platform/sensinact-utils/src/main/java/org/eclipse/sensinact/gateway/util/rest/RestLikeMapper.java - sensinact/org.eclipse.sensinact.gateway - Git at Google

 /*
  * Copyright (c) 2017 CEA.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  *    CEA - initial API and implementation
  */
 package org.eclipse.sensinact.gateway.util.rest;

 import org.osgi.framework.BundleContext;
 import org.osgi.framework.InvalidSyntaxException;
 import org.osgi.framework.ServiceReference;

 import java.util.Arrays;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;

 /**
  * Rest like URI/Resource mapper : <p/>
  * <code>
  * example : <p/>
  * <p>
  * Initial map configuration array :<p/>
  * <p>
  * PATH   |   LDAP KEY     |             CLASS<p/>
  * [first,    first-key    ,  my.class.package.MyFirstClass]<p/>
  * [second,   second-key   ,  my.class.package.MySecondClass]<p/>
  * [third,    third-key    ,  my.class.package.MyThridClass]<p/>
  * <p>
  * <p>
  * the mapper will build the set of key-words below :<p/>
  * <p>
  * [firsts,first,seconds,second,thirds,third]<p/>
  * <p>
  * then it will map this key-words to OSGi filters as below : <p/>
  * <p>
  * PATH     |                OSGi FILTER     <p/>
  * [firsts  ,  objectClass=my.class.package.MyFirstClass]<p/>
  * [first   ,  first-key=&lt;variable&gt;]<p/>
  * [seconds ,  objectClass=my.class.package.MySecondClass]<p/>
  * [second  ,  second-key=&lt;variable&gt;] <p/>
  * [thirds  ,  objectClass=my.class.package.MyThridClass]<p/>
  * [third   ,  third-key=&lt;variable&gt;]<p/>
  * <p>
  * It means that if the plural form of a key word is found in a treated URI, the next path element
  * of this URI will be interpreted as the value attached to the singular form of the same key-word
  * and will be put in the associated filter in replacement of the variable entry<p/>
  * <p>
  * Hierarchical links between entries have to be defined in another array as below <p/>
  * There must be at least one hierarchical link between each level<p/>
  * <p>
  * [&lt;parent&gt;,&lt;child&gt;,&lt;child-key&gt;,&lt;parent-key&gt;]<p/>
  * <p>
  * the child-key is the used to create a filter to append on the parent's one and vice versa<p/>
  * </code>
  */
 public class RestLikeMapper {
     private static final char AND = '&';
     private static final char EQUALITY = '=';
     private static final char LESS = '-';
     private static final char OPEN_BRACKET = '(';
     private static final char CLOSE_BRACKET = ')';
     private static final String SEPARATOR_CHAR = "/";
     private static final String PLURAL_SUFFIX = "s";
     private static final String OBJECTCLASS = "objectClass";
     private static final String VARIABLE = "#VARIABLE#";

     /**
      * the associated {@link BundleContext}
      */
     private BundleContext context;
     /**
      * filter associated to path element
      */
     private String[][] filters;
     /**
      * relationship between path elements
      */
     private String[][] hierarchies;
     /**
      * list of methods to exclude of the research of exposed
      * osgi services
      */
     private List<String> methods;

     /**
      * Constructor
      *
      * @param filters     initial configuration map
      * @param hierarchies map of dependencies between initial configuration map entries
      */
     public RestLikeMapper(BundleContext context, String[][] filters, String[][] hierarchies, String[] methods) throws RestLikeMapperException {

         if (filters == null || filters.length == 0 || filters[0].length != 3) {
             throw new RestLikeMapperException("Invalid initial configuration map");
         }
         this.context = context;
         this.filters = new String[2 * filters.length][2];
         this.hierarchies = new String[2 * hierarchies.length][2];

         int index = 0;
         int pos = 0;
         for (; index < filters.length; index++) {
             String[] mapping = filters[index];

             this.filters[pos][0] = plural(mapping[0]);

             this.filters[pos++][1] = mapping[2] == null ? null : new StringBuilder().append(OPEN_BRACKET).append(OBJECTCLASS).append(EQUALITY).append(mapping[2]).append(CLOSE_BRACKET).toString();

             this.filters[pos][0] = mapping[0];

