1 files changed, 64 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/AbstractFunction.java b/src/main/java/com/google/devtools/build/lib/syntax/AbstractFunction.java
new file mode 100644
index 0000000000..f444c231dc
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/syntax/AbstractFunction.java
@@ -0,0 +1,64 @@
+// 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.syntax;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Partial implementation of Function interface.
+ */
+public abstract class AbstractFunction implements Function {
+
+  private final String name;
+
+  protected AbstractFunction(String name) {
+    this.name = name;
+  }
+
+  /**
+   * Returns the name of this function.
+   */
+  @Override
+  public String getName() {
+    return name;
+  }
+
+  @Override
+  public Class<?> getObjectType() {
+    return null;
+  }
+
+  /**
+   * Abstract implementation of Function that accepts no parameters.
+   */
+  public abstract static class NoArgFunction extends AbstractFunction {
+
+    public NoArgFunction(String name) {
+      super(name);
+    }
+
+    @Override
+    public Object call(List<Object> args, Map<String, Object> kwargs, FuncallExpression ast,
+        Environment env) throws EvalException, InterruptedException {
+      if (args.size() != 1 || kwargs.size() != 0) {
+        throw new EvalException(ast.getLocation(), "Invalid number of arguments (expected 0)");
+      }
+      return call(args.get(0), ast, env);
+    }
+
+    public abstract Object call(Object self, FuncallExpression ast, Environment env)
+        throws EvalException, InterruptedException;
+  }
+}