Added Path type (WIP).

source/mijin/types/path.hpp

@@ -0,0 +1,129 @@
+
+#pragma once
+
+#if !defined(MIJIN_TYPES_PATH_HPP_INCLUDED)
+#define MIJIN_TYPES_PATH_HPP_INCLUDED 1
+
+#include "../internal/common.hpp"
+
+#include <string>
+#include <type_traits>
+
+namespace mijin
+{
+template<typename TChar = char, TChar separator = TChar('/'), typename TTraits = std::char_traits<TChar>, template<typename> typename TAllocator = MIJIN_DEFAULT_ALLOCATOR>
+class BasePath
+{
+public:
+    using string_t = std::basic_string<TChar, TTraits, TAllocator<char>>;
+    using size_type = string_t::size_type;
+    using difference_type = string_t::difference_type;
+private:
+    string_t storage_;
+public:
+    BasePath() = default;
+    BasePath(const BasePath&) = default;
+    BasePath(BasePath&&) = default;
+    BasePath(string_t string) MIJIN_NOEXCEPT_IF(std::is_nothrow_move_constructible<string_t>()) : storage_(std::move(string)) {
+        simplify();
+    }
+
+    BasePath& operator=(const BasePath&) = default;
+    BasePath& operator=(BasePath&&) = default;
+
+    auto operator<=>(const BasePath&) const noexcept = default;
+
+    [[nodiscard]]
+    const string_t& string() const MIJIN_NOEXCEPT
+    {
+        return storage_;
+    }
+private:
+    void simplify() MIJIN_NOEXCEPT;
+};
+
+using Path = BasePath<char>;
+using WPath = BasePath<wchar_t>;
+
+template<typename TChar, TChar separator, typename TTraits, template<typename> typename TAllocator>
+void BasePath<TChar, separator, TTraits, TAllocator>::simplify() MIJIN_NOEXCEPT
+{
+    // step 1: remove double slashes
+    difference_type moveBy = 0;
+    for (auto it = std::next(storage_.begin()); it < storage_.end(); ++it)
+    {
+        const bool doubleSlash = (*it == separator && *std::prev(it) == separator); // check this before moving the current character, as that might create a double slash itself
+        if (moveBy > 0) {
+            *std::prev(it, moveBy) = *it;
+        }
+        if (doubleSlash) {
+            ++moveBy;
+        }
+    }
+    // step 1.5: remove trailing slash (but only if it's not the only remaining char)
+    if (moveBy < static_cast<difference_type>(storage_.size() - 1) && storage_[storage_.size() - moveBy - 1] == separator) {
+        ++moveBy;
+    }
+    storage_.resize(storage_.size() - moveBy);
+
+    // step 2: get rid of any "/.." together with the preceeding segment
+    moveBy = 0;
+    for (auto it = std::next(storage_.begin(), 2); it < storage_.end(); ++it)
+    {
+        if (moveBy > 0)
+        {
+            *std::prev(it, moveBy) = *it;
+        }
+        if (*std::prev(it, moveBy) == TChar('.') && *std::prev(it, moveBy + 1) == TChar('.') && *std::prev(it, moveBy + 2) == separator
+            && (std::next(it) == storage_.end() || *std::next(it) == separator))
+        {
+            if (std::prev(it, moveBy + 2) == storage_.begin())
+            {
+                // leading "/.." -> just remove it
+                moveBy += 3;
+                continue;
+            }
+            // find the start of the preceeding segment
+            for (auto itStart = std::prev(it, moveBy + 3);; --itStart)
+            {
+                if (*std::prev(itStart) == separator || std::prev(itStart) == storage_.begin())
+                {
+                    //     /path/with/../double/dot
+                    // itStart --A     A
+                    // it -------------|
+                    // remove everything from itStart to it + two slashes
+                    moveBy += std::distance(itStart, std::prev(it, moveBy)) + 2; // skip it all
+                    break;
+                }
+            }
+        }
+    }
+    storage_.resize(storage_.size() - moveBy);
+
+    // step 3: eliminate any segments that are just "."
+    moveBy = 0;
+    if (storage_.size() == 1) {
+        return; // just stop it here
+    }
+    for (auto it = storage_.begin(); it < storage_.end(); ++it)
+    {
+        const bool atStart = (it == storage_.begin());
+        const bool atEnd = (std::next(it) == storage_.end());
+        const bool emptyEle = (*it == TChar('.') // char is a dot
+            && (atStart || *std::prev(it, moveBy + 1) == separator) // previous is a slash or doesn't exist
+            && (atEnd || *std::next(it) == separator)); // next is a slash or doesn't exist
+        if (moveBy > 0) {
+            *std::prev(it, moveBy) = *it;
+        }
+        if (emptyEle) {
+            moveBy += 2;
+            if (!atEnd) {
+                ++it; // skip the next one
+            }
+        }
+    }
+    storage_.resize(storage_.size() - moveBy);
+}
+} // namespace shiken
+
+#endif // !defined(MIJIN_TYPES_PATH_HPP_INCLUDED)