring(1, 5) 'Hello'

String.substring(Integer) : String

Returns a string containing all characters from self starting from index lower up to the end of the string included. The lower parameter should be contained between 1 and self.size() included. Lower cannot be greater than the size of the String.

Expression Result
'HelloWorld'.substring(5) 'World'
'HelloWorld'.substring(1) 'HelloWorld'

String.toInteger() : Integer

Returns an integer of value equal to self

Expression Result
'42'.toInteger() 42

String.toLower() : String

Returns the current String with all characters transformed to lower case.

Expression Result
'HelloWorld'.toLower() 'helloworld'

String.toLowerFirst() : String

Returns the self string with the first characters transformed to lower case.

Expression Result
'HelloWorld'.toLowerFirst() 'helloWorld'

String.toReal() : Double

Returns a real of value equal to self

Expression Result
'41.9'.toReal() 41.9

String.toUpper() : String

Returns the current String with all characters transformed to upper case.

Expression Result
'HelloWorld'.toUpper() 'HELLOWORLD'

String.toUpperFirst() : String

Returns the current String with the first characters transformed to upper case.

Expression Result
'helloworld'.toUpperFirst() 'Helloworld'

String.tokenize(String) : Sequence{String}

Splits the current String by using the given "delimiter" into a collection of String

Expression Result
'a, b, c, d'.tokenize(', ') ['a', 'b', 'c', 'd']

String.tokenize() : Sequence{String}

Splits the current String by whitespace delimiter into a collection of String

Expression Result
'a, b, c, d'.tokenize() ['a,', 'b,', 'c,', 'd']

String.trim() : String

Trims the given String.

Expression Result
' Hello World '.trim() 'Hello World'

Syntax Reference

References

variable_name a reference to a variable myVariable
expression . feature_name implicit collect eClass.name
expression . service_name ( ( expression ( , expression ) * ) ? ) implicit collect myVariable.toString()
expression -> service_name ( ( expression ( , expression ) * ) ? ) call on the collection itself if the expression is not a collection it will be wrapped into an ordered set mySequence->sep(‹,›)

Operators

not expression call the not service not eClass.interface
- expression call the unaryMin service -3
expression + expression call the add service 2 + 2
expression - expression call the sub service 2 – 2
expression * expression call the mult service 2 * 2
expression / expression call the divOp service 2 / 2
expression <= expression call the lessThanEqual service 2 <= 2
expression >= expression call the greaterThanEqual service 2 >= 2
expression < expression call the lessThan service 1 < 2
expression > expression call the greaterThan service 2 > 1
expression <> expression call the differs service 1 <> 2
expression != expression call the differs service 1 != 2
expression = expression call the equals service 1 = 1
expression and expression call the and service eClass.interface and eClass.abstact
expression or expression call the or service eClass.interface or eClass.abstact
expression xor expression call the xor service eClass.interface xor eClass.abstact
expression implies expression call implies service eClass.interface implies eClass.abstact

Structures

( expression ) parenthesis are used to change priority during evaluation (2 + 2 ) * 3
if expression then expression else expression endif conditional expression if eClass.abstract then ‹blue› else ‹red› endif
let new_variable_name ( : type_literal)? ( , new_variable_name ( : type_literal)?)* in expression let allows to define variables in order to factorise expression let container = self.eContainer() in container.eAllContents()

Literals

' escaped_string ' you can use java style escape sequence \u0000 \x00 \\ \' \b \t \n ... 'TODO list:\n\t- walk the dog\n\t- make diner'
[ 0 - 9]+ an integer 100
[ 0 - 9]+ . [ 0 - 9]+ a real 3.14
true the boolean value true true
false the boolean value false false
null the null value null
Sequence{ ( expression ( , expression) * ) ? } a sequence defined in extension Sequence{1, 2, 3, 3}
OrderedSet{ ( expression ( , expression) * ) ? } an ordered set defined in extension OrderedSet{1, 2, 3}
epackage_name :: eenum_name :: eenum_literal_name an EEnumLiteral art::Color::blue

Type literals

String the string type String
Integer the integer type Integer
Real the real type Real
Boolean the string type Boolean
Sequence( type_litral ) a sequence type Sequence(String)
OrderedSet( type_litral ) an ordered set type OrderedSet(String)
epackage_name :: eclassifier_name an eclassifier type ecore::EPackage
{ epackage_name :: eclassifier_name (* * epackage_name :: eclassifier_name) * } a set of eclassifiers {ecore::EPackage | ecore::EClass}

Migrating from MTL queries

As languages, AQL and MTL are very close yet there are some notable differences:

Implicit variable references

There is no implicit variable reference. With this change, you can easily find out if you are using a feature of an object or a string representation of said object. As a result, instead of using something , you must use self.something if you want to access the feature named «something» of the current object or «something» if you want to retrieve the object named something.

