Support IsOperands in change queries from plugins

Plugins currently can add search operators and "has" operands to change
queries. Now support "is" operands using a "is:<operand>_<plugin>"
syntax very similar to the "has" syntax.

Plugins can achieve this by implementing ChangeIsOperandFactory and
returning a Predicate<ChangeData>. A sample ChangeIsOpenrandFactory
class implementing, and registering, a new is:sample_pluginName
operand is shown below:

  public class SampleIsOperand implements ChangeIsOperandFactory {
    public static class Module extends AbstractModule {
      @Override
      protected void configure() {
        bind(ChangeIsOperandFactory.class)
            .annotatedWith(Exports.named("sample")
            .to(SampleIsOperand.class);
      }
    }

    @Override
    public Predicate<ChangeData> create(ChangeQueryBuilder builder){
      return new IsSamplePredicate();
    }
  }

Change-Id: Ic694673be806e23a294e0a30cb3bb1b7e59b46f8

java/com/google/gerrit/server/config/GerritGlobalModule.java

@@ -433,6 +433,7 @@ public class GerritGlobalModule extends FactoryModule {
     DynamicMap.mapOf(binder(), DynamicOptions.DynamicBean.class);
     DynamicMap.mapOf(binder(), ChangeQueryBuilder.ChangeOperatorFactory.class);
     DynamicMap.mapOf(binder(), ChangeQueryBuilder.ChangeHasOperandFactory.class);
+    DynamicMap.mapOf(binder(), ChangeQueryBuilder.ChangeIsOperandFactory.class);
     DynamicSet.setOf(binder(), ChangeAttributeFactory.class);
 
     install(new GitwebConfig.LegacyModule(cfg));

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

@@ -117,12 +117,14 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
    * <p>bind(ChangeHasOperandFactory.class) .annotatedWith(Exports.named("your has operand"))
    * .to(YourClass.class);
    */
-  private interface ChangeOperandFactory {
+  public interface ChangeOperandFactory {
     Predicate<ChangeData> create(ChangeQueryBuilder builder) throws QueryParseException;
   }
 
   public interface ChangeHasOperandFactory extends ChangeOperandFactory {}
 
+  public interface ChangeIsOperandFactory extends ChangeOperandFactory {}
+
   private static final Pattern PAT_LEGACY_ID = Pattern.compile("^[1-9][0-9]*$");
   private static final Pattern PAT_CHANGE_ID = Pattern.compile(CHANGE_ID_PATTERN);
   private static final Pattern DEF_CHANGE =
@@ -218,6 +220,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
     final CommentsUtil commentsUtil;
     final ConflictsCache conflictsCache;
     final DynamicMap<ChangeHasOperandFactory> hasOperands;
+    final DynamicMap<ChangeIsOperandFactory> isOperands;
     final DynamicMap<ChangeOperatorFactory> opFactories;
     final GitRepositoryManager repoManager;
     final GroupBackend groupBackend;
@@ -244,6 +247,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
         ChangeIndexRewriter rewriter,
         DynamicMap<ChangeOperatorFactory> opFactories,
         DynamicMap<ChangeHasOperandFactory> hasOperands,
+        DynamicMap<ChangeIsOperandFactory> isOperands,
         IdentifiedUser.GenericFactory userFactory,
         Provider<CurrentUser> self,
         PermissionBackend permissionBackend,
@@ -273,6 +277,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
           rewriter,
           opFactories,
           hasOperands,
+          isOperands,
           userFactory,
           self,
           permissionBackend,
@@ -304,6 +309,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
         ChangeIndexRewriter rewriter,
         DynamicMap<ChangeOperatorFactory> opFactories,
         DynamicMap<ChangeHasOperandFactory> hasOperands,
+        DynamicMap<ChangeIsOperandFactory> isOperands,
         IdentifiedUser.GenericFactory userFactory,
         Provider<CurrentUser> self,
         PermissionBackend permissionBackend,
@@ -351,6 +357,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
       this.starredChangesUtil = starredChangesUtil;
       this.accountCache = accountCache;
       this.hasOperands = hasOperands;
+      this.isOperands = isOperands;
       this.groupMembers = groupMembers;
       this.changeIsVisbleToPredicateFactory = changeIsVisbleToPredicateFactory;
       this.operatorAliasConfig = operatorAliasConfig;
@@ -364,6 +371,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
           rewriter,
           opFactories,
           hasOperands,
+          isOperands,
           userFactory,
           Providers.of(otherUser),
           permissionBackend,
@@ -643,6 +651,14 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
       throw new QueryParseException("'is:wip' operator is not supported by change index version");
     }
 
+    // for plugins the value will be operandName_pluginName
+    List<String> names = Lists.newArrayList(Splitter.on('_').split(value));
+    if (names.size() == 2) {
+      ChangeIsOperandFactory op = args.isOperands.get(names.get(1), names.get(0));
+      if (op != null) {
+        return op.create(this);
+      }
+    }
     return status(value);
   }