ex12_02.h

//
//  ex12_02.cpp
//  Exercise 12.2
//
//  Created by pezy on 12/22/14.
//  Copyright (c) 2014 pezy. All rights reserved.
//
//  Write your own version of the StrBlob class including the const versions of
//  front and back.

#include <vector>
#include <string>
#include <initializer_list>
#include <memory>
#include <exception>

using std::vector;
using std::string;

class StrBlob {
public:
    using size_type = vector<string>::size_type;

    StrBlob() : data(std::make_shared<vector<string>>()) {}
    StrBlob(std::initializer_list<string> il)
        : data(std::make_shared<vector<string>>(il))
    {
    }

    size_type size() const { return data->size(); }
    bool empty() const { return data->empty(); }

    void push_back(const string& t) { data->push_back(t); }
    void pop_back()
    {
        check(0, "pop_back on empty StrBlob");
        data->pop_back();
    }

    std::string& front()
    {
        check(0, "front on empty StrBlob");
        return data->front();
    }

    std::string& back()
    {
        check(0, "back on empty StrBlob");
        return data->back();
    }

    const std::string& front() const
    {
        check(0, "front on empty StrBlob");
        return data->front();
    }
    const std::string& back() const
    {
        check(0, "back on empty StrBlob");
        return data->back();
    }

private:
    void check(size_type i, const string& msg) const
    {
        if (i >= data->size()) throw std::out_of_range(msg);
    }

private:
    std::shared_ptr<vector<string>> data;
};