bdlb_bitstringutil.h

Go to the documentation of this file.

/// @file bdlb_bitstringutil.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bdlb_bitstringutil.h                                               -*-C++-*-
#ifndef INCLUDED_BDLB_BITSTRINGUTIL
#define INCLUDED_BDLB_BITSTRINGUTIL
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bdlb_bitstringutil bdlb_bitstringutil
/// @brief  Provide efficient operations on a multi-word sequence of bits.
/// @addtogroup bdl
/// @{
/// @addtogroup bdlb
/// @{
/// @addtogroup bdlb_bitstringutil
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bdlb_bitstringutil-purpose"> Purpose</a>
/// * <a href="#bdlb_bitstringutil-classes"> Classes </a>
/// * <a href="#bdlb_bitstringutil-description"> Description </a>
///   * <a href="#bdlb_bitstringutil-the-bit-string-pseudo-type"> The "Bit String" Pseudo-Type </a>
///   * <a href="#bdlb_bitstringutil-manipulator-functions"> Manipulator Functions </a>
///   * <a href="#bdlb_bitstringutil-accessor-functions"> Accessor Functions </a>
///   * <a href="#bdlb_bitstringutil-usage"> Usage </a>
///     * <a href="#bdlb_bitstringutil-example-1-maintaining-a-calendar-of-business-days"> Example 1: Maintaining a Calendar of Business Days </a>
///
/// # Purpose {#bdlb_bitstringutil-purpose}
/// Provide efficient operations on a multi-word sequence of bits.
///
/// # Classes {#bdlb_bitstringutil-classes}
///
/// - bdlb::BitStringUtil: namespace for common bit-manipulation procedures
///
/// @see  bdlb_bitutil, bdlb_bitmaskutil, bdlb_bitstringimputil,
///           bdlc_bitarray
///
/// # Description {#bdlb_bitstringutil-description}
/// This component provides a utility `struct`,
/// `bdlb::BitStringUtil`, that serves as a namespace for a collection of
/// efficient, bit-level procedures on "bit strings", sequences of bits stored
/// in arrays of 64-bit `uint64_t` values.  A number of operations of various
/// types are provided: bitwise-logical, copy, assignment, read, insert/remove,
/// compare, find, count, and print operations are offered, among others.
///
/// ## The "Bit String" Pseudo-Type {#bdlb_bitstringutil-the-bit-string-pseudo-type}
///
///
/// A contiguous sequence of bits that occupy a positive integral number of
/// sequential `uint64_t` values can be viewed as a string of bits.  This
/// component supports operations on such sequences.  The notion of "bit
/// string", a pseudo-type, is used to document those operations.
/// Correspondingly, `BitStringUtil` operations are categorized as either
/// "manipulators", operations that modify bit strings; or "accessors",
/// operations that return information and guarantee that no change to bit
/// strings occurs.
///
/// A bit string has two "structural" attributes:
/// @code
/// Capacity - The capacity, in bits, of a bit string is the number of
///            'uint64_t' values in the array multiplied by
///            'BitStringUtil::k_BITS_PER_UINT64'.  Note that the capacity of a
///            bit string is analogous to the capacity of a 'bsl::vector'.
///
/// Length   - The number of significant bits stored in the bit string.  The
///            length can never exceed the capacity, and the length is
///            analogous to the length of a 'bsl::vector'.
/// @endcode
/// Since the bit string is a pseudo-type, there is no language support for
/// managing these values; the user must do so explicitly.
///
/// Many operations on a bit string refer to a "position" within a bit string,
/// or a range of positions within a bit string:
/// @code
/// Position - The offset (in bits) of a bit value from the beginning of a
///            bit string (also called the "index" of a bit).
/// @endcode
/// The notion of "position" used in this component is a generalization of the
/// notion of a bit's position in a single integer value.
///
/// Bits within a 64-bit `uint64_t` (irrespective of the endian-ness of a
/// platform) are here numbered, starting at 0, from the least-significant bit
/// to the most-significant bit.  In illustrations, we typically show the
/// high-order bits on the left:
/// @code
///  63 62  . . . . .   5  4  3  2  1  0
/// +-----------------------------------+
/// | 1| 0| . . . . . | 1| 1| 0| 0| 1| 0|
/// +-----------------------------------+
/// @endcode
/// Thus, left-shifting (e.g., caused by `insert`ing low-order bits) causes bits
/// to move up in bit-position (to positions of higher significance) and
/// right-shifting (e.g., caused by `remove`ing low-order bits) causes bits to
/// move into positions of less significance.
///
/// This component extends this representation to an arbitrary sequence of bits
/// represented using an array of 64-bit `uint64_t` values.  For example, the
/// bit string shown below is built on an array of three `uint64_t` values.
/// Thus, it has a capacity of 192 (i.e.,
/// `3 * BitStringUtil::k_BITS_PER_UINT64`).  Note that words are ordered
/// right-to-left, so the lowest-order bits are to the right.  This is also how
/// the `bdlb::BitStringUtil::print` function orders the words it outputs:
/// @code
/// |<------ word 2 ------>|<------ word 1 ------>|<------ word 0 ------>|
/// | 191 190 . .  129 128 | 127 126 . . .  65 64 | 63 62 . . . . .  1 0 |
/// +----------------------+----------------------+----------------------+
/// @endcode
///
/// ## Manipulator Functions {#bdlb_bitstringutil-manipulator-functions}
///
///
/// Manipulator functions return `void`, and take the address of an integer as
/// the first argument in order to modify it in place.
/// @code
///
///
///                                  Assignment
///  +--------------------------------------------------------------------------+
///  | assign     | Overloaded; assign 0 or more contiguous bits to a specified |
///  |            | 'bool' value.                                               |
///  +--------------------------------------------------------------------------+
///  | assign0    | Overloaded; assign 0 or more contiguous bits to 'false'.    |
///  +--------------------------------------------------------------------------+
///  | assign1    | Overloaded; assign 0 or more contiguous bits to 'true'.     |
///  +--------------------------------------------------------------------------+
///  | assignBits | Assign up to one word of contiguous bits, taken from a      |
///  |            | 'uint64_t' argument.                                        |
