Merge pull request #218 from annagrin/dev/annagrin/string_span_fixes

Dev/annagrin/string span fixes

include/span.h

@@ -52,7 +52,7 @@
 #define GSL_MSVC_NO_SUPPORT_FOR_MOVE_CTOR_DEFAULT
 
 // noexcept is not understood 
-#ifndef GSL_THROWS_ON_CONTRACT_VIOLATION
+#ifndef GSL_THROW_ON_CONTRACT_VIOLATION
 #pragma push_macro("noexcept")
 #define noexcept /* nothing */
 #endif

include/string_span.h

@@ -20,18 +20,41 @@
 #define GSL_STRING_SPAN_H
 
 #include "gsl_assert.h"
+#include "gsl_util.h"
 #include "span.h"
 #include <cstring>
 
-// VS 2013 workarounds
 #ifdef _MSC_VER
+
+// No MSVC does constexpr fully yet
+#pragma push_macro("constexpr")
+#define constexpr /* nothing */
+
+// VS 2013 workarounds
 #if _MSC_VER <= 1800
 
 #define GSL_MSVC_HAS_TYPE_DEDUCTION_BUG
 
+// noexcept is not understood
+#ifndef GSL_THROW_ON_CONTRACT_VIOLATION
+#pragma push_macro("noexcept")
+#define noexcept /* nothing */
+#endif
+
 #endif // _MSC_VER <= 1800
 #endif // _MSC_VER
 
+// In order to test the library, we need it to throw exceptions that we can catch
+#ifdef GSL_THROW_ON_CONTRACT_VIOLATION
+
+#ifdef _MSC_VER
+#pragma push_macro("noexcept")
+#endif
+
+#define noexcept /* nothing */
+
+#endif // GSL_THROW_ON_CONTRACT_VIOLATION
+
 namespace gsl
 {
 //
@@ -56,13 +79,364 @@ using zstring = char*;
 template<std::ptrdiff_t Extent = dynamic_range>
 using wzstring = wchar_t*;
 
