/* * XBeanCompare.java * Created on June 15, 2007, 11:43 AM */ package org.mitre.oval.repository.ws.moderator.application; import java.util.HashMap; import java.util.Map; import org.apache.log4j.Logger; import org.apache.xmlbeans.SchemaProperty; import org.apache.xmlbeans.XmlCursor; import org.apache.xmlbeans.XmlObject; import org.apache.xmlbeans.impl.common.QNameHelper; import org.apache.xmlbeans.impl.common.XmlWhitespace; /** * * TODO: add in better difference reporting. It would be nice to report on what the differences are and where they were found. */ public class XBeanCompare { protected static Logger logger = Logger.getLogger(XBeanCompare.class.getPackage().getName()); /** * Compares 2 XmlObjects and returns true if they are equal. Allows for an input list * of attributes to skip value checks and a list of attributes to skip existence checks. * The comparison of XmlObjects is done without regard to child element ordering. * * NOTE: I have attempted to make the code err on side of reporting elements to be different. * 2 elements should never be considered equal if they are not, but may be considered * not equal when they actually are. This decision was made because this code was written * with the primary goal of protecting the contents of a repository. * * This comparison is done as follows: * 1- compare the elements names. (see: XBeanCompare.compareNamesAndAttributes) * 2- compare the elements attributes. (see: XBeanCompare.compareNamesAndAttributes) * 3- check that both elements have the same number of children. (uses xpath "./child::*" then gets the length of the array of children) * 4- compare child elements * - loop through all children of elm1 * - check that elm2 has a child element that matches the current elm1 child where the elm2 child has not already been used. (recursive) * - each time a match is made store the index of the elm2 child to make sure it is not used again. (this protects use against two elements with the same attributes and values.) * * @param object1 the first XmlObject * @param object2 the sceond XmlObject * @param ignoreAttrValues A map of attribute names to not compare values on. * @param ignoreAttrExistence A map of attribute local names to skip when checking existenc of attributes * @return true if the two XmlObjects are equal. */ public static boolean equals(XmlObject object1, XmlObject object2, Map ignoreAttrValues, Map ignoreAttrExistence) { boolean match = true; // Get cursors XmlCursor cur1 = object1.newCursor(); XmlCursor cur2 = object2.newCursor(); // start by making sure the element names and attribute are the same. if (!compareNamesAndAttributes(cur1, cur2, ignoreAttrValues, ignoreAttrExistence)) { match = false; } else { // now begin looking at child elements. boolean hasChildren1 = cur1.toFirstChild(); boolean hasChildren2 = cur2.toFirstChild(); if (hasChildren1 != hasChildren2) { // reset the cursors if(hasChildren1) { cur1.toParent(); } if(hasChildren2) { cur2.toParent(); } // if one element has children and the other does not return false logger.debug("Topology differs: one element has " + "children where the other does not (" + QNameHelper.pretty(cur1.getName()) + ", " + QNameHelper.pretty(cur2.getName()) + ")."); match = false; } else if (!hasChildren1 && !hasChildren2) { // neither element has children so compare the element values making sure to collapse whitespace. if (!wsCollapseEqual(cur1.getTextValue(), cur2.getTextValue())) { logger.debug("Value '" + cur1.getTextValue() + "' differs from value '" + cur2.getTextValue() + "'."); match = false; } } else { // both elements have children // get a count of all child elements for elm 1 and elm 2 - counts should be equal XmlObject[] obj1Children = object1.selectPath("./child::*"); int obj1ChildCount = obj1Children.length; XmlObject[] obj2Children = object2.selectPath("./child::*"); int obj2ChildCount = obj2Children.length; if(obj1ChildCount != obj2ChildCount) { // reset the cursors if(hasChildren1) { cur1.toParent(); } if(hasChildren2) { cur2.toParent(); } logger.debug("Topology differs: one element has " + obj1ChildCount + " child element(s) where the other has " + obj2ChildCount + " child element(s) (" + QNameHelper.pretty(cur1.getName()) + ", " + QNameHelper.pretty(cur2.getName()) + ")."); match = false; } else { // track each elm 2 index as it is used. Map matchedElmChildIndexes = new HashMap(); boolean childMatch = false; // loop through all children of element 1 // stops when finished all children or // when unable to find a matching child of elm2 do { // track the index of each child of elm 2 int elm2ChildIndex = 0; // look for a matching child elm in elm 2 do { // make sure the index has not been used. if(!matchedElmChildIndexes.containsKey(new Integer(elm2ChildIndex))) { // make recursive call childMatch = equals(cur1.getObject(), cur2.getObject(), ignoreAttrValues, ignoreAttrExistence); if(childMatch) { // store the index of the child matchedElmChildIndexes.put(new Integer(elm2ChildIndex), new Integer(elm2ChildIndex)); // stop inner loop break; } } elm2ChildIndex++; } while(cur2.toNextSibling()); // reset the second cursor cur2.toParent(); cur2.toFirstChild(); // if no matching child was found break from the