| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| /* |
| * $Id$ |
| */ |
| package org.apache.xpath; |
| |
| import javax.xml.transform.ErrorListener; |
| import javax.xml.transform.TransformerException; |
| |
| import org.apache.xalan.res.XSLMessages; |
| import org.apache.xml.dtm.DTM; |
| import org.apache.xml.dtm.DTMIterator; |
| import org.apache.xml.utils.XMLString; |
| import org.apache.xpath.objects.XNodeSet; |
| import org.apache.xpath.objects.XObject; |
| import org.apache.xpath.res.XPATHErrorResources; |
| |
| import org.xml.sax.ContentHandler; |
| |
| /** |
| * This abstract class serves as the base for all expression objects. An |
| * Expression can be executed to return a {@link org.apache.xpath.objects.XObject}, |
| * normally has a location within a document or DOM, can send error and warning |
| * events, and normally do not hold state and are meant to be immutable once |
| * construction has completed. An exception to the immutibility rule is iterators |
| * and walkers, which must be cloned in order to be used -- the original must |
| * still be immutable. |
| */ |
| public abstract class Expression implements java.io.Serializable, ExpressionNode, XPathVisitable |
| { |
| static final long serialVersionUID = 565665869777906902L; |
| /** |
| * The location where this expression was built from. Need for diagnostic |
| * messages. May be null. |
| * @serial |
| */ |
| private ExpressionNode m_parent; |
| |
| /** |
| * Tell if this expression or it's subexpressions can traverse outside |
| * the current subtree. |
| * |
| * @return true if traversal outside the context node's subtree can occur. |
| */ |
| public boolean canTraverseOutsideSubtree() |
| { |
| return false; |
| } |
| |
| // /** |
| // * Set the location where this expression was built from. |
| // * |
| // * |
| // * @param locator the location where this expression was built from, may be |
| // * null. |
| // */ |
| // public void setSourceLocator(SourceLocator locator) |
| // { |
| // m_slocator = locator; |
| // } |
| |
| /** |
| * Execute an expression in the XPath runtime context, and return the |
| * result of the expression. |
| * |
| * |
| * @param xctxt The XPath runtime context. |
| * @param currentNode The currentNode. |
| * |
| * @return The result of the expression in the form of a <code>XObject</code>. |
| * |
| * @throws javax.xml.transform.TransformerException if a runtime exception |
| * occurs. |
| */ |
| public XObject execute(XPathContext xctxt, int currentNode) |
| throws javax.xml.transform.TransformerException |
| { |
| |
| // For now, the current node is already pushed. |
| return execute(xctxt); |
| } |
| |
| /** |
| * Execute an expression in the XPath runtime context, and return the |
| * result of the expression. |
| * |
| * |
| * @param xctxt The XPath runtime context. |
| * @param currentNode The currentNode. |
| * @param dtm The DTM of the current node. |
| * @param expType The expanded type ID of the current node. |
| * |
| * @return The result of the expression in the form of a <code>XObject</code>. |
| * |
| * @throws javax.xml.transform.TransformerException if a runtime exception |
| * occurs. |
| */ |
| public XObject execute( |
| XPathContext xctxt, int currentNode, DTM dtm, int expType) |
| throws javax.xml.transform.TransformerException |
| { |
| |
| // For now, the current node is already pushed. |
| return execute(xctxt); |
| } |
| |
| /** |
| * Execute an expression in the XPath runtime context, and return the |
| * result of the expression. |
| * |
| * |
| * @param xctxt The XPath runtime context. |
| * |
| * @return The result of the expression in the form of a <code>XObject</code>. |
| * |
| * @throws javax.xml.transform.TransformerException if a runtime exception |
| * occurs. |
| */ |
| public abstract XObject execute(XPathContext xctxt) |
| throws javax.xml.transform.TransformerException; |
| |
| /** |
| * Execute an expression in the XPath runtime context, and return the |
| * result of the expression, but tell that a "safe" object doesn't have |
| * to be returned. The default implementation just calls execute(xctxt). |
| * |
| * |
| * @param xctxt The XPath runtime context. |
| * @param destructiveOK true if a "safe" object doesn't need to be returned. |
| * |
| * @return The result of the expression in the form of a <code>XObject</code>. |
| * |
| * @throws javax.xml.transform.TransformerException if a runtime exception |
