org.eclipse.ocl.helper

Interface OCLHelper<C,O,P,CT>

public interface OCLHelper<C,O,P,CT>

A utility object that provides OCL syntax completion suggestions for OCL expressions and convenient API for parsing OCL constraint expressions without the encumbrance of context declarations. The latter is most useful for processing OCL constraints and expressions embedded in the user model, where the context is implied by the placement of the constraint in the model.

An OCL helper is created by the OCL.createOCLHelper() factory method and inherits the current context Environment of the OCL that created it.

Since 1.2, the helper supplies diagnostics indicating any problems encountered while parsing. The diagnostics pertain always to the most recently executed parse operation.

Note that this interface is not intended to be implemented by clients.

See the Environment class for a description of the generic type parameters of this class.

Author:

Yasser Lulu, Christian W. Damus (cdamus)

See Also:

OCL.createOCLHelper()

Method Summary

Modifier and Type	Method and Description
CT	createBodyCondition(String expression) Creates an operation body.
CT	createConstraint(ConstraintKind kind, String expression) Creates a constraint of the specified kind, by parsing the given expression.
CT	createDerivedValueExpression(String expression) Creates a property derived value expression.
CT	createInitialValueExpression(String expression) Creates a property initial value expression.
CT	createInvariant(String expression) Creates an invariant constraint in the current classifier context.
CT	createPostcondition(String expression) Creates an operation postcondition constraint.
CT	createPrecondition(String expression) Creates an operation precondition constraint.
OCLExpression<C>	createQuery(String expression) Creates a query expression in the current classifier context.
P	defineAttribute(String defExpression) Defines an additional attribute in the context classifier, for use in formulating OCL queries and constraints.
O	defineOperation(String defExpression) Defines an additional operation in the context classifier, for use in formulating OCL queries and constraints.
P	getContextAttribute() Obtains my context attribute, if my environment is an attribute context.
C	getContextClassifier() Obtains my OCL context classifier as a classifier.
O	getContextOperation() Obtains my context operation, if my environment is an operation context.
Environment<?,C,O,P,?,?,?,?,?,CT,?,?>	getEnvironment() Obtains the environment defining my current classifier, operation, or attribute context.
OCL<?,C,O,P,?,?,?,?,?,CT,?,?>	getOCL() Obtains the OCL instance that created me.
Diagnostic	getProblems() Obtains problems, if any, found in parsing the last OCL constraint or query expression.
List<Choice>	getSyntaxHelp(ConstraintKind constraintType, String txt) Obtains syntax completion choices for the specified fragment of an OCL expression given that it is intended for a constraint of the specified kind.
boolean	isValidating() Queries whether I validate the expressions that I parse.
void	setAttributeContext(C context, P property) Sets the attribute context of the OCL expression for which syntax or parsing help is to be provided.
void	setContext(C context) Sets the classifier context of the OCL expression for which syntax or parsing help is to be provided.
void	setInstanceAttributeContext(Object instance, P property) Sets the operation context implied by the specified instance.
void	setInstanceContext(Object instance) Sets the classifier context implied by the specified instance.
void	setInstanceOperationContext(Object instance, O operation) Sets the operation context implied by the specified instance.
void	setOperationContext(C context, O operation) Sets the operation context of the OCL expression for which syntax or parsing help is to be provided.
void	setValidating(boolean validating) Sets whether I should validate the expressions that I parse.

Method Detail

setContext

void setContext(C context)

Sets the classifier context of the OCL expression for which syntax or parsing help is to be provided.

Parameters:

context - the OCL context classifier

See Also:

setOperationContext(Object, Object), setAttributeContext(Object, Object)

getContextClassifier

C getContextClassifier()

Obtains my OCL context classifier as a classifier.

Returns:

my context classifier (never null)

setOperationContext

void setOperationContext(C context,
                         O operation)

Sets the operation context of the OCL expression for which syntax or parsing help is to be provided. The operation is the model element against which the OCL will be parsed as an operation applicable to an OCL type. Note that the operation needs not necessarily be defined by the specified context classifier; it could be inherited.