outter loop if(!childMatch) { match = false; break; } } while(cur1.toNextSibling()); // if after processing all elm1 children the childMatch is true then rport true if(childMatch) { match = true; } else { match = false; } // reset the cursors cur1.toParent(); cur2.toParent(); } } } // dispose the cursors cur1.dispose(); cur2.dispose(); return match; } /** * Return true if the elements pointed to by the input XmlCursors are equivalent. * Accepts as input two list of attributes to ignore durring comparison. * * Attributes are compared as follows: * 1- loop through all attributes in elm1 and check elm2 * - if the attr exists in elm2 compare values. * - if the attr does not exist use the schema type system to determine the default value for the elm2 attr if it has one. * 2- loop through all attributes in elm2 and check elm1 * - if the attr does not exist use the schema type system to determine the default value for the elm1 attr * * * @param cur1 The first XmlCursor. * @param cur2 The second XmlCursor. * @param ignoreAttrValues A map of attribute local names to not compare values on. * @param ignoreAttrExistence A map of attribute local names to skip when checking existence of attributes * @return */ private static boolean compareNamesAndAttributes(XmlCursor cur1, XmlCursor cur2, Map ignoreAttrValues, Map ignoreAttrExistence) { // make sure the qnames are equal. // if not return false if (!cur1.getName().equals(cur2.getName())) { logger.debug("Element names '" + QNameHelper.pretty(cur1.getName()) + "' and '" + QNameHelper.pretty(cur2.getName()) + "' do not match."); return false; } String elemName = QNameHelper.pretty(cur1.getName()); // loop through all attributes on the first element if there are any; if (cur1.toFirstAttribute()) { do { // get the current attr name and value String localName1 = cur1.getName().getLocalPart(); // check the list of attributes to skip comparing if(ignoreAttrExistence.containsKey(localName1)) { logger.debug("Ignoring attribute exitence check for: " + localName1); } else { String text1 = cur1.getTextValue(); // fetch the value of the current attribute from the second element. String text2 = cur2.getAttributeText(cur1.getName()); // if the second elment does not have the attribute or the attribute does not have a default value return false . if (text2 == null) { // look up attribute default value if it has one and use that for the comparison SchemaProperty attrProperty = cur2.getObject().schemaType().getAttributeProperty(cur1.getName()); if(attrProperty.hasDefault() == SchemaProperty.CONSISTENTLY) { text2 = attrProperty.getDefaultText(); } else { logger.debug("Attribute '" + QNameHelper.pretty(cur1.getName()) + "' " + " of element '" + elemName + "' not present."); return false; } } // check the list of attribute values to ignore. if(ignoreAttrValues.containsKey(localName1)) { logger.debug("Ignoring attribute values for: " + localName1); } else { // compare the attribute values ignoring whitespace differences. // return false is not equal if (!wsCollapseEqual(text1, text2)) { logger.debug("Attribute values for '" + QNameHelper.pretty(cur1.getName()) + "' " + " of element '" + elemName + "' don't match."); return false; } } } } while (cur1.toNextAttribute()); // reset the cursor after walking through the attributes. cur1.toParent(); } // examine the attributes on the second element. // make sure that every attribute on the second element exists on the first element. // or if the attribute is not found on the first elm it is set to a default value - then must compare values. if (cur2.toFirstAttribute()) { do { // get the current attr name and value String localName2 = cur2.getName().getLocalPart(); String text2 = cur2.getTextValue(); // if the second elment does not have the attribute or the attribute does not have a default value return false. String text1 = cur1.getAttributeText(cur2.getName()); if (text1 == null) { // look up attribute default value if it has one and use that for the comparison SchemaProperty attrProperty = cur1.getObject().schemaType().getAttributeProperty(cur2.getName()); if(attrProperty.hasDefault() == SchemaProperty.CONSISTENTLY) { text1 = attrProperty.getDefaultText(); } else { logger.debug("Attribute '" + QNameHelper.pretty(cur1.getName()) + "' " + " of element '" + elemName + "' not present."); return false; } } // check the list of attribute values to ignore. if(ignoreAttrValues.containsKey(localName2)) { logger.debug("Ignoring attribute values for: " + localName2); } else { // compare the attribute values ignoring whitespace differences. // return false is not equal if (!wsCollapseEqual(text1, text2)) { logger.debug("Attribute values for '" + QNameHelper.pretty(cur2.getName()) + "' " + " of element '" + elemName + "' don't match."); return false; } } } while (cur2.toNextAttribute()); // reset the cursor after walking through the attributes. cur2.toParent(); } return true; } /** * Return true if the 2 strings are equal after xml collapsing whitespace. */ private static boolean wsCollapseEqual(String s1, String s2) { logger.debug("Comparing: " + s1 + " to " + s2); String s1c = XmlWhitespace.collapse(s1); String s2c = XmlWhitespace.collapse(s2); return (s1c.equals(s2c)); } }