+//
+// ensure_sentinel()
+//
+// Provides a way to obtain an span from a contiguous sequence
+// that ends with a (non-inclusive) sentinel value.
+//
+// Will fail-fast if sentinel cannot be found before max elements are examined.
+//
+template<typename T, const T Sentinel>
+span<T, dynamic_range> ensure_sentinel(T* seq, std::ptrdiff_t max = PTRDIFF_MAX)
+{
+    auto cur = seq;
+    while ((cur - seq) < max && *cur != Sentinel) ++cur;
+    Ensures(*cur == Sentinel);
+    return{ seq, cur - seq };
+}
+
+
+//
+// ensure_z - creates a span for a czstring or cwzstring.
+// Will fail fast if a null-terminator cannot be found before
+// the limit of size_type.
+//
+template<typename T>
+inline span<T, dynamic_range> ensure_z(T* const & sz, std::ptrdiff_t max = PTRDIFF_MAX)
+{
+    return ensure_sentinel<T, 0>(sz, max);
+}
+
+// TODO (neilmac) there is probably a better template-magic way to get the const and non-const overloads to share an implementation
+inline span<char, dynamic_range> ensure_z(char* const& sz, std::ptrdiff_t max)
+{
+    auto len = strnlen(sz, max);
+    Ensures(sz[len] == 0);
+    return{ sz, static_cast<std::ptrdiff_t>(len) };
+}
+
+inline span<const char, dynamic_range> ensure_z(const char* const& sz, std::ptrdiff_t max)
+{
+    auto len = strnlen(sz, max);
+    Ensures(sz[len] == 0);
+    return{ sz, static_cast<std::ptrdiff_t>(len) };
+}
+
+inline span<wchar_t, dynamic_range> ensure_z(wchar_t* const& sz, std::ptrdiff_t max)
+{
+    auto len = wcsnlen(sz, max);
+    Ensures(sz[len] == 0);
+    return{ sz, static_cast<std::ptrdiff_t>(len) };
+}
+
+inline span<const wchar_t, dynamic_range> ensure_z(const wchar_t* const& sz, std::ptrdiff_t max)
+{
+    auto len = wcsnlen(sz, max);
+    Ensures(sz[len] == 0);
+    return{ sz, static_cast<std::ptrdiff_t>(len) };
+}
+
+template<typename T, size_t N>
+span<T, dynamic_range> ensure_z(T(&sz)[N]) { return ensure_z(&sz[0], static_cast<std::ptrdiff_t>(N)); }
+
+template<class Cont>
+span<typename std::remove_pointer<typename Cont::pointer>::type, dynamic_range> ensure_z(Cont& cont)
+{
+    return ensure_z(cont.data(), static_cast<std::ptrdiff_t>(cont.length()));
+}
+
+template<typename CharT, std::ptrdiff_t>
+class basic_string_span;
+
+namespace details
+{
+    template <typename T>
+    struct is_basic_string_span_oracle : std::false_type
+    {};
+
+    template <typename CharT, std::ptrdiff_t Extent>
+    struct is_basic_string_span_oracle<basic_string_span<CharT, Extent>> : std::true_type
+    {};
+
+    template <typename T>
+    struct is_basic_string_span : is_basic_string_span_oracle<std::remove_cv_t<T>>
+    {};
+
+    template <typename T>
+    struct length_func
+    {};
+
+    template <>
+    struct length_func<char>
+    {
+        std::ptrdiff_t operator()(char* const ptr, std::ptrdiff_t length) noexcept
+        {
+            return narrow_cast<std::ptrdiff_t>(strnlen(ptr, length));
+        }
+    };
+
+    template <>
+    struct length_func<wchar_t>
+    {
+        std::ptrdiff_t operator()(wchar_t* const ptr, std::ptrdiff_t length) noexcept
+        {
+            return narrow_cast<std::ptrdiff_t>(wcsnlen(ptr, length));
+        }
+    };
+
+    template <>
+    struct length_func<const char>
+    {
+        std::ptrdiff_t operator()(const char* const ptr, std::ptrdiff_t length) noexcept
+        {
+            return narrow_cast<std::ptrdiff_t>(strnlen(ptr, length));
+        }
+    };
+
+    template <>
+    struct length_func<const wchar_t>
+    {
+        std::ptrdiff_t operator()(const wchar_t* const ptr, std::ptrdiff_t length) noexcept
+        {
+            return narrow_cast<std::ptrdiff_t>(wcsnlen(ptr, length));
+        }
+    };
+}
+
+
 //
 // string_span and relatives
 //
 // Note that Extent is always single-dimension only
 //
-template <class CharT, std::ptrdiff_t Extent = dynamic_range>
+template <typename CharT, std::ptrdiff_t Extent = dynamic_range>
-using basic_string_span = span<CharT, Extent>;
+class basic_string_span
+{
+    using value_type = CharT;
+    using const_value_type = std::add_const_t<value_type>;
+    using pointer = std::add_pointer_t<value_type>;
+    using reference = std::add_lvalue_reference_t<value_type>;
+    using const_reference = std::add_lvalue_reference_t<const_value_type>;
+    using bounds_type = static_bounds<Extent>;
+    using impl_type = span<value_type, Extent>;
+
+public:
+    using size_type = ptrdiff_t;
+    using iterator = typename impl_type::iterator;
+    using const_iterator = typename impl_type::const_iterator;
+    using reverse_iterator = typename impl_type::reverse_iterator;
+    using const_reverse_iterator = typename impl_type::const_reverse_iterator;
+
+    // default (empty)
+    constexpr basic_string_span() = default;
+
+    // copy
+    constexpr basic_string_span(const basic_string_span& other) = default;
+
+    // move
+    constexpr basic_string_span(basic_string_span&& other) = default;
+
+    // assign
+    constexpr basic_string_span& operator=(const basic_string_span& other) = default;
+
+    // move assign
+    constexpr basic_string_span& operator=(basic_string_span&& other) = default;
+
+    // from nullptr and length
+    constexpr basic_string_span(std::nullptr_t ptr, size_type length) noexcept
+        : span_(ptr, length)
+    {}
+
+    // For pointers and static arrays - if 0-terminated, remove 0 from the view
+
+    // from raw data and length
+    constexpr basic_string_span(pointer ptr, size_type length) noexcept
+        : span_(remove_z(ptr, length))
+    {}
+
+    // from static arrays and string literals
+    template<size_t N>
