Le méga-planet OCL (Object Constraint Language) est un langage d'expression sans effets de bord, qui utilise des types de base, des types énumérés et des constructeurs de types pour effectuer des opérations sur des collections. Il permet d'écrire des expressions et des opérations similaires à celles de langages fonctionnels, tout en se distinguant par l'absence de fonctions explicites. Le document fournit également des exemples d'expressions, de filtrage et d'itérations sur des collections, soulignant l'utilisation des quantificateurs et des opérations de collection.

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OCL : An Expression LanguageOCL : An Expression Language
Basic Types, Enumerated Types, Types ConstructorsBasic Types, Enumerated Types, Types Constructors
Expressions, OperationsExpressions, Operations
Operations on collectionsOperations on collections

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OCL = An Expression LanguageOCL = An Expression Language
No side effectNo side effect
No explicit iterationNo explicit iteration
Like a functional languageLike a functional language
but no functions (in the standard)but no functions (in the standard)
Can serve as aCan serve as a query languagequery language
This first part,
« OCL : An Expression language » is
almost independent from UML

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TypesTypes
Basic typesBasic types
IntegerInteger
RealReal
BooleanBoolean
StringString
Enumerated typesEnumerated types
MetatypesMetatypes
OclTypeOclType
OclAnyOclAny
OclStateOclState
OclExpressionOclExpression
Types from UMLTypes from UML
classesclasses
associationsassociations
……
Type constructorsType constructors
TupleType( x : T, y : T … )TupleType( x : T, y : T … )
Set(T)Set(T)
OrderedSet(T)OrderedSet(T)
Sequence(T)Sequence(T)
Bag(T)Bag(T)
Collection(T)Collection(T)

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Syntax of ExpressionsSyntax of Expressions (Simplified)
<const> 12 'hello'
<id> children Residence
<expr> <op> <expr> age>18
self like in python, « this » in java
<exprobj> . <prop> self.chairman.age
<exprobj> . <objprop>(<expr>...) self.chairman.increaseSalary(10)
<exprcoll> -> <collprop>(<expr>...) self.employees->collect(salary)
<package>::<package> … :: <element> like in C++, « . » in python and java
if <expr> then <expr> else <expr> endif if age>18 then 1200 else 50*age endif
let <id> : <type> in <expr> .<expr> let e=x*x+y in (e-20)*1,5

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ExamplesExamples
self.salary - 100
self.children->isEmpty()
self.children->forall(age>20)
self.getTaxes(1998) / self.children->size()
self.children->select( sex= Sex::male )
self.children->collect(salary)->sum()
self.children.salary->sum()
self.children->union(self.parents)->collect(age)
children
*
Person
sex:Sex
salary:real
age:integer
parents
0..2
getTaxes()
<<enumeration>>
Sex
male
female

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To be Remembered !To be Remembered !
. to get access to properties of objects
->-> to get access to properties of collectionsto get access to properties of collections
+ some rules to mix collections and objects (see later)
self.taxes(1998) / self.children -> size()
because self
is an object
because self.children
is a collection of objects

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Integer et RealInteger et Real
IntegerInteger
values :values : 1, -5, 34, 243431, -5, 34, 24343, ..., ...
operations :operations : +, -, *, div, mod, abs, max, min+, -, *, div, mod, abs, max, min
RealReal
values :values : 1.5, 1.341.5, 1.34, ..., ...
operations :operations : +, -, *, /, floor, round, max, min+, -, *, /, floor, round, max, min
Integer type « conforms » to the type Real

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BooleanBoolean
BooleanBoolean
values :values : truetrue,, falsefalse
operations :operations : notnot,, andand,, oror,, xorxor,, impliesimplies,, if-then-else-endifif-then-else-endif
partial evaluation :partial evaluation :
true oror x always true, even when x is undefined
false andand x always false, even when x is undefined
(age<40 implies salaire>1000) and (age>=40 implies salaire>2000)
if age<40 then salaire > 1000 else salaire > 2000 endif
salaire > (if age<40 then 1000 else 2000 endif)