In a lambda expression, you must now define the name of the variable used for the iteration in order to easily identify which variable is used by an expression. In Acceleo MTL, you can write Sequence{self}->collect(eAllContents(uml::Property)) and Acceleo will use the implicit iterator as a source of the operation eAllContents.

The problem comes when using a lambda like Sequence{self}->collect(something) , we can’t know if «something» is a feature of «self» or if it is another variable.

Using AQL, you will now have to write either collect(m | m.eAllContents(uml::Property)) or collect(m: uml::Model | eAllContents(uml::Property)) .

Collect and flatten

When a call or a feature acces is done on a collection the result is flattened for the first level. For instance a service returning a collection called on a collection will return a collection of elements and not a collection of collection of elements.

Type literals & children EPackages

Type literals can’t be in the form someEPackage::someSubEPackage::SomeEClass but instead someSubEPackage::SomeEClass should be directly used. Note that the name of the EPackage is mandatory. Type literals are handled just like any other type.

Calls like self.eAllContents(self.eClass()) are possible and will return all the children of type compatible with “self”.

Furthermore if you need a type literal as a parameter in your own service, you just have to have a first parameter with the type : Set<EClass> . Yes, that’s an important point, any type in AQL is possibly a union of several existing types, hence the collection here. As such the syntax for creating Sets or collections can be used as a substitute for type literals.

Enumeration literals & children EPackages

Enumeration literal should be prefixed with the name of the containing EPacakge for instance «myPackage::myEnum::value».

Collections

You can only have Sequences or OrderedSets as collections and as such the order of their elements is always deterministic. In Acceleo MTL, you had access to Sets, which are now OrderedSets and Bags, which are now Sequences. Those four kinds of collections were motivated by the fact that Sequence and OrderedSet were ordered contrary to Sets and Bags. On another side, OrderedSets and Sets did not accept any duplicate contrary to Bags and Sequences.

By careful reviewing the use of those collections in various Acceleo generators and Sirius Designers we have quickly found out that the lack of determinism in the order of the collections Sets and Bags was a major issue for our users. As a result, only two collections remain, the Sequence which can contain any kind of element and the OrderedSet which has a similar behavior except that it does not accept duplicates.

Previously in Acceleo MTL, you could transform a literal into a collection by using the operator -> on the literal directly. In Acceleo MTL, the collection created was a Bag which is not available anymore. It is recommended to use the extension notation like Sequence{self} or OrderedSet{self} . By default in AQL the created collection is an OrderedSet.

Renamed operations

Some operations have been renamed. As such «addAll» and «removeAll» have been renamed «add» and «sub» because those two names are used by AQL in order to provide access to the operator «+» and «-». As a result we can now write in AQL «firstSequence + secondSequence» or «firstSet - secondSet».

Typing

AQL is way smarter than MTL regarding to the types of your expressions. As a result, you can combine expressions using multiple types quite easily. For example, this is a valid AQL expression self.eContents(uml::Class).add(self.eContents(ecore::EClass)).name . In Acceleo MTL, we could not use this behavior because Acceleo MTL had to fall back to the concept EObject which does not have a feature «name» while AQL knows that the collection contains objects that are either «uml::Class» or «ecore::EClass» and both of those types have a feature named «name».

null handling

AQL handles null (OclVoid) differently from ocl, a null value will not cause a failure but will be silently handled.
For example, null.oclIsKindOf(ecore::EClass) would have returned true for MTL/OCL, forcing users to use not self.oclIsUndefined() and self.oclIsKindOf(ecore::EClass) instead. This is no longer true in AQL, where «null» doesn’t conform to any type, so null.oclIsKindOf(ecore::EClass) will return false. Note that it’s still possible to «cast» null in any given classifier. null.oclAsType(ecore::EClass) will not fail at runtime.

Furthermore oclIsUndefined() does not exist in AQL and should be replaced by a ... <> null expression.

Migrating from Acceleo2 queries

EClassifier references

All operations referencing a type are now using a type literal with the name of the EPackage and the name of the type instead of a string with the name of the type. As a result, eObject.eAllContents('EClass') would be translated using eObject.eAllContents('ecore::EClass') . This allows AQL to now in which EPackage to look for the type and as such, it improves the quality of the validation.

Types and cast

In order to test the type of an EObject, a common pattern in Acceleo 2 was to treat the EObject as a collection and filter said collection on the type desired to see if the size of the collection changed. In AQL, you have access to the operations oclIsTypeOf and oclIsKindOf. You can thus test the type of an EObject with the expression «eObject.oclIsKindOf(ecore::EStructuralFeature)» or «eObject.oclIsTypeOf(ecore::EAttribute)». You can use the operation oclIsKindOf to test if an object has the type of the given parameter or one of its subtype. On the other hand, you can use the operation oclIsTypeOf to test if an object has exactly the type of the given parameter.