+    constexpr basic_string_span(value_type(&arr)[N]) noexcept
+        : span_(remove_z(arr))
+    {}
+
+    // Those allow 0s within the length, so we do not remove them
+
+    // from string
+    constexpr basic_string_span(std::string& s) noexcept
+        : span_(&(s.at(0)), narrow_cast<std::ptrdiff_t>(s.length()))
+    {}
+
+    // from containers. Containers must have .size() and .data() function signatures
+    template <typename Cont, typename DataType = typename Cont::value_type,
+        typename Dummy = std::enable_if_t<!details::is_span<Cont>::value
+        && !details::is_basic_string_span<Cont>::value
+        && !(!std::is_const<value_type>::value && std::is_const<Cont>::value) // no converting const containers to non-const span
+        && std::is_convertible<DataType*, value_type*>::value
+        && std::is_same<std::decay_t<decltype(std::declval<Cont>().size(), *std::declval<Cont>().data())>, DataType>::value>
+    >
+    constexpr basic_string_span(Cont& cont)
+        : span_(cont.data(), cont.size())
+    {}
+
+    // disallow creation from temporary containers and strings
+    template <typename Cont, typename DataType = typename Cont::value_type,
+        typename Dummy = std::enable_if_t<!details::is_span<Cont>::value
+        && !details::is_basic_string_span<Cont>::value
+        && std::is_convertible<DataType*, value_type*>::value
+        && std::is_same<std::decay_t<decltype(std::declval<Cont>().size(), *std::declval<Cont>().data())>, DataType>::value>
+    >
+    basic_string_span(Cont&& cont) = delete;
+
+    // from span
+    template <typename OtherValueType, std::ptrdiff_t OtherExtent,
+        typename OtherBounds = static_bounds<OtherExtent>,
+        typename Dummy = std::enable_if_t<std::is_convertible<OtherValueType*, value_type*>::value && std::is_convertible<OtherBounds, bounds_type>::value>
+    >
+    constexpr basic_string_span(span<OtherValueType, OtherExtent> other) noexcept
+        : span_(other)
+    {}
+
+    // from string_span
+    template <typename OtherValueType, std::ptrdiff_t OtherExtent,
+        typename OtherBounds = static_bounds<OtherExtent>,
+        typename Dummy = std::enable_if_t<std::is_convertible<OtherValueType*, value_type*>::value && std::is_convertible<OtherBounds, bounds_type>::value>
+    >
+    constexpr basic_string_span(basic_string_span<OtherValueType, OtherExtent> other) noexcept
+        : span_(other.data(), other.length())
+    {}
+
+    constexpr bool empty() const noexcept
+    {
+        return length() == 0;
+    }
+
+    // first Count elements
+    template<size_type Count>
+    constexpr basic_string_span<value_type, Count> first() const noexcept
+    {
+        return{ span_.template first<Count>() };
+    }
+
+    constexpr basic_string_span<value_type, dynamic_range> first(size_type count) const noexcept
+    {
+        return{ span_.first(count) };
+    }
+
+    // last Count elements
+    template<size_type Count>
+    constexpr basic_string_span<value_type, Count> last() const noexcept
+    {
+        return{ span_.template last<Count>() };
+    }
+
+    constexpr basic_string_span<value_type, dynamic_range> last(size_type count) const noexcept
+    {
+        return{ span_.last(count) };
+    }
+
+    // create a subview of Count elements starting from Offset
+    template<size_type Offset, size_type Count>
+    constexpr basic_string_span<value_type, Count> subspan() const noexcept
+    {
+        return{ span_.template subspan<Offset, Count>() };
+    }
+
+    constexpr basic_string_span<value_type, dynamic_range> subspan(size_type offset, size_type count = dynamic_range) const noexcept
+    {
+        return{ span_.subspan(offset, count) };
+    }
+
+    constexpr reference operator[](size_type idx) const noexcept
+    {
+        return span_[idx];
+    }
+
+    constexpr pointer data() const noexcept
+    {
+        return span_.data();
+    }
+
+    // length of the span in elements
+    constexpr size_type length() const noexcept
+    {
+        return span_.size();
+    }
+
+    // length of the span in elements
+    constexpr size_type size() const noexcept
+    {
+        return span_.size();
+    }
+
+    // length of the span in bytes
+    constexpr size_type size_bytes() const noexcept
+    {
+        return span_.size_bytes();
+    }
+
+    // length of the span in bytes
+    constexpr size_type length_bytes() const noexcept
+    {
+        return span_.length_bytes();
+    }
+
+    constexpr iterator begin() const noexcept
+    {
+        return span_.begin();
+    }
+
+    constexpr iterator end() const noexcept
+    {
+        return span_.end();
+    }
+
+    constexpr const_iterator cbegin() const noexcept
+    {
+        return span_.cbegin();
+    }
+
+    constexpr const_iterator cend() const noexcept
+    {
+        span_.cend();
+    }
+
+    constexpr reverse_iterator rbegin() const noexcept
+    {
+        return span_.rbegin();
+    }
+
+    constexpr reverse_iterator rend() const noexcept
+    {
+        return span_.rend();
+    }
+
+    constexpr const_reverse_iterator crbegin() const noexcept
+    {
+        return span_.crbegin();
+    }
+
+    constexpr const_reverse_iterator crend() const noexcept
+    {
+        return span_.crend();
+    }
+
+private:
+
+    static impl_type remove_z(pointer const& sz, std::ptrdiff_t max) noexcept
+    {
+        return{ sz, details::length_func<value_type>()(sz, max)};
+    }
+
+    template<size_t N>
+    static impl_type remove_z(value_type(&sz)[N]) noexcept
+    {
+        return remove_z(&sz[0], narrow_cast<std::ptrdiff_t>(N));
+    }
+
+    impl_type span_;
+};
 
