forked from OSchip/llvm-project
50 lines
1.4 KiB
ReStructuredText
50 lines
1.4 KiB
ReStructuredText
.. title:: clang-tidy - performance-inefficient-vector-operation
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performance-inefficient-vector-operation
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========================================
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Finds possible inefficient ``std::vector`` operations (e.g. ``push_back``,
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``emplace_back``) that may cause unnecessary memory reallocations.
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Currently, the check only detects following kinds of loops with a single
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statement body:
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* Counter-based for loops start with 0:
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.. code-block:: c++
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std::vector<int> v;
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for (int i = 0; i < n; ++i) {
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v.push_back(n);
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// This will trigger the warning since the push_back may cause multiple
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// memory reallocations in v. This can be avoid by inserting a 'reserve(n)'
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// statement before the for statement.
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}
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* For-range loops like ``for (range-declaration : range_expression)``, the type
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of ``range_expression`` can be ``std::vector``, ``std::array``,
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``std::deque``, ``std::set``, ``std::unordered_set``, ``std::map``,
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``std::unordered_set``:
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.. code-block:: c++
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std::vector<int> data;
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std::vector<int> v;
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for (auto element : data) {
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v.push_back(element);
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// This will trigger the warning since the 'push_back' may cause multiple
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// memory reallocations in v. This can be avoid by inserting a
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// 'reserve(data.size())' statement before the for statement.
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}
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Options
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-------
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.. option:: VectorLikeClasses
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Semicolon-separated list of names of vector-like classes. By default only
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``::std::vector`` is considered.
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