| /******************************************************************************* |
| * Copyright (c) 2009, 2017 Cloudsmith Inc. and others. |
| * |
| * This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License 2.0 |
| * which accompanies this distribution, and is available at |
| * https://www.eclipse.org/legal/epl-2.0/ |
| * |
| * SPDX-License-Identifier: EPL-2.0 |
| * |
| * 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>)</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(); |
| } |
| } |