net.ssehub.easy.reasoning.sseReasoner.model

Class ContextStack

java.lang.Object

net.ssehub.easy.reasoning.sseReasoner.model.ContextStack

public class ContextStack
extends java.lang.Object

Implements a context stack for nested translations. The top-most context corresponds to the project, further nested contexts to visited compounds or containers. Each context contains the recent part of the variable mapping, whereby variable mapping lookup starts with the current context and takes also previous contexts into account. Each context may parts of a complex constraint accessing the path to contained compound variables (the complete constraint over all stack contexts can be obtained from composeExpression(ConstraintSyntaxTree).

However, due to IVML assignment blocks, a translation context stack is not really straightforward. In assignment blocks, additional implicit constraints to initialize annotations are introduced and translated after the actual variable has been translated, i.e., outside the context of a compound or container variable. Therefore, we allow registering contexts with their variable in the parent context for later activation and deactivation as long as the parent context exists. If re-activated, an already popped context (which must not be cleaned up then) is pushed back onto the stack. If de-activated, the re-activated context is popped again but not cleaned up. Registered contexts are cleaned up when the parent context is popped.

Author:

Holger Eichelberger

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	ContextStack.Context A linked stack entry.

Field Summary

Fields

Modifier and Type	Field and Description
private ContextStack.Context	currentContext
private java.util.Set<? extends net.ssehub.easy.varModel.model.datatypes.IDatatype>	globalExcludes
private static net.ssehub.easy.basics.pool.Pool<ContextStack.Context>	POOL
private boolean	registerContexts

Constructor Summary

Constructors

Constructor and Description
ContextStack() Creates a context stack with implicit top-most (project) context.

Method Summary

Modifier and Type	Method and Description
void	activate(net.ssehub.easy.varModel.model.AbstractVariable decl) Re-activates the context registered for decl and re-pushes it onto the stack.
boolean	alreadyProcessed(net.ssehub.easy.varModel.model.datatypes.IDatatype type) Returns whether type was already processed.
void	clear() Clears the stack, i.e., pops all contexts and clears the top-most (project) context for re-use.
net.ssehub.easy.varModel.cst.ConstraintSyntaxTree	composeExpression(net.ssehub.easy.varModel.cst.ConstraintSyntaxTree cst) Composes an all-quantified expression over the contexts of the stack.
boolean	containsMapping(net.ssehub.easy.varModel.model.AbstractVariable var) Returns whether the current context contains a mapping for var.
void	deactivate(net.ssehub.easy.varModel.model.AbstractVariable decl) Deactivates the context registered for decl.
private ContextStack.Context	findRegisteredContext(net.ssehub.easy.varModel.model.AbstractVariable decl) Looks up the actual contexts whether decl was registered previously with a context.
net.ssehub.easy.varModel.cst.ConstraintSyntaxTree	getCurrentContainer() Returns the current container expression from the top-most context.
net.ssehub.easy.varModel.model.DecisionVariableDeclaration	getCurrentIterator() Returns the current iterator variable from the top-most context.
net.ssehub.easy.varModel.model.datatypes.IDatatype	getCurrentType() Returns the type stored in the current context.
net.ssehub.easy.varModel.cst.ConstraintSyntaxTree	getMapping(net.ssehub.easy.varModel.model.AbstractVariable var) Returns the mapped access expression for var taking into account all current contexts of the stack starting with the current top-most one.
boolean	isContextsRegistering() Returns whether context registering is actually enabled.
boolean	isElementTypeExcluded(net.ssehub.easy.varModel.model.IModelElement element) Returns whether the given element if it is a type is excluded in the current context.
boolean	isTypeExcluded(net.ssehub.easy.varModel.model.datatypes.IDatatype type) Returns whether the given type is excluded in the current context.
void	popContext() Removes (and clears) the current context from the stack (except for the initial project context which remains).
private ContextStack.Context	popContextImpl() Pops the actual context if not the initial (project) context but does not clean up the popped context.
void	pushContext(net.ssehub.easy.varModel.model.AbstractVariable decl, boolean recordProcessedTypes) Pushes a new (compound) context to the stack.
void	pushContext(net.ssehub.easy.varModel.model.AbstractVariable decl, net.ssehub.easy.varModel.cst.ConstraintSyntaxTree container, net.ssehub.easy.varModel.model.DecisionVariableDeclaration iterator, boolean recordProcessedTypes) Pushes a new container context to the stack.
private void	pushContextImpl(ContextStack.Context context) Just pushes the given context without changing it.
void	recordProcessed(net.ssehub.easy.varModel.model.datatypes.IDatatype type) Records a processed type (in case of compounds also all refined types) in the closest actual context that allows recording (see ContextStack.Context.recordProcessedTypes and pushContext(AbstractVariable, ConstraintSyntaxTree, DecisionVariableDeclaration, boolean)).
private void	recordProcessed(java.util.Set<net.ssehub.easy.varModel.model.datatypes.IDatatype> processed, net.ssehub.easy.varModel.model.datatypes.Compound type) Records a processed compound.
void	registerMapping(net.ssehub.easy.varModel.model.AbstractVariable var, net.ssehub.easy.varModel.cst.ConstraintSyntaxTree acc) Registers a mapping between the variable var and its actual access expression acc into the current top-most context.
boolean	setRegisterContexts(boolean registerContexts) Enables or disables registering contexts.
void	setTypeExcludes(java.util.Set<? extends net.ssehub.easy.varModel.model.datatypes.IDatatype> excludes) Sets type excludes on the current context.
int	size() Returns the size of the context stack.
void	transferTypeExcludes(net.ssehub.easy.varModel.model.datatypes.IDatatype type) Transfers the type excludes from the next enclosing context defining type excludes to the current context.
void	unregisterMapping(net.ssehub.easy.varModel.model.AbstractVariable var) Unregisters a mapping for the variable var from the current context.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

