package org.apache.lucene.index;/** * Copyright 2004 The Apache Software Foundation * * 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. */import java.io.IOException;/** TermDocs provides an interface for enumerating &lt;document, frequency&gt; pairs for a term.  <p> The document portion names each document containing the term.  Documents are indicated by number.  The frequency portion gives the number of times the term occurred in each document.  <p> The pairs are ordered by document number. @see IndexReader#termDocs() */public interface TermDocs {  /** Sets this to the data for a term.   * The enumeration is reset to the start of the data for this term.   */  void seek(Term term) throws IOException;  /** Sets this to the data for the current term in a {@link TermEnum}.   * This may be optimized in some implementations.   */  void seek(TermEnum termEnum) throws IOException;  /** Returns the current document number.  <p> This is invalid until {@link   #next()} is called for the first time.*/  int doc();  /** Returns the frequency of the term within the current document.  <p> This   is invalid until {@link #next()} is called for the first time.*/  int freq();  /** Moves to the next pair in the enumeration.  <p> Returns true iff there is   such a next pair in the enumeration. */  boolean next() throws IOException;  /** Attempts to read multiple entries from the enumeration, up to length of   * <i>docs</i>.  Document numbers are stored in <i>docs</i>, and term   * frequencies are stored in <i>freqs</i>.  The <i>freqs</i> array must be as   * long as the <i>docs</i> array.   *   * <p>Returns the number of entries read.  Zero is only returned when the   * stream has been exhausted.  */  int read(int[] docs, int[] freqs) throws IOException;  /** Skips entries to the first beyond the current whose document number is   * greater than or equal to <i>target</i>. <p>Returns true iff there is such   * an entry.  <p>Behaves as if written: <pre>   *   boolean skipTo(int target) {   *     do {   *       if (!next())   * 	     return false;   *     } while (target > doc());   *     return true;   *   }   * </pre>   * Some implementations are considerably more efficient than that.   */  boolean skipTo(int target) throws IOException;  /** Frees associated resources. */  void close() throws IOException;}