Line data    Source code

       1             : // Copyright (C) 2012 The Android Open Source Project
       2             : //
       3             : // Licensed under the Apache License, Version 2.0 (the "License");
       4             : // you may not use this file except in compliance with the License.
       5             : // You may obtain a copy of the License at
       6             : //
       7             : // http://www.apache.org/licenses/LICENSE-2.0
       8             : //
       9             : // Unless required by applicable law or agreed to in writing, software
      10             : // distributed under the License is distributed on an "AS IS" BASIS,
      11             : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12             : // See the License for the specific language governing permissions and
      13             : // limitations under the License.
      14             : 
      15             : package com.google.gerrit.server.ioutil;
      16             : 
      17             : import java.io.PrintWriter;
      18             : 
      19             : /**
      20             :  * Simple output formatter for column-oriented data, writing its output to a {@link
      21             :  * java.io.PrintWriter} object. Handles escaping of the column data so that the resulting output is
      22             :  * unambiguous and reasonably safe and machine parsable.
      23             :  */
      24             : public class ColumnFormatter {
      25             :   private char columnSeparator;
      26             :   private boolean firstColumn;
      27             :   private final PrintWriter out;
      28             : 
      29             :   /**
      30             :    * @param out The writer to which output should be sent.
      31             :    * @param columnSeparator A character that should serve as the separator token between columns of
      32             :    *     output. As only non-printable characters in the column text are ever escaped, the column
      33             :    *     separator must be a non-printable character if the output needs to be unambiguously parsed.
      34             :    */
      35           1 :   public ColumnFormatter(PrintWriter out, char columnSeparator) {
      36           1 :     this.out = out;
      37           1 :     this.columnSeparator = columnSeparator;
      38           1 :     this.firstColumn = true;
      39           1 :   }
      40             : 
      41             :   /**
      42             :    * Adds a text string as a new column in the current line of output, taking care of escaping as
      43             :    * necessary.
      44             :    *
      45             :    * @param content the string to add.
      46             :    */
      47             :   public void addColumn(String content) {
      48           1 :     if (!firstColumn) {
      49           1 :       out.print(columnSeparator);
      50             :     }
      51           1 :     out.print(StringUtil.escapeString(content));
      52           1 :     firstColumn = false;
      53           1 :   }
      54             : 
      55             :   /**
      56             :    * Finishes the output by flushing the current line and takes care of any other cleanup action.
      57             :    */
      58             :   public void finish() {
      59           1 :     nextLine();
      60           1 :     out.flush();
      61           1 :   }
      62             : 
      63             :   /**
      64             :    * Flushes the current line of output and makes the formatter ready to start receiving new column
      65             :    * data for a new line (or end-of-file). If the current line is empty nothing is done, i.e.
      66             :    * consecutive calls to this method without intervening calls to {@link #addColumn} will be
      67             :    * squashed.
      68             :    */
      69             :   public void nextLine() {
      70           1 :     if (!firstColumn) {
      71           1 :       out.print('\n');
      72           1 :       firstColumn = true;
      73             :     }
      74           1 :   }
      75             : }