src/PlatformSupport/DoubleSupport.hpp

/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, International
 * Business Machines, Inc., http://www.ibm.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
#if !defined(DOUBLESUPPORT_HEADER_GUARD_1357924680)
#define DOUBLESUPPORT_HEADER_GUARD_1357924680



// Base include file.  Must be first.
#include <PlatformSupport/PlatformSupportDefinitions.hpp>



#include <functional>



#include <XalanDOM/XalanDOMString.hpp>



// A class to help us support IEEE 754.
class XALAN_PLATFORMSUPPORT_EXPORT DoubleSupport
{
public:

	// Use these functions to determine if a value represents one of these
	// values.  It seems that under some architectures, NaN will compare
	// as equal to any number, which is a big problem.  Hence these helper
	// functions.

	/**
	 * Determine if target is not a number
	 * 
	 * @param theNumber target number
	 * @return true if target represents the "not a number" value
	 */
	static bool
	isNaN(double	theNumber)
	{
		// Compare the two DWORDs of the double as unsigned longs.
		const DWORDPointerType	theFirstDWORD =
#if defined(XALAN_OLD_STYLE_CASTS)
			(DWORDPointerType)&theNumber;
#else
			reinterpret_cast<DWORDPointerType>(&theNumber);
#endif

		const UnalignedDWORDPointerType		theSecondDWORD =
							theFirstDWORD + 1;

		return *theFirstDWORD == *s_NaNFirstDWORD &&
			   *theSecondDWORD == *s_NaNSecondDWORD;
	}

	/**
	 * Determine if target is positive infinity
	 * 
	 * @param theNumber target number
	 * @return true if target represents the value for positive infinity
	 */
	static bool
	isPositiveInfinity(double	theNumber)
	{
		return !isNaN(theNumber) && theNumber == s_positiveInfinity;
	}

	/**
	 * Determine if target is negative infinity
	 * 
	 * @param theNumber target number
	 * @return true if target represents the value for negative infinity
	 */
	static bool
	isNegativeInfinity(double	theNumber)
	{
		return !isNaN(theNumber) && theNumber == s_negativeInfinity;
	}

	/**
	 * Determine if target is positive 0.
	 * 
	 * @param theNumber target number
	 * @return true if target represents the value for positive 0.
	 */
	static bool
	isPositiveZero(double	theNumber)
	{
		// Compare the two DWORDs of the double as unsigned longs.
		const DWORDPointerType	theFirstDWORD =
#if defined(XALAN_OLD_STYLE_CASTS)
			(DWORDPointerType)&theNumber;
#else
			reinterpret_cast<DWORDPointerType>(&theNumber);
#endif

		const UnalignedDWORDPointerType		theSecondDWORD =
							theFirstDWORD + 1;

		return *theFirstDWORD == *s_positiveZeroFirstDWORD &&
			   *theSecondDWORD == *s_positiveZeroSecondDWORD;
	}

	/**
	 * Determine if target is negative 0
	 * 
	 * @param theNumber target number
	 * @return true if target represents the value for negative 0
	 */
	static bool
	isNegativeZero(double	theNumber)
	{
		// Compare the two DWORDs of the double as unsigned longs.
		const DWORDPointerType	theFirstDWORD =
#if defined(XALAN_OLD_STYLE_CASTS)
			(DWORDPointerType)&theNumber;
#else
			reinterpret_cast<DWORDPointerType>(&theNumber);
#endif

		const UnalignedDWORDPointerType		theSecondDWORD =
							theFirstDWORD + 1;

		return *theFirstDWORD == *s_negativeZeroFirstDWORD &&
			   *theSecondDWORD == *s_negativeZeroSecondDWORD;
	}

	// These can be used to initialize values, but should not
	// be used to do equality comparisons, as == may fail on
	// some platforms.
	//

	/**
	 * Double value that represents "not a number"
	 * 
	 * @return "not a number" value
	 */
	static double
	getNaN()
	{
		return s_NaN;
	}

	/**
	 * Double value that represents positive infinity
	 * 
	 * @return positive infinity value
	 */
	static double
	getPositiveInfinity()
	{
		return s_positiveInfinity;
	}

	/**
	 * Double value that represents negative infinity
	 * 
	 * @return negative infinity value
	 */
	static double
	getNegativeInfinity()
	{
		return s_negativeInfinity;
	}

	/**
	 * Compare two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to compare
	 * @param theRHS a number to compare
	 * @return the result of the compare
	 */
	static bool
	equal(
			double	theLHS,
			double	theRHS);

	/**
	 * Compare two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to compare
	 * @param theRHS a number to compare
	 * @return the result of the compare
	 */
	static bool
	notEqual(
			double	theLHS,
			double	theRHS);

	/**
	 * Compare two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to compare
	 * @param theRHS a number to compare
	 * @return the result of the compare
	 */
	static bool
	lessThan(
			double	theLHS,
			double	theRHS);

	/**
	 * Compare two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to compare
	 * @param theRHS a number to compare
	 * @return the result of the compare
	 */
	static bool
	lessThanOrEqual(
			double	theLHS,
			double	theRHS);

	/**
	 * Compare two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to compare
	 * @param theRHS a number to compare
	 * @return the result of the compare
	 */
	static bool
	greaterThan(
			double	theLHS,
			double	theRHS);

	/**
	 * Compare two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to compare
	 * @param theRHS a number to compare
	 * @return the result of the compare
	 */
	static bool
	greaterThanOrEqual(
			double	theLHS,
			double	theRHS);

	/**
	 * Add two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to add
	 * @param theRHS a number to add
	 * @return the result of the addition
	 */
	static double
	add(
			double	theLHS,
			double	theRHS);

