sexp.h

// This file if part of the llir-opt project.
// Licensing information can be found in the LICENSE file.
// (C) 2018 Nandor Licker. All rights reserved.
 
#pragma once
 
#include <memory>
#include <vector>
 
#include <llvm/Support/raw_ostream.h>
 
 
 
class SExp {
public:
  enum class Kind {
    NUMBER,
    STRING,
    LIST,
  };
 
  class Number {
  public:
    Number(int64_t v) : k_(Kind::NUMBER), v_(v) {}
 
    int64_t Get() const { return v_; }
 
    void print(llvm::raw_ostream &os) const;
 
  private:
    Kind k_;
    int64_t v_;
  };
 
  class String {
  public:
    String(const std::string &v) : k_(Kind::STRING), v_(v) {}
 
    const std::string &Get() const { return v_; }
 
    void print(llvm::raw_ostream &os) const;
 
  private:
    Kind k_;
    std::string v_;
  };
 
  class List {
  public:
    List() : k_(Kind::LIST) {}
 
    Number *AddNumber(int64_t v);
    String *AddString(const std::string &v);
    List *AddList();
 
    size_t size() const { return v_.size(); }
    const SExp &operator[](size_t idx) const { return v_[idx]; }
 
    void print(llvm::raw_ostream &os) const;
 
  private:
    Kind k_;
    std::vector<SExp> v_;
  };
 
public:
  SExp() : s_(std::make_unique<Storage>()) {}
  SExp(int64_t v) : s_(std::make_unique<Storage>(v)) {}
  SExp(const std::string &v) : s_(std::make_unique<Storage>(v)) {}
 
  SExp(SExp &&that) : s_(std::move(that.s_)) {}
  SExp(const SExp &that) : s_(std::make_unique<Storage>(*that.s_)) {}
  ~SExp();
 
  const Number *AsNumber() const;
  Number *AsNumber();
  const String *AsString() const;
  String *AsString();
  const List *AsList() const;
  List *AsList();
 
  void print(llvm::raw_ostream &os) const;
 
private:
  union Storage {
    Kind K;
    Number N;
    String S;
    List L;
 
    Storage() { new (&L) List(); }
    Storage(int64_t v) { new (&N) Number(v); }
    Storage(const std::string &v) { new (&S) String(v); }
    Storage(const Storage &that);
    ~Storage();
  };
 
  std::unique_ptr<Storage> s_;
};