TermDocs.cs

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/* 
 * 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.
 */

using System;

namespace Lucene.Net.Index
{
    /// <summary>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.
    /// </summary>
    /// <seealso cref="IndexReader.TermDocs()" />
    public interface TermDocs : IDisposable
    {
        /// <summary>Sets this to the data for a term.
        /// The enumeration is reset to the start of the data for this term.
        /// </summary>
        void  Seek(Term term);
        
        /// <summary>Sets this to the data for the current term in a <see cref="TermEnum" />.
        /// This may be optimized in some implementations.
        /// </summary>
        void  Seek(TermEnum termEnum);

        /// <summary>Returns the current document number.  <p/> This is invalid until <see cref="Next()" />
        /// is called for the first time.
        /// </summary>
        int Doc { get; }

        /// <summary>Returns the frequency of the term within the current document.  <p/> This
        /// is invalid until <see cref="Next()" /> is called for the first time.
        /// </summary>
        int Freq { get; }

        /// <summary>Moves to the next pair in the enumeration.  <p/> Returns true iff there is
        /// such a next pair in the enumeration. 
        /// </summary>
        bool Next();
        
        /// <summary>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.  
        /// </summary>
        int Read(int[] docs, int[] freqs);
        
        /// <summary>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: <code>
        /// boolean skipTo(int target) {
        ///     do {
        ///         if (!next())
        ///             return false;
        ///     } while (target > doc());
        ///         return true;
        /// }
        /// </code>
        /// Some implementations are considerably more efficient than that.
        /// </summary>
        bool SkipTo(int target);
        
        // TODO: Determine which release this will be removed from
        /// <summary>Frees associated resources. </summary>
        [Obsolete("Use Dispose() instead")]
        void  Close();
    }
}