/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-2015 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.exist.xquery;
import java.util.ArrayList;
import java.util.List;
/**
* Basic implementation of the {@link ExpressionVisitor} interface.
* This implementation will traverse a PathExpr object if it wraps
* around a single other expression. All other methods are empty.
*
* @author wolf
*
*/
public class BasicExpressionVisitor implements ExpressionVisitor {
@Override
public void visit(Expression expression) {
processWrappers(expression);
}
@Override
public void visitCastExpr(CastExpression expression) {
//Nothing to do
}
/**
* Default implementation will traverse a PathExpr
* if it is just a wrapper around another single
* expression object.
*/
@Override
public void visitPathExpr(PathExpr expression) {
if (expression.getLength() == 1) {
final Expression next = expression.getExpression(0);
next.accept(this);
}
}
@Override
public void visitFunctionCall(FunctionCall call) {
// Nothing to do
}
@Override
public void visitGeneralComparison(GeneralComparison comparison) {
//Nothing to do
}
@Override
public void visitUnionExpr(Union union) {
//Nothing to do
}
@Override
public void visitIntersectionExpr(Intersect intersect) {
//Nothing to do
}
@Override
public void visitAndExpr(OpAnd and) {
//Nothing to do
}
@Override
public void visitOrExpr(OpOr or) {
//Nothing to do
}
@Override
public void visitLocationStep(LocationStep locationStep) {
//Nothing to do
}
@Override
public void visitFilteredExpr(FilteredExpression filtered) {
//Nothing to do
}
@Override
public void visitPredicate(Predicate predicate) {
//Nothing to do
}
@Override
public void visitVariableReference(VariableReference ref) {
//Nothing to do
}
@Override
public void visitVariableDeclaration(VariableDeclaration decl) {
// Nothing to do
}
protected void processWrappers(Expression expr) {
if (expr instanceof Atomize ||
expr instanceof DynamicCardinalityCheck ||
expr instanceof DynamicNameCheck ||
expr instanceof DynamicTypeCheck ||
expr instanceof UntypedValueCheck) {
expr.accept(this);
}
}
public static LocationStep findFirstStep(Expression expr) {
if (expr instanceof LocationStep)
{return (LocationStep) expr;}
final FirstStepVisitor visitor = new FirstStepVisitor();
expr.accept(visitor);
return visitor.firstStep;
}
public static List<LocationStep> findLocationSteps(Expression expr) {
final List<LocationStep> steps = new ArrayList<LocationStep>(5);
if (expr instanceof LocationStep) {
steps.add((LocationStep)expr);
return steps;
}
expr.accept(
new BasicExpressionVisitor() {
@Override
public void visitPathExpr(PathExpr expression) {
for (int i = 0; i < expression.getLength(); i++) {
final Expression next = expression.getExpression(i);
next.accept(this);
if (steps.size() - 1 != i) {
steps.add(null);
}
}
}
@Override
public void visitLocationStep(LocationStep locationStep) {
steps.add(locationStep);
}
}
);
return steps;
}
public static VariableReference findVariableRef(Expression expr) {
final VariableRefVisitor visitor = new VariableRefVisitor();
expr.accept(visitor);
return visitor.ref;
}
@Override
public void visitForExpression(ForExpr forExpr) {
//Nothing to do
}
@Override
public void visitLetExpression(LetExpr letExpr) {
//Nothing to do
}
@Override
public void visitOrderByClause(OrderByClause orderBy) {
// Nothing to do
}
@Override
public void visitGroupByClause(GroupByClause groupBy) {
// Nothing to do
}
@Override
public void visitWhereClause(WhereClause where) {
// Nothing to do
}
@Override
public void visitBuiltinFunction(Function function) {
//Nothing to do
}
@Override
public void visitUserFunction(UserDefinedFunction function) {
//Nothing to do
}
@Override
public void visitConditional(ConditionalExpression conditional) {
//Nothing to do
}
@Override
public void visitTryCatch(TryCatchExpression conditional) {
//Nothing to do
}
@Override
public void visitDocumentConstructor(DocumentConstructor constructor) {
// Nothing to do
}
public void visitElementConstructor(ElementConstructor constructor) {
//Nothing to do
}
@Override
public void visitTextConstructor(DynamicTextConstructor constructor) {
//Nothing to do
}
@Override
public void visitAttribConstructor(AttributeConstructor constructor) {
//Nothing to do
}
@Override
public void visitAttribConstructor(DynamicAttributeConstructor constructor) {
//Nothing to do
}
@Override
public void visitSimpleMapOperator(OpSimpleMap simpleMap) {
// Nothing to do
}
public static class FirstStepVisitor extends BasicExpressionVisitor {
private LocationStep firstStep = null;
public LocationStep getFirstStep() {
return firstStep;
}
@Override
public void visitLocationStep(LocationStep locationStep) {
firstStep = locationStep;
}
}
public static class VariableRefVisitor extends BasicExpressionVisitor {
private VariableReference ref = null;
@Override
public void visitVariableReference(VariableReference ref) {
this.ref = ref;
}
@Override
public void visitPathExpr(PathExpr expression) {
for (int i = 0; i < expression.getLength(); i++) {
final Expression next = expression.getExpression(i);
next.accept(this);
}
}
}
}