| * occurs. |
| */ |
| public XObject execute(XPathContext xctxt, boolean destructiveOK) |
| throws javax.xml.transform.TransformerException |
| { |
| return execute(xctxt); |
| } |
| |
| |
| /** |
| * Evaluate expression to a number. |
| * |
| * |
| * @param xctxt The XPath runtime context. |
| * @return The expression evaluated as a double. |
| * |
| * @throws javax.xml.transform.TransformerException |
| */ |
| public double num(XPathContext xctxt) |
| throws javax.xml.transform.TransformerException |
| { |
| return execute(xctxt).num(); |
| } |
| |
| /** |
| * Evaluate expression to a boolean. |
| * |
| * |
| * @param xctxt The XPath runtime context. |
| * @return false |
| * |
| * @throws javax.xml.transform.TransformerException |
| */ |
| public boolean bool(XPathContext xctxt) |
| throws javax.xml.transform.TransformerException |
| { |
| return execute(xctxt).bool(); |
| } |
| |
| /** |
| * Cast result object to a string. |
| * |
| * |
| * @param xctxt The XPath runtime context. |
| * @return The string this wraps or the empty string if null |
| * |
| * @throws javax.xml.transform.TransformerException |
| */ |
| public XMLString xstr(XPathContext xctxt) |
| throws javax.xml.transform.TransformerException |
| { |
| return execute(xctxt).xstr(); |
| } |
| |
| /** |
| * Tell if the expression is a nodeset expression. In other words, tell |
| * if you can execute {@link #asNode(XPathContext) asNode} without an exception. |
| * @return true if the expression can be represented as a nodeset. |
| */ |
| public boolean isNodesetExpr() |
| { |
| return false; |
| } |
| |
| /** |
| * Return the first node out of the nodeset, if this expression is |
| * a nodeset expression. |
| * @param xctxt The XPath runtime context. |
| * @return the first node out of the nodeset, or DTM.NULL. |
| * |
| * @throws javax.xml.transform.TransformerException |
| */ |
| public int asNode(XPathContext xctxt) |
| throws javax.xml.transform.TransformerException |
| { |
| DTMIterator iter = execute(xctxt).iter(); |
| return iter.nextNode(); |
| } |
| |
| /** |
| * Given an select expression and a context, evaluate the XPath |
| * and return the resulting iterator. |
| * |
| * @param xctxt The execution context. |
| * @param contextNode The node that "." expresses. |
| * |
| * |
| * @return A valid DTMIterator. |
| * @throws TransformerException thrown if the active ProblemListener decides |
| * the error condition is severe enough to halt processing. |
| * |
| * @throws javax.xml.transform.TransformerException |
| * @xsl.usage experimental |
| */ |
| public DTMIterator asIterator(XPathContext xctxt, int contextNode) |
| throws javax.xml.transform.TransformerException |
| { |
| |
| try |
| { |
| xctxt.pushCurrentNodeAndExpression(contextNode, contextNode); |
| |
| return execute(xctxt).iter(); |
| } |
| finally |
| { |
| xctxt.popCurrentNodeAndExpression(); |
| } |
| } |
| |
| /** |
| * Given an select expression and a context, evaluate the XPath |
| * and return the resulting iterator, but do not clone. |
| * |
| * @param xctxt The execution context. |
| * @param contextNode The node that "." expresses. |
| * |
| * |
| * @return A valid DTMIterator. |
| * @throws TransformerException thrown if the active ProblemListener decides |
| * the error condition is severe enough to halt processing. |
| * |
| * @throws javax.xml.transform.TransformerException |
| * @xsl.usage experimental |
| */ |
| public DTMIterator asIteratorRaw(XPathContext xctxt, int contextNode) |
| throws javax.xml.transform.TransformerException |
| { |
| |
| try |
| { |
| xctxt.pushCurrentNodeAndExpression(contextNode, contextNode); |
| |
| XNodeSet nodeset = (XNodeSet)execute(xctxt); |
| return nodeset.iterRaw(); |
| } |
| finally |
| { |
| xctxt.popCurrentNodeAndExpression(); |
| } |
| } |
| |
| |
| /** |
| * Execute an expression in the XPath runtime context, and return the |
| * result of the expression. |
| * |
| * |
| * @param xctxt The XPath runtime context. |
| * NEEDSDOC @param handler |
| * |
| * @return The result of the expression in the form of a <code>XObject</code>. |
| * |
| * @throws javax.xml.transform.TransformerException if a runtime exception |
| * occurs. |
| * @throws org.xml.sax.SAXException |
| */ |
| public void executeCharsToContentHandler( |
| XPathContext xctxt, ContentHandler handler) |
| throws javax.xml.transform.TransformerException, |
