Change WalkableGraphFactory#prepareAndGet to take multiple SkyKeys as graph roots

It also changes a few accessors of utility methods in Skyframe library. It
refactors the QueryExpressionMapper to use a general QueryExpressionVisitor.

RELNOTES: None
PiperOrigin-RevId: 165534908

1 files changed, 114 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/AggregatingQueryExpressionVisitor.java b/src/main/java/com/google/devtools/build/lib/query2/engine/AggregatingQueryExpressionVisitor.java
new file mode 100644
index 0000000000..cde80e072a
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/AggregatingQueryExpressionVisitor.java
@@ -0,0 +1,114 @@
+// Copyright 2017 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.engine;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.primitives.Booleans;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.Argument;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.ArgumentType;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunction;
+
+/**
+ * An implementation of {@link QueryExpressionVisitor} which recursively visits all nested {@link
+ * QueryExpression}s
+ */
+public abstract class AggregatingQueryExpressionVisitor<T> implements QueryExpressionVisitor<T> {
+
+  @Override
+  public T visit(BinaryOperatorExpression binaryOperatorExpression) {
+    ImmutableMap.Builder<QueryExpression, T> builder = ImmutableMap.builder();
+    for (QueryExpression expr : binaryOperatorExpression.getOperands()) {
+      builder.put(expr, expr.accept(this));
+    }
+
+    return aggregate(builder.build());
+  }
+
+  @Override
+  public T visit(FunctionExpression functionExpression) {
+    ImmutableMap.Builder<QueryExpression, T> builder = ImmutableMap.builder();
+    for (Argument argument : functionExpression.getArgs()) {
+      if (argument.getType() == ArgumentType.EXPRESSION) {
+        builder.put(argument.getExpression(), argument.getExpression().accept(this));
+      }
+    }
+
+    return aggregate(builder.build());
+  }
+
+  @Override
+  public T visit(LetExpression letExpression) {
+    return aggregate(
+        ImmutableMap.of(
+            letExpression.getVarExpr(), letExpression.getVarExpr().accept(this),
+            letExpression.getBodyExpr(), letExpression.getBodyExpr().accept(this)));
+  }
+
+  @Override
+  public T visit(SetExpression setExpression) {
+    ImmutableMap.Builder<QueryExpression, T> builder = ImmutableMap.builder();
+    for (TargetLiteral targetLiteral : setExpression.getWords()) {
+      builder.put(targetLiteral, targetLiteral.accept(this));
+    }
+
+    return aggregate(builder.build());
+  }
+
+  /**
+   * Aggregates results from all sub-expression visitations. The map is guaranteed to include
+   * results for all direct sub-expressions.
+   */
+  protected abstract T aggregate(ImmutableMap<QueryExpression, T> resultMap);
+
+  /**
+   * Returns {@code true} when the query expression contains at least one {@link QueryFunction}
+   * whose name is in the set of {@code functionName}.
+   */
+  public static class ContainsFunctionQueryExpressionVisitor
+      extends AggregatingQueryExpressionVisitor<Boolean>
+      implements QueryExpressionVisitor<Boolean> {
+
+    private final ImmutableSet<String> functionNames;
+
+    public ContainsFunctionQueryExpressionVisitor(Iterable<String> functionNames) {
+      this.functionNames = ImmutableSet.copyOf(functionNames);
+    }
+
+    @Override
+    public Boolean visit(TargetLiteral targetLiteral) {
+      return false;
+    }
+
+    @Override
+    public Boolean visit(SetExpression setExpression) {
+      return false;
+    }
+
+    @Override
+    public Boolean visit(FunctionExpression functionExpression) {
+      QueryFunction function = functionExpression.getFunction();
+      if (functionNames.contains(function.getName())) {
+        return true;
+      } else {
+        return super.visit(functionExpression);
+      }
+    }
+
+    @Override
+    protected Boolean aggregate(ImmutableMap<QueryExpression, Boolean> resultMap) {
+      return Booleans.contains(Booleans.toArray(resultMap.values()), true);
+    }
+  }
+}