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/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This file is part of the Java Expressions Library (JEL).
* For more information about JEL visit : http://fti.dn.ua/JEL/
*
* Copyright (C) 1998, 1999, 2000, 2001, 2003, 2006, 2007, 2009 Konstantin L. Metlov
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import gnu.jel.Evaluator;
import gnu.jel.CompiledExpression;
import gnu.jel.Library;
import gnu.jel.CompilationException;
public class Calculator {
static final String[] help=
{" This is a simple calculator, based on JEL.",
"",
" to use this calculator issue the following command :",
" java Calculator \"expression\"",
"",
"Don't forget to use quotes around the expression if Your shell requires",
" it. For example \"1&3\" will fail in WinNT cmd without quotes.",
" The expression language is intuitively simple. You can use binary ",
" operations : '+','-','*','/','%'(remainder),'&'(bitwise and),",
" '|'(bitwise or), '^'(bitwise xor) , unary negation '-'. Also all ",
" standard static functions of java.lang.Math are at Your disposal.",
"Examples of expressions : \"1+1\", \"sin(1)\", \"random()\" .",
"",
"Of course the use of the compiler (what JEL is actually is) is crazy for ",
"calculating expressions only once. This has a HUGE performance loss, but,",
"this is just the demo. Enjoy !!!",
"",
"(c) 2009 by Konstantin L. Metlov (metlov@fti.dn.ua)",
" This program is the free software and was distributed to You under",
" terms of GNU General Public License. You should have the text of the",
" license together with the source code of this sample and JEL itself.",
" If You don't have the source code or license- contact me immediately."
};
public static void main(String[] args) {
if (args.length==0) {
for(int i=0;i<help.length;i++)
System.err.println(help[i]);
return;
};
// Assemble the expression
StringBuffer expr_sb=new StringBuffer();
for(int i=0;i<args.length;i++) {
expr_sb.append(args[i]);
expr_sb.append(' ');
};
String expr=expr_sb.toString();
// Set up library
Class<?>[] staticLib=new Class<?>[1];
try {
staticLib[0]=Class.forName("java.lang.Math");
} catch(ClassNotFoundException e) {
// Can't be ;)) ...... in java ... ;)
};
Library lib=new Library(staticLib,null,null,null,null);
try {
lib.markStateDependent("random",null);
} catch (CompilationException e) {
// Can't be also
};
// Compile
CompiledExpression expr_c=null;
try {
expr_c=Evaluator.compile(expr,lib);
} catch (CompilationException ce) {
System.err.print("--- COMPILATION ERROR :");
System.err.println(ce.getMessage());
System.err.print(" ");
System.err.println(expr);
int column=ce.getColumn(); // Column, where error was found
for(int i=0;i<column+23-1;i++) System.err.print(' ');
System.err.println('^');
};
if (expr_c !=null) {
// Evaluate (Can do it now any number of times FAST !!!)
Object result=null;
try {
result=expr_c.evaluate(null);
} catch (Throwable e) {
System.err.println("Exception emerged from JEL compiled"+
" code (IT'S OK) :");
System.err.print(e);
};
// Print result
if (result==null)
System.out.println("void");
else
System.out.println(result.toString());
};
// Done
};
};
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