com.sun.msv.reader.xmlschema.RedefinableDeclState Maven / Gradle / Ivy
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package com.sun.msv.reader.xmlschema;
import com.sun.msv.grammar.ReferenceContainer;
import com.sun.msv.grammar.xmlschema.RedefinableExp;
import com.sun.msv.reader.ExpressionWithChildState;
/** state that parses redefinable declaration.
*
* "Declarations" are attribute, element, complexType, group, and attributeGroup.
* simpleType is treated differently.
*
*
* When this state is used under states other than RedefineState, this class
* doesn't do anything. When used under RedefineState, this class does several
* tricks to make redefinition easy.
*
*
* Redefinition is done in the following steps.
*
*
Step.1
*
* First, say redefinition of declaration "ABC" is found, "ABC" has already
* defined once and it is
*
*
* - referenced from {@link ReferenceContainer} by name, and
*
- referenced from other expressions directly.
*
*
* 
*
* Step.2
*
* In startSelf method, this class clones the current definition, and updates
* ReferenceContainer to point to the cloned definition (right side).
*
* 
*
*
* Note that other expressions hold direct reference to the original definition
* (left side), and these references are not affected by this update.
*
*
Step.3
*
* Body of redefinition is parsed and corresponding expression is created by
* derived class. This step is done no differently.
*
*
* Since ReferenceContainer has updated, any reference to this expression found
* during this step is bound to the cloned definition. This self reference usually
* happens.
*
*
Step.4
*
* After the body of redefinition is parsed, the original definition (left side)
* is updated by using new expression.
*
* 
*
*
* From now on, redefinition becomes visible to all expressions that hold
* direct reference to the original definition. The cloned definition is kept
* as-is so that any self reference found in the body will be maintained correctly.
*
*
Step.5
*
* Finally, ReferenceContainer is updated again to point to the updated definition.
* Therefore successive reference to "ABC" will be bound to the updated definition.
* Cloned old definition is kept as-is.
*
* 
*/
public abstract class RedefinableDeclState extends ExpressionWithChildState {
protected boolean isGlobal() {
return parentState instanceof GlobalDeclState;
}
/**
* Returns true if this declaration is a redefinition of an
* existing declaration.
*/
protected boolean isRedefine() {
return parentState instanceof RedefineState;
}
/**
* keeps a reference to previous declaration.
*
* this field is used only when in redefine mode. Derived class should use
* this declaration instead of getting one from ReferenceContainer through
* XMLSchemaSchema.
*/
protected RedefinableExp oldDecl;
/** gets appropriate ReferenceContainer to store this declaration. */
protected abstract ReferenceContainer getContainer();
protected void startSelf() {
super.startSelf();
if( isRedefine() ) {
final XMLSchemaReader reader = (XMLSchemaReader)this.reader;
String name = startTag.getAttribute("name");
if( name==null )
// ignore this error just for now.
// this error will be reported in annealExpression method.
return;
oldDecl = (RedefinableExp)getContainer()._get(name);
if(oldDecl==null) {
reader.reportError( XMLSchemaReader.ERR_REDEFINE_UNDEFINED, name );
// recover by creating a dummy object.
oldDecl = (RedefinableExp)getContainer()._getOrCreate(name);
return;
}
getContainer().redefine( name, oldDecl.getClone() );
}
}
protected void endSelf() {
if( oldDecl!=null )
getContainer().redefine( oldDecl.name, oldDecl );
super.endSelf();
}
}