Move general index classes from gerrit-server to gerrit-index

These classes do not depend on any Gerrit server functionality, and
could even be used to define an index without depending on the
gerrit-server package. This allows for a clearer separation of BUILD
rules; the QueryParser and antlr targets don't escape the gerrit-index
package.

The general layout thus far is to put index definition code in
com.google.gerrit.index, and query-related code (predicates, etc.)  in
com.google.gerrit.index.query.

The gerrit-index package is still of limited utility on its own, because
QueryProcessor and InternalQuery still live in the server package, and
untangling their dependencies will still be a bit more work.

Change-Id: I3c4616d08ecf19d5ccd1b9b91b3fd0b1fcedd901

gerrit-index/src/main/java/com/google/gerrit/index/query/AndPredicate.java

@@ -0,0 +1,131 @@
+// Copyright (C) 2009 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.index.query;
+
+import static com.google.common.base.Preconditions.checkState;
+
+import com.google.gwtorm.server.OrmException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+/** Requires all predicates to be true. */
+public class AndPredicate<T> extends Predicate<T> implements Matchable<T> {
+  private final List<Predicate<T>> children;
+  private final int cost;
+
+  @SafeVarargs
+  protected AndPredicate(Predicate<T>... that) {
+    this(Arrays.asList(that));
+  }
+
+  protected AndPredicate(Collection<? extends Predicate<T>> that) {
+    List<Predicate<T>> t = new ArrayList<>(that.size());
+    int c = 0;
+    for (Predicate<T> p : that) {
+      if (getClass() == p.getClass()) {
+        for (Predicate<T> gp : p.getChildren()) {
+          t.add(gp);
+          c += gp.estimateCost();
+        }
+      } else {
+        t.add(p);
+        c += p.estimateCost();
+      }
+    }
+    children = t;
+    cost = c;
+  }
+
+  @Override
+  public final List<Predicate<T>> getChildren() {
+    return Collections.unmodifiableList(children);
+  }
+
+  @Override
+  public final int getChildCount() {
+    return children.size();
+  }
+
+  @Override
+  public final Predicate<T> getChild(int i) {
+    return children.get(i);
+  }
+
+  @Override
+  public Predicate<T> copy(Collection<? extends Predicate<T>> children) {
+    return new AndPredicate<>(children);
+  }
+
+  @Override
+  public boolean isMatchable() {
+    for (Predicate<T> c : children) {
+      if (!c.isMatchable()) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @Override
+  public boolean match(T object) throws OrmException {
+    for (Predicate<T> c : children) {
+      checkState(
+          c.isMatchable(),
+          "match invoked, but child predicate %s doesn't implement %s",
+          c,
+          Matchable.class.getName());
+      if (!c.asMatchable().match(object)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @Override
+  public int getCost() {
+    return cost;
+  }
+
+  @Override
+  public int hashCode() {
+    return getChild(0).hashCode() * 31 + getChild(1).hashCode();
+  }
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == null) {
+      return false;
+    }
+    return getClass() == other.getClass()
+        && getChildren().equals(((Predicate<?>) other).getChildren());
+  }
+
+  @Override
+  public String toString() {
+    final StringBuilder r = new StringBuilder();
+    r.append("(");
+    for (int i = 0; i < getChildCount(); i++) {
+      if (i != 0) {
+        r.append(" ");
+      }
+      r.append(getChild(i));
+    }
+    r.append(")");
+    return r.toString();
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/AndSource.java

