Support searching changes by file extension

Change-Id: I76319392dfa91e18ad4be6d9673951d03aa68a00

Documentation/user-search.txt

@@ -289,6 +289,14 @@ named exactly `Foo.java` and does not match `AbstractFoo.java`.
 Regular expression matching can be enabled by starting the string
 with `^`. In this mode `file:` is an alias of `path:` (see above).
 
+[[extension]]
+extension:'EXT', ext:'EXT'::
++
+Matches any change touching a file with extension 'EXT', case-insensitive. The
+extension is defined as the portion of the filename following the final `.`.
+Files with no `.` in their name have no extension and cannot be matched with
+this operator; use `file:` instead.
+
 [[star]]
 star:'LABEL'::
 +

java/com/google/gerrit/server/index/change/ChangeField.java

@@ -37,6 +37,7 @@ import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Table;
 import com.google.common.flogger.FluentLogger;
+import com.google.common.io.Files;
 import com.google.common.primitives.Longs;
 import com.google.gerrit.common.data.SubmitRecord;
 import com.google.gerrit.common.data.SubmitRequirement;
@@ -185,6 +186,26 @@ public class ChangeField {
   public static final FieldDef<ChangeData, Iterable<String>> FILE_PART =
       exact(ChangeQueryBuilder.FIELD_FILEPART).buildRepeatable(ChangeField::getFileParts);
 
+  /** File extensions of each file modified in the current patch set. */
+  public static final FieldDef<ChangeData, Iterable<String>> EXTENSION =
+      exact(ChangeQueryBuilder.FIELD_EXTENSION).buildRepeatable(ChangeField::getExtensions);
+
+  public static Set<String> getExtensions(ChangeData cd) throws OrmException {
+    try {
+      return cd.currentFilePaths()
+          .stream()
+          // Use case-insensitive file extensions even though other file fields are case-sensitive.
+          // If we want to find "all Java files", we want to match both .java and .JAVA, even if we
+          // normally care about case sensitivity. (Whether we should change the existing file/path
+          // predicates to be case insensitive is a separate question.)
+          .map(f -> Files.getFileExtension(f).toLowerCase(Locale.US))
+          .filter(e -> !e.isEmpty())
+          .collect(toSet());
+    } catch (IOException e) {
+      throw new OrmException(e);
+    }
+  }
+
   /** Owner/creator of the change. */
   public static final FieldDef<ChangeData, Integer> OWNER =
       integer(ChangeQueryBuilder.FIELD_OWNER).build(changeGetter(c -> c.getOwner().get()));

java/com/google/gerrit/server/index/change/ChangeSchemaDefinitions.java

@@ -101,7 +101,9 @@ public class ChangeSchemaDefinitions extends SchemaDefinitions<ChangeData> {
   // Bump Lucene version requires reindexing
   @Deprecated static final Schema<ChangeData> V50 = schema(V49);
 
-  static final Schema<ChangeData> V51 = schema(V50, ChangeField.TOTAL_COMMENT_COUNT);
+  @Deprecated static final Schema<ChangeData> V51 = schema(V50, ChangeField.TOTAL_COMMENT_COUNT);
+
+  static final Schema<ChangeData> V52 = schema(V51, ChangeField.EXTENSION);
 
   public static final String NAME = "changes";
   public static final ChangeSchemaDefinitions INSTANCE = new ChangeSchemaDefinitions();

java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java

@@ -137,6 +137,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData> {
   public static final String FIELD_COMMIT = "commit";
   public static final String FIELD_COMMITTER = "committer";
   public static final String FIELD_EXACTCOMMITTER = "exactcommitter";
+  public static final String FIELD_EXTENSION = "extension";
   public static final String FIELD_CONFLICTS = "conflicts";
   public static final String FIELD_DELETED = "deleted";
   public static final String FIELD_DELTA = "delta";
@@ -732,6 +733,16 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData> {
     return new EqualsPathPredicate(FIELD_PATH, path);
   }
 
+  @Operator
+  public Predicate<ChangeData> ext(String ext) {
+    return extension(ext);
+  }
+
+  @Operator
+  public Predicate<ChangeData> extension(String ext) {
+    return new FileExtensionPredicate(ext);
+  }
+
   @Operator
   public Predicate<ChangeData> label(String name)
       throws QueryParseException, OrmException, IOException, ConfigInvalidException {

java/com/google/gerrit/server/query/change/FileExtensionPredicate.java

@@ -0,0 +1,42 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.query.change;
+
+import com.google.gerrit.server.index.change.ChangeField;
+import com.google.gwtorm.server.OrmException;
+import java.util.Locale;
+
+public class FileExtensionPredicate extends ChangeIndexPredicate {
+  private static String clean(String ext) {
+    if (ext.startsWith(".")) {
+      ext = ext.substring(1);
+    }
+    return ext.toLowerCase(Locale.US);
+  }
+
+  FileExtensionPredicate(String value) {
+    super(ChangeField.EXTENSION, clean(value));
+  }
+
+  @Override
+  public boolean match(ChangeData object) throws OrmException {
+    return ChangeField.getExtensions(object).contains(value);
+  }
+
+  @Override
+  public int getCost() {
+    return 0;
+  }
+}

javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java

@@ -1366,6 +1366,24 @@ public abstract class AbstractQueryChangesTest extends GerritServerTests {
     assertQuery("path:^dir.file.*", change);
   }
 
+  @Test
+  public void byExtension() throws Exception {
+    assume().that(getSchema().hasField(ChangeField.EXTENSION)).isTrue();
+
+    TestRepository<Repo> repo = createProject("repo");
+    Change change1 = insert(repo, newChangeWithFiles(repo, "foo.h", "foo.cc"));
+    Change change2 = insert(repo, newChangeWithFiles(repo, "bar.H", "bar.CC"));
+    Change change3 = insert(repo, newChangeWithFiles(repo, "dir/baz.h", "dir/baz.cc"));
+    Change change4 = insert(repo, newChangeWithFiles(repo, "Quux.java"));
+
+    assertQuery("extension:java", change4);
+    assertQuery("ext:java", change4);
+    assertQuery("ext:.java", change4);
+    assertQuery("ext:jAvA", change4);
+    assertQuery("ext:.jAvA", change4);
+    assertQuery("ext:cc", change3, change2, change1);
+  }
+
   @Test
   public void byComment() throws Exception {
     TestRepository<Repo> repo = createProject("repo");

polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.js

@@ -36,6 +36,8 @@
     'conflicts:',
     'deleted:',
     'delta:',
+    'ext:',
+    'extension:',
     'file:',
     'from:',
     'has:',