Allow using the FVH and Postings Highlighter without storing extra data

docs/reference/search/request/highlighting.asciidoc

@@ -66,11 +66,11 @@ a query match, effectively ignoring their positions.
 
 ==== Fast vector highlighter
 
-If `term_vector` information is provided by setting `term_vector` to
-`with_positions_offsets` in the mapping then the fast vector highlighter
-will be used instead of the plain highlighter.  The fast vector highlighter:
+If positiong and offsets are stored in term vectors on the field then the
+fast vector highlighter will be used instead of the plain highlighter.  The
+fast vector highlighter:
 
-* Is faster especially for large fields (> `1MB`)
+* Is faster for large fields (> `1MB`) but slower for small fields
 * Can be customized with `boundary_chars`, `boundary_max_scan`, and
  `fragment_offset` (see <<boundary-characters,below>>)
 * Requires setting `term_vector` to `with_positions_offsets` which
@@ -82,8 +82,8 @@ will be used instead of the plain highlighter.  The fast vector highlighter:
   highlighting a Boosting Query that boosts phrase matches over term matches
 
 Here is an example of setting the `content` field to allow for
-highlighting using the fast vector highlighter on it (this will cause
-the index to be bigger):
+highlighting using the fast vector highlighter on it.  This will store
+term vectors for all fields regardless of length.
 
 [source,js]
 --------------------------------------------------
@@ -94,6 +94,7 @@ the index to be bigger):
 }
 --------------------------------------------------
 
+
 ==== Force highlighter type
 
 The `type` field allows to force a specific highlighter type. This is useful
@@ -113,6 +114,15 @@ The following is an example that forces the use of the plain highlighter:
 }
 --------------------------------------------------
 
+
+Forcing a highlighter for which requires extra data will fail if the extra
+data is saved.  For example, forcing the `postings` highlighter without
+`index_options` set to `offsets` will cause an error.
+
+coming[1.1.0]
+You can force any highlighter regardless of the extra data stored at the
+at the cost of extra CPU time per field.
+
 ==== Force highlighting on source
 
 added[1.0.0.RC1]

src/main/java/org/apache/lucene/search/postingshighlight/CustomPostingsHighlighter.java

@@ -91,8 +91,7 @@ public CustomPostingsHighlighter(CustomPassageFormatter passageFormatter, List<O
     /*
     Our own api to highlight a single document field, passing in the query terms, and get back our own Snippet object
      */
-    public Snippet[] highlightDoc(String field, BytesRef[] terms, IndexSearcher searcher, int docId, int maxPassages) throws IOException {
-        IndexReader reader = searcher.getIndexReader();
+    public Snippet[] highlightDoc(String field, BytesRef[] terms, IndexReader reader, int docId, int maxPassages) throws IOException {
         IndexReaderContext readerContext = reader.getContext();
         List<AtomicReaderContext> leaves = readerContext.leaves();
 

src/main/java/org/apache/lucene/search/vectorhighlight/CustomFieldQuery.java

@@ -25,24 +25,24 @@
 import org.apache.lucene.queries.TermFilter;
 import org.apache.lucene.search.*;
 import org.apache.lucene.search.spans.SpanTermQuery;
-import org.apache.lucene.util.Version;
-import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.lucene.search.MultiPhrasePrefixQuery;
 import org.elasticsearch.common.lucene.search.XBooleanFilter;
 import org.elasticsearch.common.lucene.search.XFilteredQuery;
 import org.elasticsearch.common.lucene.search.function.FiltersFunctionScoreQuery;
 import org.elasticsearch.common.lucene.search.function.FunctionScoreQuery;
+import org.elasticsearch.search.highlight.AbstractDelegatingOrAnalyzingReader.TermSetSource;
 
 import java.io.IOException;
 import java.lang.reflect.Field;
 import java.util.Collection;
 import java.util.List;
+import java.util.Set;
 
 /**
  *
  */
 // LUCENE MONITOR
-public class CustomFieldQuery extends FieldQuery {
+public class CustomFieldQuery extends FieldQuery implements TermSetSource {
 
     private static Field multiTermQueryWrapperFilterQueryField;
 
@@ -158,4 +158,9 @@ void flatten(Filter sourceFilter, IndexReader reader, Collection<Query> flatQuer
             }
         }
     }
+
+    @Override
+    public Set<String> termSet(String field) {
+        return getTermSet(field);
+    }
 }