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StringString
name = nom.substring(1,1).toUpper().concat(
nom.substring(2,nom.size()).toLower())
Strings are not sequence of Sequence(char) (no char type)
Operations:Operations:
==
ss..sizesize()()
s1s1..concatconcat((s2s2))
s1s1..substringsubstring((i1i1,,i2i2))
ss..toUppertoUpper()()
ss..toLowertoLower()()
Values:Values:
''''
'a sentence''a sentence'

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EnumerationEnumeration
ValuesValues
Day::TuesdayDay::Tuesday (previous notation:(previous notation: #Tuesday#Tuesday ))
OperatorsOperators
==,, <><>
No ordering relation
<<enumeration>>
Day
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday

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ExamplesExamples
spouse->notEmpty() implies spouse.sex = Sex::female
épouse.sexe < sexe
husband
0..1
Person
sex : Sex
spouse
0..1
No ordering relationNot always
defined
<<enumeration>>
Sex
male
female

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Element vs. singletonElement vs. singleton
In almost all languagesIn almost all languages
one elementone element ee
from singleton containing this elementfrom singleton containing this element Set{e}Set{e}
self->size() = 1
Implicit conversion in OCLImplicit conversion in OCL element => singletonelement => singleton
when an collection operationwhen an collection operation
is applied to an elementis applied to an element
elemelem ->-> propprop Set{Set{elemelem}->}->propprop
≠

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CollectionsCollections
General TypeGeneral Type CollectionCollection(( TT ))
Set(Set(TT ))
{unique}{unique} {nonunique}{nonunique}
{unordered}{unordered}
{ordered}{ordered} Sequence(Sequence(TT ))
Bag(Bag(TT ))
OrderedSet(OrderedSet(TT ))

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Use of collections for role navigationUse of collections for role navigation
object . nomderoleobject . nomderole type:type:
X
1 or 0..1
X
*
X
{ordered} *
X
Set(X)
OrderedSet(X)
X
*{nonunique}
Bag(X)
X
{ordered, nonunique} *
Sequence(X)

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Collection ExpressionsCollection Expressions
ExamplesExamples
SetSet {{ 'lundi''lundi',, 'mercredi''mercredi',, 'mardi''mardi' }}
BagBag {{ 'lundi''lundi',, 'lundi''lundi',, 'mardi''mardi',, 'lundi''lundi' }}
OrderedSetOrderedSet {{ 1010,, 2020,, 55 }}
SequenceSequence {{ 'lundi''lundi',, 'lundi''lundi',, 'mardi''mardi',, 'lundi''lundi' }}
To specify rangesTo specify ranges
SequenceSequence {{ 1..5, 2..41..5, 2..4 }}
Useful for 'loops' :
Sequence { 0 .. etagesnb-1 } -> forall( i | canStop(i) )

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Operations on CollectionsOperations on Collections
Cardinality: coll -> size()
Emptyness: coll -> isEmpty()
Non emptyness: coll -> notEmpty()
Occurrence number: coll -> count(elem)
Membership: coll -> includes( elem )
Non membership: coll -> excludes( elem )
Inclusion: coll -> includesAll(coll)
Exclusion: coll -> excludesAll(coll)
Sum (of numbers): coll -> sum()

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ExamplesExamples
Set { 3, 5, 2, 45, 5 }->size()
Sequence { 1, 2, 45, 9, 3, 9 } ->count(9)
Sequence { 1, 2, 45, 2, 3, 9 } ->includes(45)
Bag { 1, 9, 9, 1 } -> count(9)
c->asSet()->size() = c->size()
c->count(x) = 0
Bag { 1, 9, 0, 1, 2, 9, 1 } -> includesAll( Bag{ 9,1,9} )

