Add convertion functions from_u8string to support c++20 + update tests

benchmark/src/test_utf_encoding.cpp

@@ -1,17 +1,22 @@
 #include "bench_framework.hpp"
 #include <mapnik/unicode.hpp>
+#include <mapnik/util/from_u8string.hpp>
 #include <mapnik/value.hpp>
 #include <boost/locale.hpp>
 #ifndef __linux__
 #include <codecvt>
+#endif
 
+using mapnik::util::from_u8string;
+
+#ifndef __linux__
 class test : public benchmark::test_case
 {
     std::string utf8_;
 public:
     test(mapnik::parameters const& params)
      : test_case(params),
-       utf8_(u8"שלום") {}
+       utf8_(from_u8string(u8"שלום")) {}
     bool validate() const
     {
         std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> utf32conv;
@@ -42,7 +47,7 @@ class test2 : public benchmark::test_case
 public:
     test2(mapnik::parameters const& params)
      : test_case(params),
-       utf8_(u8"שלום") {}
+       utf8_(from_u8string(u8"שלום")) {}
     bool validate() const
     {
         std::u32string utf32 = boost::locale::conv::utf_to_utf<char32_t>(utf8_);
@@ -69,7 +74,7 @@ class test3 : public benchmark::test_case
 public:
     test3(mapnik::parameters const& params)
      : test_case(params),
-       utf8_(u8"שלום") {}
+       utf8_(from_u8string(u8"שלום")) {}
     bool validate() const
     {
         mapnik::transcoder tr_("utf-8");

include/mapnik/util/from_u8string.hpp

@@ -0,0 +1,48 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2021 Artem Pavlenko
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ *****************************************************************************/
+
+#ifndef FROM_U8STRING_HPP
+#define FROM_U8STRING_HPP
+
+// stl
+#include <string>
+
+// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1423r2.html
+// Explicit conversion functions can be used, in a C++17 compatible manner, to cope with the change of return type to// the std::filesystem::path member functions when a UTF-8 encoded path is desired in an object of type std::string.
+
+namespace mapnik { namespace util {
+
+std::string from_u8string(const std::string &s) {
+  return s;
+}
+std::string from_u8string(std::string &&s) {
+  return std::move(s);
+}
+#if defined(__cpp_lib_char8_t)
+std::string from_u8string(const std::u8string &s) {
+  return std::string(s.begin(), s.end());
+}
+#endif
+
+}} // end of namespace mapnik
+
+#endif // FROM_U8STRING_HPP

test/unit/core/expressions_test.cpp

@@ -7,6 +7,7 @@
 #include <mapnik/feature.hpp>
 #include <mapnik/feature_factory.hpp>
 #include <mapnik/unicode.hpp>
+#include <mapnik/util/from_u8string.hpp>
 
 #include <functional>
 #include <map>
@@ -57,6 +58,7 @@ std::string parse_and_dump(std::string const& str)
 TEST_CASE("expressions")
 {
     using namespace std::placeholders;
+    using namespace mapnik::util;
     using properties_type = std::map<std::string, mapnik::value>;
     mapnik::transcoder tr("utf8");
 
@@ -102,11 +104,11 @@ TEST_CASE("expressions")
 
     // unicode attribute name
     TRY_CHECK(eval("[τ]") == prop.at("τ"));
-    TRY_CHECK(eval("[τ]") == eval(u8"[\u03C4]"));
+    TRY_CHECK(eval("[τ]") == eval(from_u8string(u8"[\u03C4]")));
 
     // change to TRY_CHECK once \u1234 escape sequence in attribute name
     // is implemented in expression grammar
-    CHECK_NOFAIL(eval("[τ]") == eval("[\\u03C3]"));
+    CHECK_NOFAIL(eval("[τ]") == eval(from_u8string(u8"[\\u03C3]")));
 
     // unary functions
     // sin / cos
@@ -190,7 +192,7 @@ TEST_CASE("expressions")
     // https://en.wikipedia.org/wiki/Chess_symbols_in_Unicode
     //'\u265C\u265E\u265D\u265B\u265A\u265D\u265E\u265C' - black chess figures
     // replace black knights with white knights
-    auto val0 = eval(u8"'\u265C\u265E\u265D\u265B\u265A\u265D\u265E\u265C'.replace('\u265E','\u2658')");
+    auto val0 = eval(from_u8string(u8"'\u265C\u265E\u265D\u265B\u265A\u265D\u265E\u265C'.replace('\u265E','\u2658')"));
     auto val1 = eval("'♜♞♝♛♚♝♞♜'.replace('♞','♘')"); // ==> expected ♜♘♝♛♚♝♘♜
     TRY_CHECK(val0 == val1);
     TRY_CHECK(val0.to_string() == val1.to_string()); // UTF-8

