Rename VariableContext to the more general purpose QueryExpressionContext and thread it through to graph traversal functions. Some other light refactorings as well.

PiperOrigin-RevId: 200292556

33 files changed, 246 insertions, 222 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/query2/AbstractBlazeQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/AbstractBlazeQueryEnvironment.java
index 0221aacd75..a378f55e85 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/AbstractBlazeQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/AbstractBlazeQueryEnvironment.java
@@ -32,10 +32,10 @@ import com.google.devtools.build.lib.query2.engine.QueryEnvironment;
 import com.google.devtools.build.lib.query2.engine.QueryEvalResult;
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.query2.engine.QueryUtil;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.AggregateAllCallback;
 import com.google.devtools.build.lib.query2.engine.ThreadSafeOutputFormatterCallback;
-import com.google.devtools.build.lib.query2.engine.VariableContext;
 import java.io.IOException;
 import java.util.Collection;
 import java.util.LinkedHashSet;
@@ -104,7 +104,11 @@ public abstract class AbstractBlazeQueryEnvironment<T> extends AbstractQueryEnvi
    */
   protected void evalTopLevelInternal(QueryExpression expr, OutputFormatterCallback<T> callback)
       throws QueryException, InterruptedException {
-    ((QueryTaskFutureImpl<Void>) eval(expr, VariableContext.<T>empty(), callback)).getChecked();
+    ((QueryTaskFutureImpl<Void>) eval(expr, createEmptyContext(), callback)).getChecked();
+  }
+
+  protected QueryExpressionContext<T> createEmptyContext() {
+    return QueryExpressionContext.empty();
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/query2/BlazeQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/BlazeQueryEnvironment.java
index 62cc674d31..0b448abe25 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/BlazeQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/BlazeQueryEnvironment.java
@@ -44,6 +44,7 @@ import com.google.devtools.build.lib.query2.engine.MinDepthUniquifier;
 import com.google.devtools.build.lib.query2.engine.QueryEvalResult;
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.MinDepthUniquifierImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.MutableKeyExtractorBackedMapImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.ThreadSafeMutableKeyExtractorBackedSetImpl;
@@ -243,7 +244,8 @@ public class BlazeQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   }
 
   @Override
-  public Collection<Target> getFwdDeps(Iterable<Target> targets) {
+  public Collection<Target> getFwdDeps(
+      Iterable<Target> targets, QueryExpressionContext<Target> context) {
     ThreadSafeMutableSet<Target> result = createThreadSafeMutableSet();
     for (Target target : targets) {
       result.addAll(getTargetsFromNodes(getNode(target).getSuccessors()));
@@ -252,7 +254,8 @@ public class BlazeQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   }
 
   @Override
-  public Collection<Target> getReverseDeps(Iterable<Target> targets) {
+  public Collection<Target> getReverseDeps(
+      Iterable<Target> targets, QueryExpressionContext<Target> context) {
     ThreadSafeMutableSet<Target> result = createThreadSafeMutableSet();
     for (Target target : targets) {
       result.addAll(getTargetsFromNodes(getNode(target).getPredecessors()));
@@ -262,7 +265,7 @@ public class BlazeQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
 
   @Override
   public ThreadSafeMutableSet<Target> getTransitiveClosure(
-      ThreadSafeMutableSet<Target> targetNodes) {
+      ThreadSafeMutableSet<Target> targetNodes, QueryExpressionContext<Target> context) {
     for (Target node : targetNodes) {
       checkBuilt(node);
     }
@@ -301,7 +304,8 @@ public class BlazeQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   }
 
   @Override
-  public Iterable<Target> getNodesOnPath(Target from, Target to) {
+  public Iterable<Target> getNodesOnPath(
+      Target from, Target to, QueryExpressionContext<Target> context) {
     ImmutableList.Builder<Target> builder = ImmutableList.builder();
     for (Node<Target> node : graph.getShortestPath(getNode(from), getNode(to))) {
       builder.add(node.getLabel());
@@ -389,7 +393,8 @@ public class BlazeQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
       final QueryExpression caller,
       ThreadSafeMutableSet<Target> nodes,
       boolean buildFiles,
-      boolean loads)
+      boolean loads,
+      QueryExpressionContext<Target> context)
       throws QueryException {
     ThreadSafeMutableSet<Target> dependentFiles = createThreadSafeMutableSet();
     Set<PackageIdentifier> seenPackages = new HashSet<>();
diff --git a/src/main/java/com/google/devtools/build/lib/query2/ConfigFunction.java b/src/main/java/com/google/devtools/build/lib/query2/ConfigFunction.java
index 7a3f6a0b63..20341fceb0 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/ConfigFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/ConfigFunction.java
@@ -23,8 +23,8 @@ import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunctio
 import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryTaskFuture;
 import com.google.devtools.build.lib.query2.engine.QueryEnvironment.ThreadSafeMutableSet;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.query2.engine.QueryUtil;
-import com.google.devtools.build.lib.query2.engine.VariableContext;
 import java.util.List;
 
 /**
@@ -64,7 +64,7 @@ public final class ConfigFunction implements QueryFunction {
   @SuppressWarnings("unchecked")
   public <T> QueryTaskFuture<Void> eval(
       QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       QueryExpression expression,
       List<Argument> args,
       final Callback<T> callback) {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/ConfiguredTargetQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/ConfiguredTargetQueryEnvironment.java
index d709e55c18..d9662e24ff 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/ConfiguredTargetQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/ConfiguredTargetQueryEnvironment.java
@@ -47,6 +47,7 @@ import com.google.devtools.build.lib.query2.engine.QueryEnvironment;
 import com.google.devtools.build.lib.query2.engine.QueryEvalResult;
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.MinDepthUniquifierImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.MutableKeyExtractorBackedMapImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.ThreadSafeMutableKeyExtractorBackedSetImpl;
@@ -455,7 +456,8 @@ public class ConfiguredTargetQueryEnvironment
   }
 
   @Override
-  public ThreadSafeMutableSet<ConfiguredTarget> getFwdDeps(Iterable<ConfiguredTarget> targets)
+  public ThreadSafeMutableSet<ConfiguredTarget> getFwdDeps(
+      Iterable<ConfiguredTarget> targets, QueryExpressionContext<ConfiguredTarget> context)
       throws InterruptedException {
     Map<SkyKey, ConfiguredTarget> targetsByKey = new HashMap<>(Iterables.size(targets));
     for (ConfiguredTarget target : targets) {
@@ -488,7 +490,8 @@ public class ConfiguredTargetQueryEnvironment
   }
 
   @Override
-  public Collection<ConfiguredTarget> getReverseDeps(Iterable<ConfiguredTarget> targets)
+  public Collection<ConfiguredTarget> getReverseDeps(
+      Iterable<ConfiguredTarget> targets, QueryExpressionContext<ConfiguredTarget> context)
       throws InterruptedException {
     Map<SkyKey, ConfiguredTarget> targetsByKey = new HashMap<>(Iterables.size(targets));
     for (ConfiguredTarget target : targets) {
@@ -604,12 +607,13 @@ public class ConfiguredTargetQueryEnvironment
     return ConfiguredTargetKey.of(target, getConfiguration(target));
   }
 
