catch2/include/internal/catch_stringref.h

/*
 *  Copyright 2016 Two Blue Cubes Ltd. All rights reserved.
 *
 *  Distributed under the Boost Software License, Version 1.0. (See accompanying
 *  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 */
#ifndef CATCH_STRINGREF_H_INCLUDED
#define CATCH_STRINGREF_H_INCLUDED

#include <cstddef>
#include <string>
#include <iosfwd>
#include <cassert>

namespace Catch {

    /// A non-owning string class (similar to the forthcoming std::string_view)
    /// Note that, because a StringRef may be a substring of another string,
    /// it may not be null terminated. c_str() must return a null terminated
    /// string, however, and so the StringRef will internally take ownership
    /// (taking a copy), if necessary. In theory this ownership is not externally
    /// visible - but it does mean (substring) StringRefs should not be shared between
    /// threads.
    class StringRef {
    public:
        using size_type = std::size_t;
        using const_iterator = const char*;

    private:
        friend struct StringRefTestAccess;

        char const* m_start;
        size_type m_size;

        char* m_data = nullptr;

        void takeOwnership();

        static constexpr char const* const s_empty = "";

    public: // construction/ assignment
        StringRef() noexcept
        :   StringRef( s_empty, 0 )
        {}

        StringRef( StringRef const& other ) noexcept
        :   m_start( other.m_start ),
            m_size( other.m_size )
        {}

        StringRef( StringRef&& other ) noexcept
        :   m_start( other.m_start ),
            m_size( other.m_size ),
            m_data( other.m_data )
        {
            other.m_data = nullptr;
        }

        StringRef( char const* rawChars ) noexcept;

        StringRef( char const* rawChars, size_type size ) noexcept
        :   m_start( rawChars ),
            m_size( size )
        {}

        StringRef( std::string const& stdString ) noexcept
        :   m_start( stdString.c_str() ),
            m_size( stdString.size() )
        {}

        ~StringRef() noexcept {
            delete[] m_data;
        }

        auto operator = ( StringRef const &other ) noexcept -> StringRef& {
            delete[] m_data;
            m_data = nullptr;
            m_start = other.m_start;
            m_size = other.m_size;
            return *this;
        }

        explicit operator std::string() const {
            return std::string(m_start, m_size);
        }

        void swap( StringRef& other ) noexcept;

    public: // operators
        auto operator == ( StringRef const& other ) const noexcept -> bool;
        auto operator != ( StringRef const& other ) const noexcept -> bool;

        auto operator[] ( size_type index ) const noexcept -> char {
            assert(index < m_size);
            return m_start[index];
        }

    public: // named queries
        auto empty() const noexcept -> bool {
            return m_size == 0;
        }
        auto size() const noexcept -> size_type {
            return m_size;
        }

        auto c_str() const -> char const*;

    public: // substrings and searches
        auto substr( size_type start, size_type size ) const noexcept -> StringRef;

        // Returns the current start pointer.
        // Note that the pointer can change when if the StringRef is a substring
        auto currentData() const noexcept -> char const*;

    public: // iterators
        const_iterator begin() const { return m_start; }
        const_iterator end() const { return m_start + m_size; }

    private: // ownership queries - may not be consistent between calls
        auto isOwned() const noexcept -> bool;
        auto isSubstring() const noexcept -> bool;
    };

    auto operator += ( std::string& lhs, StringRef const& sr ) -> std::string&;
    auto operator << ( std::ostream& os, StringRef const& sr ) -> std::ostream&;


    inline auto operator "" _sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
        return StringRef( rawChars, size );
    }

} // namespace Catch

inline auto operator "" _catch_sr( char const* rawChars, std::size_t size ) noexcept -> Catch::StringRef {
    return Catch::StringRef( rawChars, size );
}

#endif // CATCH_STRINGREF_H_INCLUDED