Parameters:

context - the OCL context classifier

operation - the OCL context operation

See Also:

setContext(Object)

getContextOperation

O getContextOperation()

Obtains my context operation, if my environment is an operation context.

Returns:

my context operation, or null if there is only a classifier or attribute context

setAttributeContext

void setAttributeContext(C context,
                         P property)

Sets the attribute context of the OCL expression for which syntax or parsing help is to be provided. The attribute is the model element against which the OCL will be parsed as an attribute available in an OCL classifier. Note that the attribute needs not necessarily be defined by the specified context classifier; it could be inherited.

Parameters:

context - the OCL context classifier

property - the OCL context attribute

See Also:

setContext(Object)

getContextAttribute

P getContextAttribute()

Obtains my context attribute, if my environment is an attribute context.

Returns:

my context attribute, or null if there is only a classifier or operation context

setInstanceContext

void setInstanceContext(Object instance)

Sets the classifier context implied by the specified instance. The appropriate classifier will be determined from the run-time type of this object, if possible. If not possible, OclAny is assumed.

This method is convenient for ad hoc parsing and evaluation of OCL constraints or expressions in the context of a model instance.

Parameters:

instance - the OCL context instance

See Also:

setContext(Object)

setInstanceOperationContext

void setInstanceOperationContext(Object instance,
                                 O operation)

Sets the operation context implied by the specified instance. The appropriate classifier will be determined from the run-time type of this object, if possible. If not possible, OclAny is assumed.

This method is convenient for ad hoc parsing and evaluation of OCL constraints or expressions in the context of a model instance.

Parameters:

instance - the OCL context instance

operation - the OCL context operation

See Also:

setOperationContext(Object, Object)

setInstanceAttributeContext

void setInstanceAttributeContext(Object instance,
                                 P property)

Sets the operation context implied by the specified instance. The appropriate classifier will be determined from the run-time type of this object, if possible. If not possible, OclAny is assumed.

This method is convenient for ad hoc parsing and evaluation of OCL constraints or expressions in the context of a model instance.

Parameters:

instance - the OCL context instance

property - the OCL context attribute

See Also:

setAttributeContext(Object, Object)

getOCL

OCL<?,C,O,P,?,?,?,?,?,CT,?,?> getOCL()

Obtains the OCL instance that created me. Note that many of the generic type parameter bindings will not be known, so clients should keep track of the OCL instance themselves where that is a problem.

Returns:

the OCL instance that created me

getEnvironment

Environment<?,C,O,P,?,?,?,?,?,CT,?,?> getEnvironment()

Obtains the environment defining my current classifier, operation, or attribute context. Accessing the environment is convenient for, e.g., adding variable definitions to insert global objects into the OCL context.

Returns:

my current context environment, or null if I have not yet been assigned a context

Since:

1.2

See Also:

setContext(Object), setOperationContext(Object, Object), setAttributeContext(Object, Object)

isValidating

boolean isValidating()

Queries whether I validate the expressions that I parse. Validation applies more well-formedness checks than are implied by parsing, especially because parsing supports partial (incomplete) expressions for syntax completion. Validation adds some amount of processing, which is not necessary in all cases.

Returns:

whether I validate the expressions that I parse. Validation is on by default

setValidating

void setValidating(boolean validating)

Sets whether I should validate the expressions that I parse.

Parameters:

validating - whether I should validate parsed expressions

createQuery

OCLExpression<C> createQuery(String expression)
                      throws ParserException

Creates a query expression in the current classifier context. This may be specified, for example, as an expression value in the model.

Parameters:

expression - the expression (without any context declaration). This expression can have any result type; it needs not be a boolean

Returns:

the query expression

Throws:

ParserException - if the expression fails to parse

createConstraint

CT createConstraint(ConstraintKind kind,
                    String expression)
             throws ParserException

Creates a constraint of the specified kind, by parsing the given expression. In the case of additional attribute or operation definition constraints, the expression must be prefixed by the signature of the feature as follows:

     attribute-name : type = expr
 

     operation-name(parameters?) : type = expr
 

Parameters:

kind - the kind of constraint to create

expression - the constraint body

Returns:

the constraint

Throws:

ParserException - on failure to parse the constraint

createInvariant

CT createInvariant(String expression)
            throws ParserException

Creates an invariant constraint in the current classifier context.

