| /* $Id$ |
| * |
| * 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. |
| */ |
| |
| |
| package org.apache.commons.digester; |
| |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.Comparator; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| |
| |
| /** |
| * <p>Extension of {@link RulesBase} for complex schema.</p> |
| * |
| * <p>This is an extension of the basic pattern matching scheme |
| * intended to improve support for mapping complex xml-schema. |
| * It is intended to be a minimal extension of the standard rules |
| * big enough to support complex schema but without the full generality |
| * offered by more exotic matching pattern rules.</p> |
| * |
| * <h4>When should you use this rather than the original?</h4> |
| * |
| * <p> |
| * This pattern-matching engine is complex and slower than the basic |
| * default RulesBase class, but offers more functionality: |
| * <ul> |
| * <li>Universal patterns allow patterns to be specified which will match |
| * regardless of whether there are "better matching" patterns available.</li> |
| * <li>Parent-match patterns (eg "a/b/?") allow matching for all direct |
| * children of a specified element.</li> |
| * <li>Ancestor-match patterns (eg "a/b/*") allow matching all elements |
| * nested within a specified element to any nesting depth.</li> |
| * <li>Completely-wild patterns ("*" or "!*") allow matching all elements.</li> |
| * </ul> |
| * </p> |
| * |
| * <h4>Universal Match Patterns</h4> |
| * |
| * <p>The default RulesBase pattern-matching engine always attempts to find |
| * the "best matching pattern", and will ignore rules associated with other |
| * patterns that match but are not "as good". As an example, if the pattern |
| * "a/b/c" is associated with rules 1 and 2, and "*/c" is associated with |
| * rules 3 and 4 then element "a/b/c" will cause only rules 1 and 2 to execute. |
| * Rules 3 and 4 do have matching patterns, but because the patterns are shorter |
| * and include wildcard characters they are regarded as being "not as good" as |
| * a direct match. In general, exact patterns are better than wildcard patterns, |
| * and among multiple patterns with wildcards, the longest is preferred. |
| * See the RulesBase class for more information.</p> |
| * |
| * <p>This feature of preferring "better" patterns can be a powerful tool. |
| * However it also means that patterns can interact in unexpected ways.</p> |
| * |
| * <p>When using the ExtendedBaseRules, any pattern prefixed with '!' bypasses |
| * the "best match" feature. Even if there is an exact match or a longer |
| * wildcard match, patterns prefixed by '!' will still be tested to see if |
| * they match, and if so their associated Rule objects will be included in |
| * the set of rules to be executed in the normal manner.</p> |
| * |
| * <ul> |
| * <li>Pattern <code>"!*/a/b"</code> matches whenever an 'b' element |
| * is inside an 'a'.</li> |
| * <li>Pattern <code>"!a/b/?"</code> matches any child of a parent |
| * matching <code>"a/b"</code> (see "Parent Match Patterns").</li> |
| * <li>Pattern <code>"!*/a/b/?"</code> matches any child of a parent |
| * matching <code>"!*/a/b"</code> (see "Parent Match Patterns").</li> |
| * <li>Pattern <code>"!a/b/*"</code> matches any element whose path |
| * starts with "a" then "b" (see "Ancestor Match Patterns").</li> |
| * <li>Pattern <code>"!*/a/b/*"</code> matches any elements whose path |
| * contains 'a/b' (see "Ancestor Match Patterns").</li> |
| * </ul> |
| * |
| * <h4>Parent Match Patterns</h4> |
| * |
| * <p> |
| * These will match direct child elements of a particular parent element. |
| * <ul> |
| * <li> |
| * <code>"a/b/c/?"</code> matches any child whose parent matches |
| * <code>"a/b/c"</code>. Exact parent rules take precedence over Ancestor |
| * Match patterns. |
| * </li> |
| * <li> |