-
   @Override
   public ThreadSafeMutableSet<ConfiguredTarget> getTransitiveClosure(
-      ThreadSafeMutableSet<ConfiguredTarget> targets) throws InterruptedException {
+      ThreadSafeMutableSet<ConfiguredTarget> targets,
+      QueryExpressionContext<ConfiguredTarget> context)
+      throws InterruptedException {
     return SkyQueryUtils.getTransitiveClosure(
-        targets, this::getFwdDeps, createThreadSafeMutableSet());
+        targets, targets1 -> getFwdDeps(targets1, context), createThreadSafeMutableSet());
   }
 
   @Override
@@ -620,10 +624,14 @@ public class ConfiguredTargetQueryEnvironment
   }
 
   @Override
-  public ImmutableList<ConfiguredTarget> getNodesOnPath(ConfiguredTarget from, ConfiguredTarget to)
+  public ImmutableList<ConfiguredTarget> getNodesOnPath(
+      ConfiguredTarget from, ConfiguredTarget to, QueryExpressionContext<ConfiguredTarget> context)
       throws InterruptedException {
     return SkyQueryUtils.getNodesOnPath(
-        from, to, this::getFwdDeps, configuredTargetKeyExtractor::extractKey);
+        from,
+        to,
+        targets -> getFwdDeps(targets, context),
+        configuredTargetKeyExtractor::extractKey);
   }
 
   @Override
@@ -672,7 +680,8 @@ public class ConfiguredTargetQueryEnvironment
       QueryExpression caller,
       ThreadSafeMutableSet<ConfiguredTarget> nodes,
       boolean buildFiles,
-      boolean loads)
+      boolean loads,
+      QueryExpressionContext<ConfiguredTarget> context)
       throws QueryException, InterruptedException {
     throw new QueryException("buildfiles() doesn't make sense for the configured target graph");
   }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/DepsUnboundedVisitor.java b/src/main/java/com/google/devtools/build/lib/query2/DepsUnboundedVisitor.java
index 55adaacdfe..cb5e19c196 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/DepsUnboundedVisitor.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/DepsUnboundedVisitor.java
@@ -28,6 +28,7 @@ import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.query2.engine.Callback;
 import com.google.devtools.build.lib.query2.engine.QueryException;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.query2.engine.Uniquifier;
 import com.google.devtools.build.skyframe.SkyKey;
 import java.util.Map;
@@ -47,6 +48,7 @@ class DepsUnboundedVisitor extends AbstractEdgeVisitor<SkyKey> {
 
   private final boolean depsNeedFiltering;
   private final Callback<Target> errorReporter;
+  private final QueryExpressionContext<Target> context;
 
   DepsUnboundedVisitor(
       SkyQueryEnvironment env,
@@ -54,11 +56,13 @@ class DepsUnboundedVisitor extends AbstractEdgeVisitor<SkyKey> {
       Callback<Target> callback,
       MultisetSemaphore<PackageIdentifier> packageSemaphore,
       boolean depsNeedFiltering,
-      Callback<Target> errorReporter) {
+      Callback<Target> errorReporter,
+      QueryExpressionContext<Target> context) {
     super(env, callback, packageSemaphore);
     this.validDepUniquifier = validDepUniquifier;
     this.depsNeedFiltering = depsNeedFiltering;
     this.errorReporter = errorReporter;
+    this.context = context;
   }
 
   /**
@@ -74,25 +78,34 @@ class DepsUnboundedVisitor extends AbstractEdgeVisitor<SkyKey> {
     private final MultisetSemaphore<PackageIdentifier> packageSemaphore;
     private final boolean depsNeedFiltering;
     private final Callback<Target> errorReporter;
+    private final QueryExpressionContext<Target> context;
 
     Factory(
         SkyQueryEnvironment env,
         Callback<Target> callback,
         MultisetSemaphore<PackageIdentifier> packageSemaphore,
         boolean depsNeedFiltering,
-        Callback<Target> errorReporter) {
+        Callback<Target> errorReporter,
+        QueryExpressionContext<Target> context) {
       this.env = env;
       this.validDepUniquifier = env.createSkyKeyUniquifier();
       this.callback = callback;
       this.packageSemaphore = packageSemaphore;
       this.depsNeedFiltering = depsNeedFiltering;
       this.errorReporter = errorReporter;
+      this.context = context;
     }
 
     @Override
     public ParallelVisitor<SkyKey, Target> create() {
       return new DepsUnboundedVisitor(
-          env, validDepUniquifier, callback, packageSemaphore, depsNeedFiltering, errorReporter);
+          env,
+          validDepUniquifier,
+          callback,
+          packageSemaphore,
+          depsNeedFiltering,
+          errorReporter,
+          context);
     }
   }
 
@@ -110,7 +123,7 @@ class DepsUnboundedVisitor extends AbstractEdgeVisitor<SkyKey> {
       packageSemaphore.acquireAll(pkgIdsNeededForTargetification);
       Iterable<Target> deps;
       try {
-        deps = env.getFwdDeps(env.makeTargetsFromSkyKeys(keys).values());
+        deps = env.getFwdDeps(env.makeTargetsFromSkyKeys(keys).values(), context);
       } finally {
         packageSemaphore.releaseAll(pkgIdsNeededForTargetification);
       }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/ParallelSkyQueryUtils.java b/src/main/java/com/google/devtools/build/lib/query2/ParallelSkyQueryUtils.java
index 1fe3bbf97f..c95a653e29 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/ParallelSkyQueryUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/ParallelSkyQueryUtils.java
@@ -28,10 +28,10 @@ import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryTaskFut
 import com.google.devtools.build.lib.query2.engine.QueryEnvironment.ThreadSafeMutableSet;
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.query2.engine.QueryUtil;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.AggregateAllCallback;
 import com.google.devtools.build.lib.query2.engine.Uniquifier;
-import com.google.devtools.build.lib.query2.engine.VariableContext;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.skyframe.SkyKey;
 import java.util.Collection;
@@ -61,7 +61,7 @@ public class ParallelSkyQueryUtils {
   static QueryTaskFuture<Void> getAllRdepsUnboundedParallel(
       SkyQueryEnvironment env,
       QueryExpression expression,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback,
       MultisetSemaphore<PackageIdentifier> packageSemaphore) {
     return env.eval(
@@ -79,7 +79,7 @@ public class ParallelSkyQueryUtils {
       SkyQueryEnvironment env,
       QueryExpression expression,
       int depth,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback,
       MultisetSemaphore<PackageIdentifier> packageSemaphore) {
     return env.eval(
@@ -98,7 +98,7 @@ public class ParallelSkyQueryUtils {
       SkyQueryEnvironment env,
       QueryExpression expression,
       Predicate<SkyKey> universe,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback,
       MultisetSemaphore<PackageIdentifier> packageSemaphore) {
     return env.eval(
@@ -111,7 +111,7 @@ public class ParallelSkyQueryUtils {
   static QueryTaskFuture<Predicate<SkyKey>> getDTCSkyKeyPredicateFuture(
       SkyQueryEnvironment env,
       QueryExpression expression,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       int processResultsBatchSize,
       int concurrencyLevel) {
     QueryTaskFuture<ThreadSafeMutableSet<Target>> universeValueFuture =
@@ -144,7 +144,7 @@ public class ParallelSkyQueryUtils {
       QueryExpression expression,
       int depth,
       Predicate<SkyKey> universe,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback,
       MultisetSemaphore<PackageIdentifier> packageSemaphore) {
     return env.eval(
@@ -173,7 +173,7 @@ public class ParallelSkyQueryUtils {
   static QueryTaskFuture<Void> getDepsUnboundedParallel(
       SkyQueryEnvironment env,
       QueryExpression expression,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback,
       MultisetSemaphore<PackageIdentifier> packageSemaphore,
       boolean depsNeedFiltering,
@@ -183,7 +183,7 @@ public class ParallelSkyQueryUtils {
         context,
         ParallelVisitor.createParallelVisitorCallback(
             new DepsUnboundedVisitor.Factory(
-                env, callback, packageSemaphore, depsNeedFiltering, errorReporter)));
+                env, callback, packageSemaphore, depsNeedFiltering, errorReporter, context)));
   }
 
