forked from OSchip/llvm-project
60 lines
1.3 KiB
ReStructuredText
60 lines
1.3 KiB
ReStructuredText
.. title:: clang-tidy - performance-inefficient-string-concatenation
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performance-inefficient-string-concatenation
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============================================
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This check warns about the performance overhead arising from concatenating
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strings using the ``operator+``, for instance:
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.. code-block:: c++
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std::string a("Foo"), b("Bar");
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a = a + b;
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Instead of this structure you should use ``operator+=`` or ``std::string``'s
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(``std::basic_string``) class member function ``append()``. For instance:
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.. code-block:: c++
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std::string a("Foo"), b("Baz");
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for (int i = 0; i < 20000; ++i) {
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a = a + "Bar" + b;
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}
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Could be rewritten in a greatly more efficient way like:
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.. code-block:: c++
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std::string a("Foo"), b("Baz");
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for (int i = 0; i < 20000; ++i) {
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a.append("Bar").append(b);
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}
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And this can be rewritten too:
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.. code-block:: c++
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void f(const std::string&) {}
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std::string a("Foo"), b("Baz");
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void g() {
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f(a + "Bar" + b);
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}
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In a slightly more efficient way like:
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.. code-block:: c++
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void f(const std::string&) {}
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std::string a("Foo"), b("Baz");
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void g() {
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f(std::string(a).append("Bar").append(b));
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}
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Options
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-------
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.. option:: StrictMode
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When zero, the check will only check the string usage in ``while``, ``for``
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and ``for-range`` statements. Default is `0`.
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