 template<std::ptrdiff_t Extent = dynamic_range>
 using string_span = basic_string_span<char, Extent>;
@@ -76,77 +450,12 @@ using wstring_span = basic_string_span<wchar_t, Extent>;
 template<std::ptrdiff_t Extent = dynamic_range>
 using cwstring_span = basic_string_span<const wchar_t, Extent>;
 
-
-//
-// ensure_sentinel() 
-//
-// Provides a way to obtain an span from a contiguous sequence
-// that ends with a (non-inclusive) sentinel value.
-//
-// Will fail-fast if sentinel cannot be found before max elements are examined.
-//
-template<class T, const T Sentinel>
-span<T, dynamic_range> ensure_sentinel(const T* seq, std::ptrdiff_t max = PTRDIFF_MAX)
-{
-    auto cur = seq;
-    while ((cur - seq) < max && *cur != Sentinel) ++cur;
-    Ensures(*cur == Sentinel);
-    return{ seq, cur - seq };
-}
-
-
-//
-// ensure_z - creates a string_span for a czstring or cwzstring.
-// Will fail fast if a null-terminator cannot be found before
-// the limit of size_type.
-//
-template<class T>
-inline basic_string_span<T, dynamic_range> ensure_z(T* const & sz, std::ptrdiff_t max = PTRDIFF_MAX)
-{
-    return ensure_sentinel<T, 0>(sz, max);
-}
-
-// TODO (neilmac) there is probably a better template-magic way to get the const and non-const overloads to share an implementation
-inline basic_string_span<char, dynamic_range> ensure_z(char* const& sz, std::ptrdiff_t max)
-{
-    auto len = strnlen(sz, max);
-    Ensures(sz[len] == 0);
-    return{ sz, static_cast<std::ptrdiff_t>(len) };
-}
-
-inline basic_string_span<const char, dynamic_range> ensure_z(const char* const& sz, std::ptrdiff_t max)
-{
-    auto len = strnlen(sz, max);
-    Ensures(sz[len] == 0); return{ sz, static_cast<std::ptrdiff_t>(len) };
-}
-
-inline basic_string_span<wchar_t, dynamic_range> ensure_z(wchar_t* const& sz, std::ptrdiff_t max)
-{
-    auto len = wcsnlen(sz, max);
-    Ensures(sz[len] == 0); return{ sz, static_cast<std::ptrdiff_t>(len) };
-}
-
-inline basic_string_span<const wchar_t, dynamic_range> ensure_z(const wchar_t* const& sz, std::ptrdiff_t max)
-{
-    auto len = wcsnlen(sz, max);
-    Ensures(sz[len] == 0); return{ sz, static_cast<std::ptrdiff_t>(len) };
-}
-
-template<class T, size_t N>
-basic_string_span<T, dynamic_range> ensure_z(T(&sz)[N]) { return ensure_z(&sz[0], static_cast<std::ptrdiff_t>(N)); }
-
-template<class Cont>
-basic_string_span<typename std::remove_pointer<typename Cont::pointer>::type, dynamic_range> ensure_z(Cont& cont)
-{
-    return ensure_z(cont.data(), static_cast<std::ptrdiff_t>(cont.length()));
-}
-
 //
 // to_string() allow (explicit) conversions from string_span to string
 //
 #ifndef GSL_MSVC_HAS_TYPE_DEDUCTION_BUG
 
-template<class CharT, ptrdiff_t Extent>
+template<typename CharT, ptrdiff_t Extent>
 std::basic_string<typename std::remove_const<CharT>::type> to_string(basic_string_span<CharT, Extent> view)
 {
     return{ view.data(), static_cast<size_t>(view.length()) };
@@ -176,10 +485,11 @@ inline std::wstring to_string(wstring_span<> view)
 
