Update from Google.

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MOE_MIGRATED_REVID=85702957

1 files changed, 87 insertions, 0 deletions

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
new file mode 100644
index 0000000000..b90bcdfde9
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/SomePathFunction.java
@@ -0,0 +1,87 @@
+// Copyright 2014 Google Inc. 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.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+import com.google.common.collect.Sets.SetView;
+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;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * A somepath(x, y) query expression, which computes the set of nodes
+ * on some arbitrary path from a target in set x to a target in set y.
+ *
+ * <pre>expr ::= SOMEPATH '(' expr ',' expr ')'</pre>
+ */
+class SomePathFunction implements QueryFunction {
+  SomePathFunction() {
+  }
+
+  @Override
+  public String getName() {
+    return "somepath";
+  }
+
+  @Override
+  public int getMandatoryArguments() {
+    return 2;
+  }
+
+  @Override
+  public List<ArgumentType> getArgumentTypes() {
+    return ImmutableList.of(ArgumentType.EXPRESSION, ArgumentType.EXPRESSION);
+  }
+
+  @Override
+  public <T> Set<T> eval(QueryEnvironment<T> env, QueryExpression expression, List<Argument> args)
+      throws QueryException {
+    Set<T> fromValue = args.get(0).getExpression().eval(env);
+    Set<T> toValue = args.get(1).getExpression().eval(env);
+
+    // Implementation strategy: for each x in "from", compute its forward
+    // transitive closure.  If it intersects "to", then do a path search from x
+    // to an arbitrary node in the intersection, and return the path.  This
+    // avoids computing the full transitive closure of "from" in some cases.
+
+    env.buildTransitiveClosure(expression, fromValue, Integer.MAX_VALUE);
+
+    // This set contains all nodes whose TC does not intersect "toValue".
+    Set<T> done = new HashSet<>();
+
+    for (T x : fromValue) {
+      if (done.contains(x)) {
+        continue;
+      }
+      Set<T> xtc = env.getTransitiveClosure(ImmutableSet.of(x));
+      SetView<T> result;
+      if (xtc.size() > toValue.size()) {
+        result = Sets.intersection(toValue, xtc);
+      } else {
+        result = Sets.intersection(xtc, toValue);
+      }
+      if (!result.isEmpty()) {
+        return env.getNodesOnPath(x, result.iterator().next());
+      }
+      done.addAll(xtc);
+    }
+    return ImmutableSet.of();
+  }
+}