-added join to string_utils;

-updated the version to 2.3.0

Author: kamchatka-volcano

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.18)
 
-project(sfun VERSION 2.2.0 DESCRIPTION "stuff from unnamed namespaces - a c++17 helper library")
+project(sfun VERSION 2.3.0 DESCRIPTION "stuff from unnamed namespaces - a c++17 helper library")
 
 if(CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
     set(SFUN_SUBPROJECT OFF)

include/sfun/string_utils.h

@@ -134,6 +134,32 @@ inline std::string replace(std::string str, std::string_view subStr, std::string
     return str;
 }
 
+template<typename TRange>
+std::string join(const TRange& range, std::string_view separator)
+{
+    static_assert(std::is_constructible_v<std::string, decltype(*std::begin(range))>);
+
+    const auto size = [&] {
+        auto res = std::size_t{};
+        std::for_each(std::begin(range), std::end(range), [&res](const auto& val) {
+            res += std::size(val);
+        });
+        if (std::size(range) > 0)
+            res += (std::size(range) - 1) * separator.size();
+        return res;
+    }();
+
+    auto res = std::string{};
+    res.reserve(size);
+    std::for_each(std::begin(range), std::end(range), [&](const auto& val){
+        res += std::string{val};
+        res += std::string{separator};
+    });
+    if (!res.empty())
+        res.resize(res.size() - separator.size());
+    return res;
+}
+
 inline bool startsWith(std::string_view str, std::string_view val)
 {
     auto res = str.find(val);

tests/test_string.cpp

@@ -65,6 +65,46 @@ TEST(String, Replace)
     EXPECT_EQ(replace("", "", ""), "");
 }
 
+TEST(String, Join)
+{
+    {
+        auto stringList = std::vector<std::string>{"a", "b", "c"};
+        EXPECT_EQ(join(stringList, ""), "abc");
+        EXPECT_EQ(join(stringList, ", "), "a, b, c");
+
+        stringList = {"a"};
+        EXPECT_EQ(join(stringList, ""), "a");
+        EXPECT_EQ(join(stringList, ", "), "a");
+
+        stringList = {};
+        EXPECT_EQ(join(stringList, ""), "");
+        EXPECT_EQ(join(stringList, ", "), "");
+    }
+    {
+        auto viewList = std::vector<std::string_view>{"a", "b" , "c"};
+        EXPECT_EQ(join(viewList, ""), "abc");
+        EXPECT_EQ(join(viewList, ", "), "a, b, c");
+
+        viewList = {"a"};
+        EXPECT_EQ(join(viewList, ""), "a");
+        EXPECT_EQ(join(viewList, ", "), "a");
+
+        viewList = {};
+        EXPECT_EQ(join(viewList, ""), "");
+        EXPECT_EQ(join(viewList, ", "), "");
+    }
+    {
+        EXPECT_EQ(join(std::vector<std::string>{"a", "b", "c"}, ""), "abc");
+        EXPECT_EQ(join(std::vector<std::string>{"a", "b", "c"}, ", "), "a, b, c");
+
+        EXPECT_EQ(join(std::vector<std::string>{"a"}, ""), "a");
+        EXPECT_EQ(join(std::vector<std::string>{"a"}, ", "), "a");
+
+        EXPECT_EQ(join(std::vector<std::string>{}, ""), "");
+        EXPECT_EQ(join(std::vector<std::string>{}, ", "), "");
+    }
+}
+
 TEST(String, StartsWith)
 {
     EXPECT_TRUE(startsWith("hello world", "hell"));