Updated string split method to accept limitParts and ignoreEmpty options.

source/mijin/util/string.hpp

@@ -5,7 +5,7 @@
 #define MIJIN_UTIL_STRING_HPP_INCLUDED 1
 
 #include <iterator>
-#include <ranges>
+#include <limits>
 #include <sstream>
 #include <string>
 #include <string_view>
@@ -28,6 +28,12 @@ namespace mijin
 // public types
 //
 
+struct SplitOptions
+{
+    std::size_t limitParts = std::numeric_limits<std::size_t>::max();
+    bool ignoreEmpty = true;
+};
+
 //
 // public functions
 //
@@ -56,11 +62,74 @@ namespace detail
 {
 template<typename TChar, typename TTraits>
 std::vector<std::basic_string_view<TChar, TTraits>> splitImpl(std::basic_string_view<TChar, TTraits> stringView,
-                                                              std::basic_string_view<TChar, TTraits> seperator)
+                                                              std::basic_string_view<TChar, TTraits> separator,
+                                                              const SplitOptions& options)
 {
-    return std::views::split(stringView, seperator)
-           | std::views::transform([](auto val) { return std::string_view(val); })
-           | std::ranges::to<std::vector>();
+    using sv_t = std::basic_string_view<TChar, TTraits>;
+
+    MIJIN_ASSERT(options.limitParts > 0, "Cannot split to zero parts.");
+    MIJIN_ASSERT(!separator.empty(), "Separator cannot be empty.");
+
+    if (separator.empty())
+    {
+        return {};
+    }
+
+    std::vector<sv_t> result;
+    if (options.limitParts <= 1)
+    {
+        result.push_back(stringView);
+        return result;
+    }
+    auto start = stringView.begin();
+    auto pos = start;
+    const auto end = stringView.end();
+
+    auto seperatorFound = [&]()
+    {
+        return pos <= (end - separator.size()) && sv_t(pos, pos + separator.size()) == separator;
+    };
+
+    while (pos != end)
+    {
+        if (seperatorFound())
+        {
+            if (!options.ignoreEmpty || pos != start)
+            {
+                result.emplace_back(start, pos);
+            }
+            start = pos = (pos + separator.size());
+            if (result.size() == options.limitParts - 1)
+            {
+                if (options.ignoreEmpty)
+                {
+                    while (seperatorFound())
+                    {
+                        pos += separator.size();
+                    }
+                }
+                result.emplace_back(pos, end);
+                return result;
+            }
+            if (!options.ignoreEmpty && pos == end)
+            {
+                // skipped a separator at the very end, add an empty entry
+                result.emplace_back("");
+                return result;
+            }
+        }
+        else
+        {
+            ++pos;
+        }
+    }
+
+    if (start != end)
+    {
+        result.emplace_back(start, end);
+    }
+
+    return result;
 }
 
 template<typename TChar, typename TTraitsA, typename TTraitsB>
@@ -87,9 +156,10 @@ static const TChar SPACE = TChar(' ');
 }
 
 template<typename TLeft, typename TRight>
-[[nodiscard]] auto split(TLeft&& left, TRight&& right)
+[[nodiscard]] auto split(TLeft&& stringView, TRight&& separator, const SplitOptions& options = {})
 {
-    return detail::splitImpl(std::basic_string_view(std::forward<TLeft>(left)), std::basic_string_view(std::forward<TRight>(right)));
+    return detail::splitImpl(std::basic_string_view(std::forward<TLeft>(stringView)),
+                             std::basic_string_view(std::forward<TRight>(separator)), options);
 }
 
 template<typename TChar, typename TTraits>