net.sourceforge.czt.base.ast

Interface Term

All Known Subinterfaces:

ListTerm<E>

All Known Implementing Classes:

ListTermImpl, TermImpl

public interface Term

A Z construct/term.

This is the base interface for all Z constructs (also called term) and thus for the AST for Z. It contains methods that each Z term must provide.

Annotations can be used by tools to provide, for instance, type information, location information, ect. They can be used to attach any type of information to a Z term.

Note that annotations are NOT considered as children of a term, that means they are not returned via the getChildren()-method.

Author:

Petra Malik

See Also:

net.sourceforge.czt.base.ast

Method Summary

Modifier and Type	Method and Description
<R> R	accept(Visitor<R> visitor) Accepts a visitor.
int	annsSize() Returns whether the annotation list size.
Term	create(Object[] args) Creates a new object of the implementing class with the objects in args as its children.
<T> T	getAnn(Class<T> aClass) Returns one of the aClass annotations of this term, or null if the term does not contain an annotation of this type.
List<Object>	getAnns() Returns a list of annotations.
Object[]	getChildren() Returns an array of all the children of this term, thus providing the possibility to write generic visitors that traverse a tree of Z terms without even knowing the kind of term they are visiting.
boolean	hasAnn() Returns true when annsSize() has more than zero elements.
<T> boolean	hasAnn(Class<T> aClass) Checks whether the term has any annotation of the given class type
<T> void	removeAnn(Class<T> aClass) Removes all annotations of the specific class.
<T> boolean	removeAnn(T annotation) Removes a specific annotation, if present.

Method Detail

accept

<R> R accept(Visitor<R> visitor)

Accepts a visitor.

This method provides support for the visitor design pattern. Depending on the kind of visitor interfaces the given visitor implements, the visited term chooses the visit-method which fits best and returns the object that a call to this method returns.

Parameters:

visitor - the visitor that wants to visit this term.

Returns:

the object which is returned by the visit-method call of the given visitor.

See Also:

net.sourceforge.czt.base.visitor

getChildren

Object[] getChildren()

Returns an array of all the children of this term, thus providing the possibility to write generic visitors that traverse a tree of Z terms without even knowing the kind of term they are visiting.

The order and types of children is the same as the arguments to the corresponding create method in the factory.

Returns:

an array of all the children of this term.

create

Term create(Object[] args)

Creates a new object of the implementing class with the objects in args as its children. The order and type of the children is similar to the one returned by getChildren().

This method is intended to be used together with method getChildren() by generic visitors.

Parameters:

args - the children of the term to be created.

Returns:

a new term t such that this.getClass() == t.getClass() and forall i t.getChildren()[i] == args[i].

See Also:

getChildren()

getAnns

List<Object> getAnns()

Returns a list of annotations.

To add or remove elements, use the methods provided by the List interface (that's why there is no need for a setter method).

Avoid calling this method directly and prefer to check with hasAnn() first. This delays creation of underlying arrays and lead to considerable memory optimisation on large specs.

Returns:

a list of annotations (should never be null).

getAnn

<T> T getAnn(Class<T> aClass)

Returns one of the aClass annotations of this term, or null if the term does not contain an annotation of this type.

Type Parameters:

T -

Parameters:

aClass -

Returns:

annsSize

int annsSize()

Returns whether the annotation list size. This method is useful to check whether to create underlying structure or not (e.g., getAnns() creates objects if null initially). This delayed instantiation saves considerable memory on large ASTs.

Returns:

size of annotation list or getAnns().size(). If 0, no array is created.

hasAnn

boolean hasAnn()

Returns true when annsSize() has more than zero elements.

Returns:

hasAnn

<T> boolean hasAnn(Class<T> aClass)

Checks whether the term has any annotation of the given class type

Type Parameters:

T - type of annotation class

Parameters:

aClass - class to check

Returns:

whether there is an annotation of that kind or not

removeAnn

<T> boolean removeAnn(T annotation)

Removes a specific annotation, if present. If there are more than one instance of T, the first one is removed. That is, the underlying annotations as returned by getAnns() are checked in order using a.equals(annotation)

Type Parameters:

T - type of annotation

Parameters:

annotation - instance to remove

Returns:

whether the given ann has been removed or not

removeAnn

<T> void removeAnn(Class<T> aClass)

Removes all annotations of the specific class.

Type Parameters:

T - type of annotation

Parameters:

aClass - class to check