Use std::string_view instead of boost::string_view

include/mapnik/enumeration.hpp

@@ -35,11 +35,7 @@
 #include <tuple>
 #include <stdexcept>
 #include <map>
-#if __cpp_lib_string_view >= 201606L
 #include <string_view>
-#endif
-
-#include <mapnik/warning.hpp>
 
 namespace mapnik {
 
@@ -62,60 +58,9 @@ class illegal_enum_value : public std::exception
 };
 
 namespace detail {
-#if __cpp_lib_string_view >= 201606L
-using mapnik_string_view = std::string_view;
-#else
-class mapnik_string_view // use std::string_view in C++17
-{
-  public:
-
-    template<std::size_t N>
-    constexpr mapnik_string_view(const char (&s)[N])
-        : size_(N)
-        , data_(s)
-    {}
-
-    constexpr mapnik_string_view(const char* s, std::size_t N)
-        : size_(N)
-        , data_(s)
-    {}
-
-    constexpr char operator[](std::size_t index) const
-    {
-        return (index >= size_) ? throw std::out_of_range("Invalid index.") : data_[index];
-    }
-
-    constexpr char const* data() const { return data_; }
-
-  private:
-    std::size_t size_;
-    const char* data_;
-};
-
-constexpr bool mapnik_string_view_equals(mapnik_string_view const& a, char const* b, std::size_t i)
-{
-    if (a[i] != b[i])
-    {
-        return false;
-    }
-    else if (a[i] == 0 || b[i] == 0)
-    {
-        return true;
-    }
-    else
-    {
-        return mapnik_string_view_equals(a, b, i + 1);
-    }
-}
-
-constexpr bool operator==(mapnik_string_view const& a, char const* b)
-{
-    return mapnik_string_view_equals(a, b, 0);
-}
-#endif
 
 template<class EnumT>
-using EnumStringT = std::tuple<EnumT, mapnik_string_view>;
+using EnumStringT = std::tuple<EnumT, std::string_view>;
 
 template<class EnumT, std::size_t N>
 using EnumMapT = std::array<EnumStringT<EnumT>, N>;

src/proj_transform_cache.cpp

@@ -26,14 +26,14 @@ MAPNIK_DISABLE_WARNING_PUSH
 #include <mapnik/warning_ignore.hpp>
 #include <boost/functional/hash.hpp>
 #include <boost/unordered_map.hpp>
-#include <boost/utility/string_view.hpp>
 MAPNIK_DISABLE_WARNING_POP
+#include <string_view>
 
 namespace mapnik {
 namespace proj_transform_cache {
 namespace {
 using key_type = std::pair<std::string, std::string>;
-using compatible_key_type = std::pair<boost::string_view, boost::string_view>;
+using compatible_key_type = std::pair<std::string_view, std::string_view>;
 
 struct compatible_hash
 {
@@ -59,7 +59,7 @@ thread_local static cache_type cache_ = {};
 
 void init(std::string const& source, std::string const& dest)
 {
-    compatible_key_type key = std::make_pair<boost::string_view, boost::string_view>(source, dest);
+    compatible_key_type key = std::make_pair<std::string_view, std::string_view>(source, dest);
     auto itr = cache_.find(key, compatible_hash{}, compatible_predicate{});
     if (itr == cache_.end())
     {
@@ -71,7 +71,7 @@ void init(std::string const& source, std::string const& dest)
 
 proj_transform const* get(std::string const& source, std::string const& dest)
 {
-    compatible_key_type key = std::make_pair<boost::string_view, boost::string_view>(source, dest);
+    compatible_key_type key = std::make_pair<std::string_view, std::string_view>(source, dest);
     auto itr = cache_.find(key, compatible_hash{}, compatible_predicate{});
     if (itr == cache_.end())
     {

src/well_known_srs.cpp

@@ -72,7 +72,7 @@ boost::optional<bool> is_known_geographic(std::string const& srs)
 
 using well_known_srs_e_str = mapnik::detail::EnumStringT<well_known_srs_enum>;
 constexpr detail::EnumMapT<well_known_srs_enum, 3> well_known_srs_e_map{{
-  well_known_srs_e_str{well_known_srs_enum::WGS_84, detail::mapnik_string_view{MAPNIK_GEOGRAPHIC_PROJ_STR}},
+  well_known_srs_e_str{well_known_srs_enum::WGS_84, MAPNIK_GEOGRAPHIC_PROJ_STR},
   well_known_srs_e_str{well_known_srs_enum::WEB_MERC, MAPNIK_WEBMERCATOR_PROJ_STR},
   well_known_srs_e_str{well_known_srs_enum::well_known_srs_enum_MAX, ""},
 }};