 #endif
 
-template<class CharT, size_t Extent = dynamic_range>
+template<typename CharT, size_t Extent = dynamic_range>
 class basic_zstring_builder
 {
 public:
+    using impl_type = span<CharT, Extent>;
     using string_span_type = basic_string_span<CharT, Extent>;
     using value_type = CharT;
     using pointer = CharT*;
@@ -203,7 +513,7 @@ public:
     iterator end() const { return sv_.end(); }
 
 private:
-    string_span_type sv_;
+    impl_type sv_;
 };
 
 template <size_t Max = dynamic_range>
@@ -213,14 +523,64 @@ template <size_t Max = dynamic_range>
 using wzstring_builder = basic_zstring_builder<wchar_t, Max>;
 }
 
+template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_range>
+bool operator==(const gsl::basic_string_span<CharT, Extent>& one, const gsl::basic_string_span<CharT, Extent>& other) noexcept
+{
+    return std::equal(one.begin(), one.end(), other.begin(), other.end());
+}
+
+template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_range>
+bool operator<(const gsl::basic_string_span<CharT, Extent>& one, const gsl::basic_string_span<CharT, Extent>& other) noexcept
+{
+    return std::lexicographical_compare(one.begin(), one.end(), other.begin(), other.end());
+}
+
+template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_range>
+bool operator<=(const gsl::basic_string_span<CharT, Extent>& one, const gsl::basic_string_span<CharT, Extent>& other) noexcept
+{
+    return !(other < one);
+}
+
+template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_range>
+bool operator>(const gsl::basic_string_span<CharT, Extent>& one, const gsl::basic_string_span<CharT, Extent>& other) noexcept
+{
+    return other < one;
+}
+
+template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_range>
+bool operator>=(const gsl::basic_string_span<CharT, Extent>& one, const gsl::basic_string_span<CharT, Extent>& other) noexcept
+{
+    return !(one < other);
+}
+
 // VS 2013 workarounds
 #ifdef _MSC_VER
+
+#undef constexpr
+#pragma pop_macro("constexpr")
+
 #if _MSC_VER <= 1800
 
+#pragma warning(pop)
+
+#ifndef GSL_THROW_ON_CONTRACT_VIOLATION
+#undef noexcept
+#pragma pop_macro("noexcept")
+#endif // GSL_THROW_ON_CONTRACT_VIOLATION
+
 #undef GSL_MSVC_HAS_TYPE_DEDUCTION_BUG
 
 #endif // _MSC_VER <= 1800
 #endif // _MSC_VER
 
+#if defined(GSL_THROW_ON_CONTRACT_VIOLATION)
+
+#undef noexcept
+
+#ifdef _MSC_VER
+#pragma pop_macro("noexcept")
+#endif
+
+#endif // GSL_THROW_ON_CONTRACT_VIOLATION
 
 #endif // GSL_STRING_SPAN_H

tests/string_span_tests.cpp

@@ -14,6 +14,7 @@
 //
 ///////////////////////////////////////////////////////////////////////////////
 
+
 #include <UnitTest++/UnitTest++.h>
 #include <string_span.h>
 #include <vector>
@@ -27,7 +28,7 @@ SUITE(string_span_tests)
 {
 
     TEST(TestLiteralConstruction)
-	{
+    {
         cwstring_span<> v = ensure_z(L"Hello");
 
         CHECK(5 == v.length());
@@ -35,7 +36,7 @@ SUITE(string_span_tests)
 #ifdef CONFIRM_COMPILATION_ERRORS
         wstring_span<> v2 = ensure0(L"Hello");
 #endif
-	}
+    }
 
     TEST(TestConstructFromStdString)
     {
@@ -51,8 +52,8 @@ SUITE(string_span_tests)
         CHECK(v.length() == static_cast<string_span<>::size_type>(vec.size()));
     }
 
-	TEST(TestStackArrayConstruction)
+    TEST(TestStackArrayConstruction)
-	{
+    {
         wchar_t stack_string[] = L"Hello";
 
         {
@@ -62,7 +63,7 @@ SUITE(string_span_tests)
 
         {
             cwstring_span<> v = stack_string;
-            CHECK(v.length() == 6);
+            CHECK(v.length() == 5);
         }
 
         {
@@ -72,9 +73,9 @@ SUITE(string_span_tests)
 
         {
             wstring_span<> v = stack_string;
-            CHECK(v.length() == 6);
+            CHECK(v.length() == 5);
         }
-	}
+    }
 
