mdds 3.2.0

* switched to using SPDX identifiers instead of having license header in
  each and every tracked files.  The repo is now REUSE 3.0 compliant.

* multi_type_vector

  * introduced new macro called MDDS_MULTI_TYPE_VECTOR_DEBUG_TRACE to
    enable call tracing instead of reusing MDDS_MULTI_TYPE_VECTOR_DEBUG,
    because the latter macro also enables expensive debug block
    integrity checks throughout the code.

  * added support for optional use of custom execution policies in
    the following operations:

    * copy construction

    * clone()

    * shrink_to_fit()

    * operator==()

    * operator!=()

* added noexcept markers to appropriate functions.  This was completed
  on the following data structures:

  * flat_segment_tree

  * segment_tree

  * multi_type_vector (both aos and soa variants)

  * multi_type_matrix

mdds 3.1.0

* multi_type_vector

  * revised push_back() to also accept an rvalue reference.

  * added emplace_back() to allow in-place construction of values.  However,
    due to limitation of how the value type is determined, the type of an
    inserted value must be default constructible, and the call incurs the
    overhead of one default construction.

* rtree

  * the erase() methods to take their iterator parameter by value.

* flat_segment_tree

  * both insert() and search() methods to take their const_iterator parameter
    by value.

  * the size of its const_iterator type has been reduced by not caching key
    and value as its data members.  Its size is now equal to the sum of the
    sizes of two pointers and one boolean value.  It also now returns
    immutable references to the stored key and value.

mdds 3.0.0

* trie_map and packed_trie_map

  * implemented equal (==) and non-equal (!=) operators in trie_map.  Previously
    only packed_trie_map implemented these operators.

  * added support for storing values that are only movable but not copyable.
    Note that when using move-only values, the copy constructors do not work.
    Also, due to this change, the trie_map::pack() method is no longer const; it
    now moves the stored values into the packed variant.  If you need to
    preserve the original values stored in the non-packed variant, make a copy
    first before calling the trie_map::pack() method.

  * simplified the template parameters so that the first template parameter
    specifies the key type.

  * revised value storage in packed_trie_map so that the size of the unit value
    type of its internal buffer would not be forced to be the size of a pointer.
    The user can now optionally specify a different-sized unsigned integer type
    as the value type of the internal buffer.  This will benefit mostly when the
    number of stored values is small so that a smaller-sized integer type can
    sufficiently store all values.  In such cases, the size of the in-memory
    buffer as well as the size of a state file will become smaller.

  * implemented a method to allow traversal of the trie structure one node at a
    time.  This can be done by first calling the root_node() method to retrieve
    the root node of the trie then traverse through its child nodes.

  * added overview section in the documentation.

* segment_tree

  * significantly revised its API design to give it necessary polish in order to
    bring its usability to an acceptable level.

  * added boundary_keys() method that returns a sorted sequence of boundary
    keys.

  * re-implemented the equal and non-equal operators to work with move-only
    values.

  * added documentation with code examples.

* sorted_string_map

  * EntryT template parameter has been removed which was previously used to
    optionally allow defining keys in the entry array as std::string_view.
    After the removal of the template parameter, keys in the entry array are
    always defined as std::string_view.

  * added find_key() method to perform reverse lookup of the key from a value,
    with two lookup algorithms to choose from - linear search and hash-based
    search.

  * added documentation with code examples.

mdds 2.1.1

* flat_segment_tree

  * added a method that returns a segment range object compatible with ranged
    for loop.

  * added a move constructor and a move assignment operator.

  * added variants of search() and search_tree() that return a result data
    structure that contains the value, the start and end keys of the range.

* multi_type_vector

  * added a range adaptor for mdds::mtv::element_block compatible with ranged
    for loop.

mdds 2.1.0

* general

  * switched to using ax_valgrind_check for running memory tests.  This
    introduces additional build targets, such as check-valgrind to run the
    tests under valgrind.

* multi_type_vector

  * delayed_delete_vector has been introduced as the new default storage type
    for the element blocks.  This storage type is optimized for use cases
    where elements get repeatedly erased from the front of the array, by
    delaying the actual deletion of the elements until much later.  This
    reduces the amount of element shifting associated with the element
    deletions, which can be costly.