@@ -0,0 +1,200 @@
+// Copyright (C) 2016 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.index.query;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.base.Throwables;
+import com.google.common.collect.FluentIterable;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Iterables;
+import com.google.gwtorm.server.ListResultSet;
+import com.google.gwtorm.server.OrmException;
+import com.google.gwtorm.server.OrmRuntimeException;
+import com.google.gwtorm.server.ResultSet;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+public class AndSource<T> extends AndPredicate<T>
+    implements DataSource<T>, Comparator<Predicate<T>> {
+  protected final DataSource<T> source;
+
+  private final IsVisibleToPredicate<T> isVisibleToPredicate;
+  private final int start;
+  private final int cardinality;
+
+  public AndSource(Collection<? extends Predicate<T>> that) {
+    this(that, null, 0);
+  }
+
+  public AndSource(Predicate<T> that, IsVisibleToPredicate<T> isVisibleToPredicate) {
+    this(that, isVisibleToPredicate, 0);
+  }
+
+  public AndSource(Predicate<T> that, IsVisibleToPredicate<T> isVisibleToPredicate, int start) {
+    this(ImmutableList.of(that), isVisibleToPredicate, start);
+  }
+
+  public AndSource(
+      Collection<? extends Predicate<T>> that,
+      IsVisibleToPredicate<T> isVisibleToPredicate,
+      int start) {
+    super(that);
+    checkArgument(start >= 0, "negative start: %s", start);
+    this.isVisibleToPredicate = isVisibleToPredicate;
+    this.start = start;
+
+    int c = Integer.MAX_VALUE;
+    DataSource<T> s = null;
+    int minCost = Integer.MAX_VALUE;
+    for (Predicate<T> p : sort(getChildren())) {
+      if (p instanceof DataSource) {
+        c = Math.min(c, ((DataSource<?>) p).getCardinality());
+
+        int cost = p.estimateCost();
+        if (cost < minCost) {
+          s = toDataSource(p);
+          minCost = cost;
+        }
+      }
+    }
+    this.source = s;
+    this.cardinality = c;
+  }
+
+  @Override
+  public ResultSet<T> read() throws OrmException {
+    try {
+      return readImpl();
+    } catch (OrmRuntimeException err) {
+      if (err.getCause() != null) {
+        Throwables.throwIfInstanceOf(err.getCause(), OrmException.class);
+      }
+      throw new OrmException(err);
+    }
+  }
+
+  private ResultSet<T> readImpl() throws OrmException {
+    if (source == null) {
+      throw new OrmException("No DataSource: " + this);
+    }
+    List<T> r = new ArrayList<>();
+    T last = null;
+    int nextStart = 0;
+    boolean skipped = false;
+    for (T data : buffer(source.read())) {
+      if (!isMatchable() || match(data)) {
+        r.add(data);
+      } else {
+        skipped = true;
+      }
+      last = data;
+      nextStart++;
+    }
+
+    if (skipped && last != null && source instanceof Paginated) {
+      // If our source is a paginated source and we skipped at
+      // least one of its results, we may not have filled the full
+      // limit the caller wants.  Restart the source and continue.
+      //
+      @SuppressWarnings("unchecked")
+      Paginated<T> p = (Paginated<T>) source;
+      while (skipped && r.size() < p.getOptions().limit() + start) {
+        skipped = false;
+        ResultSet<T> next = p.restart(nextStart);
+
+        for (T data : buffer(next)) {
+          if (match(data)) {
+            r.add(data);
+          } else {
+            skipped = true;
+          }
+          nextStart++;
+        }
+      }
+    }
+
+    if (start >= r.size()) {
+      r = ImmutableList.of();
+    } else if (start > 0) {
+      r = ImmutableList.copyOf(r.subList(start, r.size()));
+    }
+    return new ListResultSet<>(r);
+  }
+
+  @Override
+  public boolean isMatchable() {
+    return isVisibleToPredicate != null || super.isMatchable();
+  }
+
+  @Override
+  public boolean match(T object) throws OrmException {
+    if (isVisibleToPredicate != null && !isVisibleToPredicate.match(object)) {
+      return false;
+    }
+
+    if (super.isMatchable() && !super.match(object)) {
+      return false;
+    }
+
+    return true;
+  }
+
+  private Iterable<T> buffer(ResultSet<T> scanner) {
+    return FluentIterable.from(Iterables.partition(scanner, 50))
+        .transformAndConcat(this::transformBuffer);
+  }
+
+  protected List<T> transformBuffer(List<T> buffer) throws OrmRuntimeException {
+    return buffer;
+  }
+
+  @Override
+  public int getCardinality() {
+    return cardinality;
+  }
+
+  private List<Predicate<T>> sort(Collection<? extends Predicate<T>> that) {
+    List<Predicate<T>> r = new ArrayList<>(that);
+    Collections.sort(r, this);
+    return r;
+  }
+
+  @Override
+  public int compare(Predicate<T> a, Predicate<T> b) {
+    int ai = a instanceof DataSource ? 0 : 1;
+    int bi = b instanceof DataSource ? 0 : 1;
+    int cmp = ai - bi;
+
+    if (cmp == 0) {
+      cmp = a.estimateCost() - b.estimateCost();
+    }
+
+    if (cmp == 0 && a instanceof DataSource && b instanceof DataSource) {
+      DataSource<?> as = (DataSource<?>) a;
+      DataSource<?> bs = (DataSource<?>) b;
+      cmp = as.getCardinality() - bs.getCardinality();
+    }
+    return cmp;
+  }
+
+  @SuppressWarnings("unchecked")
+  private DataSource<T> toDataSource(Predicate<T> pred) {
+    return (DataSource<T>) pred;
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/DataSource.java

@@ -0,0 +1,26 @@
+// Copyright (C) 2014 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.index.query;
+
+import com.google.gwtorm.server.OrmException;
+import com.google.gwtorm.server.ResultSet;
+
+public interface DataSource<T> {
+  /** @return an estimate of the number of results from {@link #read()}. */
+  int getCardinality();
+
+  /** @return read from the database and return the results. */
+  ResultSet<T> read() throws OrmException;
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/IndexPredicate.java

@@ -0,0 +1,41 @@
+// Copyright (C) 2013 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.index.query;
+
+import com.google.gerrit.index.FieldDef;
+import com.google.gerrit.index.FieldType;
+
+/** Index-aware predicate that includes a field type annotation. */
+public abstract class IndexPredicate<I> extends OperatorPredicate<I> {
+  private final FieldDef<I, ?> def;
+
+  protected IndexPredicate(FieldDef<I, ?> def, String value) {
+    super(def.getName(), value);
+    this.def = def;
+  }
+
+  protected IndexPredicate(FieldDef<I, ?> def, String name, String value) {
+    super(name, value);
+    this.def = def;
+  }
+
+  public FieldDef<I, ?> getField() {
+    return def;
+  }
+
+  public FieldType<?> getType() {
+    return def.getType();
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/IntPredicate.java