     TEST(TestConstructFromConstCharPointer)
     {
@@ -95,7 +96,7 @@ SUITE(string_span_tests)
     {
         char stack_string[] = "Hello";
         cstring_span<> v = ensure_z(stack_string);
-	(void)v;
+        (void)v;
 #ifdef CONFIRM_COMPILATION_ERRORS
         string_span<> v2 = v;
         string_span<> v3 = "Hello";
@@ -113,6 +114,573 @@ SUITE(string_span_tests)
         CHECK(static_cast<cstring_span<>::size_type>(s2.length()) == v.length());
         CHECK(s2.length() == 5);
     }
+
+    TEST(EqualityAndImplicitConstructors)
+    {
+        {
+            cstring_span<> span = "Hello";
+
+            const char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+            const char ar1[] = "Hello";
+            const char ar2[10] = "Hello";
+            const char* ptr = "Hello";
+            const std::string str = "Hello";
+            const std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+
+            // comparison to  literal
+            CHECK(span == cstring_span<>("Hello"));
+
+            // comparison to static array with no null termination
+            CHECK(span == cstring_span<>(ar));
+
+            // comparison to static array with null at the end
+            CHECK(span == cstring_span<>(ar1));
+
+            // comparison to static array with null in the middle
+            CHECK(span == cstring_span<>(ar2));
+
+            // comparison to null-terminated c string
+            CHECK(span == cstring_span<>(ptr, 5));
+
+            // comparison to string
+            CHECK(span == cstring_span<>(str));
+
+            // comparison to vector of charaters with no null termination
+            CHECK(span == cstring_span<>(vec));
+
+            // comparison of the original data to string
+            CHECK(span.data() == std::string("Hello"));
+        }
+
+        {
+            char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+
+            string_span<> span = ar;
+
+            char ar1[] = "Hello";
+            char ar2[10] = "Hello";
+            char* ptr = ar;
+            std::string str = "Hello";
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+
+            // comparison to static array with no null termination
+            CHECK(span == string_span<>(ar));
+
+            // comparison to static array with null at the end
+            CHECK(span == string_span<>(ar1));
+
+            // comparison to static array with null in the middle
+            CHECK(span == string_span<>(ar2));
+
+            // comparison to null-terminated c string
+            CHECK(span == string_span<>(ptr, 5));
+
+            // comparison to string
+            CHECK(span == string_span<>(str));
+
+            // comparison to vector of charaters with no null termination
+            CHECK(span == string_span<>(vec));
+        }
+
+#ifdef CONFIRM_COMPILATION_ERRORS
+        {
+            cstring_span<> span = "Hello";
+
+            CHECK(span == "Hello");
+            CHECK(span == ar);
+            CHECK(span == ar1);
+            CHECK(span == ar2);
+            CHECK(span == ptr);
+            CHECK(span == str);
+            CHECK(span == vec);
+
+            char _ar[] = { 'H', 'e', 'l', 'l', 'o' };
+            char _ar1[] = "Hello";
+            char _ar2[10] = "Hello";
+            char* _ptr = _ar1;
+            std::string _str = "Hello";
+            std::vector<char> _vec = { 'H', 'e', 'l', 'l', 'o' };
+
+            CHECK(span == _ar);
+            CHECK(span == _ar1);
+            CHECK(span == _ar2);
+            CHECK(span == _ptr);
+            CHECK(span == _str);
+            CHECK(span == _vec);
+
+            string_span<> _span{ _ptr };
+
+            CHECK(_span == _ar);
+            CHECK(_span == _ar1);
+            CHECK(_span == _ar2);
+            CHECK(_span == _ptr);
+            CHECK(_span == _str);
+            CHECK(_span == _vec);
+
+            CHECK(_span == "Hello");
+            CHECK(_span == ar);
+            CHECK(_span == ar1);
+            CHECK(_span == ar2);
+            CHECK(_span == ptr);
+            CHECK(_span == str);
+            CHECK(_span == vec);
+        }
+#endif
+
+        {
+            std::vector<char> str1 = { 'H', 'e', 'l', 'l', 'o' };
+            cstring_span<> span1 = str1;
+            std::vector<char> str2 = std::move(str1);
+            cstring_span<> span2 = str2;
+
+            // comparison of spans from the same vector before and after move (ok)
+            CHECK(span1 == span2);
+        }
+    }
+
+
+    TEST(ComparisonAndImplicitConstructors)
+    {
+        {
+            cstring_span<> span = "Hello";
+
+            const char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+            const char ar1[] = "Hello";
+            const char ar2[10] = "Hello";
+            const char* ptr = "Hello";
+            const std::string str = "Hello";
+            const std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+
+            // comparison to  literal
+            CHECK(span < cstring_span<>("Helloo"));
+            CHECK(span > cstring_span<>("Hell"));
+
+            // comparison to static array with no null termination
+            CHECK(span >= cstring_span<>(ar));
+
+            // comparison to static array with null at the end
+            CHECK(span <= cstring_span<>(ar1));
+
+            // comparison to static array with null in the middle
+            CHECK(span >= cstring_span<>(ar2));
+
+            // comparison to null-terminated c string