  * added an additional template parameter to the element block types in order
    to allow the underlying storage type to be specified per element type.
    This can be used to switch between std::vector, std::deque,
    delayed_delete_vector, or any other compatible custom container types.

* sorted_string_map

  * made the entry type a template parameter to allow optionally defining the
    keys in the entry values as std::string_view.

mdds 2.0.3

* general

  * defined clang-format rules, and globally applied them to all active source
    files.

* multi_type_vector

  * revised the block position lookup implementation to avoid using the
    internal STL iterators.  The new implementation should be able to handle
    invalid position hints more gracefully without potential process
    termination.

mdds 2.0.2

* multi_type_vector

  * added optional trace function that gets called on every called public
    method.

mdds 2.0.1

* general

  * addressed various coverity issues.

* multi_type_vector

  * fixed random compiler warnings.

  * fixed event handling in copy construction.  In aos, the event object was
    not copied when the parent container was copied.  In soa, the
    element_block_acquired() callback was not called for the cloned element
    blocks.

  * added move constructors and move assignment operators to both aos and soa
    variants.

mdds 2.0.0

* general

  * set the baseline C++ version to C++17.

* multi_type_vector

  * implemented structure-of-arrays (SoA) storage as its default storage
    layout for better CPU cache efficiency.

  * added multiple block position adjustment implementations with various
    loop-unrolling factors combined with SSE2 and AVX2 features.

  * added a tool called runtime-env to benchmark different block position
    adjustment implementations to determine the optimal loop-unrolling factor.

* rectangle_set

  * permanently removed.

* rtree

  * fixed a bug where the memory positions of invalidated child nodes were not
    properly updated after tree mutation.  The problem manifested itself when
    using libc++ as stdlib with clang.

mdds 1.7.0

* trie_map

  * added copy and move constructors.

  * added a variant of find() method that returns a mutable iterator object.
    The user can now update the value associated with a key directly via the
    iterator object.

* packed_trie_map

  * added copy and move constructors.

  * added load_state() and save_state() methods to allow loading state from
    and saving state to binary files.

mdds 1.6.0

* multi_type_vector

  * switched to using binary search on block position lookup, which
    significantly improves element access performance in general, at the
    expense of slight performance degradation on block shifting.

* added support for lcov, to visualize test coverage.

mdds 1.5.0

* documentation

  * moved the documentation hosting to readthedocs.io, and adjusted the build
    steps.

  * moved the API incompatibility notes from README to the rst doc.

  * added the overview section for flat_segment_tree.

* multi_type_vector

  * fixed the static get(const const_position_type& pos) method for the
    boolean_element_block, by adding specialization for it to work around the
    issue with std::vector<bool> not having the at() method.

  * fixed an issue with the const position() method not returning a valid end
    position the same way the non-const variant does.

  * added steps to traverse blocks backward from the postiion specified in the
    position hint.  This may result in improved performance in some
    situations.

  * the standard integer blocks now use fixed size integer types i.e.

    * (u)int8_t

    * (u)int16_t

    * (u)int32_t

    * (u)int64_t

  * The numeric_element_block has been renamed to double_element_block.

  * added new block type to store float element values.

* general

  * added gdb pretty printers that prints the contents of the data structures.

mdds 1.4.3

* documentation

  * added details on how to use two type of iterators with
    flat_segment_tree.

  * added new section to describe how to use mtv::collection to iterate
    through multiple multi_type_vector instances as a single collection
    in the direction orthogonal to the direction of the individual
    vectors.

  * added new page for R-tree.

* flat_segment_tree

  * fixed invalid memory access issue related to the swap() method which
    previously did not swap the non-leaf node pool store.  The invalid
    memory access may occur after the contents of two instances get
    swapped, one instance get destroyed then the caller calls
    search_tree() on the other instance still alive.

mdds 1.4.2

* all

  * fixed CXXFLAGS incorrectly being overwritten.

  * addressed a number of Coverity issues.

mdds 1.4.1

* all

  * fixed all warnings on shadowed variables.