///  +--------------------------------------------------------------------------+
///
///
///                                 Bitwise-Logical
///  +--------------------------------------------------------------------------+
///  | andEqual   | Bitwise-AND ranges of equal length from two bit strings, a  |
///  |            | 'dstBitString' and a 'srcBitString', writing the result     |
///  |            | over the range from 'dstBitString'.                         |
///  +--------------------------------------------------------------------------+
///  | minusEqual | Bitwise-MINUS ranges of equal length from two bit strings,  |
///  |            | a 'srcBitString' from a 'dstBitString', writing the result  |
///  |            | over the range from 'dstBitString'.                         |
///  +--------------------------------------------------------------------------+
///  | orEqual    | Bitwise-OR ranges of equal length from two bit strings, a   |
///  |            | 'dstBitString' and a 'srcBitString', writing the result     |
///  |            | over the range from 'dstBitString'.                         |
///  +--------------------------------------------------------------------------+
///  | xorEqual   | Bitwise-XOR ranges of equal length from two bit strings, a  |
///  |            | 'dstBitString' and a 'srcBitString', writing the result     |
///  |            | over the range from 'dstBitString'.                         |
///  +--------------------------------------------------------------------------+
///
///
///                                       Copy
///  +--------------------------------------------------------------------------+
///  | copyRaw | Copy a range from one bit string to another range, with some   |
///  |         | restrictions on overlap between the two ranges.                |
///  +--------------------------------------------------------------------------+
///  | copy    | Copy a range from one bit string to another range, with no     |
///  |         | restrictions on overlap between the two ranges.                |
///  +--------------------------------------------------------------------------+
///
///
///                                  Insert / Remove
///  +--------------------------------------------------------------------------+
///  | insert    | Overloaded; insert 0 or more bits of a specified 'bool'      |
///  |           | value.                                                       |
///  +--------------------------------------------------------------------------+
///  | insert0   | Overloaded; insert 0 or more 'false' bits.                   |
///  +--------------------------------------------------------------------------+
///  | insert1   | Overloaded; insert 0 or more 'true' bits.                    |
///  +--------------------------------------------------------------------------+
///  | insertRaw | Make room for additional bits in a bit string by moving all  |
///  |           | bits above a given index up, leaving the values of the       |
///  |           | newly-inserted bits undefined.                               |
///  +--------------------------------------------------------------------------+
///  | remove         | Remove 0 or more bits from a bit string.                |
///  +--------------------------------------------------------------------------+
///  | removeAndFill0 | Remove 0 or more bits from a bit string and assign      |
///  |                | 'false' to vacated higher-order bits.                   |
///  +--------------------------------------------------------------------------+
///  | removeAndFill1 | Remove 0 or more bits from a bit string and assign      |
///  |                | 'true' to vacated higher-order bits.                    |
///  +--------------------------------------------------------------------------+
///
///
///                                 Other Manipulators
///  +--------------------------------------------------------------------------+
///  | swapRaw | Swap two ranges of bit strings, which must not overlap.        |
///  +--------------------------------------------------------------------------+
///  | toggle  | Negate all the bits in a range of a bit string.                |
///  +--------------------------------------------------------------------------+
///
/// @endcode
///
/// ## Accessor Functions {#bdlb_bitstringutil-accessor-functions}
///
///
/// Accessor function return a value but do not modify a bit string.
/// @code
///
///                                     Compare
///  +--------------------------------------------------------------------------+
///  | areEqual | Compare two ranges of bits for equality.                      |
///  +--------------------------------------------------------------------------+
///
///
///                                      Read
///  +--------------------------------------------------------------------------+
///  | bit  | Return the boolean value of a single bit from a bit string.       |
///  +--------------------------------------------------------------------------+
///  | bits | Return a 'uint64_t' containing at most 'k_BITS_PER_UINT64'        |
///  |      | adjacent bits from a bit string.                                  |
///  +--------------------------------------------------------------------------+
///
///
///                                      Find
///  +--------------------------------------------------------------------------+
///  | find0AtMaxIndex | Locate the highest-order 0 bit in a range.             |
///  +--------------------------------------------------------------------------+
///  | find0AtMinIndex | Locate the lowest-order 0 bit in a range.              |
///  +--------------------------------------------------------------------------+
///  | find1AtMaxIndex | Locate the highest-order 1 bit in a range.             |
///  +--------------------------------------------------------------------------+
///  | find1AtMinIndex | Locate the lowest-order 1 bit in a range.              |
///  +--------------------------------------------------------------------------+
///
///
///                                      Count
///  +--------------------------------------------------------------------------+
///  | isAny0 | Return 'true' if any bit in a range is 0, and 'false'           |
///  |        | otherwise.                                                      |