@@ -0,0 +1,56 @@
+// Copyright (C) 2009 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.index.query;
+
+/** Predicate to filter a field by matching integer value. */
+public abstract class IntPredicate<T> extends OperatorPredicate<T> {
+  private final int intValue;
+
+  public IntPredicate(String name, String value) {
+    super(name, value);
+    this.intValue = Integer.parseInt(value);
+  }
+
+  public IntPredicate(String name, int intValue) {
+    super(name, String.valueOf(intValue));
+    this.intValue = intValue;
+  }
+
+  public int intValue() {
+    return intValue;
+  }
+
+  @Override
+  public int hashCode() {
+    return getOperator().hashCode() * 31 + intValue;
+  }
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == null) {
+      return false;
+    }
+    if (getClass() == other.getClass()) {
+      final IntPredicate<?> p = (IntPredicate<?>) other;
+      return getOperator().equals(p.getOperator()) && intValue() == p.intValue();
+    }
+    return false;
+  }
+
+  @Override
+  public String toString() {
+    return getOperator() + ":" + getValue();
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/IntegerRangePredicate.java

@@ -0,0 +1,52 @@
+// Copyright (C) 2014 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.index.query;
+
+import com.google.gerrit.index.FieldDef;
+import com.google.gerrit.index.query.RangeUtil.Range;
+import com.google.gwtorm.server.OrmException;
+
+public abstract class IntegerRangePredicate<T> extends IndexPredicate<T> {
+  private final Range range;
+
+  protected IntegerRangePredicate(FieldDef<T, Integer> type, String value)
+      throws QueryParseException {
+    super(type, value);
+    range = RangeUtil.getRange(value, Integer.MIN_VALUE, Integer.MAX_VALUE);
+    if (range == null) {
+      throw new QueryParseException("Invalid range predicate: " + value);
+    }
+  }
+
+  protected abstract Integer getValueInt(T object) throws OrmException;
+
+  public boolean match(T object) throws OrmException {
+    Integer valueInt = getValueInt(object);
+    if (valueInt == null) {
+      return false;
+    }
+    return valueInt >= range.min && valueInt <= range.max;
+  }
+
+  /** Return the minimum value of this predicate's range, inclusive. */
+  public int getMinimumValue() {
+    return range.min;
+  }
+
+  /** Return the maximum value of this predicate's range, inclusive. */
+  public int getMaximumValue() {
+    return range.max;
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/IsVisibleToPredicate.java

@@ -0,0 +1,21 @@
+// Copyright (C) 2016 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.index.query;
+
+public abstract class IsVisibleToPredicate<T> extends OperatorPredicate<T> implements Matchable<T> {
+  public IsVisibleToPredicate(String name, String value) {
+    super(name, value);
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/LimitPredicate.java

@@ -0,0 +1,40 @@
+// Copyright (C) 2014 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.index.query;
+
+public class LimitPredicate<T> extends IntPredicate<T> implements Matchable<T> {
+  @SuppressWarnings("unchecked")
+  public static Integer getLimit(String fieldName, Predicate<?> p) {
+    IntPredicate<?> ip = QueryBuilder.find(p, IntPredicate.class, fieldName);
+    return ip != null ? ip.intValue() : null;
+  }
+
+  public LimitPredicate(String fieldName, int limit) throws QueryParseException {
+    super(fieldName, limit);
+    if (limit <= 0) {
+      throw new QueryParseException("limit must be positive: " + limit);
+    }
+  }
+
+  @Override
+  public boolean match(T object) {
+    return true;
+  }
+
+  @Override
+  public int getCost() {
+    return 0;
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/Matchable.java

@@ -0,0 +1,29 @@
+// Copyright (C) 2016 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.index.query;
+
+import com.google.gwtorm.server.OrmException;
+
+public interface Matchable<T> {
+  /**
+   * Does this predicate match this object?
+   *
+   * @throws OrmException
+   */
+  boolean match(T object) throws OrmException;
+
+  /** @return a cost estimate to run this predicate, higher figures cost more. */
+  int getCost();
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/NotPredicate.java

@@ -0,0 +1,99 @@
+// Copyright (C) 2009 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.index.query;
+
+import static com.google.common.base.Preconditions.checkState;
+
+import com.google.gwtorm.server.OrmException;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+/** Negates the result of another predicate. */
+public class NotPredicate<T> extends Predicate<T> implements Matchable<T> {
+  private final Predicate<T> that;
+
+  protected NotPredicate(Predicate<T> that) {
+    if (that instanceof NotPredicate) {
+      throw new IllegalArgumentException("Double negation unsupported");
+    }
+    this.that = that;
+  }
+
+  @Override
+  public final List<Predicate<T>> getChildren() {
+    return Collections.singletonList(that);
+  }
+
+  @Override
+  public final int getChildCount() {
+    return 1;
+  }
+
+  @Override
+  public final Predicate<T> getChild(int i) {
+    if (i != 0) {
+      throw new ArrayIndexOutOfBoundsException(i);
+    }
+    return that;
+  }
+
+  @Override
+  public Predicate<T> copy(Collection<? extends Predicate<T>> children) {
+    if (children.size() != 1) {
+      throw new IllegalArgumentException("Expected exactly one child");
+    }
+    return new NotPredicate<>(children.iterator().next());
+  }
+
+  @Override
+  public boolean isMatchable() {
+    return that.isMatchable();
+  }
+
+  @Override
+  public boolean match(T object) throws OrmException {
+    checkState(
+        that.isMatchable(),
+        "match invoked, but child predicate %s doesn't implement %s",
+        that,
+        Matchable.class.getName());
+    return !that.asMatchable().match(object);
+  }
+
+  @Override
+  public int getCost() {
+    return that.estimateCost();
+  }
+
+  @Override
+  public int hashCode() {
+    return ~that.hashCode();
+  }
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == null) {
+      return false;
+    }
+    return getClass() == other.getClass()
+        && getChildren().equals(((Predicate<?>) other).getChildren());
+  }
+
+  @Override
+  public final String toString() {
+    return "-" + that.toString();
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/OperatorPredicate.java