* multi_type_matrix

  * all of its walk() methods now return either a copied or moved
    instance of the function object passed in as an input argument.
    Previously these methods had no return values.

mdds 1.4.0

* rtree (new)

  * new data structure designed for optimal storage and query
    performance on multi-dimensional spatial data.  The structure allows
    storage of both point and extent-based boundaries as keys associated
    with values.

* multi_type_vector

  * mtv::elemnt_block now has the following methods: data(), cbegin(),
    cend(), crbegin() and crend().

  * multi_type_vector now has cbegin(), cend(), crbegin(), and crend()
    methods.

  * some unnecessary user-provided special members have been removed to
    avoid warnings with -Wdeprecated-copy with GCC 9.

* multi_type_matrix

  * all of its walk() methods now allow in-line lambdas to be used, by
    not taking a reference of the function object parameters.

mdds 1.3.1

* flat_segment_tree

  * fixed a bug that caused an assertion error when inserting a
    out-of-bound segment whose start value equals the max key value.

mdds 1.3.0

* multi_type_vector

  * changed the primary block array storage to remove additional
    indirection, for improved memory locality.

mdds 1.2.3

* all

  * changed the configure script to use --docdir unmodified.

* flat_segment_tree

  * added a segment iterator whose node value consists of the start
    and end keys and the value associated with each segment.  its
    start and end positions can be retrieved via begin_segment() and
    end_segment() methods.

mdds 1.2.2

* flat_segment_tree

  * fixed a bug that would cause segmentation faults with the insert()
    method with out-of-bound segment value pair.

mdds 1.2.1

* multi_type_vector

  * added size() method to the element block type, which returns the
    actual size of the element block, instead of the cached size value
    stored in the parent structure that stores the element block.

  * fixed a double-deletion bug in the swap() method which would
    triggered when used with a managed element block.

* mtv::collection

  * fixed collection iterator's get() method to properly return values
    from the boolean element block.

mdds 1.2.0

* packed_trie_map

  * added begin() and end() methods that return read-only iterators.

  * find() method now returns a const_iterator instance.

  * prefix_search() method now returns a search_results instance that
    can be iterated.

  * null value no longer needs to be passed to the constructor.

  * find() and prefix_search() now have a variant that can take a key
    value that is of key_type directly.

* trie_map

  * added begin() and end() methods that return read-only iterators.

  * find() method now returns a const_iterator instance.

  * prefix_search() method now returns a search_results instance that
    can be iterated.

  * null value no longer needs to be passed to the constructor.

  * find(), insert, and prefix_search() now have a variant that can
    take a key value that is of key_type directly.

* sorted_string_map

  * fix build failure with _GLIBCXX_DEBUG defined.

* multi_type_vector

  * remove compiler warning about shadowed variable.

  * added a supplemental class mdds::mtv::collection which allows
    multiple multi_type_vector instances of the same length to be
    grouped together in order to iterate through their elements
    sideways.

  * a variant of advance_position() static method that takes
    const_position_type has been added.

    * const_position_type advance_position(const const_position_type& pos, int steps)

* multi_type_matrix

  * matrix_position() is now a const method.

  * the sub-matrix variant of walk() method now throws size_error
    exception when invalid start and end positions are passed.

  * slight performance improvement with the sub-matrix variant of
    walk() method that involves multiple column traversal.

  * added 2 new variants of walk() methods that allow parallel walking
    with another matrix instance.

    * template<typename _Func>
      void walk(_Func& func, const multi_type_matrix& right) const

    * template<typename _Func>
      void walk(_Func& func, const multi_type_matrix& right, const size_pair_type& start, const size_pair_type& end) const

  * improved performance of copy() and resize() methods.

  * added a variant of copy() that takes an array of values.

    * template<typename _T>
      void copy(size_type rows, size_type cols, const _T& it_begin, const _T& it_end)

  * integer type has been added to the list of types the matrix can
    store.  In conjunction with this change, what was formerly known
    as the string trait structure is now known as the matrix trait,
    which specifies the actual integer type the matrix stores.

