docs/attachments/LUCENE-7627/LUCENE-7627.patch

diff --git a/lucene/core/src/java/org/apache/lucene/index/SortedDocValues.java b/lucene/core/src/java/org/apache/lucene/index/SortedDocValues.java
index e2d7dfd..087e487 100644
--- a/lucene/core/src/java/org/apache/lucene/index/SortedDocValues.java
+++ b/lucene/core/src/java/org/apache/lucene/index/SortedDocValues.java
@@ -20,6 +20,7 @@ package org.apache.lucene.index;
 import java.io.IOException;
 
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.automaton.CompiledAutomaton;
 
 /**
  * A per-document byte[] with presorted values.  This is fundamentally an
@@ -110,4 +111,25 @@ public abstract class SortedDocValues extends BinaryDocValues {
     return new SortedDocValuesTermsEnum(this);
   }
 
+  /**
+   * Returns a {@link TermsEnum} over the values, filtered by a {@link CompiledAutomaton}
+   * The enum supports {@link TermsEnum#ord()}.
+   */
+  public TermsEnum intersect(CompiledAutomaton automaton) throws IOException {
+    TermsEnum in = termsEnum();
+    switch (automaton.type) {
+      case NONE:
+        return TermsEnum.EMPTY;
+      case ALL:
+        return in;
+      case SINGLE:
+        return new SingleTermsEnum(in, automaton.term);
+      case NORMAL:
+        return new AutomatonTermsEnum(in, automaton);
+      default:
+        // unreachable
+        throw new RuntimeException("unhandled case");
+    }
+  }
+
 }
diff --git a/lucene/core/src/java/org/apache/lucene/index/SortedSetDocValues.java b/lucene/core/src/java/org/apache/lucene/index/SortedSetDocValues.java
index 6d02c25..9e1c6a3 100644
--- a/lucene/core/src/java/org/apache/lucene/index/SortedSetDocValues.java
+++ b/lucene/core/src/java/org/apache/lucene/index/SortedSetDocValues.java
@@ -20,6 +20,7 @@ package org.apache.lucene.index;
 import java.io.IOException;
 
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.automaton.CompiledAutomaton;
 
 /**
  * A multi-valued version of {@link SortedDocValues}.
@@ -102,4 +103,25 @@ public abstract class SortedSetDocValues extends DocValuesIterator {
   public TermsEnum termsEnum() throws IOException {
     return new SortedSetDocValuesTermsEnum(this);
   }
+
+  /**
+   * Returns a {@link TermsEnum} over the values, filtered by a {@link CompiledAutomaton}
+   * The enum supports {@link TermsEnum#ord()}.
+   */
+  public TermsEnum intersect(CompiledAutomaton automaton) throws IOException {
+    TermsEnum in = termsEnum();
+    switch (automaton.type) {
+      case NONE:
+        return TermsEnum.EMPTY;
+      case ALL:
+        return in;
+      case SINGLE:
+        return new SingleTermsEnum(in, automaton.term);
+      case NORMAL:
+        return new AutomatonTermsEnum(in, automaton);
+      default:
+        // unreachable
+        throw new RuntimeException("unhandled case");
+    }
+  }
 }
diff --git a/lucene/test-framework/src/java/org/apache/lucene/index/BaseDocValuesFormatTestCase.java b/lucene/test-framework/src/java/org/apache/lucene/index/BaseDocValuesFormatTestCase.java
index d55f212..8cb6665 100644
--- a/lucene/test-framework/src/java/org/apache/lucene/index/BaseDocValuesFormatTestCase.java
+++ b/lucene/test-framework/src/java/org/apache/lucene/index/BaseDocValuesFormatTestCase.java
@@ -67,6 +67,8 @@ import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.TestUtil;
 
 import com.carrotsearch.randomizedtesting.generators.RandomPicks;
+import org.apache.lucene.util.automaton.CompiledAutomaton;
+import org.apache.lucene.util.automaton.RegExp;
 
 import static org.apache.lucene.index.SortedSetDocValues.NO_MORE_ORDS;
 import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS;
@@ -906,6 +908,21 @@ public abstract class BaseDocValuesFormatTestCase extends BaseIndexFileFormatTes
     termsEnum.seekExact(2);
     assertEquals("world", termsEnum.term().utf8ToString());
     assertEquals(2, termsEnum.ord());
+
+    // NORMAL automaton
+    termsEnum = dv.intersect(new CompiledAutomaton(new RegExp(".*l.*").toAutomaton()));
+    assertEquals("hello", termsEnum.next().utf8ToString());
+    assertEquals(1, termsEnum.ord());
+    assertEquals("world", termsEnum.next().utf8ToString());
+    assertEquals(2, termsEnum.ord());
+    assertNull(termsEnum.next());
+
+    // SINGLE automaton
+    termsEnum = dv.intersect(new CompiledAutomaton(new RegExp("hello").toAutomaton()));
+    assertEquals("hello", termsEnum.next().utf8ToString());
+    assertEquals(1, termsEnum.ord());
+    assertNull(termsEnum.next());
+
     ireader.close();
     directory.close();
   }
@@ -2057,6 +2074,21 @@ public abstract class BaseDocValuesFormatTestCase extends BaseIndexFileFormatTes
     termsEnum.seekExact(2);
     assertEquals("world", termsEnum.term().utf8ToString());
     assertEquals(2, termsEnum.ord());
+
+    // NORMAL automaton
+    termsEnum = dv.intersect(new CompiledAutomaton(new RegExp(".*l.*").toAutomaton()));
+    assertEquals("hello", termsEnum.next().utf8ToString());
+    assertEquals(1, termsEnum.ord());
+    assertEquals("world", termsEnum.next().utf8ToString());
+    assertEquals(2, termsEnum.ord());
+    assertNull(termsEnum.next());
+
+    // SINGLE automaton
+    termsEnum = dv.intersect(new CompiledAutomaton(new RegExp("hello").toAutomaton()));
+    assertEquals("hello", termsEnum.next().utf8ToString());
+    assertEquals(1, termsEnum.ord());
+    assertNull(termsEnum.next());
+
     ireader.close();
     directory.close();
   }