@@ -0,0 +1,70 @@
+// Copyright (C) 2009 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.index.query;
+
+import java.util.Collection;
+
+/** Predicate to filter a field by matching value. */
+public abstract class OperatorPredicate<T> extends Predicate<T> {
+  protected final String name;
+  protected final String value;
+
+  public OperatorPredicate(String name, String value) {
+    this.name = name;
+    this.value = value;
+  }
+
+  public String getOperator() {
+    return name;
+  }
+
+  public String getValue() {
+    return value;
+  }
+
+  @Override
+  public Predicate<T> copy(Collection<? extends Predicate<T>> children) {
+    if (!children.isEmpty()) {
+      throw new IllegalArgumentException("Expected 0 children");
+    }
+    return this;
+  }
+
+  @Override
+  public int hashCode() {
+    return getOperator().hashCode() * 31 + getValue().hashCode();
+  }
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == null) {
+      return false;
+    }
+    if (getClass() == other.getClass()) {
+      final OperatorPredicate<?> p = (OperatorPredicate<?>) other;
+      return getOperator().equals(p.getOperator()) && getValue().equals(p.getValue());
+    }
+    return false;
+  }
+
+  @Override
+  public String toString() {
+    final String val = getValue();
+    if (QueryParser.isSingleWord(val)) {
+      return getOperator() + ":" + val;
+    }
+    return getOperator() + ":\"" + val + "\"";
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/OrPredicate.java

@@ -0,0 +1,131 @@
+// Copyright (C) 2009 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.index.query;
+
+import static com.google.common.base.Preconditions.checkState;
+
+import com.google.gwtorm.server.OrmException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+/** Requires one predicate to be true. */
+public class OrPredicate<T> extends Predicate<T> implements Matchable<T> {
+  private final List<Predicate<T>> children;
+  private final int cost;
+
+  @SafeVarargs
+  protected OrPredicate(Predicate<T>... that) {
+    this(Arrays.asList(that));
+  }
+
+  protected OrPredicate(Collection<? extends Predicate<T>> that) {
+    List<Predicate<T>> t = new ArrayList<>(that.size());
+    int c = 0;
+    for (Predicate<T> p : that) {
+      if (getClass() == p.getClass()) {
+        for (Predicate<T> gp : p.getChildren()) {
+          t.add(gp);
+          c += gp.estimateCost();
+        }
+      } else {
+        t.add(p);
+        c += p.estimateCost();
+      }
+    }
+    children = t;
+    cost = c;
+  }
+
+  @Override
+  public final List<Predicate<T>> getChildren() {
+    return Collections.unmodifiableList(children);
+  }
+
+  @Override
+  public final int getChildCount() {
+    return children.size();
+  }
+
+  @Override
+  public final Predicate<T> getChild(int i) {
+    return children.get(i);
+  }
+
+  @Override
+  public Predicate<T> copy(Collection<? extends Predicate<T>> children) {
+    return new OrPredicate<>(children);
+  }
+
+  @Override
+  public boolean isMatchable() {
+    for (Predicate<T> c : children) {
+      if (!c.isMatchable()) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @Override
+  public boolean match(T object) throws OrmException {
+    for (Predicate<T> c : children) {
+      checkState(
+          c.isMatchable(),
+          "match invoked, but child predicate %s doesn't implement %s",
+          c,
+          Matchable.class.getName());
+      if (c.asMatchable().match(object)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  @Override
+  public int getCost() {
+    return cost;
+  }
+
+  @Override
+  public int hashCode() {
+    return getChild(0).hashCode() * 31 + getChild(1).hashCode();
+  }
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == null) {
+      return false;
+    }
+    return getClass() == other.getClass()
+        && getChildren().equals(((Predicate<?>) other).getChildren());
+  }
+
+  @Override
+  public String toString() {
+    final StringBuilder r = new StringBuilder();
+    r.append("(");
+    for (int i = 0; i < getChildCount(); i++) {
+      if (i != 0) {
+        r.append(" OR ");
+      }
+      r.append(getChild(i));
+    }
+    r.append(")");
+    return r.toString();
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/Paginated.java

@@ -0,0 +1,25 @@
+// Copyright (C) 2010 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.index.query;
+
+import com.google.gerrit.index.QueryOptions;
+import com.google.gwtorm.server.OrmException;
+import com.google.gwtorm.server.ResultSet;
+
+public interface Paginated<T> {
+  QueryOptions getOptions();
+
+  ResultSet<T> restart(int start) throws OrmException;
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/Predicate.java

