lucene/core/src/java/org/apache/lucene/index/IndexFileNames.java - lucene-solr - Git at Google

 /*
  * 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.lucene.index;

 import java.util.regex.Pattern;
 import org.apache.lucene.codecs.Codec;

 /**
  * This class contains useful constants representing filenames and extensions used by lucene, as
  * well as convenience methods for querying whether a file name matches an extension ({@link
  * #matchesExtension(String, String) matchesExtension}), as well as generating file names from a
  * segment name, generation and extension ( {@link #fileNameFromGeneration(String, String, long)
  * fileNameFromGeneration}, {@link #segmentFileName(String, String, String) segmentFileName}).
  *
  * <p><b>NOTE</b>: extensions used by codecs are not listed here. You must interact with the {@link
  * Codec} directly.
  *
  * @lucene.internal
  */
 public final class IndexFileNames {

   /** No instance */
   private IndexFileNames() {}

   /** Name of the index segment file */
   public static final String SEGMENTS = "segments";

   /** Name of pending index segment file */
   public static final String PENDING_SEGMENTS = "pending_segments";

   /**
    * Computes the full file name from base, extension and generation. If the generation is -1, the
    * file name is null. If it's 0, the file name is &lt;base&gt;.&lt;ext&gt;. If it's &gt; 0, the
    * file name is &lt;base&gt;_&lt;gen&gt;.&lt;ext&gt;.<br>
    * <b>NOTE:</b> .&lt;ext&gt; is added to the name only if <code>ext</code> is not an empty string.
    *
    * @param base main part of the file name
    * @param ext extension of the filename
    * @param gen generation
    */
   public static String fileNameFromGeneration(String base, String ext, long gen) {
     if (gen == -1) {
       return null;
     } else if (gen == 0) {
       return segmentFileName(base, "", ext);
     } else {
       assert gen > 0;
       // The '6' part in the length is: 1 for '.', 1 for '_' and 4 as estimate
       // to the gen length as string (hopefully an upper limit so SB won't
       // expand in the middle.
       StringBuilder res =
           new StringBuilder(base.length() + 6 + ext.length())
               .append(base)
               .append('_')
               .append(Long.toString(gen, Character.MAX_RADIX));
       if (ext.length() > 0) {
         res.append('.').append(ext);
       }
       return res.toString();
     }
   }

   /**
    * Returns a file name that includes the given segment name, your own custom name and extension.
    * The format of the filename is: &lt;segmentName&gt;(_&lt;name&gt;)(.&lt;ext&gt;).
    *
    * <p><b>NOTE:</b> .&lt;ext&gt; is added to the result file name only if <code>ext</code> is not
    * empty.
    *
    * <p><b>NOTE:</b> _&lt;segmentSuffix&gt; is added to the result file name only if it's not the
    * empty string
    *
    * <p><b>NOTE:</b> all custom files should be named using this method, or otherwise some
    * structures may fail to handle them properly (such as if they are added to compound files).
    */
   public static String segmentFileName(String segmentName, String segmentSuffix, String ext) {
     if (ext.length() > 0 || segmentSuffix.length() > 0) {
       assert !ext.startsWith(".");
       StringBuilder sb =
           new StringBuilder(segmentName.length() + 2 + segmentSuffix.length() + ext.length());
       sb.append(segmentName);
       if (segmentSuffix.length() > 0) {
         sb.append('_').append(segmentSuffix);
       }
       if (ext.length() > 0) {
         sb.append('.').append(ext);
       }
       return sb.toString();
     } else {
       return segmentName;
     }
   }

   /**
    * Returns true if the given filename ends with the given extension. One should provide a
    * <i>pure</i> extension, without '.'.
    */
   public static boolean matchesExtension(String filename, String ext) {
     // It doesn't make a difference whether we allocate a StringBuilder ourself
     // or not, since there's only 1 '+' operator.
     return filename.endsWith("." + ext);
   }

   /** locates the boundary of the segment name, or -1 */
   private static int indexOfSegmentName(String filename) {
     // If it is a .del file, there's an '_' after the first character
     int idx = filename.indexOf('_', 1);
     if (idx == -1) {
       // If it's not, strip everything that's before the '.'
       idx = filename.indexOf('.');
     }
     return idx;
   }