   static class DepAndRdep {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/RBuildFilesFunction.java b/src/main/java/com/google/devtools/build/lib/query2/RBuildFilesFunction.java
index 3cffb9a1ca..7dfb1b841f 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/RBuildFilesFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/RBuildFilesFunction.java
@@ -23,7 +23,7 @@ import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunctio
 import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryTaskFuture;
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
-import com.google.devtools.build.lib.query2.engine.VariableContext;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -60,7 +60,7 @@ public class RBuildFilesFunction implements QueryFunction {
   @SuppressWarnings("unchecked") // Cast from <Target> to <T>. This will only be used with <Target>.
   public <T> QueryTaskFuture<Void> eval(
       QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       QueryExpression expression,
       List<Argument> args,
       Callback<T> callback) {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/RdepsToAllRdepsQueryExpressionMapper.java b/src/main/java/com/google/devtools/build/lib/query2/RdepsToAllRdepsQueryExpressionMapper.java
new file mode 100644
index 0000000000..3146ef6654
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/query2/RdepsToAllRdepsQueryExpressionMapper.java
@@ -0,0 +1,58 @@
+// Copyright 2014 The Bazel Authors. All rights reserved.
+//
+// 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.devtools.build.lib.query2;
+
+import com.google.devtools.build.lib.cmdline.TargetPattern;
+import com.google.devtools.build.lib.query2.engine.AllRdepsFunction;
+import com.google.devtools.build.lib.query2.engine.FunctionExpression;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.Argument;
+import com.google.devtools.build.lib.query2.engine.QueryExpression;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionMapper;
+import com.google.devtools.build.lib.query2.engine.RdepsFunction;
+import com.google.devtools.build.lib.query2.engine.TargetLiteral;
+import java.util.List;
+
+/**
+ * A {@link QueryExpressionMapper} that transforms each occurrence of an expression of the form
+ * {@literal 'rdeps(<universeScope>, <T>)'} to {@literal 'allrdeps(<T>)'}. The latter is more
+ * efficient.
+ */
+class RdepsToAllRdepsQueryExpressionMapper extends QueryExpressionMapper<Void> {
+  private final TargetPattern.Parser targetPatternParser;
+  private final String absoluteUniverseScopePattern;
+
+  RdepsToAllRdepsQueryExpressionMapper(
+      TargetPattern.Parser targetPatternParser, String universeScopePattern) {
+    this.targetPatternParser = targetPatternParser;
+    this.absoluteUniverseScopePattern = targetPatternParser.absolutize(universeScopePattern);
+  }
+
+  @Override
+  public QueryExpression visit(FunctionExpression functionExpression, Void context) {
+    if (functionExpression.getFunction().getName().equals(new RdepsFunction().getName())) {
+      List<Argument> args = functionExpression.getArgs();
+      QueryExpression universeExpression = args.get(0).getExpression();
+      if (universeExpression instanceof TargetLiteral) {
+        TargetLiteral literalUniverseExpression = (TargetLiteral) universeExpression;
+        String absolutizedUniverseExpression =
+            targetPatternParser.absolutize(literalUniverseExpression.getPattern());
+        if (absolutizedUniverseExpression.equals(absoluteUniverseScopePattern)) {
+          List<Argument> argsTail = args.subList(1, functionExpression.getArgs().size());
+          return new FunctionExpression(new AllRdepsFunction(), argsTail);
+        }
+      }
+    }
+    return super.visit(functionExpression, context);
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
index 382a8d2f73..a53f1d610d 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
@@ -61,31 +61,26 @@ import com.google.devtools.build.lib.packages.NoSuchThingException;
 import com.google.devtools.build.lib.packages.Package;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.Target;
-import com.google.devtools.build.lib.pkgcache.FilteringPolicy;
 import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
-import com.google.devtools.build.lib.pkgcache.RecursivePackageProvider;
 import com.google.devtools.build.lib.pkgcache.TargetPatternEvaluator;
 import com.google.devtools.build.lib.profiler.AutoProfiler;
 import com.google.devtools.build.lib.query2.engine.AllRdepsFunction;
 import com.google.devtools.build.lib.query2.engine.Callback;
-import com.google.devtools.build.lib.query2.engine.FunctionExpression;
 import com.google.devtools.build.lib.query2.engine.KeyExtractor;
 import com.google.devtools.build.lib.query2.engine.MinDepthUniquifier;
 import com.google.devtools.build.lib.query2.engine.OutputFormatterCallback;
 import com.google.devtools.build.lib.query2.engine.QueryEvalResult;
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
+import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.query2.engine.QueryExpressionMapper;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.MinDepthUniquifierImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.MutableKeyExtractorBackedMapImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.ThreadSafeMutableKeyExtractorBackedSetImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.UniquifierImpl;
-import com.google.devtools.build.lib.query2.engine.RdepsFunction;
 import com.google.devtools.build.lib.query2.engine.StreamableQueryEnvironment;
-import com.google.devtools.build.lib.query2.engine.TargetLiteral;
 import com.google.devtools.build.lib.query2.engine.ThreadSafeOutputFormatterCallback;
 import com.google.devtools.build.lib.query2.engine.Uniquifier;
-import com.google.devtools.build.lib.query2.engine.VariableContext;
 import com.google.devtools.build.lib.skyframe.BlacklistedPackagePrefixesValue;
 import com.google.devtools.build.lib.skyframe.ContainingPackageLookupFunction;
 import com.google.devtools.build.lib.skyframe.GraphBackedRecursivePackageProvider;
@@ -270,22 +265,13 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
             new ThreadFactoryBuilder().setNameFormat("QueryEnvironment %d").build()));
     }
     resolver =
-        createTargetPatternResolver(
+        new RecursivePackageProviderBackedTargetPatternResolver(
             graphBackedRecursivePackageProvider,
             eventHandler,
             TargetPatternEvaluator.DEFAULT_FILTERING_POLICY,
             packageSemaphore);
   }
 