| * <code>"*/a/b/c/?"</code> matches any child whose parent matches |
| * <code>"*/a/b/c"</code>. The longest matching still applies to parent |
| * matches but the length excludes the '?', which effectively means |
| * that standard wildcard matches with the same level of depth are |
| * chosen in preference. |
| * </li> |
| * </ul> |
| * </p> |
| * |
| * <h4>Ancestor Match Patterns</h4> |
| * |
| * <p> |
| * These will match elements whose parentage includes a particular sequence |
| * of elements. |
| * <ul> |
| * <li> |
| * <code>"a/b/*"</code> matches any element whose path starts with |
| * 'a' then 'b'. Exact parent and parent match rules take precedence. |
| * The longest ancestor match will take precedence. |
| * </li> |
| * <li> |
| * <code>"*/a/b/*"</code> matches any elements whose path contains |
| * an element 'a' followed by an element 'b'. The longest matching still |
| * applies but the length excludes the '*' at the end. |
| * </li> |
| * </ul> |
| * </p> |
| * |
| * <h4>Completely Wild Patterns</h4> |
| * |
| * <p>Pattern <code>"*"</code> matches every pattern that isn't matched by |
| * any other basic rule.</p> |
| * |
| * <p>Pattern <code>"!*"</code> matches every pattern.</p> |
| * |
| * <h4>Using The Extended Rules</h4> |
| * |
| * <p>By default, a Digester instance uses a {@link RulesBase} instance as |
| * its pattern matching engine. To use an ExtendedBaseRules instance, call |
| * the Digester.setRules method before adding any Rule objects to the digester |
| * instance: |
| * <pre> |
| * Digester digester = new Digester(); |
| * digester.setRules( new ExtendedBaseRules() ); |
| * </pre></p> |
| * |
| * <p>The most important thing to remember when using the extended rules is |
| * that universal and non-universal patterns are completely independent. |
| * Universal patterns are never affected by the addition of new patterns |
| * or the removal of existing ones. Non-universal patterns are never affected |
| * by the addition of new <em>universal</em> patterns or the removal of |
| * existing <em>universal</em> patterns. As in the basic matching rules, |
| * non-universal (basic) patterns <strong>can</strong> be affected by the |
| * addition of new <em>non-universal</em> patterns or the removal of existing |
| * <em>non-universal</em> patterns, because only rules associated with the |
| * "best matching" pattern for each xml element are executed. |
| * |
| * <p> This means that you can use universal patterns to build up the simple |
| * parts of your structure - for example defining universal creation and |
| * property setting rules. More sophisticated and complex mapping will require |
| * non-universal patterns and this might mean that some of the universal rules |
| * will need to be replaced by a series of special cases using non-universal |
| * rules. But by using universal rules as your backbone, these additions |
| * should not break your existing rules.</p> |
| */ |
| |
| |
| public class ExtendedBaseRules extends RulesBase { |
| |
| |
| // ----------------------------------------------------- Instance Variables |
| |
| /** |
| * Counts the entry number for the rules. |
| */ |
| private int counter = 0; |
| |
| |
| /** |
| * The decision algorithm used (unfortunately) doesn't preserve the entry |
| * order. |
| * This map is used by a comparator which orders the list of matches |
| * before it's returned. |
| * This map stores the entry number keyed by the rule. |
| */ |
| private Map<Rule, Integer> order = new HashMap<Rule, Integer>(); |
| |
| |
| // --------------------------------------------------------- Public Methods |
| |
| |
| /** |
| * Register a new Rule instance matching the specified pattern. |
| * |
| * @param pattern Nesting pattern to be matched for this Rule |
| * @param rule Rule instance to be registered |
| */ |
| @Override |