             this.filters[pos++][1] = mapping[1] == null ? null : new StringBuilder().append(OPEN_BRACKET).append(mapping[1]).append(EQUALITY).append(VARIABLE).append(CLOSE_BRACKET).toString();
         }
         this.methods = methods != null ? Arrays.asList(methods) : Collections.<String>emptyList();

         if (hierarchies == null || hierarchies.length == 0 || hierarchies[0].length != 4) {
             return;
         }
         pos = 0;
         for (String[] hierarchy : hierarchies) {
             if (hierarchy[0] != null && hierarchy[1] != null) {
                 if (hierarchy[2] != null) {
                     this.hierarchies[pos][0] = new StringBuilder().append(hierarchy[0]).append(LESS).append(hierarchy[1]).toString();

                     this.hierarchies[pos++][1] = new StringBuilder().append(OPEN_BRACKET).append(hierarchy[2].length() == 0 ? plural(hierarchy[1]) : hierarchy[2]).append(EQUALITY).append(VARIABLE).append(CLOSE_BRACKET).toString();
                 }
                 if (hierarchy[3] != null) {
                     this.hierarchies[pos][0] = new StringBuilder().append(hierarchy[1]).append(LESS).append(hierarchy[0]).toString();

                     this.hierarchies[pos++][1] = new StringBuilder().append(OPEN_BRACKET).append(hierarchy[3].length() == 0 ? plural(hierarchy[0]) : hierarchy[3]).append(EQUALITY).append(VARIABLE).append(CLOSE_BRACKET).toString();
                 }
             }
         }
         this.hierarchies = Arrays.copyOfRange(this.hierarchies, 0, pos);
     }

     /**
      * Returns the plural form of the singular word passed
      * as parameter
      *
      * @param singular the word to convert to the plural form
      * @return the plural form of the singular word passed
      * as parameter
      */
     private String plural(String singular) {
         return new StringBuilder(singular).append(PLURAL_SUFFIX).toString();
     }

     /**
      * Concatenates the two filters passed as parameters
      *
      * @param filterFst one of the two filters to concatenate
      * @param filterSnd one of the two filters to concatenate
      * @return the filter resulting of the concatenation of the
      * two filters passed as parameters
      */
     private String concat(String filterFst, String filterSnd) {
         if (filterFst == null) {
             return filterSnd;
         }
         if (filterSnd == null) {
             return filterFst;
         }
         return new StringBuilder().append(OPEN_BRACKET).append(AND).append((filterFst.charAt(0) == OPEN_BRACKET) ? "" : OPEN_BRACKET).append(filterFst).append((filterFst.charAt(filterFst.length() - 1) == CLOSE_BRACKET) ? "" : CLOSE_BRACKET).append((filterSnd.charAt(0) == OPEN_BRACKET) ? "" : OPEN_BRACKET).append(filterSnd).append((filterSnd.charAt(filterSnd.length() - 1) == CLOSE_BRACKET) ? "" : CLOSE_BRACKET).append(CLOSE_BRACKET).toString();
     }

     /**
      * Parses the URI string passed as parameter and return
      * the corresponding set of registered OSGi services
      * according to defined filters
      *
      * @param uri the URI string to parse
      * @return the set of OSGi services mapped by the
      * URI argument
      */
     public RestLikeMappingReport parseURI(String uri) {
         String[] uriElements = uri.trim().split(SEPARATOR_CHAR);
         if (uri.startsWith(SEPARATOR_CHAR)) {
             uriElements = Arrays.copyOfRange(uriElements, 1, uriElements.length);
         }
         RestLikeMappingReport report = new RestLikeMappingReport(uriElements);

         if (this.methods.contains(uriElements[uriElements.length - 1])) {
             //last uri element is a method call :
             //end of the parsing
             report.reportMethod(uriElements[uriElements.length - 1]);
             uriElements = Arrays.copyOf(uriElements, uriElements.length - 1);
         }
         LinkedList<String> fstack = new LinkedList<String>();
         int last = -1;
         String variable = null;

         for (int i = 0; i < uriElements.length; i += 2) {
             String plural = uriElements[i];

             //singular form is the next element if it exists
             String singular = i < (uriElements.length - 1) ? uriElements[i + 1] : null;

             int j = 0;
             for (; j < this.filters.length && !this.filters[j][0].equals(plural); j += 2) ;

