projects / ceph.git / blame
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|---|---|---|
| 7c673cae FG |
1 | .. Sequences/Concepts//Forward Sequence |10 |
| 2 | ||
| 3 | Forward Sequence | |
| 4 | ================ | |
| 5 | ||
| 6 | Description | |
| 7 | ----------- | |
| 8 | ||
| 9 | A |Forward Sequence| is an MPL concept representing a compile-time sequence of | |
| 10 | elements. Sequence elements are | |
| 11 | types, and are accessible through |iterators|. The |begin| and |end| metafunctions | |
| 12 | provide iterators delimiting the range of the sequence | |
| 13 | elements. A sequence guarantees that its elements are arranged in a definite, | |
| 14 | but possibly unspecified, order. Every MPL sequence is a |Forward Sequence|. | |
| 15 | ||
| 16 | Definitions | |
| 17 | ----------- | |
| 18 | ||
| 19 | * The *size* of a sequence is the number of elements it contains. The size is a | |
| 20 | nonnegative number. | |
| 21 | ||
| 22 | * A sequence is *empty* if its size is zero. | |
| 23 | ||
| 24 | ||
| 25 | Expression requirements | |
| 26 | ----------------------- | |
| 27 | ||
| 28 | For any |Forward Sequence| ``s`` the following expressions must be valid: | |
| 29 | ||
| 30 | +---------------------------+-----------------------------------+---------------------------+ | |
| 31 | | Expression | Type | Complexity | | |
| 32 | +===========================+===================================+===========================+ | |
| 33 | | ``begin<s>::type`` | |Forward Iterator| | Amortized constant time | | |
| 34 | +---------------------------+-----------------------------------+---------------------------+ | |
| 35 | | ``end<s>::type`` | |Forward Iterator| | Amortized constant time | | |
| 36 | +---------------------------+-----------------------------------+---------------------------+ | |
| 37 | | ``size<s>::type`` | |Integral Constant| | Unspecified | | |
| 38 | +---------------------------+-----------------------------------+---------------------------+ | |
| 39 | | ``empty<s>::type`` | Boolean |Integral Constant| | Constant time | | |
| 40 | +---------------------------+-----------------------------------+---------------------------+ | |
| 41 | | ``front<s>::type`` | Any type | Amortized constant time | | |
| 42 | +---------------------------+-----------------------------------+---------------------------+ | |
| 43 | ||
| 44 | ||
| 45 | Expression semantics | |
| 46 | -------------------- | |
| 47 | ||
| 48 | +---------------------------+-----------------------------------------------------------------------+ | |
| 49 | | Expression | Semantics | | |
| 50 | +===========================+=======================================================================+ | |
| 51 | | ``begin<s>::type`` | An iterator to the first element of the sequence; see |begin|. | | |
| 52 | +---------------------------+-----------------------------------------------------------------------+ | |
| 53 | | ``end<s>::type`` | A past-the-end iterator to the sequence; see |end|. | | |
| 54 | +---------------------------+-----------------------------------------------------------------------+ | |
| 55 | | ``size<s>::type`` | The size of the sequence; see |size|. | | |
| 56 | +---------------------------+-----------------------------------------------------------------------+ | |
| 57 | | ``empty<s>::type`` | |true if and only if| the sequence is empty; see |empty|. | | |
| 58 | +---------------------------+-----------------------------------------------------------------------+ | |
| 59 | | ``front<s>::type`` | The first element in the sequence; see |front|. | | |
| 60 | +---------------------------+-----------------------------------------------------------------------+ | |
| 61 | ||
| 62 | ||
| 63 | Invariants | |
| 64 | ---------- | |
| 65 | ||
| 66 | For any |Forward Sequence| ``s`` the following invariants always hold: | |
| 67 | ||
| 68 | * [``begin<s>::type``, ``end<s>::type``) is always a valid range. | |
| 69 | ||
| 70 | * An algorithm that iterates through the range [``begin<s>::type``, ``end<s>::type``) | |
| 71 | will pass through every element of ``s`` exactly once. | |
| 72 | ||
| 73 | * ``begin<s>::type`` is identical to ``end<s>::type`` if and only if ``s`` is empty. | |
| 74 | ||
| 75 | * Two different iterations through ``s`` will access its elements in the same order. | |
| 76 | ||
| 77 | ||
| 78 | Models | |
| 79 | ------ | |
| 80 | ||
| 81 | * |vector| | |
| 82 | * |map| | |
| 83 | * |range_c| | |
| 84 | * |iterator_range| | |
| 85 | * |filter_view| | |
| 86 | ||
| 87 | See also | |
| 88 | -------- | |
| 89 | ||
| 90 | |Sequences|, |Bidirectional Sequence|, |Forward Iterator|, |begin| / |end|, |size|, |empty|, |front| | |
| 91 | ||
| 92 | ||
| 93 |