-  protected RecursivePackageProviderBackedTargetPatternResolver createTargetPatternResolver(
-      RecursivePackageProvider graphBackedRecursivePackageProvider,
-      ExtendedEventHandler eventHandler,
-      FilteringPolicy policy,
-      MultisetSemaphore<PackageIdentifier> packageSemaphore) {
-    return new RecursivePackageProviderBackedTargetPatternResolver(
-        graphBackedRecursivePackageProvider, eventHandler, policy, packageSemaphore);
-  }
-
   protected MultisetSemaphore<PackageIdentifier> makeFreshPackageMultisetSemaphore() {
     return MultisetSemaphore.unbounded();
   }
@@ -320,41 +306,6 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
     }
   }
 
-  /**
-   * A {@link QueryExpressionMapper} that transforms each occurrence of an expression of the form
-   * {@literal 'rdeps(<universeScope>, <T>)'} to {@literal 'allrdeps(<T>)'}. The latter is more
-   * efficient.
-   */
-  protected static class RdepsToAllRdepsQueryExpressionMapper extends QueryExpressionMapper<Void> {
-    protected final TargetPattern.Parser targetPatternParser;
-    private final String absoluteUniverseScopePattern;
-
-    protected RdepsToAllRdepsQueryExpressionMapper(
-        TargetPattern.Parser targetPatternParser,
-        String universeScopePattern) {
-      this.targetPatternParser = targetPatternParser;
-      this.absoluteUniverseScopePattern = targetPatternParser.absolutize(universeScopePattern);
-    }
-
-    @Override
-    public QueryExpression visit(FunctionExpression functionExpression, Void context) {
-      if (functionExpression.getFunction().getName().equals(new RdepsFunction().getName())) {
-        List<Argument> args = functionExpression.getArgs();
-        QueryExpression universeExpression = args.get(0).getExpression();
-        if (universeExpression instanceof TargetLiteral) {
-          TargetLiteral literalUniverseExpression = (TargetLiteral) universeExpression;
-          String absolutizedUniverseExpression =
-              targetPatternParser.absolutize(literalUniverseExpression.getPattern());
-          if (absolutizedUniverseExpression.equals(absoluteUniverseScopePattern)) {
-            List<Argument> argsTail = args.subList(1, functionExpression.getArgs().size());
-            return new FunctionExpression(new AllRdepsFunction(), argsTail);
-          }
-        }
-      }
-      return super.visit(functionExpression, context);
-    }
-  }
-
   @Override
   public final QueryExpression transformParsedQuery(QueryExpression queryExpression) {
     QueryExpressionMapper<Void> mapper = getQueryExpressionMapper();
@@ -482,7 +433,8 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   }
 
   @Override
-  public ThreadSafeMutableSet<Target> getFwdDeps(Iterable<Target> targets)
+  public ThreadSafeMutableSet<Target> getFwdDeps(
+      Iterable<Target> targets, QueryExpressionContext<Target> context)
       throws InterruptedException {
     Map<SkyKey, Target> targetsByKey = Maps.newHashMapWithExpectedSize(Iterables.size(targets));
     for (Target target : targets) {
@@ -519,7 +471,9 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   }
 
   @Override
-  public Collection<Target> getReverseDeps(Iterable<Target> targets) throws InterruptedException {
+  public Collection<Target> getReverseDeps(
+      Iterable<Target> targets, QueryExpressionContext<Target> context)
+      throws InterruptedException {
     return getReverseDepsOfTransitiveTraversalKeys(Iterables.transform(targets, TARGET_TO_SKY_KEY));
   }
 
@@ -571,16 +525,18 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   }
 
   @Override
-  public ThreadSafeMutableSet<Target> getTransitiveClosure(ThreadSafeMutableSet<Target> targets)
+  public ThreadSafeMutableSet<Target> getTransitiveClosure(
+      ThreadSafeMutableSet<Target> targets, QueryExpressionContext<Target> context)
       throws InterruptedException {
     return SkyQueryUtils.getTransitiveClosure(
-        targets, this::getFwdDeps, createThreadSafeMutableSet());
+        targets, targets1 -> getFwdDeps(targets1, context), createThreadSafeMutableSet());
   }
 
   @Override
-  public ImmutableList<Target> getNodesOnPath(Target from, Target to)
-      throws InterruptedException {
-    return SkyQueryUtils.getNodesOnPath(from, to, this::getFwdDeps, Target::getLabel);
+  public ImmutableList<Target> getNodesOnPath(
+      Target from, Target to, QueryExpressionContext<Target> context) throws InterruptedException {
+    return SkyQueryUtils.getNodesOnPath(
+        from, to, targets -> getFwdDeps(targets, context), Target::getLabel);
   }
 
   private <R> ListenableFuture<R> safeSubmit(Callable<R> callable) {
@@ -603,7 +559,7 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   @Override
   public QueryTaskFuture<Void> eval(
       final QueryExpression expr,
-      final VariableContext<Target> context,
+      final QueryExpressionContext<Target> context,
       final Callback<Target> callback) {
     // TODO(bazel-team): As in here, use concurrency for the async #eval of other QueryEnvironment
     // implementations.
@@ -739,7 +695,11 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   @ThreadSafe
   @Override
   public ThreadSafeMutableSet<Target> getBuildFiles(
-      QueryExpression caller, ThreadSafeMutableSet<Target> nodes, boolean buildFiles, boolean loads)
+      QueryExpression caller,
+      ThreadSafeMutableSet<Target> nodes,
+      boolean buildFiles,
+      boolean loads,
+      QueryExpressionContext<Target> context)
       throws QueryException, InterruptedException {
     ThreadSafeMutableSet<Target> dependentFiles = createThreadSafeMutableSet();
     Set<PackageIdentifier> seenPackages = new HashSet<>();
@@ -1220,7 +1180,7 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   @Override
   public QueryTaskFuture<Void> getAllRdepsUnboundedParallel(
       QueryExpression expression,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback) {
     return ParallelSkyQueryUtils.getAllRdepsUnboundedParallel(
         this, expression, context, callback, packageSemaphore);
@@ -1231,15 +1191,14 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   public QueryTaskFuture<Void> getAllRdepsBoundedParallel(
       QueryExpression expression,
       int depth,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback) {
     return ParallelSkyQueryUtils.getAllRdepsBoundedParallel(
         this, expression, depth, context, callback, packageSemaphore);
   }
 