///  +--------------------------------------------------------------------------+
///  | isAny1 | Return 'true' if any bit in a range is 1, and 'false'           |
///  |        | otherwise.                                                      |
///  +--------------------------------------------------------------------------+
///  | num0   | Return the number of 0 bits in a range.                         |
///  +--------------------------------------------------------------------------+
///  | num1   | Return the number of 1 bits in a range.                         |
///  +--------------------------------------------------------------------------+
///
///
///                                     Output
///  +--------------------------------------------------------------------------+
///  | print | Output a bit string in hex.                                      |
///  +--------------------------------------------------------------------------+
///
/// @endcode
///
/// ## Usage {#bdlb_bitstringutil-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Maintaining a Calendar of Business Days {#bdlb_bitstringutil-example-1-maintaining-a-calendar-of-business-days}
///
///
/// Bit strings can be used to represent business calendars and facilitate
/// efficient operations on such calendars.  We will use bit strings to mark
/// properties of days of the year 2013.
///
/// First, create an enumeration showing the number of days in the year 2013
/// before the beginning of each month, so that:
/// @code
/// <constant for month> + <day of month> == <day of year>
///
///  enum {
///      JAN =        0,    // Note: First DOY is 'JAN + 1'.
///      FEB = JAN + 31,
///      MAR = FEB + 28,    // 2013 was not a leap year.
///      APR = MAR + 31,
///      MAY = APR + 30,
///      JUN = MAY + 31,
///      JUL = JUN + 30,
///      AUG = JUL + 31,
///      SEP = AUG + 31,
///      OCT = SEP + 30,
///      NOV = OCT + 31,
///      DEC = NOV + 30
///  };
/// @endcode
/// Then, create a bit string with sufficient capacity to represent every day
/// of a year (note that 64 * 6 = 384) and set a 1-bit in the indices
/// corresponding to the day-of-year (DOY) for each weekend day.  For
/// convenience in date calculations, the 0 index is not used; the 365 days of
/// the year are at indices `[1 .. 365]`.  Further note that the values set
/// below correspond to the year 2013:
/// @code
/// uint64_t weekends[6] = { 0 };
///
/// // We are marking only weekend days, so start with the first weekend day
/// // of the year: Saturday, January 5, 2013.
///
/// for (int i = 5; i < 366; i += 7) {
///     bdlb::BitStringUtil::assign(weekends, i,   1);
///     if (i + 1 < 366) {
///         bdlb::BitStringUtil::assign(weekends, i + 1, 1);
///     }
/// }
/// @endcode
/// Next, we can easily use `bdlb::BitStringUtil` methods to find days of
/// interest.  For example, we can find the first and last weekend days of the
/// year:
/// @code
/// const int firstWeekendDay = bdlb::BitStringUtil::find1AtMinIndex(weekends,
///                                                                  365 + 1);
/// const int lastWeekendDay  = bdlb::BitStringUtil::find1AtMaxIndex(weekends,
///                                                                  365 + 1);
///
/// assert(JAN +  5 == firstWeekendDay);
/// assert(DEC + 29 ==  lastWeekendDay);
/// @endcode
/// Then, we define the following enumeration that allows us to easily represent
/// the US holidays of the year:
/// @code
/// uint64_t holidays[6] = { 0 };
///
/// enum USHolidays2013 {
///     NEW_YEARS_DAY             = JAN +  1,
///     MARTIN_LUTHER_KING_JR_DAY = JAN + 21,
///     PRESIDENTS_DAY            = FEB + 18,
///     GOOD_FRIDAY               = MAR + 29,
///     MEMORIAL_DAY              = MAY + 27,
///     INDEPENDENCE_DAY          = JUL +  4,
///     LABOR_DAY                 = SEP +  2,
///     THANKSGIVING              = NOV + 28,
///     CHRISTMAS                 = DEC + 25
/// };
///
/// bdlb::BitStringUtil::assign(holidays, NEW_YEARS_DAY,             true);
/// bdlb::BitStringUtil::assign(holidays, MARTIN_LUTHER_KING_JR_DAY, true);
/// bdlb::BitStringUtil::assign(holidays, PRESIDENTS_DAY,            true);
/// bdlb::BitStringUtil::assign(holidays, GOOD_FRIDAY,               true);
/// bdlb::BitStringUtil::assign(holidays, MEMORIAL_DAY,              true);
/// bdlb::BitStringUtil::assign(holidays, INDEPENDENCE_DAY,          true);
/// bdlb::BitStringUtil::assign(holidays, LABOR_DAY,                 true);
/// bdlb::BitStringUtil::assign(holidays, THANKSGIVING,              true);
/// bdlb::BitStringUtil::assign(holidays, CHRISTMAS,                 true);
/// @endcode
/// Next, the following enumeration indicates the beginning of fiscal quarters:
/// @code
/// enum {
///     Q1 = JAN + 1,
///     Q2 = APR + 1,
///     Q3 = JUN + 1,
///     Q4 = OCT + 1
/// };
/// @endcode
/// Now, we can query our calendar for the first holiday in the third quarter,
/// if any:
/// @code
/// const bsl::size_t firstHolidayOfQ3 = bdlb::BitStringUtil::find1AtMinIndex(
///                                                                   holidays,
///                                                                   Q3,
///                                                                   Q4);
/// assert(INDEPENDENCE_DAY == firstHolidayOfQ3);
/// @endcode
/// Finally, our weekend and holiday calendars are readily combined to represent
/// days off for either reason (i.e., holiday or weekend):
/// @code
/// uint64_t allDaysOff[6] = { 0 };
/// bdlb::BitStringUtil::orEqual(allDaysOff, 1, weekends, 1, 365);
/// bdlb::BitStringUtil::orEqual(allDaysOff, 1, holidays, 1, 365);
///
/// bool isOffMay24 = bdlb::BitStringUtil::bit(allDaysOff, MAY + 24);
/// bool isOffMay25 = bdlb::BitStringUtil::bit(allDaysOff, MAY + 25);
/// bool isOffMay26 = bdlb::BitStringUtil::bit(allDaysOff, MAY + 26);
/// bool isOffMay27 = bdlb::BitStringUtil::bit(allDaysOff, MAY + 27);
/// bool isOffMay28 = bdlb::BitStringUtil::bit(allDaysOff, MAY + 28);
///
/// assert(false == isOffMay24);
/// assert(true  == isOffMay25);    // Saturday
/// assert(true  == isOffMay26);    // Sunday
/// assert(true  == isOffMay27);    // Note May 27, 2013 is Memorial Day.
/// assert(false == isOffMay28);
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bdl
 * @{
 */
/** @addtogroup bdlb
 * @{
 */
/** @addtogroup bdlb_bitstringutil
 * @{
 */
 
