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using System;
using System.Runtime.InteropServices;
using TextReader = System.IO.TextReader;
using IOException = System.IO.IOException;
namespace antlr
{
/*ANTLR Translator Generator
* Project led by Terence Parr at http://www.jGuru.com
* Software rights: http://www.antlr.org/license.html
*
* $Id:$
*/
//
// ANTLR C# Code Generator by Micheal Jordan
// Kunle Odutola : kunle UNDERSCORE odutola AT hotmail DOT com
// Anthony Oguntimehin
//
// With many thanks to Eric V. Smith from the ANTLR list.
//
/*A Stream of characters fed to the lexer from a InputStream that can
* be rewound via mark()/rewind() methods.
* <p>
* A dynamic array is used to buffer up all the input characters. Normally,
* "k" characters are stored in the buffer. More characters may be stored during
* guess mode (testing syntactic predicate), or when LT(i>k) is referenced.
* Consumption of characters is deferred. In other words, reading the next
* character is not done by conume(), but deferred until needed by LA or LT.
* <p>
*/
// SAS: Move most functionality into InputBuffer -- just the file-specific
// stuff is in here
public class CharBuffer : InputBuffer
{
// char source
[NonSerialized()]
internal TextReader input;
private const int BUF_SIZE = 16;
/// <summary>
/// Small buffer used to avoid reading individual chars
/// </summary>
private char[] buf = new char[BUF_SIZE];
/*Create a character buffer */
public CharBuffer(TextReader input_) : base()
{
input = input_;
}
/*Ensure that the character buffer is sufficiently full */
override public void fill(int amount)
{
try
{
syncConsume();
// Fill the buffer sufficiently to hold needed characters
int charsToRead = (amount + markerOffset) - queue.Count;
int c;
while (charsToRead > 0)
{
// Read a few characters
c = input.Read(buf, 0, BUF_SIZE);
for (int i = 0; i < c; i++)
{
// Append the next character
queue.Add(buf[i]);
}
if (c < BUF_SIZE)
{
while ((charsToRead-- > 0) && (queue.Count < BUF_SIZE))
{
queue.Add(CharScanner.EOF_CHAR);
}
break;
}
charsToRead -= c;
}
}
catch (IOException io)
{
throw new CharStreamIOException(io);
}
}
}
}
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