test/unit/datasource/csv.cpp

@@ -33,6 +33,7 @@
 #include <mapnik/expression.hpp>
 #include <mapnik/expression_evaluator.hpp>
 #include <mapnik/debug.hpp>
+#include <mapnik/util/from_u8string.hpp>
 #include <mapnik/util/fs.hpp>
 #include <boost/format.hpp>
 #include <boost/optional/optional_io.hpp>
@@ -84,7 +85,7 @@ mapnik::datasource_ptr get_csv_ds(std::string const& file_name, bool strict = tr
 } // anonymous namespace
 
 TEST_CASE("csv") {
-
+    using mapnik::util::from_u8string;
     std::string csv_plugin("./plugins/input/csv.input");
     if (mapnik::util::exists(csv_plugin))
     {
@@ -862,7 +863,7 @@ TEST_CASE("csv") {
         {
             using ustring = mapnik::value_unicode_string;
 
-            for (auto const &name : {std::string("Winthrop, WA"), std::string(u8"Qu\u00e9bec")}) {
+            for (auto const &name : {std::string("Winthrop, WA"), from_u8string(u8"Qu\u00e9bec")}) {
                 std::string csv_string =
                     (boost::format(
                         "wkt,Name\n"

test/unit/text/shaping.cpp

@@ -3,9 +3,12 @@
 #include <mapnik/text/harfbuzz_shaper.hpp>
 #include <mapnik/text/font_library.hpp>
 #include <mapnik/unicode.hpp>
+#include <mapnik/util/from_u8string.hpp>
 
 namespace {
 
+using mapnik::util::from_u8string;
+
 void test_shaping( mapnik::font_set const& fontset, mapnik::face_manager& fm,
                    std::vector<std::pair<unsigned, unsigned>> const& expected, char const* str, bool debug = false)
 {
@@ -67,19 +70,19 @@ TEST_CASE("shaping")
     {
         std::vector<std::pair<unsigned, unsigned>> expected =
             {{977, 0}, {1094, 3}, {1038, 4}, {1168, 4}, {9, 7}, {3, 8}, {11, 9}, {68, 10}, {69, 11}, {70, 12}, {12, 13}};
-        test_shaping(fontset, fm, expected, u8"སྤུ་ཧྲེང (abc)");
+        test_shaping(fontset, fm, expected, from_u8string(u8"སྤུ་ཧྲེང (abc)").c_str());
     }
 
     {
         std::vector<std::pair<unsigned, unsigned>> expected =
             {{977, 0}, {1094, 3}, {1038, 4}, {1168, 4}, {9, 7}, {3, 8}, {11, 9}, {0, 10}, {0, 11}, {0, 12}, {12, 13}};
-        test_shaping(fontset, fm, expected, u8"སྤུ་ཧྲེང (普兰镇)");
+        test_shaping(fontset, fm, expected, from_u8string(u8"སྤུ་ཧྲེང (普兰镇)").c_str());
     }
 
     {
         std::vector<std::pair<unsigned, unsigned>> expected =
             {{68, 0}, {69, 1}, {70, 2}, {3, 3}, {11, 4}, {0, 5}, {0, 6}, {0, 7}, {12, 8}};
-        test_shaping(fontset, fm, expected, u8"abc (普兰镇)");
+        test_shaping(fontset, fm, expected, from_u8string(u8"abc (普兰镇)").c_str());
     }
 
     {
@@ -94,7 +97,7 @@ TEST_CASE("shaping")
             {{0, 0}, {0, 1}, {0, 2}, {3, 3}, {0, 4}, {0, 5}, {0, 6}, {0, 7},
               {0, 8}, {0, 9}, {3, 10}, {509, 22}, {481, 21}, {438, 20}, {503, 19},
               {470, 18}, {496, 17}, {43, 16}, {3, 15}, {509, 14}, {454, 13}, {496, 12}, {43, 11}};
-        test_shaping(fontset, fm, expected, u8"ⵃⴰⵢ ⵚⵉⵏⴰⵄⵉ الحي الصناعي");
+        test_shaping(fontset, fm, expected, from_u8string(u8"ⵃⴰⵢ ⵚⵉⵏⴰⵄⵉ الحي الصناعي").c_str());
     }