/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 2001, 2002 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Xerces" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
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*
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 2001, International
* Business Machines, Inc., http://www.apache.org. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
package org.apache.xerces.impl.xs.models;
import org.apache.xerces.xni.QName;
import org.apache.xerces.impl.dtd.models.CMNode;
import org.apache.xerces.impl.xs.SchemaSymbols;
import org.apache.xerces.impl.xs.XSDeclarationPool;
import org.apache.xerces.impl.xs.XSComplexTypeDecl;
import org.apache.xerces.impl.xs.XSParticleDecl;
import org.apache.xerces.impl.xs.XSModelGroupImpl;
import org.apache.xerces.impl.xs.XSElementDecl;
import org.apache.xerces.impl.xs.models.*;
/**
* This class constructs content models for a given grammar.
*
* @author Elena Litani, IBM
* @author Sandy Gao, IBM
*
* @version $Id: CMBuilder.java,v 1.14 2002/11/08 15:55:31 sandygao Exp $
*/
public class CMBuilder {
// REVISIT: should update the decl pool to cache XSCM objects too
private XSDeclarationPool fDeclPool = null;
// It never changes, so a static member is good enough
private static XSEmptyCM fEmptyCM = new XSEmptyCM();
// needed for DFA construction
private int fLeafCount;
// needed for UPA
private int fParticleCount;
public CMBuilder() {
fDeclPool = null;
}
public CMBuilder(XSDeclarationPool pool) {
fDeclPool = pool;
}
public void setDeclPool(XSDeclarationPool declPool) {
fDeclPool = declPool;
}
/**
* Get content model for the a given type
*
* @param typeDecl get content model for which complex type
* @return a content model validator
*/
public XSCMValidator getContentModel(XSComplexTypeDecl typeDecl) {
// for complex type with empty or simple content,
// there is no content model validator
short contentType = typeDecl.getContentType();
if (contentType == XSComplexTypeDecl.CONTENTTYPE_SIMPLE ||
contentType == XSComplexTypeDecl.CONTENTTYPE_EMPTY) {
return null;
}
XSParticleDecl particle = (XSParticleDecl)typeDecl.getParticle();
// if the content is element only or mixed, but no particle
// is defined, return the empty content model
if (particle == null)
return fEmptyCM;
// if the content model contains "all" model group,
// we create an "all" content model, otherwise a DFA content model
XSCMValidator cmValidator = null;
if (particle.fType == XSParticleDecl.PARTICLE_MODELGROUP &&
((XSModelGroupImpl)particle.fValue).fCompositor == XSModelGroupImpl.MODELGROUP_ALL) {
cmValidator = createAllCM(particle);
}
else {
cmValidator = createDFACM(particle);
}
// if the validator returned is null, it means there is nothing in
// the content model, so we return the empty content model.
if (cmValidator == null)
cmValidator = fEmptyCM;
return cmValidator;
}
XSCMValidator createAllCM(XSParticleDecl particle) {
if (particle.fMaxOccurs == 0)
return null;
// get the model group, and add all children of it to the content model
XSModelGroupImpl group = (XSModelGroupImpl)particle.fValue;
// create an all content model. the parameter indicates whether
// the <all> itself is optional
XSAllCM allContent = new XSAllCM(particle.fMinOccurs == 0, group.fParticleCount);
for (int i = 0; i < group.fParticleCount; i++) {
// for all non-empty particles
if (group.fParticles[i].fType != XSParticleDecl.PARTICLE_EMPTY &&
group.fParticles[i].fMaxOccurs != 0)
// add the element decl to the all content model
allContent.addElement((XSElementDecl)group.fParticles[i].fValue,
group.fParticles[i].fMinOccurs == 0);
}
return allContent;
}
XSCMValidator createDFACM(XSParticleDecl particle) {
fLeafCount = 0;
fParticleCount = 0;
// convert particle tree to CM tree
CMNode node = buildSyntaxTree(particle);
if (node == null)
return null;
// build DFA content model from the CM tree
return new XSDFACM(node, fLeafCount);
}
// 1. convert particle tree to CM tree:
// 2. expand all occurrence values: a{n, unbounded} -> a, a, ..., a+
// a{n, m} -> a, a, ..., a?, a?, ...
// 3. convert model groups (a, b, c, ...) or (a | b | c | ...) to
// binary tree: (((a,b),c),...) or (((a|b)|c)|...)
// 4. make sure each leaf node (XSCMLeaf) has a distinct position
private CMNode buildSyntaxTree(XSParticleDecl particle) {
int maxOccurs = particle.fMaxOccurs;
int minOccurs = particle.fMinOccurs;
short type = particle.fType;
CMNode nodeRet = null;
if ((type == XSParticleDecl.PARTICLE_WILDCARD) ||
(type == XSParticleDecl.PARTICLE_ELEMENT)) {
// (task 1) element and wildcard particles should be converted to
// leaf nodes
// REVISIT: Make a clone of the leaf particle, so that if there
// are two references to the same group, we have two different
// leaf particles for the same element or wildcard decl.
// This is useful for checking UPA.
nodeRet = new XSCMLeaf(particle.fType, particle.fValue, fParticleCount++, fLeafCount++);
// (task 2) expand occurrence values
nodeRet = expandContentModel(nodeRet, minOccurs, maxOccurs);
}
else if (type == XSParticleDecl.PARTICLE_MODELGROUP) {
// (task 1,3) convert model groups to binary trees
XSModelGroupImpl group = (XSModelGroupImpl)particle.fValue;
CMNode temp = null;
// when the model group is a choice of more than one particles, but
// only one of the particle is not empty, (for example
// <choice>
// <sequence/>
// <element name="e"/>
// </choice>
// ) we can't not return that one particle ("e"). instead, we should
// treat such particle as optional ("e?").
