content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.beam.sdk.util;
  
  import java.io.Serializable;
  
  /**
   * A wrapper object storing a Python function definition that can be evaluated to Python callables
   * in Python SDK.
   *
   * <p>The snippet of Python code can be a valid Python expression (such as {@code lambda x: x * x}
   * or {str.upper}), a fully qualified name (such as {@code math.sin}), or a complete, multi-line
   * function or class definition (such as {@code def foo(x): ...} or {@code class Foo: ...}).
   *
   * <p>Any lines preceding the function definition are first evaluated to provide context in which to
   * define the function which can be useful to declare imports or any other needed values, e.g.
   *
   * <pre>
   * import math
   *
   * def helper(x):
   *   return x * x
   *
   * def func(y):
   *   return helper(y) + y
   * </pre>
   *
   * in which case {@code func} would get applied to each element.
   */
  public class PythonCallableSource implements Serializable {
    private final String pythonCallableCode;
  
    private PythonCallableSource(String pythonCallableCode) {
      this.pythonCallableCode = pythonCallableCode;
    }
  
    public static PythonCallableSource of(String pythonCallableCode) {
      // TODO(https://github.com/apache/beam/issues/21568): check syntactic correctness of Python code
      // if possible
      return new PythonCallableSource(pythonCallableCode);
    }
  
    public String getPythonCallableCode() {
      return pythonCallableCode;
    }
  }
  