SimpleCalcStreamTok.java Source code

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Here is the source code for SimpleCalcStreamTok.java

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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());
    }
}