antlraux.context
Class Scope

java.lang.Object
  |
  +--antlraux.context.Scope

public class Scope

extends java.lang.Object

This is the class tha modelizes scopes.

Scopes admit data in the form of instances of Declaration.

Usually scopes are represented as instances of Hashtable containing instances of Declaration, and organized in a pile.

This implementation is slightly different.

Firstly, the scope's hashtables' elements are linked lists instead of simple Declarations, so several elements with the same name are allowed on each tabe's position. This is more flexible than having just one declaration per position, allowing for example inserting several method declarations with the same name in a class scope (thus making polymorphism easier). The counterpoint is that now the search methods return a linked list instead of a single element - several helping methods ( searchFirst(String), searchFirstLocally(String), searchFirst(int) and searchFirstLocally(int)) have been included to ease this issue.

Other difference between this implementation of scopes is scope organization. Instead of having an explicit pile of scopes, the pile is implicit in this case. This is achieved simply making every Scope know its "father scope". In other words, each "method scope" will have to know the scope of the class that holds the method, etc. A root ("global") scope will have null as father.

Finally, the declarations are organized in two different ways:

• Declarations are sorted by name (the usual manner)
• Declarations are also sorted by "tag"

A tag is an integuer which codes the "type" of a declaration. We don't mean here if the declaration is "integuer" or "float"; there's the Declaration.type field for that. The tag says wether a declaration is a "class", a "parameter", a "method", etc.

This two types allow more powerful search techniques. For example, you can ask for "all the elements named 'foo' in a class scope", but you could also ask for "all the attributes of the class".

There are two ways of working with Scope. The first one is using the Context class. This class has facilities for authomatically checking scope closing.

The other option is not using Context, and write subclasses of Scope (like GlobalScope, ClassScope, MethodScope, etc). Override insert(Declaration) to perform insertion checks and check the opening on every constructor (see if the father scope allows "this" as a child scope)

Author:

Enrique José García Cota

See Also:

Context, Declaration

Field Summary

protected Scope	father The scope's father.
protected java.lang.String	name The name of a scope is just a "caption", that will be used for most printing procedures.
protected java.util.Hashtable	namesTable The scope's set of declarations, hashed by name.
protected int	tag This integer needed on every Scope constructor represents a type of scope.
protected java.util.Hashtable	tagsTable The scope's set of declarations, hashed by tag.

Constructor Summary

Scope(int tag, java.lang.String name)
Constructor that sets tag and name

Scope(int tag, java.lang.String name, Scope father)
Constructor that sets tag, name and father

Method Summary

void	addDeclarations(java.util.LinkedList list) It adds the declarations contained in "list" to this scope.
Scope	getFather() Accessor for father
java.lang.String	getName() Accessor for name
int	getTag() Accessor for tag
void	insert(Declaration d) Inserts a new Declaration
java.util.LinkedList	searchAll(int tag) It calls searchAllLocally(int) with tag as param and, if nothing found, it continues with the father, the father of the father, etc.
java.util.LinkedList	searchAll(int tag, java.lang.String name) It calls searchAllLocally(int, String) with tag as param and, if nothing found, it continues with the scope's father, the father of the father, etc.
java.util.LinkedList	searchAll(java.lang.String name) It calls searchAllLocally(String) with "name" as param and, if nothing found, it continues with the father, the father of the father, etc.
java.util.LinkedList	searchAllLocally(int tag) Searches in current scope every Declaration tagged like "tag"
java.util.LinkedList	searchAllLocally(int tag, java.lang.String name) Searches in current scope every Declaration tagged like "tag" and named like "name"
java.util.LinkedList	searchAllLocally(java.lang.String name) Searches in current scope every Declaration named "name"
Declaration	searchFirst(int tag) It calls searchFirstLocally(int) with "tag" as param and, if nothing found, it continues with the father, the father of the father, etc.
Declaration	searchFirst(int tag, java.lang.String name) It calls searchFirstLocally(int,String) with "tag" and "name" as params and, if nothing found, it continues with the scope's father, the father of the father, etc.
Declaration	searchFirst(java.lang.String name) It calls searchFirstLocally(String) with "name" as param and, if nothing found, it continues with the father, the father of the father, etc.
Declaration	searchFirstLocally(int tag) Searches in current scope the first (last inserted) Declaration with a tag==tag
Declaration	searchFirstLocally(int tag, java.lang.String name) Searches in current scope the first (last inserted) Declaration with a tag==tag AND name==name
Declaration	searchFirstLocally(java.lang.String name) Searches in current scope the first (last inserted) Declaration named "name"
void	setFather(Scope s) Accessor for father
void	setName(java.lang.String s) Accessor for name
void	setTag(int i) Accessor for tag
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

father

protected Scope father

The scope's father.

name

protected java.lang.String name

The name of a scope is just a "caption", that will be used for most printing procedures. It is desirable guiving an appropiate name to each Scope. For example, the global scope should be called "global", or "root", while class Foo's scope name should look like "class Foo".

tag

protected int tag

This integer needed on every Scope constructor represents a type of scope. This is, it codes if current scope is global scope, class scope, method scope, etc. It is very usefull for performing scope closing checks.

namesTable

protected java.util.Hashtable namesTable

The scope's set of declarations, hashed by name.

tagsTable

protected java.util.Hashtable tagsTable

The scope's set of declarations, hashed by tag.