             //no key-word correspondence found
             if (j == this.filters.length) {
                 break;
             }
             //current element associated filter string
             String filter = concat(this.filters[j][1], this.filters[j + 1][1] != null && singular != null ? this.filters[j + 1][1].replace(VARIABLE, singular) : null);

             //if first element...
             if (last == -1) {
                 if (filter != null) {
                     fstack.offer(filter);
                     report.reportFilter((singular != null ? i + 1 : i), filter);
                 }
                 last = j;
                 variable = singular;
                 continue;
             }
             if (filter != null) {
                 //if no string filter has been defined to precisely
                 //map the singular element to a set of ServiceReferences
                 //then define the report's index as its one. Otherwise
                 //define the report's index as the one of the next
                 //plural element
                 report.reportIndex(this.filters[j + 1][1] != null ? i + 2 : i + 1);
                 //retrieve implementation class name
                 report.reportImplementation(this.filters[j][1] != null ? this.filters[j][1].substring(new StringBuilder().append(OPEN_BRACKET).append(OBJECTCLASS).append(EQUALITY).length(), this.filters[j][1].length() - 1) : null);
             }
             //else
             int k = 0;
             //search for hierarchical link between the current element
             //and the previous one
             for (; k < this.hierarchies.length; k++) {
                 String descendant = new StringBuilder(this.filters[last + 1][0]).append(LESS).append(this.filters[j + 1][0]).toString();

                 String ascendant = new StringBuilder(this.filters[j + 1][0]).append(LESS).append(this.filters[last + 1][0]).toString();

                 String tmpFilter = null;

                 //if descendant hierarchical link...
                 if (this.hierarchies[k][0].equals(descendant)) {
                     //append the current element key filter part to the previously registered filter
                     tmpFilter = concat(fstack.pollLast(), this.hierarchies[k][1].replace(VARIABLE, singular));

                     fstack.offer(tmpFilter);
                     report.reportFilter(i - 1, tmpFilter);

                     //register the current element filter for intersection purpose with the
                     //next element
                     if (filter != null && singular != null) {
                         fstack.offer(filter);
                     }
                     break;
                 }
                 //else if ascendant hierarchical link...
                 else if (this.hierarchies[k][0].equals(ascendant)) {
                     //replace the filter registered for the previous element
                     //by the one of the current element appended with key filter part
                     //to refer to ascendant
                     fstack.pollLast();
                     report.reportFilter(i - 1, null);
                     tmpFilter = concat(filter, this.hierarchies[k][1].replace(VARIABLE, variable));

                     fstack.offer(tmpFilter);
                     report.reportFilter(i, tmpFilter);

                     //register the current element filter for intersection purpose with the
                     //next element
                     if (filter != null && singular != null) {
                         fstack.offer(filter);
                     }
                     break;
                 }
             }
             //if no hierarchical link found
             if (k == this.hierarchies.length) {
                 //end of the parsing
                 break;
             }
             last = j;
             variable = singular;
         }
         //apply filters and process the intersection
         //of resulting ServiceReference arrays two at a time
         List<ServiceReference> services = Collections.emptyList();

         while (!fstack.isEmpty()) {
             //retrieve the first registered filter...
             String filter = fstack.pop();
             try {
                 //retrieve all registered ServiceReferences compliant with the
                 //filter
                 ServiceReference[] current = context.getServiceReferences((String) null, filter);

                 if (current != null) {
                     List<ServiceReference> srs = new LinkedList<ServiceReference>(Arrays.asList(current));

                     List<ServiceReference> intersection = null;
                     List<ServiceReference> references = null;

                     if (services.size() == 0) {
                         services = srs;
                         report.reportReferences(filter, srs);

                     } else {
                         //process the intersection of the retrieved ServiceReferences
                         //and the previous ones
                         ServiceReference[] copy = new ServiceReference[current.length];
                         System.arraycopy(current, 0, copy, 0, current.length);

                         references = new LinkedList<ServiceReference>(Arrays.asList(copy));
                         references.removeAll(services);

                         intersection = new LinkedList<ServiceReference>(Arrays.asList(current));
                         intersection.removeAll(references);

                         services = intersection.size() == 0 ? srs : intersection;
                         if (services.size() == 0) {
                             //empty services set break the process
                             break;