+            CHECK(span <= cstring_span<>(ptr, 5));
+
+            // comparison to string
+            CHECK(span >= cstring_span<>(str));
+
+            // comparison to vector of charaters with no null termination
+            CHECK(span <= cstring_span<>(vec));
+        }
+
+        {
+            char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+
+            string_span<> span = ar;
+
+            char larr[] = "Hell";
+            char rarr[] = "Helloo";
+
+            char ar1[] = "Hello";
+            char ar2[10] = "Hello";
+            char* ptr = ar;
+            std::string str = "Hello";
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+
+
+            // comparison to static array with no null termination
+            CHECK(span <= string_span<>(ar));
+            CHECK(span < string_span<>(rarr));
+            CHECK(span > string_span<>(larr));
+
+            // comparison to static array with null at the end
+            CHECK(span >= string_span<>(ar1));
+
+            // comparison to static array with null in the middle
+            CHECK(span <= string_span<>(ar2));
+
+            // comparison to null-terminated c string
+            CHECK(span >= string_span<>(ptr, 5));
+
+            // comparison to string
+            CHECK(span <= string_span<>(str));
+
+            // comparison to vector of charaters with no null termination
+            CHECK(span >= string_span<>(vec));
+        }
+    }
+    TEST(EnzureRemoveZ)
+    {
+        // remove z from literals
+        {
+            cstring_span<> sp = "hello";
+            CHECK((sp.length() == 5));
+        }
+
+        // take the string as is
+        {
+            auto str = std::string("hello");
+            cstring_span<> sp = str;
+            CHECK((sp.length() == 5));
+        }
+
+        // ensure z on c strings
+        {
+            char* ptr = new char[3];
+
+            ptr[0] = 'a';
+            ptr[1] = 'b';
+            ptr[2] = '\0';
+
+            string_span<> span = ensure_z(ptr);
+            CHECK(span.length() == 2);
+
+            delete[] ptr;
+        }
+    }
+
+    TEST(Constructors)
+    {
+        // creating cstring_span
+
+        // from string temporary
+#ifdef CONFIRM_COMPILATION_ERRORS
+        {
+            cstring_span<> span = std::string("Hello");
+        }
+#endif
+
+        // from string literal
+        {
+            cstring_span<> span = "Hello";
+            CHECK(span.length() == 5);
+        }
+
+        // from const static array
+        {
+            const char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+            cstring_span<> span = ar;
+            CHECK(span.length() == 5);
+        }
+
+        // from non-const static array
+        {
+            char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+            cstring_span<> span = ar;
+            CHECK(span.length() == 5);
+        }
+
+        // from const ptr and length
+        {
+            const char* ptr = "Hello";
+            cstring_span<> span{ ptr, 5 };
+            CHECK(span.length() == 5);
+        }
+
+        // from non-const ptr and length
+        {
+            // does not compile with GCC (ISO standard does not allow converting string literals to char*)
+#ifdef CONFIRM_COMPILATION_ERRORS
+            char* ptr = "Hello";
+            cstring_span<> span{ ptr, 5 };
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from const string
+        {
+            const std::string str = "Hello";
+            cstring_span<> span = str;
+            CHECK(span.length() == 5);
+        }
+
+        // from non-const string
+        {
+            std::string str = "Hello";
+            cstring_span<> span = str;
+            CHECK(span.length() == 5);
+        }
+
+        // from const vector
+        {
+            const std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            cstring_span<> span = vec;
+            CHECK(span.length() == 5);
+        }
+
+        // from non-const vector
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            cstring_span<> span = vec;
+            CHECK(span.length() == 5);
+        }
+
+        // from const span
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            const span<const char> inner = vec;
+            cstring_span<> span = inner;
+            CHECK(span.length() == 5);
+        }
+
+        // from non-const span
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            span<char> inner = vec;
+            cstring_span<> span = inner;
+            CHECK(span.length() == 5);
+        }
+
+        // from const string_span
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            cstring_span<> tmp = vec;
+            cstring_span<> span = tmp;
+            CHECK(span.length() == 5);
+        }
+
+        // from non-const string_span
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> tmp = vec;
+            cstring_span<> span = tmp;
+            CHECK(span.length() == 5);
+        }
+
+        // creating string_span
+
+        // from string literal
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            string_span<> span = "Hello";
+#endif
+        }
+
+        // from const static array
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            const char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> span = ar;
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from non-const static array
+        {
+            char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> span = ar;