Constructor Detail

Scope

public Scope(int tag,
             java.lang.String name)

Constructor that sets tag and name

Scope

public Scope(int tag,
             java.lang.String name,
             Scope father)

Constructor that sets tag, name and father

Method Detail

getName

public java.lang.String getName()

Accessor for name

getTag

public int getTag()

Accessor for tag

getFather

public Scope getFather()

Accessor for father

setName

public void setName(java.lang.String s)

Accessor for name

setTag

public void setTag(int i)

Accessor for tag

setFather

public void setFather(Scope s)

Accessor for father

insert

public void insert(Declaration d)
            throws ContextException

Inserts a new Declaration

Parameters:

d - the Declaration that is going to be inserted in the scope.

Throws:

ContextException - if could not insert d. (Actually default implementation of insert will never throw it, but subclasses may do)

searchFirstLocally

public Declaration searchFirstLocally(int tag)

Searches in current scope the first (last inserted) Declaration with a tag==tag

Parameters:

tag - the tag of the Declaration being searched

Returns:

declaration whose tag matches "tag" or null if none found

searchFirstLocally

public Declaration searchFirstLocally(java.lang.String name)

Searches in current scope the first (last inserted) Declaration named "name"

Parameters:

name - the name of the Declaration being searched

Returns:

a declaration whose name matches ("name") or null if none found

searchFirstLocally

public Declaration searchFirstLocally(int tag,
                                      java.lang.String name)

Searches in current scope the first (last inserted) Declaration with a tag==tag AND name==name

Parameters:

tag - the tag of the Declaration being searched

name - the name of the Declaration being searched

Returns:

a declaration wose tag matches "tag" and name matches "name". if there are several matching tags in the scope, it is recommended to use searchAllLocally(int, String)

searchFirst

public Declaration searchFirst(int tag)

It calls searchFirstLocally(int) with "tag" as param and, if nothing found, it continues with the father, the father of the father, etc.

Parameters:

tag - the searched Declaration's tag

Returns:

a declaration whose tag matches "tag" or null if none found

searchFirst

public Declaration searchFirst(java.lang.String name)

It calls searchFirstLocally(String) with "name" as param and, if nothing found, it continues with the father, the father of the father, etc.

Parameters:

name - the searched Declaration's name

Returns:

a declaration whose name matches "name" or null if none found

searchFirst

public Declaration searchFirst(int tag,
                               java.lang.String name)

It calls searchFirstLocally(int,String) with "tag" and "name" as params and, if nothing found, it continues with the scope's father, the father of the father, etc.

Parameters:

name - the searched Declaration's name

tag - the searched Declaration's tag

Returns:

a declaration whose name matches "name", and whose tag matches "tag", or null if none found

searchAllLocally

public java.util.LinkedList searchAllLocally(java.lang.String name)

Searches in current scope every Declaration named "name"

Parameters:

name - the name of the Declarations being searched

Returns:

a list of declarations whose name matches ("name") or null if none found

searchAllLocally

public java.util.LinkedList searchAllLocally(int tag)

Searches in current scope every Declaration tagged like "tag"

Parameters:

tag - the tag of the Declarations being searched

Returns:

a list of declarations whose tag matches "tag" or null if none found

searchAllLocally

public java.util.LinkedList searchAllLocally(int tag,
                                             java.lang.String name)

Searches in current scope every Declaration tagged like "tag" and named like "name"

Parameters:

tag - the tag of the Declarations being searched

name - the name of the Declarations being searched

Returns:

a list of declarations whose tag matches "tag" or null if none found

searchAll

public java.util.LinkedList searchAll(java.lang.String name)

It calls searchAllLocally(String) with "name" as param and, if nothing found, it continues with the father, the father of the father, etc. This is the most powerfull (and slowest) search method.

Parameters:

name - the searched Declaration's name

Returns:

a list of declarations whose name matches "name" or null if none found

searchAll

public java.util.LinkedList searchAll(int tag)

It calls searchAllLocally(int) with tag as param and, if nothing found, it continues with the father, the father of the father, etc.

Parameters:

tag - the searched Declarations' tag

Returns:

a list of declarations tagged like "tag" or null if none found

searchAll

public java.util.LinkedList searchAll(int tag,
                                      java.lang.String name)

It calls searchAllLocally(int, String) with tag as param and, if nothing found, it continues with the scope's father, the father of the father, etc.

Parameters:

tag - the searched Declarations' tag

name - the searched Declarations' name

Returns:

a list of declarations tagged like "tag" and named like "name" or null if none found

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

addDeclarations

public void addDeclarations(java.util.LinkedList list)
                     throws ContextException

It adds the declarations contained in "list" to this scope.

Throws:

ContextException - if an error ocurrs (never by default, but subclasses may want to)