persistence.antlr.CharBuffer Maven / Gradle / Ivy
package persistence.antlr;
/* ANTLR Translator Generator
* Project led by Terence Parr at http://www.jGuru.com
* Software rights: http://www.antlr.org/license.html
*
*/
/**A Stream of characters fed to the lexer from a InputStream that can
* be rewound via mark()/rewind() methods.
*
* 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.
*
*
* @see persistence.antlr.CharQueue
*/
import java.io.Reader; // SAS: changed to properly read text files
import java.io.IOException;
// SAS: Move most functionality into InputBuffer -- just the file-specific
// stuff is in here
public class CharBuffer extends InputBuffer {
// char source
transient Reader input;
/** Create a character buffer */
public CharBuffer(Reader input_) { // SAS: for proper text i/o
super();
input = input_;
}
/** Ensure that the character buffer is sufficiently full */
public void fill(int amount) throws CharStreamException {
try {
syncConsume();
// Fill the buffer sufficiently to hold needed characters
while (queue.nbrEntries < amount + markerOffset) {
// Append the next character
queue.append((char)input.read());
}
}
catch (IOException io) {
throw new CharStreamIOException(io);
}
}
}