| /* |
| * Created on Jul 14, 2003 |
| */ |
| /* |
| * The Apache Software License, Version 1.1 |
| * |
| * Copyright (c) 2002-2003 The Apache Software Foundation. All rights |
| * reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. The end-user documentation included with the redistribution, |
| * if any, must include the following acknowledgment: |
| * "This product includes software developed by the |
| * Apache Software Foundation (http://www.apache.org/)." |
| * Alternately, this acknowledgment may appear in the software itself, |
| * if and wherever such third-party acknowledgments normally appear. |
| * |
| * 4. The names "Xalan" and "Apache Software Foundation" must |
| * not be used to endorse or promote products derived from this |
| * software without prior written permission. For written |
| * permission, please contact apache@apache.org. |
| * |
| * 5. Products derived from this software may not be called "Apache", |
| * nor may "Apache" appear in their name, without prior written |
| * permission of the Apache Software Foundation. |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR |
| * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
| * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Apache Software Foundation and was |
| * originally based on software copyright (c) 2002, International |
| * Business Machines Corporation., http://www.ibm.com. For more |
| * information on the Apache Software Foundation, please see |
| * <http://www.apache.org/>. |
| */ |
| package org.apache.xpath; |
| |
| import org.apache.xpath.expression.Expr; |
| import org.apache.xpath.expression.NodeTest; |
| import org.apache.xpath.expression.OperatorExpr; |
| import org.apache.xpath.expression.PathExpr; |
| import org.apache.xpath.expression.StepExpr; |
| |
| /** |
| * A collection of utility methods for XPath. |
| * @author <a href="mailto:villard@us.ibm.com">Lionel Villard</a> |
| * @version $Id$ |
| */ |
| public class XPath20Utilities |
| { |
| |
| /** |
| * Return true whether the specified expression matches document node. |
| * The test is performed statically, therefore there is no guarantee |
| * that the expression will indeed match the document node at runtime. |
| * (example: node()). |
| * @param Expr |
| * @return boolean |
| */ |
| static public boolean isMatchDocumentNode(Expr expr) |
| { |
| // TODO: patterns are not supported by the XPath API yet |
| // it means that pattern may be embedded in sequence |
| boolean result; |
| try |
| { |
| switch (expr.getExprType()) |
| { |
| case Expr.SEQUENCE_EXPR : |
| OperatorExpr op = (OperatorExpr) expr; |
| switch (op.getOperatorType()) |
| { |
| case OperatorExpr.COMMA : |
| |
| if (op.getOperandCount() == 1) |
| { |
| result = isMatchDocumentNode(op.getOperand(0)); |
| } else |
| { |
| result = false; |
| } |
| break; |
| case OperatorExpr.UNION_COMBINE : |
| result = false; |
| for (int i = op.getOperandCount() - 1; i >= 0; i--) |
| { |
| if (isMatchDocumentNode(op.getOperand(i))) |
| { |
| result = true; |
| break; |
| } |
| } |
| break; |
| default : |
| result = false; |
| } |
| break; |
| case Expr.PATH_EXPR : |
| PathExpr p = (PathExpr) expr; |
| // TODO: revisit after implementation of fn:root(...)=> operandCount == 1 |
| result = |
| (p.isAbsolute() && p.getOperandCount() == 0) // '/' |
| || (p.getOperandCount() == 1 && isMatchDocumentNode(p.getOperand(0))); |
| |
| break; |
| case Expr.STEP : |
| StepExpr s = (StepExpr) expr; |
| try |
| { |
| result = |
| s.getNodeTest().isKindTest() |
| && s.getNodeTest().getKindTest() |
| == NodeTest.ANY_KIND_TEST; |
| } catch (XPath20Exception e) |
| { |
| // impossible |
| result = false; |
| } |
| break; |
| |
| default : |
| result = false; |
| } |
| } catch (XPath20Exception e) |
| { |
| // Bug |
| e.printStackTrace(); |
| result = false; |
| } |
| return result; |
| } |
| |
| /** |
| * Returns true whenever the specified expression is a |
| * <em>singleton sequence</em> (a sequence with only one item). |
| */ |
| public static boolean isSingletonSequence(Expr e) |
| { |
| return e != null && e.getExprType() == Expr.SEQUENCE_EXPR |
| && ((OperatorExpr) e).getOperandCount() == 1; |
| } |
| |
| } |