#include <bdlscm_version.h>
 
#include <bdlb_bitutil.h>
 
#include <bsls_assert.h>
#include <bsls_review.h>
 
#include <bsl_cstddef.h>
#include <bsl_cstdint.h>
#include <bsl_iosfwd.h>
 
 
namespace bdlb {
 
                            // ====================
                            // struct BitStringUtil
                            // ====================
 
/// This `struct` provides a namespace for a suite of static functions to
/// manipulate and access sequences of bits stored in an array of `uint64_t`
/// (also known as a "bit string"; see {The "Bit String" Pseudo-Type}).
struct BitStringUtil {
 
    // PUBLIC TYPES
    enum { k_BITS_PER_UINT64 = 64 };  // number of bits in a 'uint64_t'
 
    // PUBLIC CLASS CONSTANTS
    static const bsl::size_t k_INVALID_INDEX = ~static_cast<bsl::size_t>(0);
 
    // CLASS METHODS
 
                                // Assign
 
    /// Set the bit at the specified `index` in the specified `bitString` to
    /// the specified `value`.  The behavior is undefined unless `index` is
    /// less than the capacity of `bitString`.
    static void assign(bsl::uint64_t *bitString,
                       bsl::size_t    index,
                       bool           value);
 
    /// Set the specified `numBits` beginning at the specified `index` in
    /// the specified `bitString` to the specified `value`.  The behavior is
    /// undefined unless `bitString` has a capacity of at least
    /// `index + numBits`.
    static void assign(bsl::uint64_t *bitString,
                       bsl::size_t    index,
                       bool           value,
                       bsl::size_t    numBits);
 
    /// Set the bit at the specified `index` in the specified `bitString` to
    /// `false`.  The behavior is undefined unless `index` is less than the
    /// capacity of `bitString`.
    static void assign0(bsl::uint64_t *bitString, bsl::size_t index);
 
    /// Set the specified `numBits` beginning at the specified `index` in
    /// the specified `bitString` to `false`.  The behavior is undefined
    /// unless `bitString` has a capacity of at least `index + numBits`.
    static void assign0(bsl::uint64_t *bitString,
                        bsl::size_t    index,
                        bsl::size_t    numBits);
 
    /// Set the bit at the specified `index` in the specified `bitString` to
    /// `true`.  The behavior is undefined unless `index` is less than the
    /// capacity of `bitString`.
    static void assign1(bsl::uint64_t *bitString, bsl::size_t index);
 
    /// Set the specified `numBits` beginning at the specified `index` in
    /// the specified `bitString` to `true`.  The behavior is undefined
    /// unless `bitString` has a capacity of at least `index + numBits`.
    static void assign1(bsl::uint64_t *bitString,
                        bsl::size_t    index,
                        bsl::size_t    numBits);
 
    /// Assign the low-order specified `numBits` from the specified
    /// `srcValue` to the `numBits` starting at the specified `index` in the
    /// specified `bitString`.  The behavior is undefined unless
    /// `numBits <= k_BITS_PER_UINT64` and `bitString` has a capacity of at
    /// least `index + numBits`.
    static void assignBits(bsl::uint64_t *bitString,
                           bsl::size_t    index,
                           bsl::uint64_t  srcValue,
                           bsl::size_t    numBits);
 
