[Feat] 详细区分左值(LvObject)与右值(RvObject -> ObjectPtr)

[Impl] 重构evaluator.cpp + hpp 全部
[Feat] 增加对于IndexExpr的解析
[Fix][Impl] 现在点运算符不由BinaryExpr负责,增加MemberExpr,单独实现解析
[Impl] 项目目录全部翻修, src/目录下单独文件夹放置每一个模块

src/Core/fig_string.hpp

@@ -0,0 +1,100 @@
+#pragma once
+#include <string>
+#include <string_view>
+
+
+namespace Fig
+{
+    // using String = std::u8string;
+    // using StringView = std::u8string_view;
+
+    class FStringView : public std::u8string_view
+    {
+    public:
+        using std::u8string_view::u8string_view;
+        
+        static FStringView fromBasicStringView(std::string_view sv)
+        {
+            return FStringView(reinterpret_cast<const char8_t*>(sv.data()), sv.size());
+        }
+
+        explicit FStringView(std::string_view sv)
+        {
+            *this = fromBasicStringView(sv);
+        }
+
+        explicit FStringView()
+        {
+            *this = fromBasicStringView(std::string_view(""));
+        }
+
+    };
+
+    class FString : public std::u8string
+    {
+    public:
+        using std::u8string::u8string;
+        explicit FString(const std::u8string &str)
+        {
+            *this = fromU8String(str);
+        }
+        explicit FString(std::string str)
+        {
+            *this = fromBasicString(str);
+        }
+        explicit FString(FStringView sv)
+        {
+            *this = fromStringView(sv);
+        }
+        std::string toBasicString() const
+        {
+            return std::string(this->begin(), this->end());
+        }
+        FStringView toStringView() const
+        {
+            return FStringView(this->data(), this->size());
+        }
+
+        static FString fromBasicString(const std::string &str)
+        {
+            return FString(str.begin(), str.end());
+        }
+
+        static FString fromStringView(FStringView sv)
+        {
+            return FString(reinterpret_cast<const char*> (sv.data()));
+        }
+
+        static FString fromU8String(const std::u8string &str)
+        {
+            return FString(str.begin(), str.end());
+        }
+
+        size_t length()
+        {
+            // get UTF8-String real length
+            size_t len = 0;
+            for (auto it = this->begin(); it != this->end(); ++it)
+            {
+                if ((*it & 0xC0) != 0x80)
+                {
+                    ++len;
+                }
+            }
+            return len;
+        }
+    };
+
+}; // namespace Fig
+
+namespace std
+{
+    template <>
+    struct hash<Fig::FString>
+    {
+        std::size_t operator()(const Fig::FString &s) const
+        {
+            return std::hash<std::u8string>{}(static_cast<const std::u8string &>(s));
+        }
+    };
+}