com.sun.tools.xjc.reader.gbind
Class Element

java.lang.Object
  com.sun.tools.xjc.reader.gbind.Expression
      com.sun.tools.xjc.reader.gbind.Element

All Implemented Interfaces:

ElementSet, java.lang.Iterable<Element>

Direct Known Subclasses:

GElement, SinkNode, SourceNode

public abstract class Element
extends Expression
implements ElementSet

Expression that represents an alphabet of a regular language.

Since this package is about a regular expression over element declarations, this represents an XML element declaration (hence the name.) Element needs to be interned, meaning one Element per one tag name.

Implements ElementSet to represent a self.

Field Summary

(package private) java.util.Set<Element>	backEdges
(package private) java.util.Set<Element>	foreEdges Once we build a graph from Expression, we represent an edge e1 -> e2 by e1.foreEdges.contains(e2) and e2.backEdges.contains(e1).
(package private) Element	prevPostOrder Previous element in the DFS post-order traveral of the element graph.

Fields inherited from class com.sun.tools.xjc.reader.gbind.Expression

EPSILON

Fields inherited from interface com.sun.tools.xjc.reader.gbind.ElementSet

EMPTY_SET

Constructor Summary

protected

Element()

Method Summary

void	addNext(Element element) For each element in this set, adds an edge to the given element.
(package private) Element	assignDfsPostOrder(Element prev) Traverses the Element graph with DFS and set prevPostOrder.
(package private) void	buildDAG(ElementSet incoming) Builds up a DAG among Elements in this expression.
void	buildStronglyConnectedComponents(java.util.List<ConnectedComponent> ccs) Builds a set of strongly connected components and puts them all into the given set.
(package private) boolean	checkCutSet(ConnectedComponent cc, java.util.Set<Element> visited) Checks if the given ConnectedComponent forms a cut-set of a graph.
boolean	contains(ElementSet rhs) Doesn't have to be strict (it's OK for this method to return false when it's actually true) since this is used just for optimization.
boolean	hasSelfLoop()
(package private) boolean	isNullable() True of \epsilon \in L(exp)
(package private) boolean	isSink() True if this Element is SinkNode.
(package private) boolean	isSource() True if this Element is SourceNode.
java.util.Iterator<Element>	iterator() Deprecated. if you statically call this method, there's something wrong.
(package private) ElementSet	lastSet() Computes LAST(exp)

Methods inherited from class java.lang.Object

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

Field Detail

foreEdges

final java.util.Set<Element> foreEdges

Once we build a graph from Expression, we represent an edge e1 -> e2 by e1.foreEdges.contains(e2) and e2.backEdges.contains(e1).

backEdges

final java.util.Set<Element> backEdges

prevPostOrder

Element prevPostOrder

Previous element in the DFS post-order traveral of the element graph.

We use prevPostOrder==null as a check if the element is visted in DFS, so this chain terminates by a self-reference, not by having null. Set in assignDfsPostOrder(Element)

Constructor Detail

Element

protected Element()

Method Detail

lastSet

ElementSet lastSet()

Description copied from class: Expression

Computes LAST(exp)

Specified by:

lastSet in class Expression

isNullable

boolean isNullable()

Description copied from class: Expression

True of \epsilon \in L(exp)

Specified by:

isNullable in class Expression

isSource

boolean isSource()

True if this Element is SourceNode.

isSink

boolean isSink()

True if this Element is SinkNode.

buildDAG

void buildDAG(ElementSet incoming)

Description copied from class: Expression

Builds up a DAG among Elements in this expression.

Specified by:

buildDAG in class Expression

addNext

public void addNext(Element element)

Description copied from interface: ElementSet

For each element in this set, adds an edge to the given element.

Specified by:

addNext in interface ElementSet

contains

public boolean contains(ElementSet rhs)

Description copied from interface: ElementSet

Doesn't have to be strict (it's OK for this method to return false when it's actually true) since this is used just for optimization. (Erring on the other side is NG)

Specified by:

contains in interface ElementSet

iterator

public java.util.Iterator<Element> iterator()

Deprecated. if you statically call this method, there's something wrong.

Just to satisfy the ElementSet contract.

Specified by:

iterator in interface java.lang.Iterable<Element>

assignDfsPostOrder

Element assignDfsPostOrder(Element prev)

Traverses the Element graph with DFS and set prevPostOrder. Should be first invoked on the source node of the graph.

buildStronglyConnectedComponents

public void buildStronglyConnectedComponents(java.util.List<ConnectedComponent> ccs)

Builds a set of strongly connected components and puts them all into the given set.

hasSelfLoop

public boolean hasSelfLoop()

checkCutSet

final boolean checkCutSet(ConnectedComponent cc,
                          java.util.Set<Element> visited)

Checks if the given ConnectedComponent forms a cut-set of a graph.

Parameters:

visited - Used to keep track of visited nodes.

Returns:

true if it is indeed a cut-set. false if not.