| org.xml.sax.SAXException |
| { |
| |
| XObject obj = execute(xctxt); |
| |
| obj.dispatchCharactersEvents(handler); |
| obj.detach(); |
| } |
| |
| /** |
| * Tell if this expression returns a stable number that will not change during |
| * iterations within the expression. This is used to determine if a proximity |
| * position predicate can indicate that no more searching has to occur. |
| * |
| * |
| * @return true if the expression represents a stable number. |
| */ |
| public boolean isStableNumber() |
| { |
| return false; |
| } |
| |
| /** |
| * This function is used to fixup variables from QNames to stack frame |
| * indexes at stylesheet build time. |
| * @param vars List of QNames that correspond to variables. This list |
| * should be searched backwards for the first qualified name that |
| * corresponds to the variable reference qname. The position of the |
| * QName in the vector from the start of the vector will be its position |
| * in the stack frame (but variables above the globalsTop value will need |
| * to be offset to the current stack frame). |
| * NEEDSDOC @param globalsSize |
| */ |
| public abstract void fixupVariables(java.util.Vector vars, int globalsSize); |
| |
| /** |
| * Compare this object with another object and see |
| * if they are equal, include the sub heararchy. |
| * |
| * @param expr Another expression object. |
| * @return true if this objects class and the expr |
| * object's class are the same, and the data contained |
| * within both objects are considered equal. |
| */ |
| public abstract boolean deepEquals(Expression expr); |
| |
| /** |
| * This is a utility method to tell if the passed in |
| * class is the same class as this. It is to be used by |
| * the deepEquals method. I'm bottlenecking it here |
| * because I'm not totally confident that comparing the |
| * class objects is the best way to do this. |
| * @return true of the passed in class is the exact same |
| * class as this class. |
| */ |
| protected final boolean isSameClass(Expression expr) |
| { |
| if(null == expr) |
| return false; |
| |
| return (getClass() == expr.getClass()); |
| } |
| |
| /** |
| * Warn the user of an problem. |
| * |
| * @param xctxt The XPath runtime context. |
| * @param msg An error msgkey that corresponds to one of the conststants found |
| * in {@link org.apache.xpath.res.XPATHErrorResources}, which is |
| * a key for a format string. |
| * @param args An array of arguments represented in the format string, which |
| * may be null. |
| * |
| * @throws TransformerException if the current ErrorListoner determines to |
| * throw an exception. |
| * |
| * @throws javax.xml.transform.TransformerException |
| */ |
| public void warn(XPathContext xctxt, String msg, Object[] args) |
| throws javax.xml.transform.TransformerException |
| { |
| |
| java.lang.String fmsg = XSLMessages.createXPATHWarning(msg, args); |
| |
| if (null != xctxt) |
| { |
| ErrorListener eh = xctxt.getErrorListener(); |
| |
| // TO DO: Need to get stylesheet Locator from here. |
| eh.warning(new TransformerException(fmsg, xctxt.getSAXLocator())); |
| } |
| } |
| |
| /** |
| * Tell the user of an assertion error, and probably throw an |
| * exception. |
| * |
| * @param b If false, a runtime exception will be thrown. |
| * @param msg The assertion message, which should be informative. |
| * |
| * @throws RuntimeException if the b argument is false. |
| * |
| * @throws javax.xml.transform.TransformerException |
| */ |
| public void assertion(boolean b, java.lang.String msg) |
| { |
| |
| if (!b) |
| { |
| java.lang.String fMsg = XSLMessages.createXPATHMessage( |
| XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION, |
| new Object[]{ msg }); |
| |
| throw new RuntimeException(fMsg); |
| } |
| } |
| |
| /** |
| * Tell the user of an error, and probably throw an |
| * exception. |
| * |
| * @param xctxt The XPath runtime context. |
| * @param msg An error msgkey that corresponds to one of the constants found |
| * in {@link org.apache.xpath.res.XPATHErrorResources}, which is |
| * a key for a format string. |
| * @param args An array of arguments represented in the format string, which |
| * may be null. |
| * |
| * @throws TransformerException if the current ErrorListoner determines to |
| * throw an exception. |
| * |
| * @throws javax.xml.transform.TransformerException |
| */ |
