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package com.feilong.lib.digester3;
/*
* 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.
*/
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.xml.sax.Attributes;
/**
*
* Extension of {@link RulesBase} for complex schema.
*
*
* 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.
*
* When should you use this rather than the original?
*
* This pattern-matching engine is complex and slower than the basic default RulesBase class, but offers more
* functionality:
*
* - Universal patterns allow patterns to be specified which will match regardless of whether there are
* "better matching" patterns available.
* - Parent-match patterns (eg "a/b/?") allow matching for all direct children of a specified element.
* - Ancestor-match patterns (eg "a/b/*") allow matching all elements nested within a specified element to any nesting
* depth.
* - Completely-wild patterns ("*" or "!*") allow matching all elements.
*
*
* Universal Match Patterns
*
* 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.
*
*
* This feature of preferring "better" patterns can be a powerful tool. However it also means that patterns can interact
* in unexpected ways.
*
*
* 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.
*
*
* - Pattern
"!*/a/b" matches whenever an 'b' element is inside an 'a'.
* - Pattern
"!a/b/?" matches any child of a parent matching "a/b" (see
* "Parent Match Patterns").
* - Pattern
"!*/a/b/?" matches any child of a parent matching "!*/a/b" (see
* "Parent Match Patterns").
* - Pattern
"!a/b/*" matches any element whose path starts with "a" then "b" (see
* "Ancestor Match Patterns").
* - Pattern
"!*/a/b/*" matches any elements whose path contains 'a/b' (see
* "Ancestor Match Patterns").
*
* Parent Match Patterns
*
* These will match direct child elements of a particular parent element.
*
* -
*
"a/b/c/?" matches any child whose parent matches "a/b/c". Exact parent rules take
* precedence over Ancestor Match patterns.
* -
*
"*/a/b/c/?" matches any child whose parent matches "*/a/b/c". 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.
*
*
* Ancestor Match Patterns
*
* These will match elements whose parentage includes a particular sequence of elements.
*
* -
*
"a/b/*" 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.
* -
*
"*/a/b/*" 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.
*
*
* Completely Wild Patterns
*
* Pattern "*" matches every pattern that isn't matched by any other basic rule.
*
*
* Pattern "!*" matches every pattern.
*
* Using The Extended Rules
*
* 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:
*
*
* Digester digester = new Digester();
* digester.setRules(new ExtendedBaseRules());
*
*
*
*
* 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 universal patterns or the
* removal of existing universal patterns. As in the basic matching rules, non-universal (basic) patterns
* can be affected by the addition of new non-universal patterns or the removal of existing
* non-universal patterns, because only rules associated with the "best matching" pattern for each xml element
* are executed.
*
* 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.
*
*/
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 order = new HashMap<>();
// --------------------------------------------------------- Public Methods
/**
* {@inheritDoc}
*/
@Override
protected void registerRule(String pattern,Rule rule){
super.registerRule(pattern, rule);
counter++;
order.put(rule, counter);
}
/**
* {@inheritDoc}
*/
@Override
public List match(String namespaceURI,String pattern,String name,Attributes attributes){
// 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 universalList = new ArrayList<>(counter);
// Universal wildcards ('*') in the middle of the pattern-string
List recList = null;
// temporary parentPattern
// we don't want to change anything....
String tempParentPattern = parentPattern;
int parentLastIndex = tempParentPattern.lastIndexOf('/');
// look for pattern. Here, we search the whole
// parent. Not ideal, but does the thing....
while (parentLastIndex > -1 && recList == null){
recList = this.cache.get(tempParentPattern + "/*/" + pattern.substring(lastIndex + 1));
if (recList != null){
// when /*/-pattern-string is found, add method
// list to universalList.
// Digester will do the rest
universalList.addAll(recList);
}else{
// if not, shorten tempParent to move /*/ one position
// to the left.
// as last part of patttern is always added
// we make sure pattern is allowed anywhere.
tempParentPattern = parentPattern.substring(0, parentLastIndex);
}
parentLastIndex = tempParentPattern.lastIndexOf('/');
}
// Universal all wildards ('!*')
// These are always matched so always add them
List 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 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
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, 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);
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 (namespaceURI != null){
// remove invalid namespaces
Iterator it = universalList.iterator();
while (it.hasNext()){
Rule rule = it.next();
String nsUri = rule.getNamespaceURI();
if (nsUri != null && !nsUri.equals(namespaceURI)){
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, (r1,r2) -> {
// 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;
}
return -1;
}else if (i2 == null){
return 1;
}
return (i1.intValue() - i2.intValue());
});
return universalList;
}
/**
* Checks the input parentPattern contains the input key at the end.
*
* @param key
* The key to be found
* @param parentPattern
* The pattern where looking for the key
* @return true, if {@code key} is found inside {@code parentPattern}, false otherwise
*/
private boolean parentMatch(String key,String parentPattern){
return parentPattern.endsWith(key.substring(1, key.length() - 2));
}
/**
* Standard match. Matches the end of the pattern to the key.
*
* @param key
* The key to be found
* @param pattern
* The pattern where looking for the key
* @return true, if {@code key} is found inside {@code pattern}, false otherwise
*/
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
*
* @param parentPattern
* The input pattern
* @return A list of {@code Rule} related to the input pattern
*/
private List findExactAncesterMatch(String parentPattern){
List 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;
}
}