NouVeL/NVL/Environment.h

#pragma once
#include <unordered_map>
#include <functional>
#include <variant>
#include "Parser.h"
#include "Common.h"

namespace NVL::Environment {
	enum class Type { Nil, StaticReference, Procedure, Number, String, Array };

	struct Variable {
		Type type;
		std::variant<Number, String, Vector<Variable>, std::function<Variable(Vector<Variable>)>> value;
		// Most things will have length 1 (including string); this is mostly for function arity and array length
		u32 length;
		bool operator==(const Variable& other) const;
		Variable(); // Makes Nil, length 0
		Variable(Type t); // Reserved for Nil
		Variable(const Number& v, bool is_ref = false);
		Variable(const String& v);
		Variable(const Vector<Variable>& v);
		Variable(const std::function<Variable(Vector<Variable>)>& v, u32 l);
	};

	class Environment {
	private:
		std::unordered_map<String, Variable> env{};
	public:
		void enter(const String& name, Variable p);
		void enter(std::initializer_list<std::pair<String, Variable>> p);
		void set(const String& name, Variable p);
		const Variable& get(const String& name) const;
		bool exists(const String& name);
	};

	extern Environment ENVIRONMENT;

	Variable Eval(const Parse::Object& obj);	
	Variable Apply(const Parse::Command& c);
	void EvalScene(const Parse::Scene & s);

	struct MarkupSegment {
		String str;
		Vector<std::pair<String, Vector<String>>> efs;
	};
	struct MarkupString {
	private:
		mutable i32 mem_length = -1;
	public:
		Vector<MarkupSegment> segments{};
		size_t length() const;
		MarkupString substr(size_t idx) const;
	};
	MarkupString UnpackMarkupVariable(const Vector<Variable>& v);
}