Casting in AQL is useless, since AQL is very understandable when it comes to types, it will always tries its best to evaluate your expression.

Since AQL is very close to Acceleo MTL, you can find some additional documentation using the Acceleo equivalence documentation in the Acceleo documentation.

eContainer(«TypeName»)

In Acceleo2 self.eContainer("TypeName") actually had the behavior of returning self if it was matching the TypeName. As such, when migrating from an eContainer(..) call you should either make sure that this behavior is not needed or use the
compatibility method provided by AQL : self.eContainerOrSelf(some::Type)

Using AQL programmatically

This section provide information and code snippet. It will help you to integrate AQL in your own tool.

Simple overview of AQL:

Type validation

For each node of the AST we create a set of possible types as follow:

A special type NothingType is used to mark a problem on a given node of the AST. Those NothingTypes are then used to create validation messages. If an AST node has only NothingTypes validation messages will be set as errors for this node, otherwise they are set as warnings.

Completion

The completion rely on the AST production and the type validation.
The identifier fragments preceding (prefix) and following (remaining) the cursor position are removed from the expression to parse. The prefix and remaining are used later to filter the proposals. Many filters can be implemented: filter only on prefix, filter on prefix and remaining, same strategies with support for camel case, ...

Completion on the AST:

Creating and setting the environment

To get a fresh environment you can use one of the following snippet:

			IQueryEnvironment queryEnvironment = Query.newEnvironmentWithDefaultServices(null);

To get an environment with predefined services.

or

			IQueryEnvironment queryEnvironment = Query.newEnvironment(null);

To get an environment with no predefined services. It can be useful to create your own language primitives.

Note that you can also provide a CrossReferenceProvider to define the scope of cross references in your environment. See CrossReferencerToAQL for more details.

You can register new services Class as follow:

			ServiceRegistrationResult registrationResult = queryEnvironment.registerServicePackage(MyServices.class);

The registration result contains information about services overrides.

You can also register your EPackages. Only registered EPackages are used to validate and evaluate AQL expression.

			queryEnvironment.registerEPackage(MyEPackage.eINSTANCE);

In some cases you might also want to create custom mappings between an EClass and its Class. A basic case is the use of EMap:

			queryEnvironment.registerCustomClassMapping(EcorePackage.eINSTANCE.getEStringToStringMapEntry(), EStringToStringMapEntryImpl.class);

By default the EClass is mapped to Map.Entry which is not an EObject. This prevents using services on EObject.

Building an AQL expression

The first step is building your expression from a String to an AST:

			QueryBuilderEngine builder = new QueryBuilderEngine(queryEnvironment);
AstResult astResult = builder.build("self.name");

Evaluating an AQL expression

To evaluate an AQL expression you can use the QueryEvaluationEngine

			QueryEvaluationEngine engine = new QueryEvaluationEngine(queryEnvironment);
Map<String, Object> variables = Maps.newHashMap();
variables.put("self", EcorePackage.eINSTANCE);
EvaluationResult evaluationResult = engine.eval(astResult, variables);

Here we only use one variable for demonstration purpose.

Validating an AQL expression (optional)

This step is optional for evaluation. You can evaluate an AQL expression without validating it in the first place.

			Map<String, Set<IType>> variableTypes = new LinkedHashMap<String, Set<IType>>();
Set<IType> selfTypes = new LinkedHashSet<IType>();
selfTypes.add(new EClassifierType(queryEnvironment, EcorePackage.eINSTANCE.getEPackage()));
variableTypes.put("self", selfTypes);
AstValidator validator = new AstValidator(queryEnvironment, variableTypes);
IValidationResult validationResult = validator.validate(astResult);

Completing an AQL expression

To do this use the QueryCompletionEngine, it will build the query and validate it for you. It will also compute needed prefix and suffix if any:

			Map<String, Set<IType>> variableTypes = new LinkedHashMap<String, Set<IType>>();
Set<IType> selfTypes = new LinkedHashSet<IType>();
selfTypes.add(new EClassifierType(queryEnvironment, EcorePackage.eINSTANCE.getEPackage()));
variableTypes.put("self", selfTypes);
QueryCompletionEngine engine = new QueryCompletionEngine(queryEnvironment);
ICompletionResult completionResult = engine.getCompletion("self.", 5, variableTypes);
List<ICompletionProposal> proposals = completionResult.getProposals(new BasicFilter(completionResult));

Here 5 is the offset where the completion should be computed in the given expression.