                         } else {
                             //If the intersection set is empty then keep all ServiceReferences
                             report.reportReferences(filter, intersection.size() == 0 ? srs : intersection);
                         }
                     }
                 } else {
                     //invalid filter : break
                     break;
                 }
             } catch (InvalidSyntaxException e) {
                 report.reportError(new RestLikeMapperException(e.getMessage() + " : " + filter, e));
             }
         }
         return report;
     }
 }
	/*
	* Copyright (c) 2017 CEA.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* CEA - initial API and implementation
	*/
	package org.eclipse.sensinact.gateway.util.rest;

	import org.osgi.framework.BundleContext;
	import org.osgi.framework.InvalidSyntaxException;
	import org.osgi.framework.ServiceReference;

	import java.util.Arrays;
	import java.util.Collections;
	import java.util.LinkedList;
	import java.util.List;

	/**
	* Rest like URI/Resource mapper : <p/>
	* <code>
	* example : <p/>
	* <p>
	* Initial map configuration array :<p/>
	* <p>
	* PATH \| LDAP KEY \| CLASS<p/>
	* [first, first-key , my.class.package.MyFirstClass]<p/>
	* [second, second-key , my.class.package.MySecondClass]<p/>
	* [third, third-key , my.class.package.MyThridClass]<p/>
	* <p>
	* <p>
	* the mapper will build the set of key-words below :<p/>
	* <p>
	* [firsts,first,seconds,second,thirds,third]<p/>
	* <p>
	* then it will map this key-words to OSGi filters as below : <p/>
	* <p>
	* PATH \| OSGi FILTER <p/>
	* [firsts , objectClass=my.class.package.MyFirstClass]<p/>
	* [first , first-key=<variable>]<p/>
	* [seconds , objectClass=my.class.package.MySecondClass]<p/>
	* [second , second-key=<variable>] <p/>
	* [thirds , objectClass=my.class.package.MyThridClass]<p/>
	* [third , third-key=<variable>]<p/>
	* <p>
	* It means that if the plural form of a key word is found in a treated URI, the next path element
	* of this URI will be interpreted as the value attached to the singular form of the same key-word
	* and will be put in the associated filter in replacement of the variable entry<p/>
	* <p>
	* Hierarchical links between entries have to be defined in another array as below <p/>
	* There must be at least one hierarchical link between each level<p/>
	* <p>
	* [<parent>,<child>,<child-key>,<parent-key>]<p/>
	* <p>
	* the child-key is the used to create a filter to append on the parent's one and vice versa<p/>
	* </code>
	*/
	public class RestLikeMapper {
	private static final char AND = '&';
	private static final char EQUALITY = '=';
	private static final char LESS = '-';
	private static final char OPEN_BRACKET = '(';
	private static final char CLOSE_BRACKET = ')';
	private static final String SEPARATOR_CHAR = "/";
	private static final String PLURAL_SUFFIX = "s";
	private static final String OBJECTCLASS = "objectClass";
	private static final String VARIABLE = "#VARIABLE#";

	/**
	* the associated {@link BundleContext}
	*/
	private BundleContext context;
	/**
	* filter associated to path element
	*/
	private String[][] filters;
	/**
	* relationship between path elements
	*/
	private String[][] hierarchies;
	/**
	* list of methods to exclude of the research of exposed
	* osgi services
	*/
	private List<String> methods;

	/**
	* Constructor
	*
	* @param filters initial configuration map
	* @param hierarchies map of dependencies between initial configuration map entries
	*/
	public RestLikeMapper(BundleContext context, String[][] filters, String[][] hierarchies, String[] methods) throws RestLikeMapperException {

	if (filters == null \|\| filters.length == 0 \|\| filters[0].length != 3) {
	throw new RestLikeMapperException("Invalid initial configuration map");
	}
	this.context = context;
	this.filters = new String[2 * filters.length][2];
	this.hierarchies = new String[2 * hierarchies.length][2];

	int index = 0;
	int pos = 0;
	for (; index < filters.length; index++) {
	String[] mapping = filters[index];

	this.filters[pos][0] = plural(mapping[0]);

	this.filters[pos++][1] = mapping[2] == null ? null : new StringBuilder().append(OPEN_BRACKET).append(OBJECTCLASS).append(EQUALITY).append(mapping[2]).append(CLOSE_BRACKET).toString();

	this.filters[pos][0] = mapping[0];