                                // Bitwise-Logical
 
    /// Bitwise AND the specified `numBits` of the specified `dstBitString`
    /// starting at the specified `dstIndex` with the `numBits` of the
    /// specified `srcBitString` starting at the specified `srcIndex`, and
    /// write the result over the bits that were read from `dstBitString`.
    /// The behavior is undefined unless `dstBitString` has a length of at
    /// least `dstIndex + numBits` and `srcBitString` has a length of at
    /// least `srcIndex + numBits`.
    static void andEqual(bsl::uint64_t       *dstBitString,
                         bsl::size_t          dstIndex,
                         const bsl::uint64_t *srcBitString,
                         bsl::size_t          srcIndex,
                         bsl::size_t          numBits);
 
    /// Bitwise MINUS the specified `numBits` of the specified
    /// `srcBitString` starting at the specified `srcIndex` from the
    /// `numBits` of the specified `dstBitString` starting at the specified
    /// `dstIndex`, and write the result over the bits that were read from
    /// `dstBitString`.  The behavior is undefined unless `dstBitString` has
    /// a length of at least `dstIndex + numBits` and `srcBitString` has a
    /// length of at least `srcIndex + numBits`.  Note that the logical
    /// difference `A - B` is defined to be `A & !B`.
    static void minusEqual(bsl::uint64_t       *dstBitString,
                           bsl::size_t          dstIndex,
                           const bsl::uint64_t *srcBitString,
                           bsl::size_t          srcIndex,
                           bsl::size_t          numBits);
 
    /// Bitwise OR the specified `numBits` of the specified `dstBitString`
    /// starting at the specified `dstIndex` with the `numBits` of the
    /// specified `srcBitString` starting at the specified `srcIndex`, and
    /// write the result over the bits that were read from `dstBitString`.
    /// The behavior is undefined unless `dstBitString` has a length of at
    /// least `dstIndex + numBits` and `srcBitString` has a length of at
    /// least `srcIndex + numBits`.
    static void orEqual(bsl::uint64_t       *dstBitString,
                        bsl::size_t          dstIndex,
                        const bsl::uint64_t *srcBitString,
                        bsl::size_t          srcIndex,
                        bsl::size_t          numBits);
 
    /// Bitwise XOR the specified `numBits` of the specified `dstBitString`
    /// starting at the specified `dstIndex` with the `numBits` of the
    /// specified `srcBitString` starting at the specified `srcIndex`, and
    /// write the result over the bits that were read from `dstBitString`.
    /// The behavior is undefined unless `dstBitString` has a length of at
    /// least `dstIndex + numBits` and `srcBitString` has a length of at
    /// least `srcIndex + numBits`.
    static void xorEqual(bsl::uint64_t       *dstBitString,
                         bsl::size_t          dstIndex,
                         const bsl::uint64_t *srcBitString,
                         bsl::size_t          srcIndex,
                         bsl::size_t          numBits);
 
                                // Copy
 
    /// Copy to the specified `dstBitString`, beginning at the specified
    /// `dstIndex`, the specified `numBits` beginning at the specified
    /// `srcIndex` in the specified `srcBitString`.  This function works
    /// correctly regardless of whether the source and destination ranges
    /// overlap.  The behavior is undefined unless `dstBitString` has a
    /// capacity of at least `dstIndex + numBits` and `srcBitString` has a
    /// length of at least `srcIndex + numBits`.
    static void copy(bsl::uint64_t       *dstBitString,
                     bsl::size_t          dstIndex,
                     const bsl::uint64_t *srcBitString,
                     bsl::size_t          srcIndex,
                     bsl::size_t          numBits);
 
    /// Copy to the specified `dstBitString`, beginning at the specified
    /// `dstIndex`, the specified `numBits` beginning at the specified
    /// `srcIndex` in the specified `srcBitString`.  The behavior is
    /// undefined unless `dstBitString` has a capacity of at least
    /// `dstIndex + numBits`, `srcBitString` has a length of at least
    /// `srcIndex + numBits`, and the source and destination ranges either
    /// do not overlap, or the destination range is equal to the source
    /// range, or the start of the destination range is below the start of
    /// the source range.
    static void copyRaw(bsl::uint64_t       *dstBitString,
                        bsl::size_t          dstIndex,
                        const bsl::uint64_t *srcBitString,
                        bsl::size_t          srcIndex,
                        bsl::size_t          numBits);
 
                                // Insert / Remove
 
    /// Insert the specified `numBits`, each having the specified `value`,
    /// into the specified `bitString` having the specified `initialLength`,
    /// beginning at the specified `dstIndex`.  Bits at or above `dstIndex`
    /// are shifted up by `numBits` index positions and the length of
    /// `bitString` is increased by `numBits`.  The behavior is undefined
    /// unless `dstIndex <= initialLength` and `bitString` has a capacity of
    /// at least `initialLength + numBits`.
    static void insert(bsl::uint64_t *bitString,
                       bsl::size_t    initialLength,
                       bsl::size_t    dstIndex,
                       bool           value,
                       bsl::size_t    numBits);
 
    /// Insert the specified `numBits` 0 bits into the specified `bitString`
    /// having the specified `initialLength` beginning at the specified
    /// `dstIndex`.  Bits at or above `dstIndex` are shifted up by `numBits`
    /// index positions and the length of `bitString` is increased by
    /// `numBits`.  The behavior is undefined unless
    /// `dstIndex <= initialLength` and `bitString` has a capacity of at
    /// least `initialLength + numBits`.
    static void insert0(bsl::uint64_t *bitString,
                        bsl::size_t    initialLength,
                        bsl::size_t    dstIndex,
                        bsl::size_t    numBits);
 
