com.sun.xml.bind.v2.schemagen.Tree Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package com.sun.xml.bind.v2.schemagen;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import com.sun.xml.bind.v2.schemagen.xmlschema.ContentModelContainer;
import com.sun.xml.bind.v2.schemagen.xmlschema.Particle;
import com.sun.xml.bind.v2.schemagen.xmlschema.TypeDefParticle;
import com.sun.xml.bind.v2.schemagen.xmlschema.Occurs;
/**
* Normalized representation of the content model.
*
*
* This is built from bottom up so that we can eliminate redundant constructs,
* and produce the most concise content model definition in XML.
*
* @author Kohsuke Kawaguchi
*/
abstract class Tree {
/**
* Returns "T?" from "T".
*
* @param really
* if false this method becomes no-op. This is so that we can write
* the caller fluently.
*/
Tree makeOptional(boolean really) {
return really?new Optional(this) :this;
}
/**
* Returns "T+" from "T".
*
* @param really
* if false this method becomes no-op. This is so that we can write
* the caller fluently.
*/
Tree makeRepeated(boolean really) {
return really?new Repeated(this) :this;
}
/**
* Returns a group tree.
*/
static Tree makeGroup(GroupKind kind, List children ) {
// pointless binary operator.
if(children.size()==1)
return children.get(0);
// we neither have epsilon or emptySet, so can't handle children.length==0 nicely
// eliminated nesting groups of the same kind.
// this is where binary tree would have shined.
List normalizedChildren = new ArrayList(children.size());
for (Tree t : children) {
if (t instanceof Group) {
Group g = (Group) t;
if(g.kind==kind) {
normalizedChildren.addAll(Arrays.asList(g.children));
continue;
}
}
normalizedChildren.add(t);
}
return new Group(kind,normalizedChildren.toArray(new Tree[normalizedChildren.size()]));
}
/**
* Returns true if this tree accepts empty sequence.
*/
abstract boolean isNullable();
/**
* Returns true if the top node of this tree can
* appear as a valid top-level content model in XML Schema.
*
*
* Model groups and occurrences that have model group in it can.
*/
boolean canBeTopLevel() { return false; }
/**
* Writes out the content model.
*
* Normall this runs recursively until we write out the whole content model.
*/
protected abstract void write(ContentModelContainer parent, boolean isOptional, boolean repeated);
/**
* Writes inside the given complex type.
*/
protected void write(TypeDefParticle ct) {
if(canBeTopLevel())
write(ct._cast(ContentModelContainer.class), false, false);
else
// need a dummy wrapper
new Group(GroupKind.SEQUENCE,this).write(ct);
}
/**
* Convenience method to write occurrence constraints.
*/
protected final void writeOccurs(Occurs o, boolean isOptional, boolean repeated) {
if(isOptional)
o.minOccurs(0);
if(repeated)
o.maxOccurs("unbounded");
}
/**
* Represents a terminal tree node, such as element, wildcard, etc.
*/
abstract static class Term extends Tree {
boolean isNullable() {
return false;
}
}
/**
* "T?"
*/
private static final class Optional extends Tree {
private final Tree body;
private Optional(Tree body) {
this.body = body;
}
@Override
boolean isNullable() {
return true;
}
@Override
Tree makeOptional(boolean really) {
return this;
}
@Override
protected void write(ContentModelContainer parent, boolean isOptional, boolean repeated) {
body.write(parent,true,repeated);
}
}
/**
* "T+"
*/
private static final class Repeated extends Tree {
private final Tree body;
private Repeated(Tree body) {
this.body = body;
}
@Override
boolean isNullable() {
return body.isNullable();
}
@Override
Tree makeRepeated(boolean really) {
return this;
}
@Override
protected void write(ContentModelContainer parent, boolean isOptional, boolean repeated) {
body.write(parent,isOptional,true);
}
}
/**
* "S|T", "S,T", and "S&T".
*/
private static final class Group extends Tree {
private final GroupKind kind;
private final Tree[] children;
private Group(GroupKind kind, Tree... children) {
this.kind = kind;
this.children = children;
}
@Override
boolean canBeTopLevel() {
return true;
}
@Override
boolean isNullable() {
if(kind== GroupKind.CHOICE) {
for (Tree t : children) {
if(t.isNullable())
return true;
}
return false;
} else {
for (Tree t : children) {
if(!t.isNullable())
return false;
}
return true;
}
}
@Override
protected void write(ContentModelContainer parent, boolean isOptional, boolean repeated) {
Particle c = kind.write(parent);
writeOccurs(c,isOptional,repeated);
for (Tree child : children) {
child.write(c,false,false);
}
}
}
}