TextReader.cs source code in C# .NET

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Code:

/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / IO / TextReader.cs / 1305376 / TextReader.cs

                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
/*============================================================
** 
** Class:  TextReader 
**
** [....] 
**
**
** Purpose: Abstract base class for all Text-only Readers.
** Subclasses will include StreamReader & StringReader. 
**
** 
===========================================================*/ 

using System; 
using System.Text;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using System.Reflection; 
using System.Security.Permissions;
using System.Diagnostics.Contracts; 
 
namespace System.IO {
    // This abstract base class represents a reader that can read a sequential 
    // stream of characters.  This is not intended for reading bytes -
    // there are methods on the Stream class to read bytes.
    // A subclass must minimally implement the Peek() and Read() methods.
    // 
    // This class is intended for character input, not bytes.
    // There are methods on the Stream class for reading bytes. 
    [Serializable] 
    [ComVisible(true)]
#if FEATURE_REMOTING 
    public abstract class TextReader : MarshalByRefObject, IDisposable {
#if false
    }
#endif // false 
#else // FEATURE_REMOTING
    public abstract class TextReader : IDisposable { 
#endif // FEATURE_REMOTING 
        public static readonly TextReader Null = new NullTextReader();
 
        protected TextReader() {}

        // Closes this TextReader and releases any system resources associated with the
        // TextReader. Following a call to Close, any operations on the TextReader 
        // may raise exceptions.
        // 
        // This default method is empty, but descendant classes can override the 
        // method to provide the appropriate functionality.
        public virtual void Close() 
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        } 

        public void Dispose() 
        { 
            Dispose(true);
            GC.SuppressFinalize(this); 
        }

        protected virtual void Dispose(bool disposing)
        { 
        }
 
        // Returns the next available character without actually reading it from 
        // the input stream. The current position of the TextReader is not changed by
        // this operation. The returned value is -1 if no further characters are 
        // available.
        //
        // This default method simply returns -1.
        // 
        [Pure]
        public virtual int Peek() 
        { 
            Contract.Ensures(Contract.Result() >= -1);
 
            return -1;
        }

        // Reads the next character from the input stream. The returned value is 
        // -1 if no further characters are available.
        // 
        // This default method simply returns -1. 
        //
        public virtual int Read() 
        {
            Contract.Ensures(Contract.Result() >= -1);
            return -1;
        } 

        // Reads a block of characters. This method will read up to 
        // count characters from this TextReader into the 
        // buffer character array starting at position
        // index. Returns the actual number of characters read. 
        //
        public virtual int Read([In, Out] char[] buffer, int index, int count)
        {
            if (buffer==null) 
                throw new ArgumentNullException("buffer", Environment.GetResourceString("ArgumentNull_Buffer"));
            if (index < 0) 
                throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum")); 
            if (count < 0)
                throw new ArgumentOutOfRangeException("count", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum")); 
            if (buffer.Length - index < count)
                throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
            Contract.Ensures(Contract.Result() >= 0);
            Contract.Ensures(Contract.Result() <= Contract.OldValue(count)); 
            Contract.EndContractBlock();
 
            int n = 0; 
            do {
                int ch = Read(); 
                if (ch == -1) break;
                buffer[index + n++] = (char)ch;
            } while (n < count);
            return n; 
        }
 
        // Reads all characters from the current position to the end of the 
        // TextReader, and returns them as one string.
        public virtual String ReadToEnd() 
        {
            Contract.Ensures(Contract.Result() != null);

            char[] chars = new char[4096]; 
            int len;
            StringBuilder sb = new StringBuilder(4096); 
            while((len=Read(chars, 0, chars.Length)) != 0) 
            {
                sb.Append(chars, 0, len); 
            }
            return sb.ToString();
        }
 
        // Blocking version of read.  Returns only when count
        // characters have been read or the end of the file was reached. 
        // 
        public virtual int ReadBlock([In, Out] char[] buffer, int index, int count)
        { 
            Contract.Ensures(Contract.Result() >= 0);
            Contract.Ensures(Contract.Result() <= count);

            int i, n = 0; 
            do {
                n += (i = Read(buffer, index + n, count - n)); 
            } while (i > 0 && n < count); 
            return n;
        } 

        // Reads a line. A line is defined as a sequence of characters followed by
        // a carriage return ('\r'), a line feed ('\n'), or a carriage return
        // immediately followed by a line feed. The resulting string does not 
        // contain the terminating carriage return and/or line feed. The returned
        // value is null if the end of the input stream has been reached. 
        // 
        public virtual String ReadLine()
        { 
            StringBuilder sb = new StringBuilder();
            while (true) {
                int ch = Read();
                if (ch == -1) break; 
                if (ch == '\r' || ch == '\n')
                { 
                    if (ch == '\r' && Peek() == '\n') Read(); 
                    return sb.ToString();
                } 
                sb.Append((char)ch);
            }
            if (sb.Length > 0) return sb.ToString();
            return null; 
        }
 
 
        [HostProtection(Synchronization=true)]
        public static TextReader Synchronized(TextReader reader) 
        {
            if (reader==null)
                throw new ArgumentNullException("reader");
            Contract.Ensures(Contract.Result() != null); 
            Contract.EndContractBlock();
 
            if (reader is SyncTextReader) 
                return reader;
 
            return new SyncTextReader(reader);
        }

        [Serializable] 
        private sealed class NullTextReader : TextReader
        { 
            public NullTextReader(){} 

            public override int Read(char[] buffer, int index, int count) 
            {
                return 0;
            }
 
            public override String ReadLine()
            { 
                return null; 
            }
        } 

        [Serializable]
        internal sealed class SyncTextReader : TextReader
        { 
            internal TextReader _in;
 
            internal SyncTextReader(TextReader t) 
            {
                _in = t; 
            }

            [MethodImplAttribute(MethodImplOptions.Synchronized)]
            public override void Close() 
            {
                // So that any overriden Close() gets run 
                _in.Close(); 
            }
 
            [MethodImplAttribute(MethodImplOptions.Synchronized)]
            protected override void Dispose(bool disposing)
            {
                // Explicitly pick up a potentially methodimpl'ed Dispose 
                if (disposing)
                    ((IDisposable)_in).Dispose(); 
            } 

            [MethodImplAttribute(MethodImplOptions.Synchronized)] 
            public override int Peek()
            {
                return _in.Peek();
            } 

            [MethodImplAttribute(MethodImplOptions.Synchronized)] 
            public override int Read() 
            {
                return _in.Read(); 
            }

            [MethodImplAttribute(MethodImplOptions.Synchronized)]
            public override int Read([In, Out] char[] buffer, int index, int count) 
            {
                return _in.Read(buffer, index, count); 
            } 

            [MethodImplAttribute(MethodImplOptions.Synchronized)] 
            public override int ReadBlock([In, Out] char[] buffer, int index, int count)
            {
                return _in.ReadBlock(buffer, index, count);
            } 

            [MethodImplAttribute(MethodImplOptions.Synchronized)] 
            public override String ReadLine() 
            {
                return _in.ReadLine(); 
            }

            [MethodImplAttribute(MethodImplOptions.Synchronized)]
            public override String ReadToEnd() 
            {
                return _in.ReadToEnd(); 
            } 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

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