    /// Insert the specified `numBits` 1 bits into the specified `bitString`
    /// having the specified `initialLength` beginning at the specified
    /// `dstIndex`.  Bits at or above `dstIndex` are shifted up by `numBits`
    /// index positions and the length of `bitString` is increased by
    /// `numBits`.  The behavior is undefined unless
    /// `dstIndex <= initialLength` and `bitString` has a capacity of at
    /// least `initialLength + numBits`.
    static void insert1(bsl::uint64_t *bitString,
                        bsl::size_t    initialLength,
                        bsl::size_t    dstIndex,
                        bsl::size_t    numBits);
 
    /// Insert the specified `numBits` into the specified `bitString` having
    /// the specified `initialLength` beginning at the specified `dstIndex`.
    /// Bits at or above `dstIndex` are shifted up by `numBits` index
    /// positions and the length of `bitString` is increased by `numBits`.
    /// The values of the inserted bits are undefined.  The behavior is
    /// undefined unless `dstIndex <= initialLength` and `bitString` has a
    /// capacity of at least `initialLength + numBits`.  Note that the
    /// inserted bits are not assigned any value.
    static void insertRaw(bsl::uint64_t *bitString,
                          bsl::size_t    initialLength,
                          bsl::size_t    dstIndex,
                          bsl::size_t    numBits);
 
    /// Remove the specified `numBits` from the specified `bitString` of the
    /// specified `length` beginning at the specified `index`.  Bits above
    /// `index + numBits` are shifted down by `numBits` index positions and
    /// the length of `bitString` is reduced by `numBits`.  The values of
    /// the vacated high-order bits are not modified.  The behavior is
    /// undefined unless `index + numBits <= length`.
    static void remove(bsl::uint64_t *bitString,
                       bsl::size_t    length,
                       bsl::size_t    index,
                       bsl::size_t    numBits);
 
    /// Remove the specified `numBits` from the specified `bitString` having
    /// the specified `length` beginning at the specified `index`.  Bits
    /// above `index + numBits` are shifted down by `numBits` index
    /// positions and the last `numBits` of `bitString` are set to 0.  The
    /// length of `bitString` is not changed.  The behavior is undefined
    /// unless `index + numBits <= length`.
    static void removeAndFill0(bsl::uint64_t *bitString,
                               bsl::size_t    length,
                               bsl::size_t    index,
                               bsl::size_t    numBits);
 
    /// Remove the specified `numBits` from the specified `bitString` having
    /// the specified `length` beginning at the specified `index`.  Bits
    /// above `index + numBits` are shifted down by `numBits` index
    /// positions and the last `numBits` of `bitString` are set to 1.  The
    /// length of `bitString` is not changed.  The behavior is undefined
    /// unless `index + numBits <= length`.
    static void removeAndFill1(bsl::uint64_t *bitString,
                               bsl::size_t    length,
                               bsl::size_t    index,
                               bsl::size_t    numBits);
 
                                // Other Manipulators
 
    /// Exchange the specified `numBits` beginning at the specified `index1`
    /// in the specified `bitString1` with the `numBits` beginning at the
    /// specified `index2` in the specified `bitString2`.  The behavior is
    /// undefined unless `bitString1` has a length of at least
    /// `index1 + numBits`, `bitString2` has a length of at least
    /// `index2 + numBits`, and there is *no* overlap between the swapped
    /// ranges of bits.
    static void swapRaw(bsl::uint64_t *bitString1,
                        bsl::size_t    index1,
                        bsl::uint64_t *bitString2,
                        bsl::size_t    index2,
                        bsl::size_t    numBits);
 
    /// Invert the values of the specified `numBits` in the specified
    /// `bitString` beginning at the specified `index`.  The behavior is
    /// undefined unless `bitString` has a length of at least
    /// `index + numBits`.
    static void toggle(bsl::uint64_t *bitString,
                       bsl::size_t    index,
                       bsl::size_t    numBits);
 
                                // Compare
 
    /// Return `true` if the specified low-order `numBits` in the specified
    /// `bitString1` are bitwise equal to the corresponding bits in the
    /// specified `bitString2`, and `false` otherwise.  The behavior is
    /// undefined unless both `bitString1` and `bitString2` have a length of
    /// at least `numBits`.
    static bool areEqual(const bsl::uint64_t *bitString1,
                         const bsl::uint64_t *bitString2,
                         bsl::size_t          numBits);
 
    /// Return `true` if the specified `numBits` beginning at the specified
    /// `index1` in the specified `bitString1` are bitwise equal to the
    /// `numBits` beginning at the specified `index2` in the specified
    /// `bitString2`, and `false` otherwise.  The behavior is undefined
    /// unless `bitString1` has a length of at least `index1 + numBits` and
    /// `bitString2` has a length of at least `index2 + numBits`.
    static bool areEqual(const bsl::uint64_t *bitString1,
                         bsl::size_t          index1,
                         const bsl::uint64_t *bitString2,
                         bsl::size_t          index2,
                         bsl::size_t          numBits);
 
