/* * Copyright 2005 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; namespace Lucene.Net.Store { /// Abstract base class for input from a file in a {@link Directory}. A /// random-access input stream. Used for all Lucene index input operations. /// /// /// public abstract class IndexInput : System.ICloneable { private char[] chars; // used by readString() /// Reads and returns a single byte. /// /// public abstract byte ReadByte(); /// Reads a specified number of bytes into an array at the specified offset. /// the array to read bytes into /// /// the offset in the array to start storing bytes /// /// the number of bytes to read /// /// /// public abstract void ReadBytes(byte[] b, int offset, int len); /// Reads four bytes and returns an int. /// /// public virtual int ReadInt() { return ((ReadByte() & 0xFF) << 24) | ((ReadByte() & 0xFF) << 16) | ((ReadByte() & 0xFF) << 8) | (ReadByte() & 0xFF); } /// Reads an int stored in variable-length format. Reads between one and /// five bytes. Smaller values take fewer bytes. Negative numbers are not /// supported. /// /// /// public virtual int ReadVInt() { byte b = ReadByte(); int i = b & 0x7F; for (int shift = 7; (b & 0x80) != 0; shift += 7) { b = ReadByte(); i |= (b & 0x7F) << shift; } return i; } /// Reads eight bytes and returns a long. /// /// public virtual long ReadLong() { return (((long) ReadInt()) << 32) | (ReadInt() & 0xFFFFFFFFL); } /// Reads a long stored in variable-length format. Reads between one and /// nine bytes. Smaller values take fewer bytes. Negative numbers are not /// supported. /// public virtual long ReadVLong() { byte b = ReadByte(); long i = b & 0x7F; for (int shift = 7; (b & 0x80) != 0; shift += 7) { b = ReadByte(); i |= (b & 0x7FL) << shift; } return i; } /// Reads a string. /// /// public virtual System.String ReadString() { int length = ReadVInt(); if (chars == null || length > chars.Length) chars = new char[length]; ReadChars(chars, 0, length); return new System.String(chars, 0, length); } /// Reads UTF-8 encoded characters into an array. /// the array to read characters into /// /// the offset in the array to start storing characters /// /// the number of characters to read /// /// /// public virtual void ReadChars(char[] buffer, int start, int length) { int end = start + length; for (int i = start; i < end; i++) { byte b = ReadByte(); if ((b & 0x80) == 0) buffer[i] = (char) (b & 0x7F); else if ((b & 0xE0) != 0xE0) { buffer[i] = (char) (((b & 0x1F) << 6) | (ReadByte() & 0x3F)); } else buffer[i] = (char) (((b & 0x0F) << 12) | ((ReadByte() & 0x3F) << 6) | (ReadByte() & 0x3F)); } } /// Closes the stream to futher operations. public abstract void Close(); /// Returns the current position in this file, where the next read will /// occur. /// /// /// public abstract long GetFilePointer(); /// Sets current position in this file, where the next read will occur. /// /// public abstract void Seek(long pos); /// The number of bytes in the file. public abstract long Length(); /// Returns a clone of this stream. /// ///

Clones of a stream access the same data, and are positioned at the same /// point as the stream they were cloned from. /// ///

Expert: Subclasses must ensure that clones may be positioned at /// different points in the input from each other and from the stream they /// were cloned from. ///

public virtual System.Object Clone() { IndexInput clone = null; try { clone = (IndexInput) base.MemberwiseClone(); } catch (System.Exception) { } clone.chars = null; return clone; } } }