| public void add(String pattern, Rule rule) { |
| super.add(pattern, rule); |
| counter++; |
| order.put(rule, counter); |
| } |
| |
| |
| /** |
| * Return a List of all registered Rule instances that match the specified |
| * nesting pattern, or a zero-length List if there are no matches. If more |
| * than one Rule instance matches, they <strong>must</strong> be returned |
| * in the order originally registered through the <code>add()</code> |
| * method. |
| * |
| * @param pattern Nesting pattern to be matched |
| */ |
| @Override |
| public List<Rule> match(String namespace, String pattern) { |
| // calculate the pattern of the parent |
| // (if the element has one) |
| String parentPattern = ""; |
| int lastIndex = pattern.lastIndexOf('/'); |
| |
| boolean hasParent = true; |
| if (lastIndex == -1) { |
| // element has no parent |
| hasParent = false; |
| |
| } else { |
| // calculate the pattern of the parent |
| parentPattern = pattern.substring(0, lastIndex); |
| |
| } |
| |
| |
| // we keep the list of universal matches separate |
| List<Rule> universalList = new ArrayList<Rule>(counter); |
| |
| // Universal all wildards ('!*') |
| // These are always matched so always add them |
| List<Rule> tempList = this.cache.get("!*"); |
| if (tempList != null) { |
| universalList.addAll(tempList); |
| } |
| |
| // Universal exact parent match |
| // need to get this now since only wildcards are considered later |
| tempList = this.cache.get("!" + parentPattern + "/?"); |
| if (tempList != null) { |
| universalList.addAll(tempList); |
| } |
| |
| |
| // base behaviour means that if we certain matches, we don't continue |
| // but we just have a single combined loop and so we have to set |
| // a variable |
| boolean ignoreBasicMatches = false; |
| |
| |
| // see if we have an exact basic pattern match |
| List<Rule> rulesList = this.cache.get(pattern); |
| if (rulesList != null) { |
| // we have a match! |
| // so ignore all basic matches from now on |
| ignoreBasicMatches = true; |
| |
| } else { |
| |
| // see if we have an exact child match |
| if (hasParent) { |
| // matching children takes preference |
| rulesList = this.cache.get(parentPattern + "/?"); |
| if (rulesList != null) { |
| // we have a match! |
| // so ignore all basic matches from now on |
| ignoreBasicMatches = true; |
| |
| } else { |
| // we don't have a match yet - so try exact ancester |
| // |
| rulesList = findExactAncesterMatch(pattern); |
| if (rulesList != null) { |
| // we have a match! |
| // so ignore all basic matches from now on |
| ignoreBasicMatches = true; |
| } |
| } |
| } |
| } |
| |
| |
| // OK - we're ready for the big loop! |
| // Unlike the basic rules case, |
| // we have to go through for all those universal rules in all cases. |
| |
| // Find the longest key, ie more discriminant |
| String longKey = ""; |
| int longKeyLength = 0; |
| |
| for (String key : this.cache.keySet()) { |
| |
| // find out if it's a univeral pattern |
| // set a flag |
| boolean isUniversal = key.startsWith("!"); |
| if (isUniversal) { |
| // and find the underlying key |
| key = key.substring(1, key.length()); |
| } |
| |
| |
| // don't need to check exact matches |
| boolean wildcardMatchStart = key.startsWith("*/"); |
| boolean wildcardMatchEnd = key.endsWith("/*"); |
| if (wildcardMatchStart || (isUniversal && wildcardMatchEnd)) { |
| |
| boolean parentMatched = false; |
| boolean basicMatched = false; |
| boolean ancesterMatched = false; |
| |
| boolean parentMatchEnd = key.endsWith("/?"); |
| if (parentMatchEnd) { |
| // try for a parent match |
| parentMatched = parentMatch(key, pattern, parentPattern); |
| |
| } else if (wildcardMatchEnd) { |
| // check for ancester match |
| if (wildcardMatchStart) { |
| String patternBody = key.substring(2, key.length() - 2); |
| if (pattern.endsWith(patternBody)) { |
