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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *  http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17
    18  package org.apache.any23.mime.purifier;
    19
    20  import java.io.IOException;
    21  import java.io.InputStream;
    22
    23  /**
    24   * Implementation of {@link Purifier} that removes all the eventual blank characters at the header of a file that might
    25   * prevents its <i>MIME Type</i> detection.
    26   *
    27   * @author Davide Palmisano ( dpalmisano@gmail.com )
    28   */
    29  public class WhiteSpacesPurifier implements Purifier {
    30
    31      /**
    32       * {@inheritDoc}
    33       */
    34      public void purify(InputStream inputStream) throws IOException {
    35          if (!inputStream.markSupported())
    36              throw new IllegalArgumentException("Provided InputStream does not support marks");
    37
    38          // mark the current position
    39          inputStream.mark(Integer.MAX_VALUE);
    40          int byteRead = inputStream.read();
    41          char charRead = (char) byteRead;
    42          while (isBlank(charRead) && (byteRead != -1)) {
    43              // if here means that the previos character must be removed, so mark.
    44              inputStream.mark(Integer.MAX_VALUE);
    45              byteRead = inputStream.read();
    46              charRead = (char) byteRead;
    47          }
    48          // if exit go back to the last valid mark.
    49          inputStream.reset();
    50      }
    51
    52      private boolean isBlank(char c) {
    53          return c == '\t' || c == '\n' || c == ' ' || c == '\r' || c == '\b' || c == '\f';
    54      }
    55  }