1 files changed, 83 insertions, 0 deletions
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
new file mode 100644
index 0000000000..1dbe5e63d3
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/RegexFilterExpression.java
@@ -0,0 +1,83 @@
+// 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.devtools.build.lib.query2.engine.QueryEnvironment.Argument;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunction;
+
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.regex.Pattern;
+
+/**
+ * An abstract class that provides generic regex filter expression. Actual
+ * expression are implemented by the subclasses.
+ */
+abstract class RegexFilterExpression implements QueryFunction {
+  protected RegexFilterExpression() {
+  }
+
+  @Override
+  public <T> Set<T> eval(QueryEnvironment<T> env, QueryExpression expression, List<Argument> args)
+      throws QueryException {
+    Pattern compiledPattern;
+    try {
+      compiledPattern = Pattern.compile(getPattern(args));
+    } catch (IllegalArgumentException e) {
+      throw new QueryException(expression, "illegal pattern regexp in '" + this + "': "
+                               + e.getMessage());
+    }
+
+    QueryExpression argument = args.get(args.size() - 1).getExpression();
+
+    Set<T> result = new LinkedHashSet<>();
+    for (T target : argument.eval(env)) {
+      for (String str : getFilterStrings(env, args, target)) {
+        if ((str != null) && compiledPattern.matcher(str).find()) {
+          result.add(target);
+          break;
+        }
+      }
+    }
+    return result;
+  }
+
+  /**
+   * Returns string for the given target that must be matched against pattern.
+   * May return null, in which case matching is guaranteed to fail.
+   */
+  protected abstract <T> String getFilterString(
+      QueryEnvironment<T> env, List<Argument> args, T target);
+
+  /**
+   * Returns a list of strings for the given target that must be matched against
+   * pattern. The filter matches if *any* of these strings matches.
+   *
+   * <p>Unless subclasses have an explicit reason to override this method, it's fine
+   * to keep the default implementation that just delegates to {@link #getFilterString}.
+   * Overriding this method is useful for subclasses that want to match against a
+   * universe of possible values. For example, with configurable attributes, an
+   * attribute might have different values depending on the build configuration. One
+   * may wish the filter to match if *any* of those values matches.
+   */
+  protected <T> Iterable<String> getFilterStrings(
+      QueryEnvironment<T> env, List<Argument> args, T target) {
+    String filterString = getFilterString(env, args, target);
+    return filterString == null ? ImmutableList.<String>of() : ImmutableList.of(filterString);
+  }
+
+  protected abstract String getPattern(List<Argument> args);
+}