Roland Conybeare
d1fa15f248
git-subtree-dir: xo-unit git-subtree-mainline:e9ee6992cagit-subtree-split:b531e382c2
129 lines
3.2 KiB
ReStructuredText
129 lines
3.2 KiB
ReStructuredText
.. _bu-store-class:
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Basis Unit Store
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================
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.. ditaa::
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:--scale: 0.85
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+----------------+---------------+
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| quantity | xquantity |
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+----------------+---------------+
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| scaled_unit |
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+--------------------------------+
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| natural_unit |
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+--------------------------------+
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| bpu |
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+----------------+ |
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|cBLU bu_store | |
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+----------------+---------------+
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| basis_unit |
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+--------------------------------+
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| dimension |
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+--------------------------------+
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.. code-block:: cpp
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#include <xo/unit/bu_store.hpp>
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namespace bu = xo::qty::detail::bu;
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A :code:`xo::qty::bu_store` is a small, constexpr, key-value store associating
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abbreviations with basis units. To satisfy the constexpr requirement,
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all unit abbreviations are irrevocably established from ``bu_store``'s constructor.
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The constant ``bu_abbrev_store`` contains a single instance of ``bu_store``,
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recording all built-in units along with their associated abbreviations
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.. uml::
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:caption: basis-unit store
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:scale: 99%
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:align: center
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map mass_table<<bu_dim_store>> {
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bu::milligram => "mg"
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bu::gram => "g"
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bu::kilogram => "kg"
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}
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map distance_table<<bu_dim_store>> {
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bu::millimeter => "mm"
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bu::meter => "m"
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bu::kilometer => "km"
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}
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map time_table<<bu_dim_store>> {
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bu::millisecond => "ms"
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bu::second => "s"
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bu::minute => "min"
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bu::hour => "hr"
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}
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object bu_abbrev_store<<bu_store>>
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bu_abbrev_store : bu_abbrev_vv[dim::mass] = mass_table
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bu_abbrev_store : bu_abbrev_vv[dim::distance] = distance_table
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bu_abbrev_store : bu_abbrev_vv[dim::time] = time_table
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bu_abbrev_store o-- mass_table
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bu_abbrev_store o-- distance_table
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bu_abbrev_store o-- time_table
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This class exists to support the implementation of ``natural_unit::abbrev()``.
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Application code is not expected to interact directly with it.
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Class
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-----
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.. doxygenclass:: xo::qty::detail::bu_store
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For example, this would be possible:
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.. code-block:: cpp
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#include <xo/unit/bu_store.hpp>
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namespace bu = using xo::qty::detail::bu;
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using xo::qty::detail::bu_store;
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using xo::qty::dim;
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using xo::flatstring;
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constexpr bu_store store;
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static_assert(store.bu_abbrev(bu::minute) == flatstring("min"));
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static_assert(store.bu_abbrev(bu::microgram) == flatstring("ug"));
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.. doxygengroup:: bu-store-constructors
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.. doxygengroup:: bu-store-access-methods
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.. doxygengroup:: bu-store-implementation-methods
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.. doxygenclass:: xo::qty::detail::bu_dim_store
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.. doxygengroup:: bu-dim-store-type-traits
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.. doxygengroup:: bu-dim-store-instance-vars
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Constants
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---------
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Provides dictionary of unit abbreviations
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Application code is not expected to interact directly with ``bu_abbrev_store``.
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.. doxygenvariable:: xo::qty::bu_abbrev_store
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Functions
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---------
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.. doxygenfunction:: xo::qty::bu_abbrev
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For example:
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.. code-block:: cpp
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#include <xo/unit/bu_store.hpp>
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namespace bu = xo::qty::bu;
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using xo::qty::bu_abbrev;
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using xo::flatstring;
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static_assert(bu_abbrev(bu::kilogram) == xo::flatstring("kg"));
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