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Operations on SetsOperations on Sets
UnionUnion ens ->ens -> unionunion( ens )( ens )
IntersectionIntersection ens ->ens -> intersectionintersection( ens )( ens )
DifferenceDifference ens1 - ens2ens1 - ens2
Adding an elementAdding an element ens ->ens -> includingincluding(elem)(elem)
Removing an elementRemoving an element ens ->ens -> excludingexcluding(elem)(elem)
Sequence conversionSequence conversion ens ->ens -> asSequence()asSequence()
Bag conversionBag conversion ens ->ens -> asBag()asBag()
Conversion to ordered setConversion to ordered set ens ->ens -> asOrderedSet()asOrderedSet()

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Filtering: select, reject and anyFiltering: select, reject and any
coll -> select( cond )
select elements satisfying the conditionselect elements satisfying the condition
coll -> reject( cond )
reject elementsreject elements
coll -> any( cond )
selectselect anyany element satisfying the conditionelement satisfying the condition
• non deterministnon determinist
• useful when there is only one elementuseful when there is only one element
• "undefined" if the collection is empty"undefined" if the collection is empty

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ExamplesExamples
self.children ->select( age>10 and sex = Sex::Male)
self.children ->reject(e : Person | e.children->isEmpty())->notEmpty()
members->any(title='president')
children*
Member
sex : Sexe
age : integer
title : string
parents0..2Club members
*

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Syntax AlternativesSyntax Alternatives
self.employees->select(age > 50)
self.employees->select( p | p.age>50 )
self.employees->select( p : Person | p.age>50)
Person
age : integer
Company
employees
*

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forall, exists, oneforall, exists, one
coll ->coll -> forallforall( cond )( cond )
coll ->coll -> existsexists( cond )( cond )
coll ->coll -> oneone( cond )( cond )
self.enfants->forall(age<10)
self.enfants->exists(sexe=Sexe::Masculin)
self.enfants->one(age>=18)
children*
Person
sexe : Sex
age : integer
parents0..2

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Syntax ComparisonSyntax Comparison
children->forall( p : Person | p.age<10)
∀ c ∈ children . c.age < 10

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Quantifiers: more about syntaxQuantifiers: more about syntax
It's possible toIt's possible to
give a name to a variablegive a name to a variable
explicit its typeexplicit its type
use various variables at the same timeuse various variables at the same time
self.children->forall( age < self.age )
self.enfants->forall( e | e.age < self.age - 7)
self.children->forall( e : Personne | e.age < self.age - 7)
self.children->exists( e1,e2 | e1.age = e2.age )
self.children->exists( e1,e2 | e1.age = e2.age and e1<>e2 )
self.children->forall( e1,e2 : Personne |
e1 <> e2 implies e1.firstname <> e2.firstname)
children*
Person
age
firstname

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UnicityUnicity
coll -> isUnique ( expr )
True if all elements return a different value for exprTrue if all elements return a different value for expr
self.children -> isUnique ( firstname )
instead ofinstead of
self.children->forall( p1,p2 : Person |
p1 <> p2 implies p1.firstname <> e2.firstname)
Useful to define the notion of "imported key" for instance
children*
Person
age
firstname

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isUnique vs. {unique}isUnique vs. {unique}
self.children -> isUnique ( firstname )
children*
Person
age
firstname
{unique}

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Image of an expression: collectImage of an expression: collect
coll ->coll -> collectcollect( expr )( expr )
"image" of a function (map, apply, ...)
expr evaluated for each element
result in:
a Bag if coll is a Set or a Bag
a Sequence if coll is a Sequence or a OrderedSet
self.enfants->collect(age) = Bag{10,5,10,7}
self.employés->collect(salaire/10)->sum()
children*
Person
age
employees
*
Company Employee
salary

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Collect: Simplified Syntax!Collect: Simplified Syntax!
.. with a collectionwith a collection ↔↔ collectcollect
children*
Person
age
self.children.age
self.children->collect(age)

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Collect Possible Duplicates→Collect Possible Duplicates→
The result is a Bag or Sequence because of possible duplicatesThe result is a Bag or Sequence because of possible duplicates
To get a setTo get a set
self.children.age->asSet()
. shortcut very usefull to navigate!. shortcut very usefull to navigate!
self.children.children.cars
children*
Person
age
Cars
cars
**