   protected QueryTaskFuture<Predicate<SkyKey>> getUniverseDTCSkyKeyPredicateFuture(
-      QueryExpression universe,
-      VariableContext<Target> context) {
+      QueryExpression universe, QueryExpressionContext<Target> context) {
     return ParallelSkyQueryUtils.getDTCSkyKeyPredicateFuture(
         this,
         universe,
@@ -1253,7 +1212,7 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   public QueryTaskFuture<Void> getRdepsUnboundedParallel(
       QueryExpression expression,
       QueryExpression universe,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback) {
     return transformAsync(
         getUniverseDTCSkyKeyPredicateFuture(universe, context),
@@ -1264,7 +1223,7 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
   @Override
   public QueryTaskFuture<Void> getDepsUnboundedParallel(
       QueryExpression expression,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback,
       Callback<Target> errorReporter) {
     return ParallelSkyQueryUtils.getDepsUnboundedParallel(
@@ -1283,7 +1242,7 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
       QueryExpression expression,
       int depth,
       QueryExpression universe,
-      VariableContext<Target> context,
+      QueryExpressionContext<Target> context,
       Callback<Target> callback) {
     return transformAsync(
         getUniverseDTCSkyKeyPredicateFuture(universe, context),
@@ -1318,32 +1277,4 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
       }
     }
   }
-
-  /** Pair of a key and a depth, useful for driving usages of {@link MinDepthUniquifier}. */
-  public static class KeyAtDepth {
-    public final SkyKey key;
-    public final int depth;
-
-    public KeyAtDepth(SkyKey key, int depth) {
-      this.key = key;
-      this.depth = depth;
-    }
-
-    @Override
-    public int hashCode() {
-      // N.B. - We deliberately use a garbage-free hashCode implementation (rather than e.g.
-      // Objects#hash). This method is very hot during large visitations done by
-      // ParallelSkyQueryUtils.
-      return 31 * key.hashCode() + Integer.hashCode(depth);
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-      if (!(obj instanceof KeyAtDepth)) {
-        return false;
-      }
-      KeyAtDepth other = (KeyAtDepth) obj;
-      return key.equals(other.key) && depth == other.depth;
-    }
-  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/AbstractQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/engine/AbstractQueryEnvironment.java
index 818813c75c..6971d07801 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/AbstractQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/AbstractQueryEnvironment.java
@@ -118,7 +118,7 @@ public abstract class AbstractQueryEnvironment<T> implements QueryEnvironment<T>
 
   @Override
   public QueryTaskFuture<Void> eval(
-      QueryExpression expr, VariableContext<T> context, final Callback<T> callback) {
+      QueryExpression expr, QueryExpressionContext<T> context, final Callback<T> callback) {
     // Not all QueryEnvironment implementations embrace the async+streaming evaluation framework. In
     // particular, the streaming callbacks employed by functions like 'deps' use
     // QueryEnvironment#buildTransitiveClosure. So if the implementation of that method does some
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/AllPathsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/AllPathsFunction.java
index e0b5a45acd..f3c80b2ee4 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/AllPathsFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/AllPathsFunction.java
@@ -54,7 +54,7 @@ public class AllPathsFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final QueryExpression expression,
       List<Argument> args,
       final Callback<T> callback) {
@@ -79,14 +79,14 @@ public class AllPathsFunction implements QueryFunction {
 
             env.buildTransitiveClosure(expression, fromValue, Integer.MAX_VALUE);
 
-            Set<T> reachableFromX = env.getTransitiveClosure(fromValue);
+            Set<T> reachableFromX = env.getTransitiveClosure(fromValue, context);
             Predicate<T> reachable = Predicates.in(reachableFromX);
             Uniquifier<T> uniquifier = env.createUniquifier();
             Collection<T> result = uniquifier.unique(intersection(reachableFromX, toValue));
             callback.process(result);
             Collection<T> worklist = result;
             while (!worklist.isEmpty()) {
-              Iterable<T> reverseDeps = env.getReverseDeps(worklist);
+              Iterable<T> reverseDeps = env.getReverseDeps(worklist, context);
               worklist = uniquifier.unique(Iterables.filter(reverseDeps, reachable));
               callback.process(worklist);
             }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/AllRdepsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/AllRdepsFunction.java
index 6292b7f969..a90c8eba7b 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/AllRdepsFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/AllRdepsFunction.java
@@ -53,7 +53,7 @@ public class AllRdepsFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       QueryExpression expression,
       List<Argument> args,
       Callback<T> callback) {
@@ -81,7 +81,7 @@ public class AllRdepsFunction implements QueryFunction {
       final QueryEnvironment<T> env,
       QueryExpression expression,
       final Predicate<T> universe,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final Callback<T> callback,
       final int depth) {
     final MinDepthUniquifier<T> minDepthUniquifier = env.createMinDepthUniquifier();
@@ -104,7 +104,8 @@ public class AllRdepsFunction implements QueryFunction {
               Iterables.addAll(
                   next,
                   env.getReverseDeps(
-                      minDepthUniquifier.uniqueAtDepthLessThanOrEqualTo(currentInUniverse, i)));
+                      minDepthUniquifier.uniqueAtDepthLessThanOrEqualTo(currentInUniverse, i),
+                      context));
               callback.process(currentInUniverse);
               if (next.isEmpty()) {
                 // Exit when there are no more nodes to visit.
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/BinaryOperatorExpression.java b/src/main/java/com/google/devtools/build/lib/query2/engine/BinaryOperatorExpression.java
index 3b4968806e..5f4f82e5a8 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/BinaryOperatorExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/BinaryOperatorExpression.java
@@ -57,7 +57,7 @@ public class BinaryOperatorExpression extends QueryExpression {
 
   @Override
   public <T> QueryTaskFuture<Void> eval(
-      QueryEnvironment<T> env, VariableContext<T> context, Callback<T> callback) {
+      QueryEnvironment<T> env, QueryExpressionContext<T> context, Callback<T> callback) {
     switch (operator) {
       case PLUS:
       case UNION:
@@ -82,7 +82,7 @@ public class BinaryOperatorExpression extends QueryExpression {
   private static <T> QueryTaskFuture<Void> evalPlus(
       ImmutableList<QueryExpression> operands,
       QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       Callback<T> callback) {
     ArrayList<QueryTaskFuture<Void>> queryTasks = new ArrayList<>(operands.size());
     for (QueryExpression operand : operands) {
@@ -92,13 +92,13 @@ public class BinaryOperatorExpression extends QueryExpression {
   }
 
   /**
-   * Evaluates an expression of the form "e1 - e2 - ... - eK" by noting its equivalence to
-   * "e1 - (e2 + ... + eK)" and evaluating the subexpressions on the right-hand-side separately.
+   * Evaluates an expression of the form "e1 - e2 - ... - eK" by noting its equivalence to "e1 - (e2
+   * + ... + eK)" and evaluating the subexpressions on the right-hand-side separately.
    */
   private static <T> QueryTaskFuture<Void> evalMinus(
       final ImmutableList<QueryExpression> operands,
       final QueryEnvironment<T> env,
-      final VariableContext<T> context,
+      final QueryExpressionContext<T> context,
       final Callback<T> callback) {
     QueryTaskFuture<ThreadSafeMutableSet<T>> lhsValueFuture =
         QueryUtil.evalAll(env, context, operands.get(0));
@@ -131,7 +131,7 @@ public class BinaryOperatorExpression extends QueryExpression {
 
   private <T> QueryTaskFuture<Void> evalIntersect(
       final QueryEnvironment<T> env,
-      final VariableContext<T> context,
+      final QueryExpressionContext<T> context,
       final Callback<T> callback) {
     // For each right-hand side operand, intersection cannot be performed in a streaming manner; the
     // entire result of that operand is needed. So, in order to avoid pinning too much in memory at
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/BuildFilesFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/BuildFilesFunction.java
index ac55028c17..06371f856c 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/BuildFilesFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/BuildFilesFunction.java
@@ -42,7 +42,7 @@ public class BuildFilesFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final QueryExpression expression,
       List<Argument> args,
       final Callback<T> callback) {
@@ -56,9 +56,10 @@ public class BuildFilesFunction implements QueryFunction {
               throws QueryException, InterruptedException {
             ThreadSafeMutableSet<T> result = env.createThreadSafeMutableSet();
             Iterables.addAll(result, partialResult);
-            callback.process(uniquifier.unique(
-                env.getBuildFiles(
-                    expression, result, /* BUILD */ true, /* load */ true)));
+            callback.process(
+                uniquifier.unique(
+                    env.getBuildFiles(
+                        expression, result, /*buildFiles=*/ true, /*loads=*/ true, context)));
           }
         });
   }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/DepsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/DepsFunction.java
index 803c975d90..190e29137e 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/DepsFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/DepsFunction.java
@@ -48,13 +48,11 @@ final class DepsFunction implements QueryFunction {
     return ImmutableList.of(ArgumentType.EXPRESSION, ArgumentType.INTEGER);
   }
 