+            CHECK(span.length() == 5);
+        }
+
+        // from const ptr and length
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            const char* ptr = "Hello";
+            string_span<> span{ ptr, 5 };
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from non-const ptr and length
+        {
+            char ar[] = { 'H', 'e', 'l', 'l', 'o' };
+            char* ptr = ar;
+            string_span<> span{ ptr, 5 };
+            CHECK(span.length() == 5);
+        }
+
+        // from const string
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            const std::string str = "Hello";
+            string_span<> span = str;
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from non-const string
+        {
+            std::string str = "Hello";
+            string_span<> span = str;
+            CHECK(span.length() == 5);
+        }
+
+        // from const vector
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            const std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> span = vec;
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from non-const vector
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> span = vec;
+            CHECK(span.length() == 5);
+        }
+
+        // from const span
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            const span<const char> inner = vec;
+            string_span<> span = inner;
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from non-const span
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            span<char> inner = vec;
+            string_span<> span = inner;
+            CHECK(span.length() == 5);
+        }
+
+        // from non-const span of non-const data from const vector
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            const std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            const span<char> inner = vec;
+            string_span<> span = inner;
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from const string_span
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            cstring_span<> tmp = vec;
+            string_span<> span = tmp;
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from non-const string_span
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> tmp = vec;
+            string_span<> span = tmp;
+            CHECK(span.length() == 5);
+        }
+
+        // from non-const string_span from const vector
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            const std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> tmp = vec;
+            string_span<> span = tmp;
+            CHECK(span.length() == 5);
+#endif
+        }
+
+        // from const string_span of non-const data
+        {
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            const string_span<> tmp = vec;
+            string_span<> span = tmp;
+            CHECK(span.length() == 5);
+        }
+    }
+
+    template<typename T>
+    T move_wrapper(T&& t)
+    {
+        return std::move(t);
+    }
+
+    template <class T>
+    T create() { return T{}; }
+
+    template <class T>
+    void use(basic_string_span<T, gsl::dynamic_range> s) {}
+
+    TEST(MoveConstructors)
+    {
+        // move string_span
+        {
+            cstring_span<> span = "Hello";
+            auto span1 = std::move(span);
+            CHECK(span1.length() == 5);
+        }
+        {
+            cstring_span<> span = "Hello";
+            auto span1 = move_wrapper(std::move(span));
+            CHECK(span1.length() == 5);
+        }
+        {
+            cstring_span<> span = "Hello";
+            auto span1 = move_wrapper(std::move(span));
+            CHECK(span1.length() == 5);
+        }
+
+        // move span
+        {
+            span<const char> span = ensure_z("Hello");
+            cstring_span<> span1 = std::move(span);
+            CHECK(span1.length() == 5);
+        }
+        {
+            span<const char> span = ensure_z("Hello");
+            cstring_span<> span2 = move_wrapper(std::move(span));
+            CHECK(span2.length() == 5);
+        }
+
+        // move string
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            std::string str = "Hello";
+            string_span<> span = std::move(str);
+            CHECK(span.length() == 5);
+#endif
+        }
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            std::string str = "Hello";
+            string_span<> span = move_wrapper<std::string>(std::move(str));
+            CHECK(span.length() == 5);
+#endif
+        }
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            use<char>(create<string>());
+#endif
+        }
+
+        // move container
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> span = std::move(vec);
+            CHECK(span.length() == 5);
+#endif
+        }
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            std::vector<char> vec = { 'H', 'e', 'l', 'l', 'o' };
+            string_span<> span = move_wrapper<std::vector<char>>(std::move(vec));
+            CHECK(span.length() == 5);
+#endif
+        }
+        {
+#ifdef CONFIRM_COMPILATION_ERRORS
+            use<char>(create<std::vector<char>>());
+#endif
+        }
+    }
+
+    TEST(Conversion)
+    {
+#ifdef CONFIRM_COMPPILATION_ERRORS
+        cstring_span<> span = "Hello";
+        cwstring_span<> wspan{ span };
+        CHECK(wspan.length() == 5);
+#endif
+    }
 }
 
 int main(int, const char *[])