   /**
    * Strips the segment name out of the given file name. If you used {@link #segmentFileName} or
    * {@link #fileNameFromGeneration} to create your files, then this method simply removes whatever
    * comes before the first '.', or the second '_' (excluding both).
    *
    * @return the filename with the segment name removed, or the given filename if it does not
    *     contain a '.' and '_'.
    */
   public static String stripSegmentName(String filename) {
     int idx = indexOfSegmentName(filename);
     if (idx != -1) {
       filename = filename.substring(idx);
     }
     return filename;
   }

   /** Returns the generation from this file name, or 0 if there is no generation. */
   public static long parseGeneration(String filename) {
     assert filename.startsWith("_");
     String parts[] = stripExtension(filename).substring(1).split("_");
     // 4 cases:
     // segment.ext
     // segment_gen.ext
     // segment_codec_suffix.ext
     // segment_gen_codec_suffix.ext
     if (parts.length == 2 || parts.length == 4) {
       return Long.parseLong(parts[1], Character.MAX_RADIX);
     } else {
       return 0;
     }
   }

   /**
    * Parses the segment name out of the given file name.
    *
    * @return the segment name only, or filename if it does not contain a '.' and '_'.
    */
   public static String parseSegmentName(String filename) {
     int idx = indexOfSegmentName(filename);
     if (idx != -1) {
       filename = filename.substring(0, idx);
     }
     return filename;
   }

   /**
    * Removes the extension (anything after the first '.'), otherwise returns the original filename.
    */
   public static String stripExtension(String filename) {
     int idx = filename.indexOf('.');
     if (idx != -1) {
       filename = filename.substring(0, idx);
     }
     return filename;
   }

   /**
    * Return the extension (anything after the first '.'), or null if there is no '.' in the file
    * name.
    */
   public static String getExtension(String filename) {
     final int idx = filename.indexOf('.');
     if (idx == -1) {
       return null;
     } else {
       return filename.substring(idx + 1, filename.length());
     }
   }

   /** All files created by codecs much match this pattern (checked in SegmentInfo). */
   public static final Pattern CODEC_FILE_PATTERN = Pattern.compile("_[a-z0-9]+(_.*)?\\..*");
 }
	/*
	* 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.lucene.index;

	import java.util.regex.Pattern;
	import org.apache.lucene.codecs.Codec;

	/**
	* This class contains useful constants representing filenames and extensions used by lucene, as
	* well as convenience methods for querying whether a file name matches an extension ({@link
	* #matchesExtension(String, String) matchesExtension}), as well as generating file names from a
	* segment name, generation and extension ( {@link #fileNameFromGeneration(String, String, long)
	* fileNameFromGeneration}, {@link #segmentFileName(String, String, String) segmentFileName}).
	*
	* <p><b>NOTE</b>: extensions used by codecs are not listed here. You must interact with the {@link
	* Codec} directly.
	*
	* @lucene.internal
	*/
	public final class IndexFileNames {

	/** No instance */
	private IndexFileNames() {}

	/** Name of the index segment file */
	public static final String SEGMENTS = "segments";

	/** Name of pending index segment file */
	public static final String PENDING_SEGMENTS = "pending_segments";

	/**
	* Computes the full file name from base, extension and generation. If the generation is -1, the
	* file name is null. If it's 0, the file name is <base>.<ext>. If it's > 0, the
	* file name is <base>_<gen>.<ext>.<br>
	* <b>NOTE:</b> .<ext> is added to the name only if <code>ext</code> is not an empty string.
	*
	* @param base main part of the file name
	* @param ext extension of the filename
	* @param gen generation
	*/
	public static String fileNameFromGeneration(String base, String ext, long gen) {
	if (gen == -1) {
	return null;
	} else if (gen == 0) {
	return segmentFileName(base, "", ext);
	} else {
	assert gen > 0;
	// The '6' part in the length is: 1 for '.', 1 for '_' and 4 as estimate
	// to the gen length as string (hopefully an upper limit so SB won't
	// expand in the middle.
	StringBuilder res =
	new StringBuilder(base.length() + 6 + ext.length())
	.append(base)
	.append('_')
	.append(Long.toString(gen, Character.MAX_RADIX));
	if (ext.length() > 0) {
	res.append('.').append(ext);
	}
	return res.toString();
	}
	}