// the following boolean variable is true when there are at least
// 2 non-empty children.
boolean twoChildren = false;
for (int i = 0; i < group.fParticleCount; i++) {
// first convert each child to a CM tree
temp = buildSyntaxTree(group.fParticles[i]);
// then combine them using binary operation
if (temp != null) {
if (nodeRet == null) {
nodeRet = temp;
}
else {
nodeRet = new XSCMBinOp(group.fCompositor, nodeRet, temp);
// record the fact that there are at least 2 children
twoChildren = true;
}
}
}
// (task 2) expand occurrence values
if (nodeRet != null) {
// when the group is "choice", there is only one non-empty
// child, and the group had more than one children, we need
// to create a zero-or-one (optional) node for the non-empty
// particle.
if (group.fCompositor == XSModelGroupImpl.MODELGROUP_CHOICE &&
!twoChildren && group.fParticleCount > 1) {
nodeRet = new XSCMUniOp(XSParticleDecl.PARTICLE_ZERO_OR_ONE, nodeRet);
}
nodeRet = expandContentModel(nodeRet, minOccurs, maxOccurs);
}
}
return nodeRet;
}
// 2. expand all occurrence values: a{n, unbounded} -> a, a, ..., a+
// a{n, m} -> a, a, ..., a?, a?, ...
// 4. make sure each leaf node (XSCMLeaf) has a distinct position
private CMNode expandContentModel(CMNode node,
int minOccurs, int maxOccurs) {
CMNode nodeRet = null;
if (minOccurs==1 && maxOccurs==1) {
nodeRet = node;
}
else if (minOccurs==0 && maxOccurs==1) {
//zero or one
nodeRet = new XSCMUniOp(XSParticleDecl.PARTICLE_ZERO_OR_ONE, node);
}
else if (minOccurs == 0 && maxOccurs==SchemaSymbols.OCCURRENCE_UNBOUNDED) {
//zero or more
nodeRet = new XSCMUniOp(XSParticleDecl.PARTICLE_ZERO_OR_MORE, node);
}
else if (minOccurs == 1 && maxOccurs==SchemaSymbols.OCCURRENCE_UNBOUNDED) {
//one or more
nodeRet = new XSCMUniOp(XSParticleDecl.PARTICLE_ONE_OR_MORE, node);
}
else if (maxOccurs == SchemaSymbols.OCCURRENCE_UNBOUNDED) {
// => a,a,..,a+
// create a+ node first, then put minOccurs-1 a's in front of it
// for the first time "node" is used, we don't need to make a copy
// and for other references to node, we make copies
nodeRet = new XSCMUniOp(XSParticleDecl.PARTICLE_ONE_OR_MORE, node);
for (int i=0; i < minOccurs-1; i++) {
// (task 4) we need to call copyNode here, so that we append
// an entire new copy of the node (a subtree). this is to ensure
// all leaf nodes have distinct position
nodeRet = new XSCMBinOp(XSModelGroupImpl.MODELGROUP_SEQUENCE,
copyNode(node), nodeRet);
}
}
else {
// {n,m} => a,a,a,...(a),(a),...
// first n a's, then m-n a?'s.
// copyNode is called, for the same reason as above
if (minOccurs > 0) {
nodeRet = node;
for (int i=0; i<minOccurs-1; i++) {
nodeRet = new XSCMBinOp(XSModelGroupImpl.MODELGROUP_SEQUENCE,
nodeRet, copyNode(node));
}
}
if (maxOccurs > minOccurs) {
node = new XSCMUniOp(XSParticleDecl.PARTICLE_ZERO_OR_ONE, node);
if (nodeRet == null) {
nodeRet = node;
}
else {
nodeRet = new XSCMBinOp(XSModelGroupImpl.MODELGROUP_SEQUENCE,
nodeRet, copyNode(node));
}
for (int i=minOccurs; i<maxOccurs-1; i++) {
nodeRet = new XSCMBinOp(XSModelGroupImpl.MODELGROUP_SEQUENCE,
nodeRet, copyNode(node));
}
}
}
return nodeRet;
}
// 4. make sure each leaf node (XSCMLeaf) has a distinct position
private CMNode copyNode(CMNode node) {
int type = node.type();
// for choice or sequence, copy the two subtrees, and combine them
if (type == XSModelGroupImpl.MODELGROUP_CHOICE ||
type == XSModelGroupImpl.MODELGROUP_SEQUENCE) {
XSCMBinOp bin = (XSCMBinOp)node;
node = new XSCMBinOp(type, copyNode(bin.getLeft()),
copyNode(bin.getRight()));
}
// for ?+*, copy the subtree, and put it in a new ?+* node
else if (type == XSParticleDecl.PARTICLE_ZERO_OR_MORE ||
type == XSParticleDecl.PARTICLE_ONE_OR_MORE ||
type == XSParticleDecl.PARTICLE_ZERO_OR_ONE) {
XSCMUniOp uni = (XSCMUniOp)node;
node = new XSCMUniOp(type, copyNode(uni.getChild()));
}
// for element/wildcard (leaf), make a new leaf node,
// with a distinct position
else if (type == XSParticleDecl.PARTICLE_ELEMENT ||
type == XSParticleDecl.PARTICLE_WILDCARD) {
XSCMLeaf leaf = (XSCMLeaf)node;
node = new XSCMLeaf(leaf.type(), leaf.getLeaf(), leaf.getParticleId(), fLeafCount++);
}
return node;
}
}