Extract commonly used Parser code to new Parser component

src/Parser/Parsing/ILexer.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "IParserLineStream.h"
+#include "Parsing/IParserValue.h"
+
+template<typename TokenType>
+class ILexer
+{
+    // TokenType must inherit IParserValue
+    static_assert(std::is_base_of<IParserValue, TokenType>::value);
+
+public:
+    ILexer() = default;
+    virtual ~ILexer() = default;
+    ILexer(const ILexer& other) = default;
+    ILexer(ILexer&& other) noexcept = default;
+    ILexer& operator=(const ILexer& other) = default;
+    ILexer& operator=(ILexer&& other) noexcept = default;
+
+    virtual const TokenType& GetToken(unsigned index) = 0;
+    virtual void PopTokens(int amount) = 0;
+
+    _NODISCARD virtual bool IsEof() = 0;
+    _NODISCARD virtual const TokenPos& GetPos() = 0;
+    _NODISCARD virtual ParserLine GetLineForPos(const TokenPos& pos) const = 0;
+};