[haiku-development] Re: DeskCalc Improvements (was need strtold() function)
- From: Stephan Assmus <superstippi@xxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Thu, 31 Dec 2009 10:01:31 +0100
Hi John,
On 2009-12-31 at 09:30:41 [+0100], John Scipione <jscipione@xxxxxxxxx>
wrote:
> > I rewrote my DeskCalc changes so that I would not be doing any char*
> > manipulation. To achieve this had to extend the ExpressionParser Class
> > with two new methods: EvaluateToStandard() and EvaluateToScientific().
> > Each of these methods takes an int32 argument to specify the number of
> > digits to grab. Trailing zeros after the decimal point are removed.
> > Please review my patch below. Should patch from the haiku/ directory.
> >
> > Index: headers/private/shared/ExpressionParser.h
> > ===================================================================
> > --- headers/private/shared/ExpressionParser.h (revision 34828)
> > +++ headers/private/shared/ExpressionParser.h (working copy)
> > @@ -45,6 +45,11 @@
> > void
> > SetSupportHexInput(bool enabled);
> >
> > BString Evaluate(const
> > char* expressionString);
> > + BString
> > EvaluateToStandard(
> > + const char* expressionString,
> > + int32 decimalPlaces);
> > + BString
> > EvaluateToScientific(const char*
> > + expressionString, int32
> > decimalPlaces);
> > int64
> > EvaluateToInt64(const char* expressionString);
> > double
> > EvaluateToDouble(const char* expressionString);
> >
> > Index: src/apps/deskcalc/CalcView.cpp
> > ===================================================================
> > --- src/apps/deskcalc/CalcView.cpp (revision 34828)
> > +++ src/apps/deskcalc/CalcView.cpp (working copy)
> > @@ -894,6 +894,9 @@
> > void
> > CalcView::Evaluate()
> > {
> > + const double STD_NOTATION_UPPER = 1e16;
> > + const double STD_NOTATION_LOWER = 1e-16;
> > +
> > BString expression = fExpressionTextView->Text();
> >
> > if (expression.Length() == 0) {
> > @@ -903,21 +906,39 @@
> >
> > _AudioFeedback(false);
> >
> > + ExpressionParser parser;
> > + double value = 0.00;
> > + BString result;
> > +
> > // evaluate expression
> > - BString value;
> > -
> > try {
> > - ExpressionParser parser;
> > - value = parser.Evaluate(expression.String());
> > + value = parser.EvaluateToDouble(expression.String());
> > } catch (ParseException e) {
> > BString error(e.message.String());
> > error << " at " << (e.position + 1);
> > - fExpressionTextView->SetText(error.String());
> > - return;
> > + // just print error
> > + result.SetTo("error");
> > + fExpressionTextView->SetExpression(result.String());
> > + return;
> > }
> >
> > + if (value == 0) {
> > + result.SetTo("0");
> > + fExpressionTextView->SetExpression(result.String());
> > + return;
> > + } else if (((value < STD_NOTATION_UPPER)
> > + && (value > STD_NOTATION_LOWER))
> > + || ((value > -STD_NOTATION_UPPER)
> > + && (value < -STD_NOTATION_LOWER))) {
> > + // Standard Notation
> > + result = parser.EvaluateToStandard(expression.String(), 16);
> > + } else {
> > + // Scientific Notation
> > + result = parser.EvaluateToScientific(expression.String(), 12);
> > + }
> > +
> > // render new result to display
> > - fExpressionTextView->SetExpression(value.String());
> > + fExpressionTextView->SetExpression(result.String());
> > }
> >
> >
> > Index: src/kits/shared/ExpressionParser.cpp
> > ===================================================================
> > --- src/kits/shared/ExpressionParser.cpp (revision 34828)
> > +++ src/kits/shared/ExpressionParser.cpp (working copy)
> > @@ -317,6 +317,14 @@
> > BString
> > ExpressionParser::Evaluate(const char* expressionString) {
> > + return EvaluateToStandard(expressionString, kMaxDecimalPlaces);
> > +}
> > +
> > +
> > +BString
> > +ExpressionParser::EvaluateToStandard(const char* expressionString,
> > + int32 decimalPlaces)
> > +{
> > fTokenizer->SetTo(expressionString);
> >
> > MAPM value = _ParseBinary();
> > @@ -327,11 +335,14 @@
> > if (value == 0)
> > return BString("0");
> >
> > - char* buffer = value.toFixPtStringExp(kMaxDecimalPlaces, '.',
> > 0, 0);
> > + if (decimalPlaces <= 0)
> > + decimalPlaces = kMaxDecimalPlaces;
> > +
> > + char* buffer = value.toFixPtStringExp(decimalPlaces, '.', 0, 0);
> > if (buffer == NULL)
> > throw ParseException("out of memory", 0);
> >
> > - // remove surplus zeros
> > + // remove trailing decimal zeros
> > int32 lastChar = strlen(buffer) - 1;
> > if (strchr(buffer, '.')) {
> > while (buffer[lastChar] == '0')
> > @@ -343,6 +354,50 @@
> > BString result(buffer, lastChar + 1);
> > free(buffer);
> > return result;
> > +}
> > +
> > +
> > +BString
> > +ExpressionParser::EvaluateToScientific(const char* expressionString,
> > + int32 decimalPlaces)
> > +{
> > + fTokenizer->SetTo(expressionString);
> > +
> > + MAPM value = _ParseBinary();
> > + Token token = fTokenizer->NextToken();
> > + if (token.type != TOKEN_END_OF_LINE)
> > + throw ParseException("parse error", token.position);
> > +
> > + if (value == 0)
> > + return BString("0");
> > +
> > + if (decimalPlaces <= 0)
> > + decimalPlaces = kMaxDecimalPlaces;
> > +
> > + // max number of characters possible for 32 bits of decimal places
> > is
> > + // decimal places + 15 for -0.9999999....E+2147483647
> > + // 3 + decimal digits + 2 + 10 = decimalPlaces + 15
> > + char buffer[decimalPlaces + 15];
> > + value.toString(buffer, decimalPlaces);
> > + if (buffer == NULL)
> > + throw ParseException("out of memory", 0);
"buffer" is stack allocated, the allocation check should be "copy&paste
left-over". :-)
> > +
> > + BString result(buffer, decimalPlaces + 15);
> > +
> > + // remove trailing decimal zeros
> > + if (result.FindFirst('.') != B_ERROR) {
> > + int32 offset = result.FindLast('E');
> > + if (offset != B_ERROR) {
> > + offset--; // go to character before 'E'
> > + while(result[offset] == '0') {
> > + result = result.Remove(offset, sizeof(char));
> > + offset--;
> > + }
> > + if(result[offset] == '.')
> > + result = result.Remove(offset, sizeof(char));
> > + }
> > + }
> > + return result;
> > }
> >
>
> Minor bug in patch:
> if (decimalPlaces <= 0)
> decimalPlaces = kMaxDecimalPlaces;
> should read:
> if (decimalPlaces < 0)
> decimalPlaces = kMaxDecimalPlaces;
>
> Not worth posting another patch, but 0 decimal places is valid.
Thanks for your work! Can you post another version where you use spaces
instead of tabs? (Maybe it's just an editor setting?)
Best regards,
-Stephan
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