	/**
	* Returns a file name that includes the given segment name, your own custom name and extension.
	* The format of the filename is: <segmentName>(_<name>)(.<ext>).
	*
	* <p><b>NOTE:</b> .<ext> is added to the result file name only if <code>ext</code> is not
	* empty.
	*
	* <p><b>NOTE:</b> _<segmentSuffix> is added to the result file name only if it's not the
	* empty string
	*
	* <p><b>NOTE:</b> all custom files should be named using this method, or otherwise some
	* structures may fail to handle them properly (such as if they are added to compound files).
	*/
	public static String segmentFileName(String segmentName, String segmentSuffix, String ext) {
	if (ext.length() > 0 \|\| segmentSuffix.length() > 0) {
	assert !ext.startsWith(".");
	StringBuilder sb =
	new StringBuilder(segmentName.length() + 2 + segmentSuffix.length() + ext.length());
	sb.append(segmentName);
	if (segmentSuffix.length() > 0) {
	sb.append('_').append(segmentSuffix);
	}
	if (ext.length() > 0) {
	sb.append('.').append(ext);
	}
	return sb.toString();
	} else {
	return segmentName;
	}
	}

	/**
	* Returns true if the given filename ends with the given extension. One should provide a
	* <i>pure</i> extension, without '.'.
	*/
	public static boolean matchesExtension(String filename, String ext) {
	// It doesn't make a difference whether we allocate a StringBuilder ourself
	// or not, since there's only 1 '+' operator.
	return filename.endsWith("." + ext);
	}

	/** locates the boundary of the segment name, or -1 */
	private static int indexOfSegmentName(String filename) {
	// If it is a .del file, there's an '_' after the first character
	int idx = filename.indexOf('_', 1);
	if (idx == -1) {
	// If it's not, strip everything that's before the '.'
	idx = filename.indexOf('.');
	}
	return idx;
	}

	/**
	* Strips the segment name out of the given file name. If you used {@link #segmentFileName} or
	* {@link #fileNameFromGeneration} to create your files, then this method simply removes whatever
	* comes before the first '.', or the second '_' (excluding both).
	*
	* @return the filename with the segment name removed, or the given filename if it does not
	* contain a '.' and '_'.
	*/
	public static String stripSegmentName(String filename) {
	int idx = indexOfSegmentName(filename);
	if (idx != -1) {
	filename = filename.substring(idx);
	}
	return filename;
	}

	/** Returns the generation from this file name, or 0 if there is no generation. */
	public static long parseGeneration(String filename) {
	assert filename.startsWith("_");
	String parts[] = stripExtension(filename).substring(1).split("_");
	// 4 cases:
	// segment.ext
	// segment_gen.ext
	// segment_codec_suffix.ext
	// segment_gen_codec_suffix.ext
	if (parts.length == 2 \|\| parts.length == 4) {
	return Long.parseLong(parts[1], Character.MAX_RADIX);
	} else {
	return 0;
	}
	}

	/**
	* Parses the segment name out of the given file name.
	*
	* @return the segment name only, or filename if it does not contain a '.' and '_'.
	*/
	public static String parseSegmentName(String filename) {
	int idx = indexOfSegmentName(filename);
	if (idx != -1) {
	filename = filename.substring(0, idx);
	}
	return filename;
	}

	/**
	* Removes the extension (anything after the first '.'), otherwise returns the original filename.
	*/
	public static String stripExtension(String filename) {
	int idx = filename.indexOf('.');
	if (idx != -1) {
	filename = filename.substring(0, idx);
	}
	return filename;
	}

	/**
	* Return the extension (anything after the first '.'), or null if there is no '.' in the file
	* name.
	*/
	public static String getExtension(String filename) {
	final int idx = filename.indexOf('.');
	if (idx == -1) {
	return null;
	} else {
	return filename.substring(idx + 1, filename.length());
	}
	}

	/** All files created by codecs much match this pattern (checked in SegmentInfo). */
	public static final Pattern CODEC_FILE_PATTERN = Pattern.compile("_[a-z0-9]+(_.)?\\..");
	}