LUCENE-7417: Highlighter WSTE didn't handle single-term MultiPhraseQuery.

Also updated to Java 5 for-each in this method.

lucene/CHANGES.txt

@@ -36,7 +36,21 @@ Other
 
 ======================= Lucene 6.3.0 =======================
 
-(No changes)
+API Changes
+
+New Features
+
+Bug Fixes
+
+* LUCENE-7417: The standard Highlighter could throw an IllegalArgumentException when
+  trying to highlight a query containing a degenerate case of a MultiPhraseQuery with one
+  term.  (Thomas Kappler via David Smiley)
+
+Improvements
+
+Optimizations
+
+Other
 
 ======================= Lucene 6.2.0 =======================
 

lucene/highlighter/src/java/org/apache/lucene/search/highlight/WeightedSpanTermExtractor.java

@@ -118,8 +118,7 @@ public class WeightedSpanTermExtractor {
       Term[] phraseQueryTerms = phraseQuery.getTerms();
       if (phraseQueryTerms.length == 1) {
         extractWeightedSpanTerms(terms, new SpanTermQuery(phraseQueryTerms[0]), boost);
-      }
-      else {
+      } else {
         SpanQuery[] clauses = new SpanQuery[phraseQueryTerms.length];
         for (int i = 0; i < phraseQueryTerms.length; i++) {
           clauses[i] = new SpanTermQuery(phraseQueryTerms[i]);
@@ -153,8 +152,8 @@ public class WeightedSpanTermExtractor {
       // this query is TermContext sensitive.
       extractWeightedTerms(terms, query, boost);
     } else if (query instanceof DisjunctionMaxQuery) {
-      for (Iterator<Query> iterator = ((DisjunctionMaxQuery) query).iterator(); iterator.hasNext();) {
-        extract(iterator.next(), boost, terms);
+      for (Query clause : ((DisjunctionMaxQuery) query)) {
+        extract(clause, boost, terms);
       }
     } else if (query instanceof ToParentBlockJoinQuery) {
       extract(((ToParentBlockJoinQuery) query).getChildQuery(), boost, terms);
@@ -184,16 +183,15 @@ public class WeightedSpanTermExtractor {
             disjuncts = (disjunctLists[positions[i]] = new ArrayList<>(termArray.length));
             ++distinctPositions;
           }
-          for (int j = 0; j < termArray.length; ++j) {
-            disjuncts.add(new SpanTermQuery(termArray[j]));
+          for (Term aTermArray : termArray) {
+            disjuncts.add(new SpanTermQuery(aTermArray));
           }
         }
 
         int positionGaps = 0;
         int position = 0;
         final SpanQuery[] clauses = new SpanQuery[distinctPositions];
-        for (int i = 0; i < disjunctLists.length; ++i) {
-          List<SpanQuery> disjuncts = disjunctLists[i];
+        for (List<SpanQuery> disjuncts : disjunctLists) {
           if (disjuncts != null) {
             clauses[position++] = new SpanOrQuery(disjuncts
                 .toArray(new SpanQuery[disjuncts.size()]));
@@ -202,11 +200,15 @@ public class WeightedSpanTermExtractor {
           }
         }
 
-        final int slop = mpq.getSlop();
-        final boolean inorder = (slop == 0);
+        if (clauses.length == 1) {
+          extractWeightedSpanTerms(terms, clauses[0], boost);
+        } else {
+          final int slop = mpq.getSlop();
+          final boolean inorder = (slop == 0);
 
-        SpanNearQuery sp = new SpanNearQuery(clauses, slop + positionGaps, inorder);
-        extractWeightedSpanTerms(terms, sp, boost);
+          SpanNearQuery sp = new SpanNearQuery(clauses, slop + positionGaps, inorder);
+          extractWeightedSpanTerms(terms, sp, boost);
+        }
       }
     } else if (query instanceof MatchAllDocsQuery) {
       //nothing

lucene/highlighter/src/test/org/apache/lucene/search/highlight/HighlighterTest.java

@@ -94,7 +94,6 @@ import org.apache.lucene.util.LuceneTestCase;
 import org.apache.lucene.util.automaton.Automata;
 import org.apache.lucene.util.automaton.CharacterRunAutomaton;
 import org.apache.lucene.util.automaton.RegExp;
-import org.junit.Test;
 import org.w3c.dom.Element;
 import org.w3c.dom.NodeList;
 
@@ -1580,30 +1579,39 @@ public class HighlighterTest extends BaseTokenStreamTestCase implements Formatte
     helper.start();
   }
 
-  @Test
   public void testHighlighterWithPhraseQuery() throws IOException, InvalidTokenOffsetsException {
+    final String fieldName = "substring";
 
+    final PhraseQuery query = new PhraseQuery(fieldName, new BytesRef[] { new BytesRef("uchu") });
+
+    assertHighlighting(query, new SimpleHTMLFormatter("<b>", "</b>"), "Buchung", "B<b>uchu</b>ng", fieldName);
+  }
+
+  public void testHighlighterWithMultiPhraseQuery() throws IOException, InvalidTokenOffsetsException {
+    final String fieldName = "substring";
+
+    final MultiPhraseQuery mpq = new MultiPhraseQuery.Builder()
+        .add(new Term(fieldName, "uchu")).build();
+
+    assertHighlighting(mpq, new SimpleHTMLFormatter("<b>", "</b>"), "Buchung", "B<b>uchu</b>ng", fieldName);
+  }
+
+  private void assertHighlighting(Query query, Formatter formatter, String text, String expected, String fieldName)
+      throws IOException, InvalidTokenOffsetsException {
     final Analyzer analyzer = new Analyzer() {
       @Override
       protected TokenStreamComponents createComponents(String fieldName) {
         return new TokenStreamComponents(new NGramTokenizer(4, 4));
       }
     };
-    final String fieldName = "substring";
-
-    final List<BytesRef> list = new ArrayList<>();
-    list.add(new BytesRef("uchu"));
-    final PhraseQuery query = new PhraseQuery(fieldName, list.toArray(new BytesRef[list.size()]));
 
     final QueryScorer fragmentScorer = new QueryScorer(query, fieldName);
-    final SimpleHTMLFormatter formatter = new SimpleHTMLFormatter("<b>", "</b>");
 
     final Highlighter highlighter = new Highlighter(formatter, fragmentScorer);
     highlighter.setTextFragmenter(new SimpleFragmenter(100));
-    final String fragment = highlighter.getBestFragment(analyzer, fieldName, "Buchung");
-
-    assertEquals("B<b>uchu</b>ng",fragment);
+    final String fragment = highlighter.getBestFragment(analyzer, fieldName, text);
 
+    assertEquals(expected, fragment);
   }
 
   public void testUnRewrittenQuery() throws Exception {