WireFormat.java

/* Copyright (c) 2008 Google Inc.
 *
 * 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.gdata.wireformats;

import com.google.gdata.data.XmlEventSource;
import com.google.gdata.wireformats.input.InputProperties;
import com.google.gdata.wireformats.output.OutputProperties;

import java.io.Reader;
import java.io.Writer;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.List;

/**
 * Top-level information about a wire format. All wire formats have an
 * associated generator and parser, plus a method to validate content
 * model metadata to ensure it's compatible with the wire format.
 */
public abstract class WireFormat {

  /**
   * XML wire format.
   */
  public static final XmlWireFormat XML = new XmlWireFormat();

  /**
   * List of all supported wire formats.
   */
  public static final List<WireFormat> ALL =

      Arrays.asList(new WireFormat [] {XML});


  /**
   * Logical name for the wire format.
   */
  protected final String name;

  /**
   * Constructs a new wire format with the specific logical name.
   * @param name wire format name.
   */
  protected WireFormat(String name) {
    this.name = name;
  }

  /**
   * Returns the wire format name.
   * @return logical name of wire format.
   */
  public String getName() {
    return name;
  }

  /**
   * Create a wire format generator.
   *
   * @param outProps the output properties to use for output
   * @param w writer where output is sent to
   * @param cs character set used to encode output
   * @param prettyPrint {@code true} if output should be in prettyprint format
   * @return wire format generator
   */
  public abstract WireFormatGenerator createGenerator(OutputProperties outProps,
      Writer w, Charset cs, boolean prettyPrint);

  /**
   * Create a wire format parser.
   *
   * @param inProps the input properties to use when parsing
   * @param r reader where input is retrieved from
   * @param cs character set used to encode output
   * @return wire format parser
   */
  public abstract WireFormatParser createParser(InputProperties inProps,
      Reader r, Charset cs);

  /**
   * Create a wire format parser for a given xml event source.  By default this
   * throws {@link UnsupportedOperationException}, subclasses can implement this
   * if they choose to.
   */
  public WireFormatParser createParser(InputProperties inProps,
      XmlEventSource source) {
    throw new UnsupportedOperationException(
        "Wire format does not support xml event sources.");
  }
}