* point_quad_tree

  * search_result has been renamed to search_results.

mdds 1.1.0

* all

  * switched our build system to using automake.

* packed_trie_map (new)

  * new data structure that implements a trie also known as a prefix
    tree.  This implementation requires all key values be known at
    construction time, after which its content is considered
    immutable.  Internally it packs all its nodes in a single
    contiguous array for space and lookup efficiencies.

* trie_map (new)

  * new data structure that implements a trie.  It works similar to
    packed_trie_map except that this version is mutable.

* multi_type_matrix

  * added a variant of walk() that takes the upper-left and
    lower-right corners to allow walking through a subset of the
    original matrix.

* multi_type_vector

  * fixed incorrect return values of the increment and decrement
    operators of in-block iterators.  They would previously return a
    value_type pointer which did not conform to the behaviors of STL
    iterators.

  * added support for custom event handlers for element block
    acquisitions and releases.

* flat_segment_tree

  * fixed incorrect return values of the increment and decrement
    operators of its leaf-node iterators as in multi_type_vector's
    fix.

* sorted_string_map

  * significantly improved the performance of its find() method by
    switching from using linear search to using binary search.  The
    improvement is especially visible with a large number of elements.

mdds 1.0.0

* all

  * introduced API versioning to ease parallel installation of API
    incompatible versions.  Version 1.0.0 will have an API versoin of
    1.0.

  * C++11 is now a hard requirement.

  * added API documentation via Doxygen, Sphinx and Breathe.

* mixed_type_matrix

  * officially removed for good in favor of multi_type_matrix.

* multi_type_vector

  * added memory usage reduction by conditionally shrinking the
    capacity of the underlying vector containers.

  * added slight performance gain by revising block adjustment policy
    during splitting of blocks.

* sorted_string_map

  * fixed a bug where a non-matching key was incorrectly returned as a
    matching key.

mdds 0.12.1

* flat_segment_tree

  * removed construction-from-int requirement from value_type to allow
    non-numeric types to be stored.

* multi_type_vector

  * added static method advance_position() to allow incrementing or
    decrementing the logical position of a position_type object:

    * position_type advance_position(const position_type& pos, int steps)

mdds 0.12.0

* segment_tree

  * removed pointer requirement from value_type to allow non-pointer
    type to be stored.

* multi_type_vector

  * fixed a bug in the equality operator method.

mdds 0.11.2

* multi_type_vector

  * fixed various memory leaks associated with the set() method when a
    value overwrites an existing element in a managed block.

mdds 0.11.1

* all

  * fixed a large number of outstanding defects reported by Coverity
    Scan.

* multi_type_vector

  * fixed 2 cases of double-free bug in the variant of swap() that
    allows segmented swapping.

mdds 0.11.0

* sorted_string_map (new)

  * new data structure to support efficient mapping of textural keys
    to numeric values when the key values are known at compile time.

* multi_type_vector

  * fixed a bug in transfer() where two adjacent blocks of identical
    type would fail to be merged in some circumstances.

  * added shrink_to_fit() to allow trimming of any excess capacity
    from all non-empty blocks.

  * fixed a double-free bug in the variant of swap() that allows
    segmented swapping.

  * improved the exception message when the block position lookup
    fails to find valid block position, to make it easier to debug.

mdds 0.10.3

* multi_type_vector

  * added 2 variants of release_range() that take start and end positions,
    to allow releasing of elements in specified interval.  One of the
    variants takes iterator as a block position hint.

    * iterator release_range(size_type start_pos, size_type end_pos)

    * iterator release_range(const iterator& pos_hint, size_type start_pos, size_type end_pos)

  * added push_back() and push_back_empty(), to allow efficient way to
    append new values to the end of the container.

    * template<typename _T>
      iterator push_back(const _T& value)

    * iterator push_back_empty()

mdds 0.10.2

* multi_type_vector

  * fixed a bug in transfer() that would trigger an assertion and
    eventually lead to a crash.  The problem occurred when a range of
    data to be transferred spanned over 2 blocks and consisted of the
    lower part of an upper block and the upper part of a lower block.

mdds 0.10.1

* multi_type_matrix

  * added a variant of set_empty() that takes an additional length
    parameter.