	/**
	 * Subtract two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to subtract
	 * @param theRHS a number to subtract
	 * @return the result of the subtraction
	 */
	static double
	subtract(
			double	theLHS,
			double	theRHS);

	/**
	 * Multiply two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to multiply
	 * @param theRHS a number to multiply
	 * @return the result of the multiplication
	 */
	static double
	multiply(
			double	theLHS,
			double	theRHS);

	/**
	 * Divide two double values, taking into account
	 * the fact that we must support IEEE 754
	 *
	 * @param theLHS a number to divide
	 * @param theRHS a number to divide
	 * @return the result of the division
	 */
	static double
	divide(
			double	theLHS,
			double	theRHS);

	/**
	 * Determine the modulus two double values,
	 * taking into account the fact that we must
	 * support IEEE 754
	 *
	 * @param theLHS a number to divide
	 * @param theRHS a number to divide
	 * @return the result of the modulus
	 */
	static double
	modulus(
			double	theLHS,
			double	theRHS);

	/**
	 * Determine the negative of a double value,
	 * taking into account the fact that we must
	 * support IEEE 754
	 *
	 * @param theDouble a number to negate
	 * @return the result of the negation
	 */
	static double
	negative(double	theDouble);

	// Some functors to do the same thing.  This is for
	// STL integration...
	#if defined(XALAN_NO_NAMESPACES)
	struct equalFunction : public binary_function<const double&, const double&, bool>
	#else
	struct equalFunction : public std::binary_function<const double&, const double&, bool>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return equal(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct notEqualFunction : public binary_function<const double&, const double&, bool>
	#else
	struct notEqualFunction : public std::binary_function<const double&, const double&, bool>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return notEqual(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct lessThanFunction : public binary_function<const double&, const double&, bool>
	#else
	struct lessThanFunction : public std::binary_function<const double&, const double&, bool>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return lessThan(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct lessThanOrEqualFunction : public binary_function<const double&, const double&, bool>
	#else
	struct lessThanOrEqualFunction : public std::binary_function<const double&, const double&, bool>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return lessThanOrEqual(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct greaterThanFunction : public binary_function<const double&, const double&, bool>
	#else
	struct greaterThanFunction : public std::binary_function<const double&, const double&, bool>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return greaterThan(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct greaterThanOrEqualFunction : public binary_function<const double&, const double&, bool>
	#else
	struct greaterThanOrEqualFunction : public std::binary_function<const double&, const double&, bool>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return greaterThanOrEqual(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct addFunction : public binary_function<const double&, const double&, double>
	#else
	struct addFunction : public std::binary_function<const double&, const double&, double>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return add(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct subtractFunction : public binary_function<const double&, const double&, double>
	#else
	struct subtractFunction : public std::binary_function<const double&, const double&, double>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return subtract(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct multiplyFunction : public binary_function<const double&, const double&, double>
	#else
	struct multiplyFunction : public std::binary_function<const double&, const double&, double>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return multiply(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct divideFunction : public binary_function<const double&, const double&, double>
	#else
	struct divideFunction : public std::binary_function<const double&, const double&, double>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return divide(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct modulusFunction : public binary_function<const double&, const double&, double>
	#else
	struct modulusFunction : public std::binary_function<const double&, const double&, double>
	#endif
	{
		result_type
		operator()(
			first_argument_type		theLHS,
			second_argument_type	theRHS) const
		{
			return modulus(theLHS, theRHS);
		}
	};

	#if defined(XALAN_NO_NAMESPACES)
	struct negativeFunction : public unary_function<const double&, double>
	#else
	struct negativeFunction : public std::unary_function<const double&, double>
	#endif
	{
		result_type
		operator()(argument_type	theDouble) const
		{
			return negative(theDouble);
		}
	};

	/**
	 * Determine whether or not a string contains
	 * a valid floating point number.
	 *
	 * @param theString The string to check.
	 * @return true if the string is valid, false if not.
	 */
	static bool
	isValid(const XalanDOMString	theString);

	/**
	 * Determine whether or not a string contains
	 * a valid floating point number.
	 *
	 * @param theString The string to check.
	 * @return true if the string is valid, false if not.
	 */
	static bool
	isValid(const XalanDOMChar*		theString);

	/**
	 * Convert a string to a double value.  Returns
	 * NaN if the string is not a valid floating
	 * point number.
	 *
	 * @param theString The string to convert.
	 * @return The result of the conversion
	 */
	static double
	toDouble(const XalanDOMString&	theString);

	/**
	 * Convert a string to a double value.  Returns
	 * NaN if the string is not a valid floating
	 * point number.
	 *
	 * @param theString The string to convert.
	 * @return The result of the conversion
	 */
	static double
	toDouble(const XalanDOMChar*	theString);

	/**
	 * Round a number according to the XPath
	 * rules.
	 *
	 * @param theValue The value to round.
	 * @return The result of the rounding
	 */
	static double
	round(double	theValue);

	typedef const unsigned int*						DWORDPointerType;
	typedef XALAN_UNALIGNED const unsigned int*		UnalignedDWORDPointerType;

private:

	static const double			s_NaN;
	static const double			s_positiveInfinity;
	static const double			s_negativeInfinity;
	static const double			s_positiveZero;
	static const double			s_negativeZero;

	static const DWORDPointerType			s_NaNFirstDWORD;
	static const UnalignedDWORDPointerType	s_NaNSecondDWORD;

	static const DWORDPointerType			s_positiveZeroFirstDWORD;
	static const UnalignedDWORDPointerType	s_positiveZeroSecondDWORD;

	static const DWORDPointerType			s_negativeZeroFirstDWORD;
	static const UnalignedDWORDPointerType	s_negativeZeroSecondDWORD;
};



#endif	// DOUBLESUPPORT_HEADER_GUARD_1357924680