substring_checks.h

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#ifndef GUL17_SUBSTRING_CHECKS_H_
#define GUL17_SUBSTRING_CHECKS_H_
 
#include <string_view>
 
#include "gul17/case_ascii.h"
#include "gul17/internal.h"
 
namespace gul17 {
 
constexpr inline bool contains(std::string_view haystack, std::string_view needle) noexcept
{
    return haystack.find(needle) != std::string_view::npos;
}
 
constexpr inline bool contains(std::string_view haystack, char needle) noexcept
{
    return haystack.find(needle) != std::string_view::npos;
}
 
constexpr inline bool ends_with(std::string_view str, std::string_view suffix) noexcept
{
    const auto hsl = str.length();
    const auto sl = suffix.length();
 
    return hsl >= sl && str.compare(hsl - sl, sl, suffix) == 0;
}
 
constexpr inline bool ends_with(std::string_view str, char c) noexcept
{
    return !str.empty() && str.back() == c;
}
 
constexpr inline bool starts_with(std::string_view str, std::string_view prefix) noexcept
{
    const auto hsl = str.length();
    const auto hl = prefix.length();
 
    return hsl >= hl && std::string_view{ str.data(), hl }.compare(prefix) == 0;
}
 
constexpr inline bool starts_with(std::string_view str, char c) noexcept
{
    return !str.empty() && str.front() == c;
}
 
//
// Case insensitive std::variants following
//
 
constexpr inline bool equals_nocase(std::string_view str1, std::string_view str2) noexcept
{
    if (str1.size() != str2.size())
        return false;
 
    // Hand-rolled version of std::equal() to maintain constexprness prior to C++20
    auto it1 = str1.cbegin();
    auto it2 = str2.cbegin();
 
    while (it1 != str1.cend())
    {
        if (lowercase_ascii(*it1) != lowercase_ascii(*it2))
            return false;
 
        ++it1;
        ++it2;
    }
 
    return true;
}
 
constexpr inline bool contains_nocase(std::string_view haystack, std::string_view needle) noexcept
{
    auto const haysize = haystack.size();
    auto const needlesize = needle.size();
    if (haysize < needlesize)
        return false;
    for (std::size_t i = 0; i <= haysize - needlesize; ++i) {
        auto j = needlesize;
        while (j-- > 0) {
            if (lowercase_ascii(haystack[j]) != lowercase_ascii(needle[j]))
                break;
        }
        if (j == std::size_t(-1)) {
            return true;
        }
        haystack.remove_prefix(1);
    }
    return false;
}
 
constexpr inline bool contains_nocase(std::string_view haystack, char needle) noexcept
{
    needle = lowercase_ascii(needle);
    while (not haystack.empty()) {
        if (lowercase_ascii(haystack.front()) == needle)
            return true;
        haystack.remove_prefix(1);
    }
    return false;
}
 
constexpr inline bool ends_with_nocase(std::string_view str, std::string_view suffix) noexcept
{
    while (not str.empty()) {
        if (suffix.empty())
            return true;
        if (lowercase_ascii(str.back()) != lowercase_ascii(suffix.back()))
            return false;
        str.remove_suffix(1);
        suffix.remove_suffix(1);
    }
    return suffix.empty();
}
 
constexpr inline bool ends_with_nocase(std::string_view str, char c) noexcept
{
    return !str.empty() && lowercase_ascii(str.back()) == lowercase_ascii(c);
}
 
constexpr inline bool starts_with_nocase(std::string_view str, std::string_view prefix) noexcept
{
    while (not str.empty()) {
        if (prefix.empty())
            return true;
        if (lowercase_ascii(str.front()) != lowercase_ascii(prefix.front()))
            return false;
        str.remove_prefix(1);
        prefix.remove_prefix(1);
    }
    return prefix.empty();
}
 
constexpr inline bool starts_with_nocase(std::string_view str, char c) noexcept
{
    return !str.empty() && lowercase_ascii(str.front()) == lowercase_ascii(c);
}
 
 
} // namespace gul17
 
#endif
 
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