Helfer ForeignMemory

Jan Burse, erstellt 20. Apr 2019
package jekdev.reference.system;
import jekpro.frequent.stream.ForeignStream;
import jekpro.model.pretty.Foyer;
import jekpro.tools.call.InterpreterMessage;
import jekpro.tools.term.Knowledgebase;
import jekpro.tools.term.TermCompound;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.StringReader;
import java.io.StringWriter;
/**
* The foreign predicates for the module memory.
* <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 ForeignMemory {
public static final int MASK_OPEN_BINR = 0x00000001;
/**
* <p>Open a memory read stream.
*
* @param data The initial data.
* @param opt The open options.
* @throws InterpreterMessage Validation error.
*/
public static Object sysMemoryRead(Object data, Object opt)
throws InterpreterMessage {
int flags = decodeOpenOptions(opt);
if ((flags & MASK_OPEN_BINR) != 0) {
byte[] buf;
if (data instanceof byte[]) {
buf = (byte[]) data;
} else {
InterpreterMessage.checkInstantiated(data);
throw new InterpreterMessage(InterpreterMessage.typeError("bytes", data));
}
return new ByteArrayInputStream(buf);
} else {
String str = InterpreterMessage.castString(data);
return new StringReader(str);
}
}
/**
* <p>Create a memory write stream.</p>
*
* @param opt The options.
* @return The memory write stream.
* @throws InterpreterMessage Validation error.
*/
public static Object sysMemoryWrite(Object opt)
throws InterpreterMessage {
int flags = decodeOpenOptions(opt);
if ((flags & MASK_OPEN_BINR) != 0) {
return new ByteArrayOutputStream();
} else {
return new StringWriter();
}
}
/**
* <p>Retrieve the data of the stream.</p>
*
* @param str The stream.
* @throws InterpreterMessage Validation error.
* @throws InterpreterMessage Shit happens.
*/
public static Object sysMemoryGet(Object str)
throws InterpreterMessage {
if (str instanceof StringWriter) {
return str.toString();
} else if (str instanceof ByteArrayOutputStream) {
return ((ByteArrayOutputStream) str).toByteArray();
} else {
throw new InterpreterMessage(
InterpreterMessage.domainError("stream", str));
}
}
/**
* <p>Decode the memory options.</p>
*
* @param opt The memory options term.
* @throws InterpreterMessage Validation error.
*/
private static int decodeOpenOptions(Object opt)
throws InterpreterMessage {
int flags = 0;
while (opt instanceof TermCompound &&
((TermCompound) opt).getArity() == 2 &&
((TermCompound) opt).getFunctor().equals(
Knowledgebase.OP_CONS)) {
Object temp = ((TermCompound) opt).getArg(0);
if (temp instanceof TermCompound &&
((TermCompound) temp).getArity() == 1 &&
((TermCompound) temp).getFunctor().equals(ForeignStream.OP_TYPE)) {
Object help = ((TermCompound) temp).getArg(0);
switch (ForeignStream.atomToType(help)) {
case ForeignStream.TYPE_BINARY:
flags |= MASK_OPEN_BINR;
break;
case ForeignStream.TYPE_TEXT:
flags &= ~MASK_OPEN_BINR;
break;
default:
throw new InterpreterMessage(InterpreterMessage.domainError(
InterpreterMessage.OP_DOMAIN_FLAG_VALUE, help));
}
} else {
InterpreterMessage.checkInstantiated(temp);
throw new InterpreterMessage(InterpreterMessage.domainError(
ForeignStream.OP_OPEN_OPTION, temp));
}
opt = ((TermCompound) opt).getArg(1);
}
if (opt.equals(Foyer.OP_NIL)) {
/* */
} else {
InterpreterMessage.checkInstantiated(opt);
throw new InterpreterMessage(InterpreterMessage.typeError(
InterpreterMessage.OP_TYPE_LIST, opt));
}
return flags;
}
}

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