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/*******************************************************************************
* Copyright (c) 2009, 2017 Cloudsmith Inc. and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Cloudsmith Inc. - initial API and implementation
*******************************************************************************/
package org.eclipse.equinox.internal.p2.metadata.expression;
import java.util.Iterator;
import org.eclipse.equinox.p2.metadata.expression.IEvaluationContext;
import org.eclipse.equinox.p2.metadata.expression.IExpressionVisitor;
import org.eclipse.equinox.p2.metadata.index.IIndex;
import org.eclipse.equinox.p2.metadata.index.IIndexProvider;
/**
* Some kind of operation that is performed for each element of a collection. I.e.
* <code>x.<operation>(y | <expression&rt;)</code>
*/
public abstract class CollectionFilter extends Unary {
public static void appendProlog(StringBuffer bld, Variable rootVariable, Expression lhs, String operator) {
if (lhs != rootVariable) {
appendOperand(bld, rootVariable, lhs, PRIORITY_COLLECTION);
bld.append('.');
}
bld.append(operator);
bld.append('(');
}
public final LambdaExpression lambda;
protected CollectionFilter(Expression collection, LambdaExpression lambda) {
super(collection);
this.lambda = lambda;
}
@Override
public boolean accept(IExpressionVisitor visitor) {
return super.accept(visitor) && lambda.accept(visitor);
}
@Override
public int compareTo(Expression e) {
int cmp = super.compareTo(e);
if (cmp == 0)
cmp = lambda.compareTo(((CollectionFilter) e).lambda);
return cmp;
}
@Override
public boolean equals(Object o) {
return super.equals(o) && lambda.equals(((CollectionFilter) o).lambda);
}
@Override
public final Object evaluate(IEvaluationContext context) {
Iterator<?> lval = getInnerIterator(context);
context = lambda.prolog(context);
return evaluate(context, lval);
}
@Override
public final Iterator<?> evaluateAsIterator(IEvaluationContext context) {
Iterator<?> lval = getInnerIterator(context);
context = lambda.prolog(context);
return evaluateAsIterator(context, lval);
}
@Override
public void toString(StringBuffer bld, Variable rootVariable) {
appendProlog(bld, rootVariable, operand, getOperator());
appendOperand(bld, rootVariable, lambda, PRIORITY_LAMBDA);
bld.append(')');
}
@Override
public int hashCode() {
int result = 31 + operand.hashCode();
return 31 * result + lambda.hashCode();
}
@Override
public int getPriority() {
return PRIORITY_COLLECTION;
}
protected abstract Object evaluate(final IEvaluationContext context, Iterator<?> iterator);
protected Iterator<?> evaluateAsIterator(IEvaluationContext context, Iterator<?> iterator) {
throw new UnsupportedOperationException();
}
private transient IIndexProvider<?> lastIndexProvider;
private transient IIndex<?> lastIndex;
private IIndex<?> getIndex(Class<?> elementClass, IIndexProvider<?> indexProvider) {
if (lastIndexProvider == indexProvider)
return lastIndex;
for (String member : getIndexCandidateMembers(elementClass, lambda.getItemVariable(), lambda.getOperand())) {
IIndex<?> index = indexProvider.getIndex(member);
if (index != null)
lastIndex = index;
}
lastIndexProvider = indexProvider;
return lastIndex;
}
protected Iterator<?> getInnerIterator(IEvaluationContext context) {
Object collection = operand.evaluate(context);
if (collection instanceof Everything<?>) {
// Try to find an index
//
IIndexProvider<?> indexProvider = context.getIndexProvider();
if (indexProvider != null) {
Class<?> elementClass = ((Everything<?>) collection).getElementClass();
IIndex<?> index = getIndex(elementClass, indexProvider);
if (index != null) {
Iterator<?> indexed = index.getCandidates(context, lambda.getItemVariable(), lambda.getOperand());
if (indexed != null)
return indexed;
}
}
}
// No index. We need every element
if (collection instanceof IRepeatableIterator<?>)
return ((IRepeatableIterator<?>) collection).getCopy();
Iterator<?> itor = RepeatableIterator.create(collection);
if (operand instanceof Variable)
((Variable) operand).setValue(context, itor);
return itor;
}
@Override
int countAccessToEverything() {
return operand.countAccessToEverything() + lambda.countAccessToEverything();
}
}
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