	this.filters[pos++][1] = mapping[1] == null ? null : new StringBuilder().append(OPEN_BRACKET).append(mapping[1]).append(EQUALITY).append(VARIABLE).append(CLOSE_BRACKET).toString();
	}
	this.methods = methods != null ? Arrays.asList(methods) : Collections.<String>emptyList();

	if (hierarchies == null \|\| hierarchies.length == 0 \|\| hierarchies[0].length != 4) {
	return;
	}
	pos = 0;
	for (String[] hierarchy : hierarchies) {
	if (hierarchy[0] != null && hierarchy[1] != null) {
	if (hierarchy[2] != null) {
	this.hierarchies[pos][0] = new StringBuilder().append(hierarchy[0]).append(LESS).append(hierarchy[1]).toString();

	this.hierarchies[pos++][1] = new StringBuilder().append(OPEN_BRACKET).append(hierarchy[2].length() == 0 ? plural(hierarchy[1]) : hierarchy[2]).append(EQUALITY).append(VARIABLE).append(CLOSE_BRACKET).toString();
	}
	if (hierarchy[3] != null) {
	this.hierarchies[pos][0] = new StringBuilder().append(hierarchy[1]).append(LESS).append(hierarchy[0]).toString();

	this.hierarchies[pos++][1] = new StringBuilder().append(OPEN_BRACKET).append(hierarchy[3].length() == 0 ? plural(hierarchy[0]) : hierarchy[3]).append(EQUALITY).append(VARIABLE).append(CLOSE_BRACKET).toString();
	}
	}
	}
	this.hierarchies = Arrays.copyOfRange(this.hierarchies, 0, pos);
	}

	/**
	* Returns the plural form of the singular word passed
	* as parameter
	*
	* @param singular the word to convert to the plural form
	* @return the plural form of the singular word passed
	* as parameter
	*/
	private String plural(String singular) {
	return new StringBuilder(singular).append(PLURAL_SUFFIX).toString();
	}

	/**
	* Concatenates the two filters passed as parameters
	*
	* @param filterFst one of the two filters to concatenate
	* @param filterSnd one of the two filters to concatenate
	* @return the filter resulting of the concatenation of the
	* two filters passed as parameters
	*/
	private String concat(String filterFst, String filterSnd) {
	if (filterFst == null) {
	return filterSnd;
	}
	if (filterSnd == null) {
	return filterFst;
	}
	return new StringBuilder().append(OPEN_BRACKET).append(AND).append((filterFst.charAt(0) == OPEN_BRACKET) ? "" : OPEN_BRACKET).append(filterFst).append((filterFst.charAt(filterFst.length() - 1) == CLOSE_BRACKET) ? "" : CLOSE_BRACKET).append((filterSnd.charAt(0) == OPEN_BRACKET) ? "" : OPEN_BRACKET).append(filterSnd).append((filterSnd.charAt(filterSnd.length() - 1) == CLOSE_BRACKET) ? "" : CLOSE_BRACKET).append(CLOSE_BRACKET).toString();
	}

	/**
	* Parses the URI string passed as parameter and return
	* the corresponding set of registered OSGi services
	* according to defined filters
	*
	* @param uri the URI string to parse
	* @return the set of OSGi services mapped by the
	* URI argument
	*/
	public RestLikeMappingReport parseURI(String uri) {
	String[] uriElements = uri.trim().split(SEPARATOR_CHAR);
	if (uri.startsWith(SEPARATOR_CHAR)) {
	uriElements = Arrays.copyOfRange(uriElements, 1, uriElements.length);
	}
	RestLikeMappingReport report = new RestLikeMappingReport(uriElements);

	if (this.methods.contains(uriElements[uriElements.length - 1])) {
	//last uri element is a method call :
	//end of the parsing
	report.reportMethod(uriElements[uriElements.length - 1]);
	uriElements = Arrays.copyOf(uriElements, uriElements.length - 1);
	}
	LinkedList<String> fstack = new LinkedList<String>();
	int last = -1;
	String variable = null;

	for (int i = 0; i < uriElements.length; i += 2) {
	String plural = uriElements[i];

	//singular form is the next element if it exists
	String singular = i < (uriElements.length - 1) ? uriElements[i + 1] : null;

	int j = 0;
	for (; j < this.filters.length && !this.filters[j][0].equals(plural); j += 2) ;