-  /**
-   * Breadth-first search from the arguments.
-   */
+  /** Breadth-first search from the arguments. */
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final QueryExpression expression,
       List<Argument> args,
       final Callback<T> callback) {
@@ -92,7 +90,7 @@ final class DepsFunction implements QueryFunction {
                 minDepthUniquifier.uniqueAtDepthLessThanOrEqualTo(current, i);
             callback.process(toProcess);
             current = env.createThreadSafeMutableSet();
-            Iterables.addAll(current, env.getFwdDeps(toProcess));
+            Iterables.addAll(current, env.getFwdDeps(toProcess, context));
             if (current.isEmpty()) {
               // Exit when there are no more nodes to visit.
               break;
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/FunctionExpression.java b/src/main/java/com/google/devtools/build/lib/query2/engine/FunctionExpression.java
index 04c4358b4e..c5bd36509b 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/FunctionExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/FunctionExpression.java
@@ -46,7 +46,7 @@ public class FunctionExpression extends QueryExpression {
 
   @Override
   public <T> QueryTaskFuture<Void> eval(
-      QueryEnvironment<T> env, VariableContext<T> context, Callback<T> callback) {
+      QueryEnvironment<T> env, QueryExpressionContext<T> context, Callback<T> callback) {
     return function.eval(env, context, this, args, callback);
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/LabelsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/LabelsFunction.java
index edd0935fc7..161fe5b330 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/LabelsFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/LabelsFunction.java
@@ -55,7 +55,7 @@ public class LabelsFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final QueryExpression expression,
       final List<Argument> args,
       final Callback<T> callback) {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/LetExpression.java b/src/main/java/com/google/devtools/build/lib/query2/engine/LetExpression.java
index 336f94ff0c..7709ce75fe 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/LetExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/LetExpression.java
@@ -68,7 +68,7 @@ public class LetExpression extends QueryExpression {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      final VariableContext<T> context,
+      final QueryExpressionContext<T> context,
       final Callback<T> callback) {
     if (!NAME_PATTERN.matcher(varName).matches()) {
       return env.immediateFailedFuture(
@@ -78,7 +78,7 @@ public class LetExpression extends QueryExpression {
         QueryUtil.evalAll(env, context, varExpr);
     Function<ThreadSafeMutableSet<T>, QueryTaskFuture<Void>> evalBodyAsyncFunction =
         varValue -> {
-          VariableContext<T> bodyContext = VariableContext.with(context, varName, varValue);
+          QueryExpressionContext<T> bodyContext = context.with(varName, varValue);
           return env.eval(bodyExpr, bodyContext, callback);
         };
     return env.transformAsync(varValueFuture, evalBodyAsyncFunction);
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/LoadFilesFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/LoadFilesFunction.java
index e70f8b696b..716a05cb98 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/LoadFilesFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/LoadFilesFunction.java
@@ -38,7 +38,7 @@ public class LoadFilesFunction implements QueryEnvironment.QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final QueryExpression expression,
       List<QueryEnvironment.Argument> args,
       final Callback<T> callback) {
@@ -52,12 +52,10 @@ public class LoadFilesFunction implements QueryEnvironment.QueryFunction {
               throws QueryException, InterruptedException {
             ThreadSafeMutableSet<T> result = env.createThreadSafeMutableSet();
             Iterables.addAll(result, partialResult);
-            callback.process(uniquifier.unique(
-                env.getBuildFiles(
-                    expression,
-                    result,
-                    /* BUILD */ false,
-                    /* load */ true)));
+            callback.process(
+                uniquifier.unique(
+                    env.getBuildFiles(
+                        expression, result, /*buildFiles=*/ false, /*loads=*/ true, context)));
           }
         });
   }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryEnvironment.java
index da460e2c5e..4be94bba4b 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryEnvironment.java
@@ -112,18 +112,19 @@ public interface QueryEnvironment<T> {
     Iterable<ArgumentType> getArgumentTypes();
 
     /**
-     * Returns a {@link QueryTaskFuture} representing the asynchronous application of this
-     * {@link QueryFunction} to the given {@code args}, feeding the results to the given
-     * {@code callback}.
+     * Returns a {@link QueryTaskFuture} representing the asynchronous application of this {@link
+     * QueryFunction} to the given {@code args}, feeding the results to the given {@code callback}.
      *
      * @param env the query environment this function is evaluated in.
      * @param expression the expression being evaluated.
+     * @param context the context relevant to the expression being evaluated. Contains the variable
+     *     bindings from {@link LetExpression}s.
      * @param args the input arguments. These are type-checked against the specification returned by
      *     {@link #getArgumentTypes} and {@link #getMandatoryArguments}
      */
     <T> QueryTaskFuture<Void> eval(
         QueryEnvironment<T> env,
-        VariableContext<T> context,
+        QueryExpressionContext<T> context,
         QueryExpression expression,
         List<Argument> args,
         Callback<T> callback);
@@ -159,16 +160,19 @@ public interface QueryEnvironment<T> {
   T getOrCreate(T target);
 
   /** Returns the direct forward dependencies of the specified targets. */
-  Iterable<T> getFwdDeps(Iterable<T> targets) throws InterruptedException;
+  Iterable<T> getFwdDeps(Iterable<T> targets, QueryExpressionContext<T> context)
+      throws InterruptedException;
 
   /** Returns the direct reverse dependencies of the specified targets. */
-  Iterable<T> getReverseDeps(Iterable<T> targets) throws InterruptedException;
+  Iterable<T> getReverseDeps(Iterable<T> targets, QueryExpressionContext<T> context)
+      throws InterruptedException;
 
   /**
    * Returns the forward transitive closure of all of the targets in "targets". Callers must ensure
    * that {@link #buildTransitiveClosure} has been called for the relevant subgraph.
    */
-  ThreadSafeMutableSet<T> getTransitiveClosure(ThreadSafeMutableSet<T> targets)
+  ThreadSafeMutableSet<T> getTransitiveClosure(
+      ThreadSafeMutableSet<T> targets, QueryExpressionContext<T> context)
       throws InterruptedException;
 
   /**
@@ -185,11 +189,12 @@ public interface QueryEnvironment<T> {
                               int maxDepth) throws QueryException, InterruptedException;
 