| ancesterMatched = true; |
| } else { |
| ancesterMatched = (pattern.indexOf(patternBody + "/") > -1); |
| } |
| } else { |
| String bodyPattern = key.substring(0, key.length() - 2); |
| if (pattern.startsWith(bodyPattern)) |
| { |
| if (pattern.length() == bodyPattern.length()) { |
| // exact match |
| ancesterMatched = true; |
| } else { |
| ancesterMatched = ( pattern.charAt(bodyPattern.length()) == '/' ); |
| } |
| } else { |
| ancesterMatched = false; |
| } |
| } |
| } else { |
| // try for a base match |
| basicMatched = basicMatch(key, pattern); |
| } |
| |
| if (parentMatched || basicMatched || ancesterMatched) { |
| if (isUniversal) { |
| // universal rules go straight in |
| // (no longest matching rule) |
| tempList = this.cache.get("!" + key); |
| if (tempList != null) { |
| universalList.addAll(tempList); |
| } |
| |
| } else { |
| if (!ignoreBasicMatches) { |
| // ensure that all parent matches are SHORTER |
| // than rules with same level of matching. |
| // |
| // the calculations below don't work for universal |
| // matching, but we don't care because in that case |
| // this if-stmt is not entered. |
| int keyLength = key.length(); |
| if (wildcardMatchStart) { |
| --keyLength; |
| } |
| if (wildcardMatchEnd) { |
| --keyLength; |
| } else if (parentMatchEnd) { |
| --keyLength; |
| } |
| |
| if (keyLength > longKeyLength) { |
| rulesList = this.cache.get(key); |
| longKey = key; |
| longKeyLength = keyLength; |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| |
| // '*' works in practice as a default matching |
| // (this is because anything is a deeper match!) |
| if (rulesList == null) { |
| rulesList = this.cache.get("*"); |
| } |
| |
| // if we've matched a basic pattern, then add to the universal list |
| if (rulesList != null) { |
| universalList.addAll(rulesList); |
| } |
| |
| |
| // don't filter if namespace is null |
| if (namespace != null) { |
| // remove invalid namespaces |
| Iterator<Rule> it = universalList.iterator(); |
| while (it.hasNext()) { |
| Rule rule = it.next(); |
| String ns_uri = rule.getNamespaceURI(); |
| if (ns_uri != null && !ns_uri.equals(namespace)) { |
| it.remove(); |
| } |
| } |
| } |
| |
| |
| // need to make sure that the collection is sort in the order |
| // of addition. We use a custom comparator for this |
| Collections.sort( |
| universalList, |
| new Comparator<Rule>() { |
| |
| public int compare(Rule r1, Rule r2) throws ClassCastException { |
| // Get the entry order from the map |
| Integer i1 = order.get(r1); |
| Integer i2 = order.get(r2); |
| |
| // and use that to perform the comparison |
| if (i1 == null) { |
| if (i2 == null) { |
| |
| return 0; |
| |
| } else { |
| |
| return -1; |
| |
| } |
| } else if (i2 == null) { |
| return 1; |
| } |
| |
| return (i1.intValue() - i2.intValue()); |
| } |
| }); |
| |
| return universalList; |
| } |
| |
| /** |
| * Matching parent. |
| */ |
| private boolean parentMatch(String key, String pattern, String parentPattern) { |
| return parentPattern.endsWith(key.substring(1, key.length() - 2)); |
| } |
| |
| /** |
| * Standard match. |
| * Matches the end of the pattern to the key. |
| */ |
| private boolean basicMatch(String key, String pattern) { |
| return (pattern.equals(key.substring(2)) || |
| pattern.endsWith(key.substring(1))); |
| } |
| |
| /** |
| * Finds an exact ancester match for given pattern |
| */ |
| private List<Rule> findExactAncesterMatch(String parentPattern) { |
| List<Rule> matchingRules = null; |
| int lastIndex = parentPattern.length(); |
| while (lastIndex-- > 0) { |
| lastIndex = parentPattern.lastIndexOf('/', lastIndex); |
| if (lastIndex > 0) { |
| matchingRules = this.cache.get(parentPattern.substring(0, lastIndex) + "/*"); |
| if (matchingRules != null) { |
| return matchingRules; |
| } |
| } |
| } |
| return null; |
| } |
| } |
