Mega Code Archive
SimpleCalc -- simple calculator to show StringTokenizer
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/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.io.PrintWriter;
import java.io.BufferedReader;
import java.io.StringReader;
import java.io.StringWriter;
import junit.framework.TestCase;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StreamTokenizer;
import java.util.Stack;
/**
* SimpleCalc -- simple calculator to show StringTokenizer
*
* @author Ian Darwin, http://www.darwinsys.com/
* @version $Id: SimpleCalcStreamTok.java,v 1.10 2004/03/10 18:22:26 ian Exp $
*/
class SimpleCalcStreamTok {
/** The StreamTokenizer Input */
protected StreamTokenizer tf;
/** The Output File */
protected PrintWriter out = new PrintWriter(System.out, true);
/** The variable name (not used in this version) */
protected String variable;
/** The operand stack */
protected Stack s;
/* Driver - main program */
public static void main(String[] av) throws IOException {
if (av.length == 0)
new SimpleCalcStreamTok(new InputStreamReader(System.in)).doCalc();
else
for (int i = 0; i < av.length; i++)
new SimpleCalcStreamTok(av[i]).doCalc();
}
/** Construct by filename */
public SimpleCalcStreamTok(String fileName) throws IOException {
this(new FileReader(fileName));
}
/** Construct from an existing Reader */
public SimpleCalcStreamTok(Reader rdr) throws IOException {
tf = new StreamTokenizer(rdr);
// Control the input character set:
tf.slashSlashComments(true); // treat "//" as comments
tf.ordinaryChar('-'); // used for subtraction
tf.ordinaryChar('/'); // used for division
s = new Stack();
}
/**
* Construct from a Reader and a PrintWriter
*/
public SimpleCalcStreamTok(Reader in, PrintWriter out) throws IOException {
this(in);
setOutput(out);
}
/**
* Change the output destination.
*/
public void setOutput(PrintWriter out) {
this.out = out;
}
protected void doCalc() throws IOException {
int iType;
double tmp;
while ((iType = tf.nextToken()) != StreamTokenizer.TT_EOF) {
switch (iType) {
case StreamTokenizer.TT_NUMBER: // Found a number, push value to
// stack
push(tf.nval);
break;
case StreamTokenizer.TT_WORD:
// Found a variable, save its name. Not used here.
variable = tf.sval;
break;
case '+':
// + operator is commutative.
push(pop() + pop());
break;
case '-':
// - operator: order matters.
tmp = pop();
push(pop() - tmp);
break;
case '*':
// Multiply is commutative
push(pop() * pop());
break;
case '/':
// Handle division carefully: order matters!
tmp = pop();
push(pop() / tmp);
break;
case '=':
out.println(peek());
break;
default:
out.println("What's this? iType = " + iType);
}
}
}
void push(double val) {
s.push(new Double(val));
}
double pop() {
return ((Double) s.pop()).doubleValue();
}
double peek() {
return ((Double) s.peek()).doubleValue();
}
void clearStack() {
s.removeAllElements();
}
}
public class SimpleCalcTest extends TestCase {
final String TEST = "// This file is a test of the SimpleCalc class\n"
+ "2 4 + = 3 / = // should print 6, 2\n"
+ "22 7 / = // should print 3.141592857...\n";
final String EXPECT = "6.0\n" + "2.0\n" + "3.142857142857143\n";
public void testIt() throws Exception {
BufferedReader is = new BufferedReader(new StringReader(TEST));
StringWriter fluffy = new StringWriter();
PrintWriter ps = new PrintWriter(fluffy);
SimpleCalcStreamTok sc = new SimpleCalcStreamTok(is, ps);
assertEquals(EXPECT, fluffy.getBuffer().toString());
}
}
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