   /** Returns the ordered sequence of nodes on some path from "from" to "to". */
-  Iterable<T> getNodesOnPath(T from, T to) throws InterruptedException;
+  Iterable<T> getNodesOnPath(T from, T to, QueryExpressionContext<T> context)
+      throws InterruptedException;
 
   /**
-   * Returns a {@link QueryTaskFuture} representing the asynchronous evaluation of the given
-   * {@code expr} and passing of the results to the given {@code callback}.
+   * Returns a {@link QueryTaskFuture} representing the asynchronous evaluation of the given {@code
+   * expr} and passing of the results to the given {@code callback}.
    *
    * <p>Note that this method should guarantee that the callback does not see repeated elements.
    *
@@ -197,7 +202,7 @@ public interface QueryEnvironment<T> {
    * @param callback The caller callback to notify when results are available
    */
   QueryTaskFuture<Void> eval(
-      QueryExpression expr, VariableContext<T> context, Callback<T> callback);
+      QueryExpression expr, QueryExpressionContext<T> context, Callback<T> callback);
 
   /**
    * An asynchronous computation of part of a query evaluation.
@@ -402,7 +407,9 @@ public interface QueryEnvironment<T> {
       QueryExpression caller,
       ThreadSafeMutableSet<T> nodes,
       boolean buildFiles,
-      boolean loads) throws QueryException, InterruptedException;
+      boolean loads,
+      QueryExpressionContext<T> context)
+      throws QueryException, InterruptedException;
 
   /**
    * Returns an object that can be used to query information about targets. Implementations should
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryExpression.java b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryExpression.java
index 3a9afe8303..0326df9bcc 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryExpression.java
@@ -62,18 +62,14 @@ public abstract class QueryExpression {
    * specified environment, notifying the callback with a result. Note that it is allowed to notify
    * the callback with partial results instead of just one final result.
    *
-   * <p>Failures resulting from evaluation of an ill-formed query cause
-   * QueryException to be thrown.
+   * <p>Failures resulting from evaluation of an ill-formed query cause QueryException to be thrown.
    *
-   * <p>The reporting of failures arising from errors in BUILD files depends on
-   * the --keep_going flag.  If enabled (the default), then QueryException is
-   * thrown.  If disabled, evaluation will stumble on to produce a (possibly
-   * inaccurate) result, but a result nonetheless.
+   * <p>The reporting of failures arising from errors in BUILD files depends on the --keep_going
+   * flag. If enabled (the default), then QueryException is thrown. If disabled, evaluation will
+   * stumble on to produce a (possibly inaccurate) result, but a result nonetheless.
    */
   public abstract <T> QueryTaskFuture<Void> eval(
-      QueryEnvironment<T> env,
-      VariableContext<T> context,
-      Callback<T> callback);
+      QueryEnvironment<T> env, QueryExpressionContext<T> context, Callback<T> callback);
 
   /**
    * Collects all target patterns that are referenced anywhere within this query expression and adds
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/VariableContext.java b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryExpressionContext.java
index 9feb85242f..1971918225 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/VariableContext.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryExpressionContext.java
@@ -16,19 +16,20 @@ package com.google.devtools.build.lib.query2.engine;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
-
 import java.util.Map;
 import java.util.Set;
-
 import javax.annotation.Nullable;
 
-/** An immutable context of variable bindings for variables introduced by {@link LetExpression}s. */
+/**
+ * An immutable context, including variable bindings for variables introduced by {@link
+ * LetExpression}s.
+ */
 @Immutable
 @ThreadSafe
-public class VariableContext<T> {
-  private final ImmutableMap<String, Set<T>> context;
+public class QueryExpressionContext<T> {
+  protected final ImmutableMap<String, Set<T>> context;
 
-  private VariableContext(ImmutableMap<String, Set<T>> context) {
+  protected QueryExpressionContext(ImmutableMap<String, Set<T>> context) {
     this.context = context;
   }
 
@@ -41,21 +42,21 @@ public class VariableContext<T> {
     return context.get(name);
   }
 
-  /** Returns a {@link VariableContext} with no variables defined. */
-  public static <T> VariableContext<T> empty() {
-    return new VariableContext<>(ImmutableMap.<String, Set<T>>of());
+  /** Returns a {@link QueryExpressionContext} with no variables defined. */
+  public static <T> QueryExpressionContext<T> empty() {
+    return new QueryExpressionContext<>(ImmutableMap.<String, Set<T>>of());
   }
-
   /**
-   * Returns a {@link VariableContext} that has all the same bindings as the given
-   * {@code variableContext} and also the binding of {@code name} to {@code value}.
+   * Returns a {@link QueryExpressionContext} that has all the same bindings as the given {@code
+   * variableContext} and also the binding of {@code name} to {@code value}.
    */
-  static <T> VariableContext<T> with(
-      VariableContext<T> variableContext,
-      String name,
-      Set<T> value) {
+  protected QueryExpressionContext<T> with(String name, Set<T> value) {
+    return new QueryExpressionContext<>(withNewVariable(name, value));
+  }
+
+  protected final ImmutableMap<String, Set<T>> withNewVariable(String name, Set<T> value) {
     ImmutableMap.Builder<String, Set<T>> newContextBuilder = ImmutableMap.builder();
-    for (Map.Entry<String, Set<T>> entry : variableContext.context.entrySet()) {
+    for (Map.Entry<String, Set<T>> entry : context.entrySet()) {
       if (!entry.getKey().equals(name)) {
         // The binding of 'name' to 'value' should override any existing binding of name in
         // 'variableContext'. These are the semantics we want in order for nested let-expressions
@@ -64,7 +65,12 @@ public class VariableContext<T> {
       }
     }
     newContextBuilder.put(name, value);
-    return new VariableContext<>(newContextBuilder.build());
+    return newContextBuilder.build();
+  }
+
+  @Override
+  public String toString() {
+    return "QueryExpressionContext: " + context;
   }
 }
 
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java
index e860cb9060..fce662fcef 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java
@@ -121,7 +121,7 @@ public final class QueryUtil {
    * <p>Should only be used by QueryExpressions when it is the only way of achieving correctness.
    */
   public static <T> QueryTaskFuture<ThreadSafeMutableSet<T>> evalAll(
-      QueryEnvironment<T> env, VariableContext<T> context, QueryExpression expr) {
+      QueryEnvironment<T> env, QueryExpressionContext<T> context, QueryExpression expr) {
     final AggregateAllCallback<T, ThreadSafeMutableSet<T>> callback = newAggregateAllCallback(env);
     return env.whenSucceedsCall(
         env.eval(expr, context, callback),
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/RdepsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/RdepsFunction.java
index e40960a843..6f30313b3d 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/RdepsFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/RdepsFunction.java
@@ -53,7 +53,7 @@ public final class RdepsFunction extends AllRdepsFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       QueryExpression expression,
       List<Argument> args,
       Callback<T> callback) {
@@ -81,7 +81,7 @@ public final class RdepsFunction extends AllRdepsFunction {
   private static <T> QueryTaskFuture<Void> evalWithBoundedDepth(
       QueryEnvironment<T> env,
       QueryExpression rdepsFunctionExpressionForErrorMessages,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       QueryExpression argumentExpression,
       int depth,
       QueryExpression universeExpression,
@@ -94,15 +94,14 @@ public final class RdepsFunction extends AllRdepsFunction {
           try {
             env.buildTransitiveClosure(
                 rdepsFunctionExpressionForErrorMessages, universeValue, Integer.MAX_VALUE);
-            universe = Predicates.in(env.getTransitiveClosure(universeValue));
+            universe = Predicates.in(env.getTransitiveClosure(universeValue, context));
           } catch (InterruptedException e) {
             return env.immediateCancelledFuture();
           } catch (QueryException e) {
             return env.immediateFailedFuture(e);
           }
 