    * void set_empty(size_type row, size_type col, size_type length)

mdds 0.10.0

* flat_segment_tree

  * significant performance improvement on build_tree() and
    search_tree(), by optimizing the non-leaf node object generation
    and storage to achieve better locality of reference.

* segment_tree

  * slight performance improvement on build_tree(), as a result of the
    optimization done for flat_segment_tree since these two structures
    share the same tree generation code.

* multi_type_vector

  * improved debug message on mis-matched block types (only when
    MDDS_MULTI_TYPE_VECTOR_DEBUG is defined).

mdds 0.9.1

* multi_type_vector

  * added several convenience methods for position objects.

  * performance improvement on setting array values.

  * added new constructor that takes an array of values as initial
    element values.

* multi_type_matrix

  * setter methods that take a position object to also return a
    position object.

  * added several convenience methods for position objects.

  * added new constructor that takes an array of values as initial
    element values.

mdds 0.9.0

* multi_type_vector

  * added another block function template to make it easier to declare
    container with 3 custom element types.

  * added two variants of release():

    * template<typename _T> iterator
      release(size_type pos, _T& value)

    * template<typename _T> iterator
      release(const iterator& pos_hint, size_type pos, _T& value)

  * added a variant of release() that takes no arguments.  This one
    releases all elements and makes the container empty afterward.

  * added a new variant of position() that takes const_iterator as
    position hint.

    * std::pair<const_iterator, size_type>
      position(const const_iterator& pos_hint, size_type pos) const

  * fixed a memory leak in

    * set(size_type pos, const _T& it_begin, const _T& it_end).

  * added compile-time macro MDDS_MULTI_TYPE_VECTOR_USE_DEQUE to allow
    users to specify std::deque as the underlying data array.  By
    default, multi_type_vector uses std::vector as the underlying data
    array container.

  * added a new variant of swap() that allows partial swapping of
    content with another container.

  * added static block type identifier so that the numeric block type
    ID can be deduced from the block type directly.

  * value_type (which is a type of object returned when dereferencing
    an iterator) now stores 'position' which is the logical position
    of the first element of a block.

  * added position_type and const_position_type which are typedefs to
    the return types of position() methods.

* multi_type_matrix:

  * get_numeric(), get_boolean(), and get_string() are made more
    efficient.

  * added position() method that returns a reference object to an
    element (position object).

  * added variants of get_numeric(), get_boolean() and get_string()
    that retrieves elements from position objects.

  * added variants of set() that sets new element values via position
    objects.

mdds 0.8.1

* multi_type_vector

  * fixed a bug in the erase() method where adjacent blocks of the
    same type would fail to merge after the erase() call.

  * add a variant of the position() method that takes an iterator as
    positional hint.  Note that there is no variant of position() that
    takes const_iterator.

mdds 0.8.0

* all

  * added .pc file for pkg-config.

* flat_segment_tree

  * changed the return type of search_tree from bool to
    std::pair<const_iterator,bool>, to make it consistent with the
    search() method.  Note that this is an API-incompatible change.

* multi_type_vector

  * added char and unsigned char types to the standard types supported
    by default.

  * added position() member method that takes a logical element
    position and returns a pair of block iterator where the element
    resides and its offset within that block.

  * added at() static member method to the data block, which calls the
    at() method of the underlying std::vector container.

  * added release() member method to allow caller to release an object
    stored inside a managed block.

  * added two templates to ease creation of custom element block
    functions when using one or two custom element types.

  * added transfer() member method to allow elements in a specified
    range to be transferred from one container to another.  When
    transferring elements stored in a managed element block, the
    ownership of those elements is also transferred.

mdds 0.7.1

* multi_type_vector

  * fixed a bug in set_empty() where emptying a whole or partial block
    would fail to merge its adjacent block(s) even when they are also
    empty.

mdds 0.7.0

* multi_type_vector

  * add variants of set() methods (both single- and multi-value)
    insert(), set_empty() and insert_empty() methods that take an
    iterator as an additional position hint parameter for block lookup
    speed optimization.

  * add support for non-const iterators which allow the client code to
    modify values directly from the iterators.

