Helper ForeignByte

Jan Burse, created Jan 16. 2020
package jekpro.frequent.stream;
import jekpro.reference.arithmetic.SpecialEval;
import jekpro.tools.call.InterpreterMessage;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
/**
* The foreign predicates for the module byte.
* <p/>
* Warranty & Liability
* To the extent permitted by applicable law and unless explicitly
* otherwise agreed upon, XLOG Technologies GmbH makes no warranties
* regarding the provided information. XLOG Technologies GmbH assumes
* no liability that any problems might be solved with the information
* provided by XLOG Technologies GmbH.
* <p/>
* Rights & License
* All industrial property rights regarding the information - copyright
* and patent rights in particular - are the sole property of XLOG
* Technologies GmbH. If the company was not the originator of some
* excerpts, XLOG Technologies GmbH has at least obtained the right to
* reproduce, change and translate the information.
* <p/>
* Reproduction is restricted to the whole unaltered document. Reproduction
* of the information is only allowed for non-commercial uses. Selling,
* giving away or letting of the execution of the library is prohibited.
* The library can be distributed as part of your applications and libraries
* for execution provided this comment remains unchanged.
* <p/>
* Restrictions
* Only to be distributed with programs that add significant and primary
* functionality to the library. Not to be distributed with additional
* software intended to replace any components of the library.
* <p/>
* Trademarks
* Jekejeke is a registered trademark of XLOG Technologies GmbH.
*/
public final class ForeignByte {
/****************************************************************/
/* Byte I/O */
/****************************************************************/
/**
* <p>Write a byte to a binary stream.</p>
*
* @param para The stream.
* @param val The byte.
* @throws ClassCastException Validation error.
* @throws IOException IO error.
*/
public static void sysPutByte(OutputStream para, Integer val)
throws ClassCastException, IOException {
int k = SpecialEval.castOctet(val);
para.write(k);
}
/**
* <p>Peek a byte from a binary stream.</p>
*
* @param para The stream.
* @return The peeked byte or -1.
* @throws IOException IO error.
*/
public static int sysPeekByte(InputStream para)
throws IOException {
para.mark(1);
int val;
try {
val = para.read();
} catch (IOException x) {
para.reset();
throw x;
}
para.reset();
return val;
}
/****************************************************************/
/* General Stream Operations */
/****************************************************************/
/**
* <p>Check whether stream is at end.</p>
*
* @param para The stream.
* @return True if stream is at end.
* @throws InterpreterMessage Validation error.
* @throws IOException IO error.
*/
public static boolean sysAtEndOfStream(Object para)
throws InterpreterMessage, IOException {
if (para instanceof Reader) {
Reader reader = (Reader) para;
reader.mark(1);
boolean flag;
try {
flag = (reader.read() == -1);
} catch (IOException x) {
reader.reset();
throw x;
}
reader.reset();
return flag;
} else if (para instanceof InputStream) {
InputStream is = (InputStream) para;
is.mark(1);
boolean flag;
try {
flag = (is.read() == -1);
} catch (IOException x) {
is.reset();
throw x;
}
is.reset();
return flag;
} else {
throw new InterpreterMessage(
InterpreterMessage.permissionError("input",
"stream", para));
}
}
}

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