@@ -0,0 +1,165 @@
+// Copyright (C) 2009 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.index.query;
+
+import static com.google.common.base.Preconditions.checkState;
+
+import com.google.common.collect.Iterables;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * An abstract predicate tree for any form of query.
+ *
+ * <p>Implementations should be immutable, such that the meaning of a predicate never changes once
+ * constructed. They should ensure their immutable promise by defensively copying any structures
+ * which might be modified externally, but was passed into the object's constructor.
+ *
+ * <p>However, implementations <i>may</i> retain non-thread-safe caches internally, to speed up
+ * evaluation operations within the context of one thread's evaluation of the predicate. As a
+ * result, callers should assume predicates are not thread-safe, but that two predicate graphs
+ * produce the same results given the same inputs if they are {@link #equals(Object)}.
+ *
+ * <p>Predicates should support deep inspection whenever possible, so that generic algorithms can be
+ * written to operate against them. Predicates which contain other predicates should override {@link
+ * #getChildren()} to return the list of children nested within the predicate.
+ *
+ * @param <T> type of object the predicate can evaluate in memory.
+ */
+public abstract class Predicate<T> {
+  /** A predicate that matches any input, always, with no cost. */
+  @SuppressWarnings("unchecked")
+  public static <T> Predicate<T> any() {
+    return (Predicate<T>) Any.INSTANCE;
+  }
+
+  /** Combine the passed predicates into a single AND node. */
+  @SafeVarargs
+  public static <T> Predicate<T> and(Predicate<T>... that) {
+    if (that.length == 1) {
+      return that[0];
+    }
+    return new AndPredicate<>(that);
+  }
+
+  /** Combine the passed predicates into a single AND node. */
+  public static <T> Predicate<T> and(Collection<? extends Predicate<T>> that) {
+    if (that.size() == 1) {
+      return Iterables.getOnlyElement(that);
+    }
+    return new AndPredicate<>(that);
+  }
+
+  /** Combine the passed predicates into a single OR node. */
+  @SafeVarargs
+  public static <T> Predicate<T> or(Predicate<T>... that) {
+    if (that.length == 1) {
+      return that[0];
+    }
+    return new OrPredicate<>(that);
+  }
+
+  /** Combine the passed predicates into a single OR node. */
+  public static <T> Predicate<T> or(Collection<? extends Predicate<T>> that) {
+    if (that.size() == 1) {
+      return Iterables.getOnlyElement(that);
+    }
+    return new OrPredicate<>(that);
+  }
+
+  /** Invert the passed node. */
+  public static <T> Predicate<T> not(Predicate<T> that) {
+    if (that instanceof NotPredicate) {
+      // Negate of a negate is the original predicate.
+      //
+      return that.getChild(0);
+    }
+    return new NotPredicate<>(that);
+  }
+
+  /** Get the children of this predicate, if any. */
+  public List<Predicate<T>> getChildren() {
+    return Collections.emptyList();
+  }
+
+  /** Same as {@code getChildren().size()} */
+  public int getChildCount() {
+    return getChildren().size();
+  }
+
+  /** Same as {@code getChildren().get(i)} */
+  public Predicate<T> getChild(int i) {
+    return getChildren().get(i);
+  }
+
+  /** Create a copy of this predicate, with new children. */
+  public abstract Predicate<T> copy(Collection<? extends Predicate<T>> children);
+
+  public boolean isMatchable() {
+    return this instanceof Matchable;
+  }
+
+  @SuppressWarnings("unchecked")
+  public Matchable<T> asMatchable() {
+    checkState(isMatchable(), "not matchable");
+    return (Matchable<T>) this;
+  }
+
+  /** @return a cost estimate to run this predicate, higher figures cost more. */
+  public int estimateCost() {
+    if (!isMatchable()) {
+      return 1;
+    }
+    return asMatchable().getCost();
+  }
+
+  @Override
+  public abstract int hashCode();
+
+  @Override
+  public abstract boolean equals(Object other);
+
+  private static class Any<T> extends Predicate<T> implements Matchable<T> {
+    private static final Any<Object> INSTANCE = new Any<>();
+
+    private Any() {}
+
+    @Override
+    public Predicate<T> copy(Collection<? extends Predicate<T>> children) {
+      return this;
+    }
+
+    @Override
+    public boolean match(T object) {
+      return true;
+    }
+
+    @Override
+    public int getCost() {
+      return 0;
+    }
+
+    @Override
+    public int hashCode() {
+      return System.identityHashCode(this);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+      return other == this;
+    }
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/QueryBuilder.java

