TermBuffer.cs :  » Search-Engines » dotLucene » Lucene » Net » Index » C# / CSharp Open Source

/*
 * 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.
 */

using System;
using IndexInputLucene.Net.Store.IndexInput;

namespace Lucene.Net.Index{
  
  sealed class TermBuffer : System.ICloneable
  {
    private static readonly char[] NO_CHARS = new char[0];
    
    private System.String field;
    private char[] text = NO_CHARS;
    private int textLength;
    private Term term; // cached
    
    public int CompareTo(TermBuffer other)
    {
      if ((System.Object) field == (System.Object) other.field)
          // fields are interned
        return CompareChars(text, textLength, other.text, other.textLength);
      else
        return String.CompareOrdinal(field, other.field);
    }
    
    private static int CompareChars(char[] v1, int len1, char[] v2, int len2)
    {
      int end = System.Math.Min(len1, len2);
      for (int k = 0; k < end; k++)
      {
        char c1 = v1[k];
        char c2 = v2[k];
        if (c1 != c2)
        {
          return c1 - c2;
        }
      }
      return len1 - len2;
    }
    
    private void  SetTextLength(int newLength)
    {
      if (text.Length < newLength)
      {
        char[] newText = new char[newLength];
        Array.Copy(text, 0, newText, 0, textLength);
        text = newText;
      }
      textLength = newLength;
    }
    
    public void  Read(IndexInput input, FieldInfos fieldInfos)
    {
      this.term = null; // invalidate cache
      int start = input.ReadVInt();
      int length = input.ReadVInt();
      int totalLength = start + length;
      SetTextLength(totalLength);
      input.ReadChars(this.text, start, length);
      this.field = fieldInfos.FieldName(input.ReadVInt());
    }
    
    public void  Set(Term term)
    {
      if (term == null)
      {
        Reset();
        return ;
      }
      
      // copy text into the buffer
      SetTextLength(term.Text().Length);

            System.String sourceString = term.Text();
            int sourceEnd = term.Text().Length;
            for (int i = 0; i < sourceEnd; i++)
            {
                text[i] = (char) sourceString[i];
            }
      
      this.field = term.Field();
      this.term = term;
    }
    
    public void  Set(TermBuffer other)
    {
      SetTextLength(other.textLength);
      Array.Copy(other.text, 0, text, 0, textLength);
      
      this.field = other.field;
      this.term = other.term;
    }
    
    public void  Reset()
    {
      this.field = null;
      this.textLength = 0;
      this.term = null;
    }
    
    public Term ToTerm()
    {
      if (field == null)
          // unset
        return null;
      
      if (term == null)
        term = new Term(field, new System.String(text, 0, textLength), false);
      
      return term;
    }
    
    public System.Object Clone()
    {
      TermBuffer clone = null;
      try
      {
        clone = (TermBuffer) base.MemberwiseClone();
      }
      catch (System.Exception)
      {
      }
      
      clone.text = new char[text.Length];
      Array.Copy(text, 0, clone.text, 0, textLength);
      
      return clone;
    }
  }
}