POOL

private static final net.ssehub.easy.basics.pool.Pool<ContextStack.Context> POOL

currentContext

private ContextStack.Context currentContext

registerContexts

private boolean registerContexts

globalExcludes

private java.util.Set<? extends net.ssehub.easy.varModel.model.datatypes.IDatatype> globalExcludes

Constructor Detail

ContextStack

public ContextStack()

Creates a context stack with implicit top-most (project) context.

Method Detail

setRegisterContexts

public boolean setRegisterContexts(boolean registerContexts)

Enables or disables registering contexts.

Parameters:

registerContexts - whether newly pushed contexts shall be registered from now on

Returns:

the old state, to be used in a local variable to call this method with the previous state correctly

isContextsRegistering

public boolean isContextsRegistering()

Returns whether context registering is actually enabled.

Returns:

true if context registering is enabled, false else

clear

public void clear()

Clears the stack, i.e., pops all contexts and clears the top-most (project) context for re-use.

pushContext

public void pushContext(net.ssehub.easy.varModel.model.AbstractVariable decl,
                        boolean recordProcessedTypes)

Pushes a new (compound) context to the stack. No processed types are recorded.

Parameters:

decl - the variable to register the new context with if enabled, may be null to explicitly prevent registration

recordProcessedTypes - whether processed types indicated by #recordType(IDatatype) shall be recorded or not (false)

pushContext

public void pushContext(net.ssehub.easy.varModel.model.AbstractVariable decl,
                        net.ssehub.easy.varModel.cst.ConstraintSyntaxTree container,
                        net.ssehub.easy.varModel.model.DecisionVariableDeclaration iterator,
                        boolean recordProcessedTypes)

Pushes a new container context to the stack. All parameters may be null.

Parameters:

decl - the variable to register the new context with if enabled, may be null to explicitly prevent registration

container - the container expression (may be null)

iterator - a container iterator variable for container, may be null but only if container is null

recordProcessedTypes - whether processed types indicated by #recordType(IDatatype) shall be recorded or not (false)

pushContextImpl

private void pushContextImpl(ContextStack.Context context)

Just pushes the given context without changing it.

Parameters:

context - the context to be pushed

popContext

public void popContext()

Removes (and clears) the current context from the stack (except for the initial project context which remains). Contexts are only cleaned up and released to the pool if they are not registered with a parent context.

popContextImpl

private ContextStack.Context popContextImpl()

Pops the actual context if not the initial (project) context but does not clean up the popped context.

Returns:

the popped context, null in case of the initial (project) context

registerMapping

public void registerMapping(net.ssehub.easy.varModel.model.AbstractVariable var,
                            net.ssehub.easy.varModel.cst.ConstraintSyntaxTree acc)

Registers a mapping between the variable var and its actual access expression acc into the current top-most context. Overrides any existing mapping in the top-most context. Preceeds any existing mapping in a previous still active context.

Parameters:

var - the variable

acc - the access expression

unregisterMapping

public void unregisterMapping(net.ssehub.easy.varModel.model.AbstractVariable var)

Unregisters a mapping for the variable var from the current context.

Parameters:

var - the variable to be unregistered

containsMapping

public boolean containsMapping(net.ssehub.easy.varModel.model.AbstractVariable var)

Returns whether the current context contains a mapping for var.

Parameters:

var - the variable to look for

Returns:

true if there is a mapping, false else

getMapping

public net.ssehub.easy.varModel.cst.ConstraintSyntaxTree getMapping(net.ssehub.easy.varModel.model.AbstractVariable var)

Returns the mapped access expression for var taking into account all current contexts of the stack starting with the current top-most one.

