bloglang/12/type_env.hpp

#pragma once
#include <map>
#include <string>
#include <set>
#include "type.hpp"

struct type_env;
using type_env_ptr = std::shared_ptr<type_env>;

enum class visibility { global,local };

struct type_env {
    struct variable_data {
        type_scheme_ptr type;
        visibility vis;

        variable_data()
            : variable_data(nullptr, visibility::local) {}
        variable_data(type_scheme_ptr t, visibility v)
            : type(std::move(t)), vis(v) {}
    };

    type_env_ptr parent;
    std::map<std::string, variable_data> names;
    std::map<std::string, type_ptr> type_names;

    type_env(type_env_ptr p) : parent(std::move(p)) {}
    type_env() : type_env(nullptr) {}

    void find_free(const type_mgr& mgr, std::set<std::string>& into) const;
    void find_free_except(const type_mgr& mgr, const std::string& avoid,
            std::set<std::string>& into) const;
    type_scheme_ptr lookup(const std::string& name) const;
    bool is_global(const std::string& name) const;
    type_ptr lookup_type(const std::string& name) const;
    void bind(const std::string& name, type_ptr t,
            visibility v = visibility::local);
    void bind(const std::string& name, type_scheme_ptr t,
            visibility v = visibility::local);
    void bind_type(const std::string& type_name, type_ptr t);
    void generalize(const std::string& name, type_mgr& mgr);
};


type_env_ptr type_scope(type_env_ptr parent);