Disabled 'is_palindrome' for 'const char*'

This commit is contained in:
Alexander Zaitsev
2016-08-15 04:09:48 +03:00
parent 4fcb7afa84
commit 774fb437f3
2 changed files with 18 additions and 0 deletions

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@ -79,6 +79,8 @@ All of the variants of `is_palindrome` take their parameters by value or const r
* If you use version of 'is_palindrome' without custom predicate, 'is_palindrome' uses default 'operator==' for elements. If you want use custom predicate, you must redefine 'operator=='. * If you use version of 'is_palindrome' without custom predicate, 'is_palindrome' uses default 'operator==' for elements. If you want use custom predicate, you must redefine 'operator=='.
* Don't use 'const char*' with 'is_palindrome', because 'const char*' is always non-palindromic ('\0' at the end). If you will try to compile 'is_palindrome' with 'const char*', you will get an error.
[endsect] [endsect]
[/ File is_palindrome.qbk [/ File is_palindrome.qbk

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@ -102,6 +102,22 @@ bool is_palindrome(const R& range, Predicate p)
return is_palindrome(boost::begin(range), boost::end(range), p); return is_palindrome(boost::begin(range), boost::end(range), p);
} }
//Disable is_palindrome for const char* because it work not properly.
//Please use string_view for const char* cases.
//Here we use dirty hack to disable 'is_palindrome' with 'const char*'
//URL: http://stackoverflow.com/questions/14637356/static-assert-fails-compilation-even-though-template-function-is-called-nowhere
template<typename T>
struct foobar : std::false_type
{ };
template<typename T = int>
bool is_palindrome(const char* str)
{
static_assert(foobar<T>::value, "Using 'is_palindrome' for 'const char*' is dangerous, because result is always false"
"(reason: '\0' in the end of the string). You can use string_view in this case");
return false;
}
}} }}
#endif // BOOST_ALGORITHM_IS_PALINDROME_HPP #endif // BOOST_ALGORITHM_IS_PALINDROME_HPP