org.antlr.runtime.ANTLRReaderStream Maven / Gradle / Ivy
package org.antlr.runtime;
import java.io.*;
/** Vacuum all input from a Reader and then treat it like a StringStream.
* Manage the buffer manually to avoid unnecessary data copying.
*
* If you need encoding, use ANTLRInputStream.
*/
public class ANTLRReaderStream extends ANTLRStringStream {
public static final int READ_BUFFER_SIZE = 1024;
public static final int INITIAL_BUFFER_SIZE = 1024;
public ANTLRReaderStream() {
}
public ANTLRReaderStream(Reader r) throws IOException {
this(r, INITIAL_BUFFER_SIZE, READ_BUFFER_SIZE);
}
public ANTLRReaderStream(Reader r, int size) throws IOException {
this(r, size, READ_BUFFER_SIZE);
}
public ANTLRReaderStream(Reader r, int size, int readChunkSize) throws IOException {
load(r, size, readChunkSize);
}
public void load(Reader r, int size, int readChunkSize)
throws IOException
{
if ( r==null ) {
return;
}
if ( size<=0 ) {
size = INITIAL_BUFFER_SIZE;
}
if ( readChunkSize<=0 ) {
size = READ_BUFFER_SIZE;
}
// System.out.println("load "+size+" in chunks of "+readChunkSize);
try {
// alloc initial buffer size.
data = new char[size];
// read all the data in chunks of readChunkSize
int numRead=0;
int p = 0;
do {
if ( p+readChunkSize > data.length ) { // overflow?
// System.out.println("### overflow p="+p+", data.length="+data.length);
char[] newdata = new char[data.length*2]; // resize
System.arraycopy(data, 0, newdata, 0, data.length);
data = newdata;
}
numRead = r.read(data, p, readChunkSize);
// System.out.println("read "+numRead+" chars; p was "+p+" is now "+(p+numRead));
p += numRead;
} while (numRead!=-1); // while not EOF
// set the actual size of the data available;
// EOF subtracted one above in p+=numRead; add one back
super.n = p+1;
//System.out.println("n="+n);
}
finally {
r.close();
}
}
}