| public void error(XPathContext xctxt, String msg, Object[] args) |
| throws javax.xml.transform.TransformerException |
| { |
| |
| java.lang.String fmsg = XSLMessages.createXPATHMessage(msg, args); |
| |
| if (null != xctxt) |
| { |
| ErrorListener eh = xctxt.getErrorListener(); |
| TransformerException te = new TransformerException(fmsg, this); |
| |
| eh.fatalError(te); |
| } |
| } |
| |
| /** |
| * Get the first non-Expression parent of this node. |
| * @return null or first ancestor that is not an Expression. |
| */ |
| public ExpressionNode getExpressionOwner() |
| { |
| ExpressionNode parent = exprGetParent(); |
| while((null != parent) && (parent instanceof Expression)) |
| parent = parent.exprGetParent(); |
| return parent; |
| } |
| |
| //=============== ExpressionNode methods ================ |
| |
| /** This pair of methods are used to inform the node of its |
| parent. */ |
| public void exprSetParent(ExpressionNode n) |
| { |
| assertion(n != this, "Can not parent an expression to itself!"); |
| m_parent = n; |
| } |
| |
| public ExpressionNode exprGetParent() |
| { |
| return m_parent; |
| } |
| |
| /** This method tells the node to add its argument to the node's |
| list of children. */ |
| public void exprAddChild(ExpressionNode n, int i) |
| { |
| assertion(false, "exprAddChild method not implemented!"); |
| } |
| |
| /** This method returns a child node. The children are numbered |
| from zero, left to right. */ |
| public ExpressionNode exprGetChild(int i) |
| { |
| return null; |
| } |
| |
| /** Return the number of children the node has. */ |
| public int exprGetNumChildren() |
| { |
| return 0; |
| } |
| |
| //=============== SourceLocator methods ================ |
| |
| /** |
| * Return the public identifier for the current document event. |
| * |
| * <p>The return value is the public identifier of the document |
| * entity or of the external parsed entity in which the markup that |
| * triggered the event appears.</p> |
| * |
| * @return A string containing the public identifier, or |
| * null if none is available. |
| * @see #getSystemId |
| */ |
| public String getPublicId() |
| { |
| if(null == m_parent) |
| return null; |
| return m_parent.getPublicId(); |
| } |
| |
| /** |
| * Return the system identifier for the current document event. |
| * |
| * <p>The return value is the system identifier of the document |
| * entity or of the external parsed entity in which the markup that |
| * triggered the event appears.</p> |
| * |
| * <p>If the system identifier is a URL, the parser must resolve it |
| * fully before passing it to the application.</p> |
| * |
| * @return A string containing the system identifier, or null |
| * if none is available. |
| * @see #getPublicId |
| */ |
| public String getSystemId() |
| { |
| if(null == m_parent) |
| return null; |
| return m_parent.getSystemId(); |
| } |
| |
| /** |
| * Return the line number where the current document event ends. |
| * |
| * <p><strong>Warning:</strong> The return value from the method |
| * is intended only as an approximation for the sake of error |
| * reporting; it is not intended to provide sufficient information |
| * to edit the character content of the original XML document.</p> |
| * |
| * <p>The return value is an approximation of the line number |
| * in the document entity or external parsed entity where the |
| * markup that triggered the event appears.</p> |
| * |
| * @return The line number, or -1 if none is available. |
| * @see #getColumnNumber |
| */ |
| public int getLineNumber() |
| { |
| if(null == m_parent) |
| return 0; |
| return m_parent.getLineNumber(); |
| } |
| |
| /** |
| * Return the character position where the current document event ends. |
| * |
| * <p><strong>Warning:</strong> The return value from the method |
| * is intended only as an approximation for the sake of error |
| * reporting; it is not intended to provide sufficient information |
| * to edit the character content of the original XML document.</p> |
| * |
| * <p>The return value is an approximation of the column number |
| * in the document entity or external parsed entity where the |
| * markup that triggered the event appears.</p> |
| * |
| * @return The column number, or -1 if none is available. |
| * @see #getLineNumber |
| */ |
| public int getColumnNumber() |
| { |
| if(null == m_parent) |
| return 0; |
| return m_parent.getColumnNumber(); |
| } |
| } |