NumberFormatting.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
//
// This software owned by Onix Solutions Limited [OnixS] and is 
// protected by copyright law and international copyright treaties.
//
// Access to and use of the software is governed by the terms of the applicable 
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// agreements granting a non-assignable, non-transferable and non-exclusive license 
// to use the software for it's own data processing purposes under the terms defined 
// in the Agreement.
//
// Except as otherwise granted within the terms of the Agreement, copying or 
// reproduction of any part of this source code or associated reference material 
// to any other location for further reproduction or redistribution, and any 
// amendments to this copyright notice, are expressly prohibited.
//
// Any reproduction or redistribution for sale or hiring of the Software not in 
// accordance with the terms of the Agreement is a violation of copyright law.
//

#pragma once

#include <limits>

#include <boost/type_traits.hpp>

#include <OnixS/SgxTitan/Trading/OUCH/String.h>
#include <OnixS/SgxTitan/Trading/OUCH/Integral.h>


ONIXS_SGXTITAN_OUCH_NAMESPACE_BEGIN
                //

                template
                    <
                    typename Integer
                    >
                    inline
                    typename
                    boost::enable_if
                    <
                    boost::is_signed<Integer>,
                    bool
                    >::
                    type
                    isNegative(
                        Integer& integer)
                {
                    return (0 > integer);
                }

                template
                    <
                    typename Integer
                    >
                    inline
                    typename
                    boost::enable_if
                    <
                    boost::is_unsigned<Integer>,
                    bool
                    >::
                    type
                    isNegative(
                        Integer&)
                {
                    return false;
                }

                //

                inline
                void
                addNegativeSign(
                        std::string& str)
                {
                    const Char Minus = '-';

                    str += Minus;
                }

                template
                        <
                                typename Integer
                        >
                inline
                typename
                boost::enable_if
                        <
                                boost::is_signed<Integer>
                        >::
                type
                addNegativeSign(
                        std::string& str,
                        Integer integer)
                {
                    if (0 > integer)
                        addNegativeSign(str);
                }

                template
                        <
                                typename Integer
                        >
                inline
                typename
                boost::enable_if
                        <
                                boost::is_unsigned<Integer>
                        >::
                type
                addNegativeSign(
                        std::string&,
                        Integer)
                {
                }

                //


                template
                    <
                    typename Integer
                    >
                    inline
                    typename
                    boost::enable_if
                    <
                    boost::is_integral<Integer>,
                    size_t
                    >::
                    type
                    countDigits(
                        Integer integer)
                {
                    size_t qty = 0;

                    do
                    {
                        ++qty;

                        integer /= 10;
                    } while (integer);

                    return qty;
                }

                template
                    <
                    typename Integer
                    >
                    typename
                    boost::enable_if
                    <
                    boost::is_integral<Integer>,
                    size_t
                    >::
                    type
                    digitsToStr(
                        Char* str,
                        Integer integer)
                {
                    const Char map[] =
                            "9876543210123456789";

                    const Char* digits =
                            static_cast<const Char*>(map) +
                            9;

                    Char* carriage = str;

                    do
                    {
                        *carriage++ = *(
                            digits + (integer % 10));

                        integer /= 10;
                    } while (integer);

                    const
                        size_t
                        digitsQty = (
                            carriage - str);

                    while (
                        str != carriage &&
                        str != --carriage)
                    {
                        const Char digit = *str;

                        *str++ = *carriage;

                        *carriage = digit;
                    }

                    return digitsQty;
                }

                //

                template
                    <
                    typename Integer
                    >
                    inline
                    typename
                    boost::enable_if
                    <
                    boost::is_integral<Integer>,
                    size_t
                    >::
                    type
                    measureInteger(
                        Integer integer)
                {
                    const
                        size_t
                        signLength =
                        isNegative(integer)
                        ? 1
                        : 0;

                    return (
                        signLength +
                        countDigits(integer)
                        );
                }

                //

                template
                    <
                    typename Integer
                    >
                    typename
                    boost::enable_if
                    <
                    boost::is_integral<Integer>
                    >::
                    type
                    integerToStr(
                        std::string& str,
                        Integer integer)
                {
                    addNegativeSign(
                            str,
                            integer);

                    Char digits
                        [
                            std::
                            numeric_limits<Integer>::
                        digits10 +
                        2
                        ];

                    str.append
                    (
                        digits,
                        digitsToStr
                        (
                            digits,
                            integer
                        )
                    );
                }

                /// Functions below serialize integer and decimal 
                /// numbers in a "%<width>.<precision>" printf format. 
                /// Formatted value is never truncated if width is less 
                /// than a number of digits in a whole part of a number. 
                /// Value truncating is used as rounding strategy when 
                /// fractional part has grater precision than requested 
                /// one. 

                class FormatSpec
                {
                    size_t width_;
                    size_t precision_;
                    Char filler_;

                public:
                    FormatSpec()
                    : width_(0)
                    , precision_(0)
                    , filler_(' ')
                    {
                    }

                    Char filler() const
                    {
                        return filler_;
                    }

                    void filler(Char filler)
                    {
                        filler_ = filler;
                    }

                    size_t width() const
                    {
                        return width_;
                    }

                    void width(size_t width)
                    {
                        width_ = width;
                    }

                    size_t precision() const
                    {
                        return precision_;
                    }

                    void precision(size_t precision)
                    {
                        precision_ = precision;
                    }
                };

                inline
                    void
                    addIntegerAlignmentSpace(
                        std::string& str,
                        const FormatSpec& format,
                        size_t digitsQty)
                {
                    digitsQty =
                        std::max(
                            digitsQty,
                            format.precision());

                    if (format.width() > digitsQty)
                    {
                        str.append(
                            format.width() - digitsQty,
                            format.filler());
                    }
                }

                inline
                    void
                    addIntegerPrecisionZeros(
                        std::string& str,
                        const FormatSpec& format,
                        size_t digitsQty)
                {
                    if (format.precision() > digitsQty)
                    {
                        const Char Zero = '0';

                        str.append(
                            format.precision() - digitsQty,
                            Zero);
                    }
                }

                template
                    <
                    typename Integer
                    >
                    typename
                    boost::enable_if
                    <
                    boost::is_integral<Integer>
                    >::
                    type
                    integerToStr(
                        std::string& str,
                        const FormatSpec& format,
                        Integer integer)
                {
                    const
                        bool
                        negative =
                        isNegative(integer);

                    Char digits
                        [
                            std::
                            numeric_limits<Integer>::
                        digits10 +
                        2
                        ];

                    const
                        size_t
                        digitsQty =
                        digitsToStr(
                            digits, integer);

                    addIntegerAlignmentSpace
                    (
                        str,
                        format,
                        digitsQty +
                        (negative ? 1 : 0)
                    );

                    if (negative)
                        addNegativeSign(str);

                    addIntegerPrecisionZeros
                    (
                        str,
                        format,
                        digitsQty
                    );

                    str.append
                    (
                        digits,
                        digitsQty
                    );
                ONIXS_SGXTITAN_OUCH_NAMESPACE_END
}