added query modifier 'on'. This makes it possible to search for date

occurrences within the (web) page documents (not the document
last-modified!). This works only if the solr field dates_in_content_sxt
is enabled. A search request may then have the form "term on:<date>",
like
gift on:24.12.2014
gift on:2014/12/24
* on:2014/12/31
For the date format you may use any kind of human-readable date
representation(!yes!) - the on:<date> parser tries to identify language
and also knows event names, like:
bunny on:eastern
.. as long as the date term has no spaces inside (use a dot). Further
enhancement will be made to accept also strings encapsulated with
quotes.

source/net/yacy/document/DateDetection.java

@@ -35,6 +35,8 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import net.yacy.cora.date.GenericFormatter;
+
 /**
  * The purpose of this class exceeds the demands on simple date parsing using a SimpleDateFormat
  * because it tries to 
@@ -494,6 +496,20 @@ public static LinkedHashSet<Date> parse(String text) {
         return dates;
     }
 
+    public static Date parseLine(String text) {
+        Date d = null;
+        try {d = CONFORM.parse(text);} catch (ParseException e) {}
+        if (d == null) try {d = GenericFormatter.FORMAT_SHORT_DAY.parse(text);} catch (ParseException e) {}
+        if (d == null) try {d = GenericFormatter.FORMAT_RFC1123_SHORT.parse(text);} catch (ParseException e) {}
+        if (d == null) try {d = GenericFormatter.FORMAT_ANSIC.parse(text);} catch (ParseException e) {}
+
+        if (d == null) {
+            Set<Date> dd = parse(text);
+            if (dd.size() >= 1) d = dd.iterator().next();
+        }
+        return d;
+    }
+
     private static LinkedHashSet<Date> parseRawDate(String text) {
         // get parse alternatives for different date styles; we consider that one document uses only one style
         LinkedHashSet<Date> DMYDates = EndianStyle.DMY.parse(text);

source/net/yacy/search/query/QueryModifier.java

@@ -22,13 +22,15 @@
 
 import java.net.MalformedURLException;
 import java.util.ArrayList;
+import java.util.Date;
 
 import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.params.MultiMapSolrParams;
 
 import net.yacy.cora.document.id.DigestURL;
 import net.yacy.cora.util.CommonPattern;
 import net.yacy.cora.util.ConcurrentLog;
+import net.yacy.document.DateDetection;
 import net.yacy.kelondro.util.ISO639;
 import net.yacy.search.schema.CollectionSchema;
 import net.yacy.server.serverObjects;
@@ -37,7 +39,7 @@
 public class QueryModifier {
 
     private final StringBuilder modifier;
-    public String sitehost, sitehash, filetype, protocol, language, author, collection;
+    public String sitehost, sitehash, filetype, protocol, language, author, collection, on;
 
     public QueryModifier() {
         this.sitehash = null;
@@ -47,6 +49,7 @@ public QueryModifier() {
         this.language = null;
         this.author = null;
         this.collection = null;
+        this.on = null;
         this.modifier = new StringBuilder(20);
     }
 
@@ -142,6 +145,18 @@ public String parse(String querystring) {
             querystring = querystring.replace("collection:" + this.collection, "");
             add("collection:" + this.collection);
         }
+
+        // parse on-date
+        final int oni = querystring.indexOf("on:", 0);
+        if ( oni >= 0 ) {
+            int ftb = querystring.indexOf(' ', oni);
+            if ( ftb == -1 ) {
+                ftb = querystring.length();
+            }
+            this.on = querystring.substring(oni + 3, ftb);
+            querystring = querystring.replace("on:" + this.on, "");
+            add("on:" + this.on);
+        }
 
         // parse language
         final int langi = querystring.indexOf("/language/");
@@ -240,6 +255,10 @@ private StringBuilder apply(String FQ) {
             fq.append(" AND ").append(QueryModifier.parseCollectionExpression(this.collection));
         }
 
+        if (this.on != null && this.on.length() > 0 && fq.indexOf(CollectionSchema.dates_in_content_sxt.getSolrFieldName()) < 0) {
+            fq.append(" AND ").append(QueryModifier.parseOnExpression(this.on));
+        }
+
         if (this.protocol != null && this.protocol.length() > 0 && fq.indexOf(CollectionSchema.url_protocol_s.getSolrFieldName()) < 0) {
             fq.append(" AND ").append(CollectionSchema.url_protocol_s.getSolrFieldName()).append(":\"").append(this.protocol).append('\"');
         }
@@ -295,6 +314,15 @@ public static String parseCollectionExpression(String collectionDescription) {
             filterQuery.append(CollectionSchema.collection_sxt.getSolrFieldName()).append(":\"").append(sites.get(0)).append('\"');
         }
         return filterQuery.toString();
+    }
+
+    public static String parseOnExpression(String onDescription) {
+        Date onDate = DateDetection.parseLine(onDescription);
+        StringBuilder filterQuery = new StringBuilder(20);
+        if (onDate != null) {
+            filterQuery.append(CollectionSchema.dates_in_content_sxt.getSolrFieldName()).append(":\"").append(org.apache.solr.schema.TrieDateField.formatExternal(onDate)).append('\"');
+        }
+        return filterQuery.toString();
 
     }
 

source/net/yacy/search/query/QueryParams.java

@@ -481,6 +481,10 @@ private String getFacets() {
             fq.append(" AND ").append(QueryModifier.parseCollectionExpression(this.modifier.collection));
         }
 
+        if (this.modifier.on != null && this.modifier.on.length() > 0 && this.solrSchema.contains(CollectionSchema.dates_in_content_sxt)) {
+            fq.append(" AND ").append(QueryModifier.parseOnExpression(this.modifier.on));
+        }
+
         if (this.modifier.protocol != null) {
             fq.append(" AND {!tag=").append(CollectionSchema.url_protocol_s.getSolrFieldName()).append("}").append(CollectionSchema.url_protocol_s.getSolrFieldName()).append(':').append(this.modifier.protocol);
         }