Parameters:

var - the variable to return the mapping for

Returns:

the mapped access expression or null if there is no registered mapping

getCurrentContainer

public net.ssehub.easy.varModel.cst.ConstraintSyntaxTree getCurrentContainer()

Returns the current container expression from the top-most context.

Returns:

the container expression (may be null for the initial project context or a compound context)

getCurrentIterator

public net.ssehub.easy.varModel.model.DecisionVariableDeclaration getCurrentIterator()

Returns the current iterator variable from the top-most context.

Returns:

the iterator variable (may be null for the initial project context or a compound context)

composeExpression

public net.ssehub.easy.varModel.cst.ConstraintSyntaxTree composeExpression(net.ssehub.easy.varModel.cst.ConstraintSyntaxTree cst)
                                                                    throws net.ssehub.easy.varModel.cst.CSTSemanticException

Composes an all-quantified expression over the contexts of the stack. If no stack contains container/iterator, cst will be returned.

Parameters:

cst - the constraint expression to be composed, shall contain the access expression of the top-most context to be effective

Returns:

the composed expression or cst if there is nothing to compose

Throws:

net.ssehub.easy.varModel.cst.CSTSemanticException - if the composed expression is not valid

findRegisteredContext

private ContextStack.Context findRegisteredContext(net.ssehub.easy.varModel.model.AbstractVariable decl)

Looks up the actual contexts whether decl was registered previously with a context.

Parameters:

decl - the declaration to search for

Returns:

the registered context or null if none was registered

activate

public void activate(net.ssehub.easy.varModel.model.AbstractVariable decl)

Re-activates the context registered for decl and re-pushes it onto the stack. Nothing happens if no context was registered.

Parameters:

decl - the declaration

deactivate

public void deactivate(net.ssehub.easy.varModel.model.AbstractVariable decl)

Deactivates the context registered for decl. Nothing happens if no context was registered.

Parameters:

decl - the declaration

recordProcessed

public void recordProcessed(net.ssehub.easy.varModel.model.datatypes.IDatatype type)

Records a processed type (in case of compounds also all refined types) in the closest actual context that allows recording (see ContextStack.Context.recordProcessedTypes and pushContext(AbstractVariable, ConstraintSyntaxTree, DecisionVariableDeclaration, boolean)). Stores type in the current context for retrieval via getCurrentType().

Parameters:

type - the type to record

recordProcessed

private void recordProcessed(java.util.Set<net.ssehub.easy.varModel.model.datatypes.IDatatype> processed,
                             net.ssehub.easy.varModel.model.datatypes.Compound type)

Records a processed compound.

Parameters:

processed - the set of already processed types (may be modified as a side effect)

type - the type to be recorded

alreadyProcessed

public boolean alreadyProcessed(net.ssehub.easy.varModel.model.datatypes.IDatatype type)

Returns whether type was already processed. All current contexts with enabled recording are considered.

Parameters:

type - the type to look for

Returns:

true if the type was already processed, false if not

size

public int size()

Returns the size of the context stack.

Returns:

the size

setTypeExcludes

public void setTypeExcludes(java.util.Set<? extends net.ssehub.easy.varModel.model.datatypes.IDatatype> excludes)

Sets type excludes on the current context. Type excludes are only valid on the given context, but defined type excludes on the next enclosing context may be transferred.

Parameters:

excludes - the type excludes, null for none

See Also:

isTypeExcluded(IDatatype), isElementTypeExcluded(IModelElement)

transferTypeExcludes

public void transferTypeExcludes(net.ssehub.easy.varModel.model.datatypes.IDatatype type)

Transfers the type excludes from the next enclosing context defining type excludes to the current context. Clears the type excludes in the originating context.

Parameters:

type - the type causing the transfer, to be stored in the current context (@link #getCurrentType()}

See Also:

setTypeExcludes(Set), isTypeExcluded(IDatatype), isElementTypeExcluded(IModelElement)

isElementTypeExcluded

public boolean isElementTypeExcluded(net.ssehub.easy.varModel.model.IModelElement element)

Returns whether the given element if it is a type is excluded in the current context.

Parameters:

element - the element to check for

Returns:

true if excluded, false else

isTypeExcluded

public boolean isTypeExcluded(net.ssehub.easy.varModel.model.datatypes.IDatatype type)

Returns whether the given type is excluded in the current context.

Parameters:

type - the type to check for

Returns:

true if excluded, false else

getCurrentType

public net.ssehub.easy.varModel.model.datatypes.IDatatype getCurrentType()

Returns the type stored in the current context.

Returns:

the type, may be null if there is none