  * set() methods (both single- and multi-parameter variants),
    set_empty(), insert() and insert_empty() methods now return
    iterator that references the block to which the values are set or
    inserted.

  * fixed bugs in set() method (single-parameter variant) which would
    insert a new block at incorrect position.

  * fixed bugs in set() method (multi-parameter variant) which would
    fail to merge neighboring blocks of identical type under certain
    conditions.

mdds 0.6.1

* all

  * use property files in the Visual Studio project files, to share
    some of the common custom build variables across all projects.

  * various build fixes and compiler warning eliminations.

  * fixed link error with boost 1.50.

  * fixed make installer script which previously would not install
    mdds/compat headers.

* flat_segment_tree

  * fixed a bug in its iterator implementation, which previously would
    always treat the last valid position before the end position as
    the end position.  This fix affects both in const_iterator and
    const_reverse_iterator.

mdds 0.6.0

* all

  * added MSVS Solution file, to make it easier to build unit test
    programs on Windows.

* mixed_type_matrix

  * improved performance of size() method by caching it.

* multi_type_vector (new)

  * new data structure to support efficient storage of data of different
    types.

* multi_type_matrix (new)

  * new data structure to eventually replace mixed_type_matrix.  It uses
    multi_type_vector as its backend storage.

mdds 0.5.4

* segment_tree

  * fixed build breakage, to allow it to be buildable when UNIT_TEST
    is not defined.

  * fixed a crasher with MSVC when comparing iterators of empty
    search_result instances.

* point_quad_tree

  * fixed a bug where de-referencing copied search_result iterators
    would return an uninitialized node data.

mdds 0.5.3

* mixed_type_matrix

  * re-implemented the filled storage for better performance, with two
    separate implementations for zero and emtpy matrix types.  The
    newer implementation should improve object creation time
    considerably.

mdds 0.5.2

* flat_segment_tree

  * fixed a crash on assignment by properly implementing assignment
    operator().

  * fixed several bugs in shift_right():

    * shifting of all existing nodes was not handled properly.

    * leaf nodes were not properly linked under certain conditions.

    * shifting with skip node option was not properly skipping the
      node at insertion position when the insertion position was at
      the leftmost node.

  * implemented min_key(), max_key(), default_value(), clear() and
    swap().

  * fixed a bug in operator==() where two different containers were
    incorrectly evaluated to be equal.

  * added quickcheck test code.

mdds 0.5.1

  * fixed build issues on Windows, using MSVC compilers.

mdds 0.5.0

  * flat_segment_tree's search methods now return a std::pair of
    const_iterator and bool, instead of just returning bool.

  * fixed a weird enum value mis-handling with mixed_type_matrix when
    compiled with MSVC++.

  * added new insert() method to flat_segment_tree that takes a
    positional hint in order to speed up insertion speed.  Also, all
    three insert() methods now return the start position of the
    segment that an inserted segment belongs to.

  * slight performance improvement on the insert methods of
    flat_segment_tree.

  * slight performance improvement on the iterators of
    flat_segment_tree.

  * re-organized the structure of flat_segment_tree to split it into
    multiple headers.

  * properly support prefix, docdir, includedir configure options.

  * support DESTDIR environment variable for make install.

mdds 0.4.0

  * implemented mixed_type_matrix.

mdds 0.3.1

  * added support for boost::unordered_map (boost) and std::hash_map
    (stlport) in addition to C++0x's std::unordered_map.

mdds 0.3.0

  * implemented point_quad_tree.

mdds 0.2.1

  * added example files on how to use these data structures.

  * fixed a bug in segment_tree::search_result object, to make it work
    with empty result set.

  * fixed segment_tree to make it really usable outside of unit test
    code.

mdds 0.2.0

  * other general performance improvements.

  * lots of code cleanups.

  * support for search result iterator in segment_tree and
    rectangle_set, for better search performance.

  * implemented rectnagle_set.

  * fixed lots of bugs in the segment_tree implementation.

mdds 0.1.2

  * implemented segment_tree.

  * node_base class is now without virtual methods to avoid vtable
    generation.