Parameters:

expression - the constraint expression (without any context declaration). This must be a boolean-valued expression

Returns:

the invariant constraint

Throws:

ParserException - if the expression fails to parse

createPrecondition

CT createPrecondition(String expression)
               throws ParserException

Creates an operation precondition constraint. This is appropriate only if my context is an operation.

Parameters:

expression - the constraint expression (without any context declaration). This must be a boolean-valued expression

Returns:

the precondition

Throws:

ParserException - if the expression fails to parse

See Also:

setOperationContext(Object, Object)

createPostcondition

CT createPostcondition(String expression)
                throws ParserException

Creates an operation postcondition constraint. This is appropriate only if my context is an operation.

Parameters:

expression - the constraint expression (without any context declaration). This must be a boolean-valued expression

Returns:

the postcondition

Throws:

ParserException - if the expression fails to parse

See Also:

setOperationContext(Object, Object)

createBodyCondition

CT createBodyCondition(String expression)
                throws ParserException

Creates an operation body. This is appropriate only if my context is an operation.

Parameters:

expression - the constraint expression (without any context declaration). Ordinarily, this is an expression of the same type as the operation, specifying the value of the operation. Alternatively, this may be a boolean-valued expression phrased like a post-condition (according to the well-formedness rules of UML constraints)

Returns:

the body condition

Throws:

ParserException - if the expression fails to parse

See Also:

setOperationContext(Object, Object)

createInitialValueExpression

CT createInitialValueExpression(String expression)
                         throws ParserException

Creates a property initial value expression. This is appropriate only if my context is a property.

Parameters:

expression - the initial value expression (without any context declaration). This must conform to my context property type

Returns:

the initial value expression

Throws:

ParserException - if the expression fails to parse or is not valid for my context property

See Also:

setAttributeContext(Object, Object)

createDerivedValueExpression

CT createDerivedValueExpression(String expression)
                         throws ParserException

Creates a property derived value expression. This is appropriate only if my context is a property.

Parameters:

expression - the derived value expression (without any context declaration). This must conform to my context property type

Returns:

the derived value expression

Throws:

ParserException - if the expression fails to parse or is not valid for my context property

See Also:

setAttributeContext(Object, Object)

defineOperation

O defineOperation(String defExpression)
           throws ParserException

Defines an additional operation in the context classifier, for use in formulating OCL queries and constraints. This is a "def expression", taking the form of:

     operation-name(parameters?) : type = expr
 

Parameters:

defExpression - the definition expression (without any other context declaration).

Returns:

the newly defined operation

Throws:

ParserException - if the expression fails to parse

defineAttribute

P defineAttribute(String defExpression)
           throws ParserException

Defines an additional attribute in the context classifier, for use in formulating OCL queries and constraints. This is a "def expression", taking the form of:

     attribute-name : type = expr
 

Parameters:

defExpression - the definition expression (without any other context declaration).

Returns:

the newly defined attribute

Throws:

ParserException - if the expression fails to parse

getSyntaxHelp

List<Choice> getSyntaxHelp(ConstraintKind constraintType,
                           String txt)

Obtains syntax completion choices for the specified fragment of an OCL expression given that it is intended for a constraint of the specified kind. The choices returned (if any) will be appropriate for appending to the end of the specified text in the context of this kind of constraint.

Parameters:

constraintType - the kind of constraint that is being composed, or null to indicate completions for a query expression

txt - a partial OCL expression for which to seek choices that could be appended to it

Returns:

a list of Choices, possibly empty. The ordering of the list may or may not indicate relative relevance or frequency of a choice

getProblems

Diagnostic getProblems()

Obtains problems, if any, found in parsing the last OCL constraint or query expression.

Returns:

parsing problems or null if all was OK

Since:

1.2