	//no key-word correspondence found
	if (j == this.filters.length) {
	break;
	}
	//current element associated filter string
	String filter = concat(this.filters[j][1], this.filters[j + 1][1] != null && singular != null ? this.filters[j + 1][1].replace(VARIABLE, singular) : null);

	//if first element...
	if (last == -1) {
	if (filter != null) {
	fstack.offer(filter);
	report.reportFilter((singular != null ? i + 1 : i), filter);
	}
	last = j;
	variable = singular;
	continue;
	}
	if (filter != null) {
	//if no string filter has been defined to precisely
	//map the singular element to a set of ServiceReferences
	//then define the report's index as its one. Otherwise
	//define the report's index as the one of the next
	//plural element
	report.reportIndex(this.filters[j + 1][1] != null ? i + 2 : i + 1);
	//retrieve implementation class name
	report.reportImplementation(this.filters[j][1] != null ? this.filters[j][1].substring(new StringBuilder().append(OPEN_BRACKET).append(OBJECTCLASS).append(EQUALITY).length(), this.filters[j][1].length() - 1) : null);
	}
	//else
	int k = 0;
	//search for hierarchical link between the current element
	//and the previous one
	for (; k < this.hierarchies.length; k++) {
	String descendant = new StringBuilder(this.filters[last + 1][0]).append(LESS).append(this.filters[j + 1][0]).toString();

	String ascendant = new StringBuilder(this.filters[j + 1][0]).append(LESS).append(this.filters[last + 1][0]).toString();

	String tmpFilter = null;

	//if descendant hierarchical link...
	if (this.hierarchies[k][0].equals(descendant)) {
	//append the current element key filter part to the previously registered filter
	tmpFilter = concat(fstack.pollLast(), this.hierarchies[k][1].replace(VARIABLE, singular));

	fstack.offer(tmpFilter);
	report.reportFilter(i - 1, tmpFilter);

	//register the current element filter for intersection purpose with the
	//next element
	if (filter != null && singular != null) {
	fstack.offer(filter);
	}
	break;
	}
	//else if ascendant hierarchical link...
	else if (this.hierarchies[k][0].equals(ascendant)) {
	//replace the filter registered for the previous element
	//by the one of the current element appended with key filter part
	//to refer to ascendant
	fstack.pollLast();
	report.reportFilter(i - 1, null);
	tmpFilter = concat(filter, this.hierarchies[k][1].replace(VARIABLE, variable));

	fstack.offer(tmpFilter);
	report.reportFilter(i, tmpFilter);

	//register the current element filter for intersection purpose with the
	//next element
	if (filter != null && singular != null) {
	fstack.offer(filter);
	}
	break;
	}
	}
	//if no hierarchical link found
	if (k == this.hierarchies.length) {
	//end of the parsing
	break;
	}
	last = j;
	variable = singular;
	}
	//apply filters and process the intersection
	//of resulting ServiceReference arrays two at a time
	List<ServiceReference> services = Collections.emptyList();

	while (!fstack.isEmpty()) {
	//retrieve the first registered filter...
	String filter = fstack.pop();
	try {
	//retrieve all registered ServiceReferences compliant with the
	//filter
	ServiceReference[] current = context.getServiceReferences((String) null, filter);

	if (current != null) {
	List<ServiceReference> srs = new LinkedList<ServiceReference>(Arrays.asList(current));

	List<ServiceReference> intersection = null;
	List<ServiceReference> references = null;

	if (services.size() == 0) {
	services = srs;
	report.reportReferences(filter, srs);

	} else {
	//process the intersection of the retrieved ServiceReferences
	//and the previous ones
	ServiceReference[] copy = new ServiceReference[current.length];
	System.arraycopy(current, 0, copy, 0, current.length);

	references = new LinkedList<ServiceReference>(Arrays.asList(copy));
	references.removeAll(services);

	intersection = new LinkedList<ServiceReference>(Arrays.asList(current));
	intersection.removeAll(references);

	services = intersection.size() == 0 ? srs : intersection;
	if (services.size() == 0) {
	//empty services set break the process
	break;

	} else {
	//If the intersection set is empty then keep all ServiceReferences
	report.reportReferences(filter, intersection.size() == 0 ? srs : intersection);
	}
	}
	} else {
	//invalid filter : break
	break;
	}
	} catch (InvalidSyntaxException e) {
	report.reportError(new RestLikeMapperException(e.getMessage() + " : " + filter, e));
	}
	}
	return report;
	}
	}