@@ -0,0 +1,350 @@
+// Copyright (C) 2009 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.index.query;
+
+import static com.google.gerrit.index.query.Predicate.and;
+import static com.google.gerrit.index.query.Predicate.not;
+import static com.google.gerrit.index.query.Predicate.or;
+import static com.google.gerrit.index.query.QueryParser.AND;
+import static com.google.gerrit.index.query.QueryParser.DEFAULT_FIELD;
+import static com.google.gerrit.index.query.QueryParser.EXACT_PHRASE;
+import static com.google.gerrit.index.query.QueryParser.FIELD_NAME;
+import static com.google.gerrit.index.query.QueryParser.NOT;
+import static com.google.gerrit.index.query.QueryParser.OR;
+import static com.google.gerrit.index.query.QueryParser.SINGLE_WORD;
+
+import com.google.common.base.Strings;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import org.antlr.runtime.tree.Tree;
+
+/**
+ * Base class to support writing parsers for query languages.
+ *
+ * <p>Subclasses may document their supported query operators by declaring public methods that
+ * perform the query conversion into a {@link Predicate}. For example, to support "is:starred",
+ * "is:unread", and nothing else, a subclass may write:
+ *
+ * <pre>
+ * &#064;Operator
+ * public Predicate is(String value) {
+ *   if (&quot;starred&quot;.equals(value)) {
+ *     return new StarredPredicate();
+ *   }
+ *   if (&quot;unread&quot;.equals(value)) {
+ *     return new UnreadPredicate();
+ *   }
+ *   throw new IllegalArgumentException();
+ * }
+ * </pre>
+ *
+ * <p>The available operator methods are discovered at runtime via reflection. Method names (after
+ * being converted to lowercase), correspond to operators in the query language, method string
+ * values correspond to the operator argument. Methods must be declared {@code public}, returning
+ * {@link Predicate}, accepting one {@link String}, and annotated with the {@link Operator}
+ * annotation.
+ *
+ * <p>Subclasses may also declare a handler for values which appear without operator by overriding
+ * {@link #defaultField(String)}.
+ *
+ * @param <T> type of object the predicates can evaluate in memory.
+ */
+public abstract class QueryBuilder<T> {
+  /** Converts a value string passed to an operator into a {@link Predicate}. */
+  public interface OperatorFactory<T, Q extends QueryBuilder<T>> {
+    Predicate<T> create(Q builder, String value) throws QueryParseException;
+  }
+
+  /**
+   * Defines the operators known by a QueryBuilder.
+   *
+   * <p>This class is thread-safe and may be reused or cached.
+   *
+   * @param <T> type of object the predicates can evaluate in memory.
+   * @param <Q> type of the query builder subclass.
+   */
+  public static class Definition<T, Q extends QueryBuilder<T>> {
+    private final Map<String, OperatorFactory<T, Q>> opFactories = new HashMap<>();
+
+    public Definition(Class<Q> clazz) {
+      // Guess at the supported operators by scanning methods.
+      //
+      Class<?> c = clazz;
+      while (c != QueryBuilder.class) {
+        for (Method method : c.getDeclaredMethods()) {
+          if (method.getAnnotation(Operator.class) != null
+              && Predicate.class.isAssignableFrom(method.getReturnType())
+              && method.getParameterTypes().length == 1
+              && method.getParameterTypes()[0] == String.class
+              && (method.getModifiers() & Modifier.ABSTRACT) == 0
+              && (method.getModifiers() & Modifier.PUBLIC) == Modifier.PUBLIC) {
+            final String name = method.getName().toLowerCase();
+            if (!opFactories.containsKey(name)) {
+              opFactories.put(name, new ReflectionFactory<T, Q>(name, method));
+            }
+          }
+        }
+        c = c.getSuperclass();
+      }
+    }
+  }
+
+  /**
+   * Locate a predicate in the predicate tree.
+   *
+   * @param p the predicate to find.
+   * @param clazz type of the predicate instance.
+   * @return the predicate, null if not found.
+   */
+  @SuppressWarnings("unchecked")
+  public static <T, P extends Predicate<T>> P find(Predicate<T> p, Class<P> clazz) {
+    if (clazz.isAssignableFrom(p.getClass())) {
+      return (P) p;
+    }
+
+    for (Predicate<T> c : p.getChildren()) {
+      P r = find(c, clazz);
+      if (r != null) {
+        return r;
+      }
+    }
+
+    return null;
+  }
+
+  /**
+   * Locate a predicate in the predicate tree.
+   *
+   * @param p the predicate to find.
+   * @param clazz type of the predicate instance.
+   * @param name name of the operator.
+   * @return the first instance of a predicate having the given type, as found by a depth-first
+   *     search.
+   */
+  @SuppressWarnings("unchecked")
+  public static <T, P extends OperatorPredicate<T>> P find(
+      Predicate<T> p, Class<P> clazz, String name) {
+    if (p instanceof OperatorPredicate
+        && ((OperatorPredicate<?>) p).getOperator().equals(name)
+        && clazz.isAssignableFrom(p.getClass())) {
+      return (P) p;
+    }
+
+    for (Predicate<T> c : p.getChildren()) {
+      P r = find(c, clazz, name);
+      if (r != null) {
+        return r;
+      }
+    }
+
+    return null;
+  }
+
+  protected final Definition<T, ? extends QueryBuilder<T>> builderDef;
+
+  protected final Map<String, OperatorFactory<?, ?>> opFactories;
+
+  @SuppressWarnings({"unchecked", "rawtypes"})
+  protected QueryBuilder(Definition<T, ? extends QueryBuilder<T>> def) {
+    builderDef = def;
+    opFactories = (Map) def.opFactories;
+  }
+
+  /**
+   * Parse a user-supplied query string into a predicate.
+   *
+   * @param query the query string.
+   * @return predicate representing the user query.
+   * @throws QueryParseException the query string is invalid and cannot be parsed by this parser.
+   *     This may be due to a syntax error, may be due to an operator not being supported, or due to
