fractiondata.cpp

嵌入式Qt下的一个计算器源码

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** Copyright (C) 2000-2006 TROLLTECH ASA. All rights reserved.
**
** This file is part of the Phone Edition of the Qtopia Toolkit.
**
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** authorized distributors may use this file in accordance with
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**   information about Trolltech's Commercial License Agreements.
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** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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****************************************************************************/
#ifdef ENABLE_FRACTION
#include <qstring.h>

#include "fractiondata.h"
#include "engine.h"

// Data type functions
bool FractionData::push(char c, bool commit) {
    if (formattedOutput.length() > 15)
	return false;
    if ( numerator == 0 && c == '0' )
        return !edited;
    if (edited && numerator == 0)
        edited = false;
    
    if (!edited) {
        numerator = 0;
        nString.truncate(0);
        dString.truncate(0);
        if (commit)
            edited = true;
            dEdited = false;
    }
        
    if (c == '/') {
	if (dEdited) 
	    return false;
	if (commit) {
            if (numerator == 0){
                numerator = 1;
                nString.setNum(1);
            }
	    denominator = 0;
	    dEdited = true;
            edited = true;
            dString.truncate(0);
	    buildFormattedString();
	}
	return true;
    }

    // append char and test result
    bool ok = false;
    QString tmpString;
    qlonglong num;
    if (dEdited) {
	tmpString = dString;
	tmpString.append(QChar(c));
	num = tmpString.toLongLong(&ok);
	if (ok && commit) {
	    dString = tmpString;
	    denominator = num;
	}
    } else {
	tmpString = nString;
	tmpString.append(QChar(c));
	num = tmpString.toLongLong(&ok);
	if (ok && commit) {
	    nString = tmpString;
	    numerator = num;
            edited = true;
	}
    }
    if (ok && commit)
	buildFormattedString();
    return ok;
}
// puts dString and nString together
void FractionData::buildFormattedString() {
    formattedOutput.truncate(0);
    if (denominator < 0) {
	numerator = 0 - numerator;
	nString.truncate(0);
	nString.setNum(numerator);
	denominator = 0 - denominator;
	dString.truncate(0);
	dString.setNum(denominator);
	buildFormattedString();
	return;
    }

    formattedOutput.append(nString);
    
    if (dEdited && denominator != 1) {
	formattedOutput.append(QChar('/'));
	if (denominator) 
	    formattedOutput.append(dString);
    }
    if (!formattedOutput.length())
	formattedOutput.append(QChar('0'));
}
bool FractionData::del() {
    if (!edited)
        return true;

    if (dEdited) {
	if (dString.length())  {
	    dString.truncate(dString.length()-1);
            bool ok = true;
	    denominator=dString.toLongLong(&ok);
            if (!ok) {
                denominator = 1;
                dEdited = false;
            }
	} else {
	    dEdited = false;
	}
    } else {
        if (formattedOutput.length() == 1 || 
                (formattedOutput.length() == 2) && formattedOutput[0] == '-') {
            nString.truncate(0);
            nString.append("0");
            edited = false;
            numerator = 0;
            return true;
        } else 
	    nString.truncate(nString.length()-1);
            numerator = numerator / 10;
    }

    buildFormattedString();
    return false;
}
void FractionData::clear() {
    edited = false;
    dEdited = false;
    nString.truncate(0);
    dString.truncate(0);
    formattedOutput.truncate(0);
    formattedOutput.append("0");
    numerator = 0;
    denominator = 1;
    buildFormattedString();
}

void FractionData::set(qlonglong n,qlonglong d) {
    clear();
    if (!d)
	d = 1;
    qlonglong GCM = findGCM(n,d);
    numerator = n / GCM;
    denominator = d / GCM;
    if (d == 1) 
	dEdited = false;
    else
	dEdited = true;
    nString.setNum(numerator);
    dString.setNum(denominator);
    buildFormattedString();
}
// find greatest common d
qlonglong FractionData::doFindGCM ( qlonglong a, qlonglong b ) {
    qlonglong remainder = b % a;
    if ( remainder )
	return doFindGCM( remainder,a);
    return a;
}

// wrapper that makes sure that a and b
// are the right way round
qlonglong FractionData::findGCM ( qlonglong a, qlonglong b ) {
    if ( a == b )
	return a;
    if ( a > b )
	return doFindGCM ( a, b );
    else
	return doFindGCM ( b, a );
}

#endif //ENABLE_FRACTION