                                // Read
 
    /// Return the bit value at the specified `index` in the specified
    /// `bitString`.  The behavior is undefined unless `index` is less than
    /// the length of `bitString`.
    static bool bit(const bsl::uint64_t *bitString, bsl::size_t index);
 
    /// Return the specified `numBits` beginning at the specified `index` in
    /// the specified `bitString` as the low-order bits of the returned
    /// value.  The behavior is undefined unless
    /// `numBits <= k_BITS_PER_UINT64` and `bitString` has a length of at
    /// least `index + numBits`.
    static bsl::uint64_t bits(const bsl::uint64_t *bitString,
                              bsl::size_t          index,
                              bsl::size_t          numBits);
 
                                // Find
 
    /// Return the index of the most-significant 0 bit in the specified
    /// `bitString` having the specified `length`, if such a bit exists, and
    /// `k_INVALID_INDEX` otherwise.
    static bsl::size_t find0AtMaxIndex(const bsl::uint64_t *bitString,
                                       bsl::size_t          length);
 
    /// Return the index of the most-significant 0 bit in the specified
    /// `bitString` in the specified range `[begin .. end)`, if such a bit
    /// exists, and `k_INVALID_INDEX` otherwise.  The behavior is undefined
    /// unless `begin <= end` and `end` is less than or equal to the length
    /// of `bitString`.
    static bsl::size_t find0AtMaxIndex(const bsl::uint64_t *bitString,
                                       bsl::size_t          begin,
                                       bsl::size_t          end);
 
    /// Return the index of the least-significant 0 bit in the specified
    /// `bitString` having the specified `length`, if such a bit exists, and
    /// `k_INVALID_INDEX` otherwise.
    static bsl::size_t find0AtMinIndex(const bsl::uint64_t *bitString,
                                       bsl::size_t          length);
 
    /// Return the index of the least-significant 0 bit in the specified
    /// `bitString` in the specified range `[begin .. end)`, if such a bit
    /// exists, and `k_INVALID_INDEX` otherwise.  The behavior is undefined
    /// unless `begin <= end` and `end` is less than or equal to the length
    /// of `bitString`.
    static bsl::size_t find0AtMinIndex(const bsl::uint64_t *bitString,
                                       bsl::size_t          begin,
                                       bsl::size_t          end);
 
    /// Return the index of the most-significant 1 bit in the specified
    /// `bitString` having the specified `length`, if such a bit exists, and
    /// `k_INVALID_INDEX` otherwise.
    static bsl::size_t find1AtMaxIndex(const bsl::uint64_t *bitString,
                                       bsl::size_t          length);
 
    /// Return the index of the most-significant 1 bit in the specified
    /// `bitString` in the specified range `[begin .. end)`, if such a bit
    /// exists, and `k_INVALID_INDEX` otherwise.  The behavior is undefined
    /// unless `begin <= end` and `end` is less than or equal to the length
    /// of `bitString`.
    static bsl::size_t find1AtMaxIndex(const bsl::uint64_t *bitString,
                                       bsl::size_t          begin,
                                       bsl::size_t          end);
 
    /// Return the index of the least-significant 1 bit in the specified
    /// `bitString` having the specified `length`, if such a bit exists, and
    /// `k_INVALID_INDEX` otherwise.
    static bsl::size_t find1AtMinIndex(const bsl::uint64_t *bitString,
                                       bsl::size_t          length);
 
    /// Return the index of the least-significant 1 bit in the specified
    /// `bitString` in the specified range `[begin .. end)`, if such a bit
    /// exists, and `k_INVALID_INDEX` otherwise.  The behavior is undefined
    /// unless `begin <= end` and `end` is less than or equal to the length
    /// of `bitString`.
    static bsl::size_t find1AtMinIndex(const bsl::uint64_t *bitString,
                                       bsl::size_t          begin,
                                       bsl::size_t          end);
 
                                // Count
 
    /// Return `true` if any of the specified `numBits` beginning at the
    /// specified `index` in the specified `bitString` are 0, and `false`
    /// otherwise.  The behavior is undefined unless `bitString` has a
    /// length of at least `index + numBits`.
    static bool isAny0(const bsl::uint64_t *bitString,
                       bsl::size_t          index,
                       bsl::size_t          numBits);
 
    /// Return `true` if any of the specified `numBits` beginning at the
    /// specified `index` in the specified `bitString` are 1, and `false`
    /// otherwise.  The behavior is undefined unless `bitString` has a
    /// length of at least `index + numBits`.
    static bool isAny1(const bsl::uint64_t *bitString,
                       bsl::size_t          index,
                       bsl::size_t          numBits);
 
    /// Return the number of 0 bits in the specified `numBits` beginning at
    /// the specified `index` in the specified `bitString`.  The behavior is
    /// undefined unless `bitString` has a length of at least
    /// `index + numBits`.
    static bsl::size_t num0(const bsl::uint64_t *bitString,
                            bsl::size_t          index,
                            bsl::size_t          numBits);
 
    /// Return the number of 1 bits in the specified `numBits` beginning at
    /// the specified `index` in the specified `bitString`.  The behavior is
    /// undefined unless `bitString` has a length of at least
    /// `index + numBits`.
    static bsl::size_t num1(const bsl::uint64_t *bitString,
                            bsl::size_t          index,
                            bsl::size_t          numBits);
 