+   *     an invalid value being passed to a recognized operator.
+   */
+  public Predicate<T> parse(String query) throws QueryParseException {
+    if (Strings.isNullOrEmpty(query)) {
+      throw new QueryParseException("query is empty");
+    }
+    return toPredicate(QueryParser.parse(query));
+  }
+
+  /**
+   * Parse multiple user-supplied query strings into a list of predicates.
+   *
+   * @param queries the query strings.
+   * @return predicates representing the user query, in the same order as the input.
+   * @throws QueryParseException one of the query strings is invalid and cannot be parsed by this
+   *     parser. This may be due to a syntax error, may be due to an operator not being supported,
+   *     or due to an invalid value being passed to a recognized operator.
+   */
+  public List<Predicate<T>> parse(List<String> queries) throws QueryParseException {
+    List<Predicate<T>> predicates = new ArrayList<>(queries.size());
+    for (String query : queries) {
+      predicates.add(parse(query));
+    }
+    return predicates;
+  }
+
+  private Predicate<T> toPredicate(Tree r) throws QueryParseException, IllegalArgumentException {
+    switch (r.getType()) {
+      case AND:
+        return and(children(r));
+      case OR:
+        return or(children(r));
+      case NOT:
+        return not(toPredicate(onlyChildOf(r)));
+
+      case DEFAULT_FIELD:
+        return defaultField(onlyChildOf(r));
+
+      case FIELD_NAME:
+        return operator(r.getText(), onlyChildOf(r));
+
+      default:
+        throw error("Unsupported operator: " + r);
+    }
+  }
+
+  private Predicate<T> operator(String name, Tree val) throws QueryParseException {
+    switch (val.getType()) {
+        // Expand multiple values, "foo:(a b c)", as though they were written
+        // out with the longer form, "foo:a foo:b foo:c".
+        //
+      case AND:
+      case OR:
+        {
+          List<Predicate<T>> p = new ArrayList<>(val.getChildCount());
+          for (int i = 0; i < val.getChildCount(); i++) {
+            final Tree c = val.getChild(i);
+            if (c.getType() != DEFAULT_FIELD) {
+              throw error("Nested operator not expected: " + c);
+            }
+            p.add(operator(name, onlyChildOf(c)));
+          }
+          return val.getType() == AND ? and(p) : or(p);
+        }
+
+      case SINGLE_WORD:
+      case EXACT_PHRASE:
+        if (val.getChildCount() != 0) {
+          throw error("Expected no children under: " + val);
+        }
+        return operator(name, val.getText());
+
+      default:
+        throw error("Unsupported node in operator " + name + ": " + val);
+    }
+  }
+
+  @SuppressWarnings("unchecked")
+  private Predicate<T> operator(String name, String value) throws QueryParseException {
+    @SuppressWarnings("rawtypes")
+    OperatorFactory f = opFactories.get(name);
+    if (f == null) {
+      throw error("Unsupported operator " + name + ":" + value);
+    }
+    return f.create(this, value);
+  }
+
+  private Predicate<T> defaultField(Tree r) throws QueryParseException {
+    switch (r.getType()) {
+      case SINGLE_WORD:
+      case EXACT_PHRASE:
+        if (r.getChildCount() != 0) {
+          throw error("Expected no children under: " + r);
+        }
+        return defaultField(r.getText());
+
+      default:
+        throw error("Unsupported node: " + r);
+    }
+  }
+
+  /**
+   * Handle a value present outside of an operator.
+   *
+   * <p>This default implementation always throws an "Unsupported query: " message containing the
+   * input text. Subclasses may override this method to perform do-what-i-mean guesses based on the
+   * input string.
+   *
+   * @param value the value supplied by itself in the query.
+   * @return predicate representing this value.
+   * @throws QueryParseException the parser does not recognize this value.
+   */
+  protected Predicate<T> defaultField(String value) throws QueryParseException {
+    throw error("Unsupported query:" + value);
+  }
+
+  private List<Predicate<T>> children(Tree r) throws QueryParseException, IllegalArgumentException {
+    List<Predicate<T>> p = new ArrayList<>(r.getChildCount());
+    for (int i = 0; i < r.getChildCount(); i++) {
+      p.add(toPredicate(r.getChild(i)));
+    }
+    return p;
+  }
+
+  private Tree onlyChildOf(Tree r) throws QueryParseException {
+    if (r.getChildCount() != 1) {
+      throw error("Expected exactly one child: " + r);
+    }
+    return r.getChild(0);
+  }
+
+  protected static QueryParseException error(String msg) {
+    return new QueryParseException(msg);
+  }
+
+  protected static QueryParseException error(String msg, Throwable why) {
+    return new QueryParseException(msg, why);
+  }
+
+  /** Denotes a method which is a query operator. */
+  @Retention(RetentionPolicy.RUNTIME)
+  @Target(ElementType.METHOD)
+  protected @interface Operator {}
+
+  private static class ReflectionFactory<T, Q extends QueryBuilder<T>>
+      implements OperatorFactory<T, Q> {
+    private final String name;
+    private final Method method;
+
+    ReflectionFactory(String name, Method method) {
+      this.name = name;
+      this.method = method;
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public Predicate<T> create(Q builder, String value) throws QueryParseException {
+      try {
+        return (Predicate<T>) method.invoke(builder, value);
+      } catch (RuntimeException | IllegalAccessException e) {
+        throw error("Error in operator " + name + ":" + value, e);
+      } catch (InvocationTargetException e) {
+        if (e.getCause() instanceof QueryParseException) {
+          throw (QueryParseException) e.getCause();
+        }
+        throw error("Error in operator " + name + ":" + value, e.getCause());
+      }
+    }
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/QueryResult.java