-          return AllRdepsFunction.eval(
-              env, argumentExpression, universe, context, callback, depth);
+          return AllRdepsFunction.eval(env, argumentExpression, universe, context, callback, depth);
         };
 
     return env.transformAsync(universeValueFuture, evalInUniverseAsyncFunction);
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/RegexFilterExpression.java b/src/main/java/com/google/devtools/build/lib/query2/engine/RegexFilterExpression.java
index 136e0a6273..f6f748c8e1 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/RegexFilterExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/RegexFilterExpression.java
@@ -34,7 +34,7 @@ public abstract class RegexFilterExpression implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       QueryExpression expression,
       final List<Argument> args,
       Callback<T> callback) {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/SetExpression.java b/src/main/java/com/google/devtools/build/lib/query2/engine/SetExpression.java
index 3f883c144f..853972e8e7 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/SetExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/SetExpression.java
@@ -48,7 +48,7 @@ public class SetExpression extends QueryExpression {
 
   @Override
   public <T> QueryTaskFuture<Void> eval(
-      QueryEnvironment<T> env, VariableContext<T> context, Callback<T> callback) {
+      QueryEnvironment<T> env, QueryExpressionContext<T> context, Callback<T> callback) {
     ArrayList<QueryTaskFuture<Void>> queryTasks = new ArrayList<>(words.size());
     for (TargetLiteral expr : words) {
       queryTasks.add(env.eval(expr, context, callback));
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/SiblingsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/SiblingsFunction.java
index 5d03bfd949..4a8ea7f7ca 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/SiblingsFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/SiblingsFunction.java
@@ -48,7 +48,7 @@ public class SiblingsFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final QueryExpression expression,
       List<Argument> args,
       final Callback<T> callback) {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/SomeFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/SomeFunction.java
index 995e288f29..882cbc9b12 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/SomeFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/SomeFunction.java
@@ -52,7 +52,7 @@ class SomeFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final QueryExpression expression,
       List<Argument> args,
       final Callback<T> callback) {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/SomePathFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/SomePathFunction.java
index 93650d5fbb..4f436d1db2 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/SomePathFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/SomePathFunction.java
@@ -53,7 +53,7 @@ class SomePathFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       final QueryExpression expression,
       List<Argument> args,
       final Callback<T> callback) {
@@ -83,7 +83,7 @@ class SomePathFunction implements QueryFunction {
             for (T x : uniquifier.unique(fromValue)) {
               ThreadSafeMutableSet<T> xSet = env.createThreadSafeMutableSet();
               xSet.add(x);
-              ThreadSafeMutableSet<T> xtc = env.getTransitiveClosure(xSet);
+              ThreadSafeMutableSet<T> xtc = env.getTransitiveClosure(xSet, context);
               SetView<T> result;
               if (xtc.size() > toValue.size()) {
                 result = Sets.intersection(toValue, xtc);
@@ -91,7 +91,7 @@ class SomePathFunction implements QueryFunction {
                 result = Sets.intersection(xtc, toValue);
               }
               if (!result.isEmpty()) {
-                callback.process(env.getNodesOnPath(x, result.iterator().next()));
+                callback.process(env.getNodesOnPath(x, result.iterator().next(), context));
                 return null;
               }
               uniquifier.unique(xtc);
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/StreamableQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/engine/StreamableQueryEnvironment.java
index f36bee0063..07cf9a226c 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/StreamableQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/StreamableQueryEnvironment.java
@@ -22,30 +22,28 @@ public interface StreamableQueryEnvironment<T> extends QueryEnvironment<T> {
   QueryTaskFuture<Void> getAllRdepsBoundedParallel(
       QueryExpression expression,
       int depth,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       Callback<T> callback);
 
   QueryTaskFuture<Void> getAllRdepsUnboundedParallel(
-      QueryExpression expression,
-      VariableContext<T> context,
-      Callback<T> callback);
+      QueryExpression expression, QueryExpressionContext<T> context, Callback<T> callback);
 
   QueryTaskFuture<Void> getRdepsBoundedParallel(
       QueryExpression expression,
       int depth,
       QueryExpression universe,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       Callback<T> callback);
 
   QueryTaskFuture<Void> getRdepsUnboundedParallel(
       QueryExpression expression,
       QueryExpression universe,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       Callback<T> callback);
 
   QueryTaskFuture<Void> getDepsUnboundedParallel(
       QueryExpression expression,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       Callback<T> callback,
       Callback<T> errorReporter);
 }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/TargetLiteral.java b/src/main/java/com/google/devtools/build/lib/query2/engine/TargetLiteral.java
index 4e3a8e7eb2..6f9976537c 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/TargetLiteral.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/TargetLiteral.java
@@ -45,7 +45,7 @@ public final class TargetLiteral extends QueryExpression {
   }
 
   private <T> QueryTaskFuture<Void> evalVarReference(
-      QueryEnvironment<T> env, VariableContext<T> context, Callback<T> callback) {
+      QueryEnvironment<T> env, QueryExpressionContext<T> context, Callback<T> callback) {
     String varName = LetExpression.getNameFromReference(pattern);
     Set<T> value = context.get(varName);
     if (value == null) {
@@ -64,7 +64,7 @@ public final class TargetLiteral extends QueryExpression {
 
   @Override
   public <T> QueryTaskFuture<Void> eval(
-      QueryEnvironment<T> env, VariableContext<T> context, Callback<T> callback) {
+      QueryEnvironment<T> env, QueryExpressionContext<T> context, Callback<T> callback) {
     if (isVariableReference()) {
       return evalVarReference(env, context, callback);
     } else {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/TestsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/TestsFunction.java
index 7119cb47ad..ff00be44b5 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/TestsFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/TestsFunction.java
@@ -63,7 +63,7 @@ public class TestsFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      VariableContext<T> context,
+      QueryExpressionContext<T> context,
       QueryExpression expression,
       List<Argument> args,
       final Callback<T> callback) {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/VisibleFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/VisibleFunction.java
index 072013371d..c76d0da170 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/VisibleFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/VisibleFunction.java
@@ -56,7 +56,7 @@ public class VisibleFunction implements QueryFunction {
   @Override
   public <T> QueryTaskFuture<Void> eval(
       final QueryEnvironment<T> env,
-      final VariableContext<T> context,
+      final QueryExpressionContext<T> context,
       QueryExpression expression,
       final List<Argument> args,
       final Callback<T> callback) {