// bbldc_basicactual365fixed.h                                        -*-C++-*-
#ifndef INCLUDED_BBLDC_BASICACTUAL365FIXED
#define INCLUDED_BBLDC_BASICACTUAL365FIXED

#include <bsls_ident.h>
BSLS_IDENT("$Id: $")

//@PURPOSE: Provide stateless functions for the Actual/365 (fixed) convention.
//
//@CLASSES:
//  bbldc::BasicActual365Fixed: Actual/365 fixed convention stateless functions
//
//@DESCRIPTION: This component provides a `struct`,
// `bbldc::BasicActual365Fixed`, that serves as a namespace for defining a
// suite of date-related functions used to compute the day count and year
// fraction between two dates as per the Actual/365 (fixed) day-count
// convention.  In this day-count convention, we simply measure the number of
// days occurring in a time period, and to calculate years, divide that by 365.
// Note that this means the number of years between January 1, 2004 and January
// 1, 2005 comes out to about 1.00274.  No end-of-month rule adjustments are
// made.  Given `beginDate` and `endDate`:
// ```
// yearsDiff ::= sign(endDate - beginDate) *
//                                (days between beginDate and endDate) / 365.0
// ```
//
///Usage
///-----
// This section illustrates intended use of this component.
//
///Example 1: Computing Day Count and Year Fraction
/// - - - - - - - - - - - - - - - - - - - - - - - -
// The following snippets of code illustrate how to use
// `bbldc::BasicActual365Fixed` methods.  First, create four `bdlt::Date`
// variables:
// ```
// const bdlt::Date dA(2004, 2, 1);
// const bdlt::Date dB(2004, 3, 1);
// const bdlt::Date dC(2004, 5, 1);
// const bdlt::Date dD(2005, 2, 1);
// ```
// Then, compute the day count between some pairs of these dates:
// ```
// int daysDiff;
// daysDiff = bbldc::BasicActual365Fixed::daysDiff(dA, dB);
// assert( 29 == daysDiff);
// daysDiff = bbldc::BasicActual365Fixed::daysDiff(dA, dC);
// assert( 90 == daysDiff);
// daysDiff = bbldc::BasicActual365Fixed::daysDiff(dA, dD);
// assert(366 == daysDiff);
// daysDiff = bbldc::BasicActual365Fixed::daysDiff(dB, dC);
// assert( 61 == daysDiff);
// ```
// Finally, compute the year fraction between some of the dates:
// ```
// double yearsDiff;
// yearsDiff = bbldc::BasicActual365Fixed::yearsDiff(dA, dC);
// // Need fuzzy comparison since 'yearsDiff' is a 'double'.
// assert(yearsDiff > 0.2465 && yearsDiff < 0.2466);
// yearsDiff = bbldc::BasicActual365Fixed::yearsDiff(dA, dD);
// assert(yearsDiff > 1.0027 && yearsDiff < 1.0028);
// ```

#include <bblscm_version.h>

#include <bdlt_date.h>

namespace BloombergLP {
namespace bbldc {

                        // ==========================
                        // struct BasicActual365Fixed
                        // ==========================

/// This `struct` provides a namespace for a suite of pure functions that
/// compute values based on dates according to the Actual/365 fixed
/// day-count convention.
struct BasicActual365Fixed {

    // CLASS METHODS

    /// Return the (signed) number of days between the specified `beginDate`
    /// and `endDate` according to the Actual/365 fixed day-count
    /// convention.  If `beginDate <= endDate`, then the result is
    /// non-negative.  Note that reversing the order of `beginDate` and
    /// `endDate` negates the result.
    static int daysDiff(const bdlt::Date& beginDate,
                        const bdlt::Date& endDate);

    /// Return the (signed fractional) number of years between the specified
    /// `beginDate` and `endDate` according to the Actual/365 fixed
    /// day-count convention.  If `beginDate <= endDate`, then the result is
    /// non-negative.  Note that reversing the order of `beginDate` and
    /// `endDate` negates the result; specifically,
    /// `|yearsDiff(b, e) + yearsDiff(e, b)| <= 1.0e-15` for all dates `b`
    /// and `e`.
    static double yearsDiff(const bdlt::Date& beginDate,
                            const bdlt::Date& endDate);
};

// ============================================================================
//                             INLINE DEFINITIONS
// ============================================================================

                        // --------------------------
                        // struct BasicActual365Fixed
                        // --------------------------

// CLASS METHODS
inline
int BasicActual365Fixed::daysDiff(const bdlt::Date& beginDate,
                                  const bdlt::Date& endDate)
{
    return endDate - beginDate;
}

}  // close package namespace
}  // close enterprise namespace

#endif

// ----------------------------------------------------------------------------
// Copyright 2015 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------