@@ -0,0 +1,51 @@
+// Copyright (C) 2014 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.index.query;
+
+import com.google.auto.value.AutoValue;
+import com.google.gerrit.common.Nullable;
+import java.util.List;
+
+/** Results of a query over entities. */
+@AutoValue
+public abstract class QueryResult<T> {
+  public static <T> QueryResult<T> create(
+      @Nullable String query, Predicate<T> predicate, int limit, List<T> entites) {
+    boolean more;
+    if (entites.size() > limit) {
+      more = true;
+      entites = entites.subList(0, limit);
+    } else {
+      more = false;
+    }
+    return new AutoValue_QueryResult<>(query, predicate, entites, more);
+  }
+
+  /** @return the original query string, or null if the query was created programmatically. */
+  @Nullable
+  public abstract String query();
+
+  /** @return the predicate after all rewriting and other modification by the query subsystem. */
+  public abstract Predicate<T> predicate();
+
+  /** @return the query results. */
+  public abstract List<T> entities();
+
+  /**
+   * @return whether the query could be retried with a higher start/limit to produce more results.
+   *     Never true if {@link #entities()} is empty.
+   */
+  public abstract boolean more();
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/RangeUtil.java

@@ -0,0 +1,118 @@
+// Copyright (C) 2014 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.index.query;
+
+import com.google.common.primitives.Ints;
+import com.google.gerrit.common.Nullable;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public final class RangeUtil {
+  private static final Pattern RANGE_PATTERN = Pattern.compile("(>|>=|=|<|<=|)([+-]?\\d+)$");
+
+  private RangeUtil() {}
+
+  public static class Range {
+    /** The prefix of the query, before the range component. */
+    public final String prefix;
+
+    /** The minimum value specified in the query, inclusive. */
+    public final int min;
+
+    /** The maximum value specified in the query, inclusive. */
+    public final int max;
+
+    public Range(String prefix, int min, int max) {
+      this.prefix = prefix;
+      this.min = min;
+      this.max = max;
+    }
+  }
+
+  /**
+   * Determine the range of values being requested in the given query.
+   *
+   * @param rangeQuery the raw query, e.g. "{@code added:>12345}"
+   * @param minValue the minimum possible value for the field, inclusive
+   * @param maxValue the maximum possible value for the field, inclusive
+   * @return the calculated {@link Range}, or null if the query is invalid
+   */
+  @Nullable
+  public static Range getRange(String rangeQuery, int minValue, int maxValue) {
+    Matcher m = RANGE_PATTERN.matcher(rangeQuery);
+    String prefix;
+    String test;
+    Integer queryInt;
+    if (m.find()) {
+      prefix = rangeQuery.substring(0, m.start());
+      test = m.group(1);
+      queryInt = value(m.group(2));
+      if (queryInt == null) {
+        return null;
+      }
+    } else {
+      return null;
+    }
+
+    return getRange(prefix, test, queryInt, minValue, maxValue);
+  }
+
+  /**
+   * Determine the range of values being requested in the given query.
+   *
+   * @param prefix a prefix string which is copied into the range
+   * @param test the test operator, one of &gt;, &gt;=, =, &lt;, or &lt;=
+   * @param queryInt the integer being queried
+   * @param minValue the minimum possible value for the field, inclusive
+   * @param maxValue the maximum possible value for the field, inclusive
+   * @return the calculated {@link Range}
+   */
+  public static Range getRange(
+      String prefix, String test, int queryInt, int minValue, int maxValue) {
+    int min;
+    int max;
+    switch (test) {
+      case "=":
+      default:
+        min = max = queryInt;
+        break;
+      case ">":
+        min = Ints.saturatedCast(queryInt + 1L);
+        max = maxValue;
+        break;
+      case ">=":
+        min = queryInt;
+        max = maxValue;
+        break;
+      case "<":
+        min = minValue;
+        max = Ints.saturatedCast(queryInt - 1L);
+        break;
+      case "<=":
+        min = minValue;
+        max = queryInt;
+        break;
+    }
+
+    return new Range(prefix, min, max);
+  }
+
+  private static Integer value(String value) {
+    if (value.startsWith("+")) {
+      value = value.substring(1);
+    }
+    return Ints.tryParse(value);
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/RegexPredicate.java

@@ -0,0 +1,27 @@
+// Copyright (C) 2013 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.index.query;
+
+import com.google.gerrit.index.FieldDef;
+
+public abstract class RegexPredicate<I> extends IndexPredicate<I> {
+  protected RegexPredicate(FieldDef<I, ?> def, String value) {
+    super(def, value);
+  }
+
+  protected RegexPredicate(FieldDef<I, ?> def, String name, String value) {
+    super(def, name, value);
+  }
+}

gerrit-index/src/main/java/com/google/gerrit/index/query/TimestampRangePredicate.java

@@ -0,0 +1,40 @@
+// Copyright (C) 2013 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.index.query;
+
+import com.google.gerrit.index.FieldDef;
+import com.google.gwtjsonrpc.common.JavaSqlTimestampHelper;
+import java.sql.Timestamp;
+import java.util.Date;
+
+// TODO: Migrate this to IntegerRangePredicate
+public abstract class TimestampRangePredicate<I> extends IndexPredicate<I> {
+  protected static Timestamp parse(String value) throws QueryParseException {
+    try {
+      return JavaSqlTimestampHelper.parseTimestamp(value);
+    } catch (IllegalArgumentException e) {
+      // parseTimestamp's errors are specific and helpful, so preserve them.
+      throw new QueryParseException(e.getMessage(), e);
+    }
+  }
+
+  protected TimestampRangePredicate(FieldDef<I, Timestamp> def, String name, String value) {
+    super(def, name, value);
+  }
+
+  public abstract Date getMinTimestamp();
+
+  public abstract Date getMaxTimestamp();
+}