                                // Printing
 
    /// Format to the specified output `stream` the specified low-order
    /// `numBits` in the specified `bitString` in hexadecimal, and return a
    /// reference to `stream`.  The highest order bits are printed first, in
    /// groups of 16 nibbles, 64 nibbles per line (in the case of multi-line
    /// output).  Optionally specify `level`, the indentation level for each
    /// line output.  Optionally specify `spacesPerLevel`, the number of
    /// spaces per indentation level.  Each line is indented by the absolute
    /// value of `level * spacesPerLevel`.  If `spacesPerLevel` is negative,
    /// suppress line breaks and format the entire output on one line.  If
    /// `stream` is initially invalid, this operation has no effect.  Note
    /// that a trailing newline is provided in multiline mode only.
    static bsl::ostream& print(bsl::ostream&        stream,
                               const bsl::uint64_t *bitString,
                               bsl::size_t          numBits,
                               int                  level          = 1,
                               int                  spacesPerLevel = 4);
};
 
// ============================================================================
//                              INLINE DEFINITIONS
// ============================================================================
 
                            // --------------------
                            // struct BitStringUtil
                            // --------------------
 
// CLASS METHODS
 
                            // Manipulators
 
                                // Assign
 
inline
void BitStringUtil::assign(bsl::uint64_t *bitString,
                           bsl::size_t    index,
                           bool           value)
{
    BSLS_ASSERT(bitString);
 
    const bsl::size_t idx =                       index  / k_BITS_PER_UINT64;
    const int         pos = static_cast<unsigned>(index) % k_BITS_PER_UINT64;
 
    if (value) {
        bitString[idx] |=  (1ULL << pos);
    }
    else {
        bitString[idx] &= ~(1ULL << pos);
    }
}
 
inline
void BitStringUtil::assign0(bsl::uint64_t *bitString, bsl::size_t index)
{
    BSLS_ASSERT(bitString);
 
    const bsl::size_t idx =                       index  / k_BITS_PER_UINT64;
    const int         pos = static_cast<unsigned>(index) % k_BITS_PER_UINT64;
 
    bitString[idx] &= ~(1ULL << pos);
}
 
inline
void BitStringUtil::assign1(bsl::uint64_t *bitString, bsl::size_t index)
{
    BSLS_ASSERT(bitString);
 
    const bsl::size_t idx =                       index  / k_BITS_PER_UINT64;
    const int         pos = static_cast<unsigned>(index) % k_BITS_PER_UINT64;
 
    bitString[idx] |= 1ULL << pos;
}
 
                                // Insert / Remove
 
inline
void BitStringUtil::insert(bsl::uint64_t *bitString,
                           bsl::size_t    initialLength,
                           bsl::size_t    dstIndex,
                           bool           value,
                           bsl::size_t    numBits)
{
    BSLS_ASSERT(bitString);
 
    insertRaw(bitString, initialLength, dstIndex, numBits);
    assign(bitString, dstIndex, value, numBits);
}
 
inline
void BitStringUtil::insert0(bsl::uint64_t *bitString,
                            bsl::size_t    initialLength,
                            bsl::size_t    dstIndex,
                            bsl::size_t    numBits)
{
    BSLS_ASSERT(bitString);
 
    insertRaw(bitString, initialLength, dstIndex, numBits);
    assign0(bitString, dstIndex, numBits);
}
 
inline
void BitStringUtil::insert1(bsl::uint64_t *bitString,
                            bsl::size_t    initialLength,
                            bsl::size_t    dstIndex,
                            bsl::size_t    numBits)
{
    BSLS_ASSERT(bitString);
 
    insertRaw(bitString, initialLength, dstIndex, numBits);
    assign1(bitString, dstIndex, numBits);
}
 
inline
void BitStringUtil::removeAndFill0(bsl::uint64_t *bitString,
                                   bsl::size_t    length,
                                   bsl::size_t    index,
                                   bsl::size_t    numBits)
{
    BSLS_ASSERT(bitString);
 
    remove(bitString, length, index, numBits);
    assign0(bitString, length - numBits, numBits);
}
 
inline
void BitStringUtil::removeAndFill1(bsl::uint64_t *bitString,
                                   bsl::size_t    length,
                                   bsl::size_t    index,
                                   bsl::size_t    numBits)
{
    BSLS_ASSERT(bitString);
 
    remove(bitString, length, index, numBits);
    assign1(bitString, length - numBits, numBits);
}
 
                                // Accessors
 
                                // Read
inline
bool BitStringUtil::bit(const bsl::uint64_t *bitString, bsl::size_t index)
{
    BSLS_ASSERT(bitString);
 
    const bsl::size_t idx =                       index  / k_BITS_PER_UINT64;
    const int         pos = static_cast<unsigned>(index) % k_BITS_PER_UINT64;
 
    return bitString[idx] & (1ULL << pos);
}
 
                                // Count
 
inline
bsl::size_t BitStringUtil::num0(const bsl::uint64_t *bitString,
                                bsl::size_t          index,
                                bsl::size_t          numBits)
{
    BSLS_ASSERT(bitString);
 
    return numBits - num1(bitString, index, numBits);
}
 
}  // close package 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 ----------------------------------
 
/** @} */
/** @} */
/** @} */