C++ primer StrBlobPtr和StrBlobPtr

  1 #include <iostream>
  2 #include <stdio.h>
  3 #include <string>
  4 #include <memory>
  5 #include <algorithm>
  6 #include <initializer_list>
  7 #include <memory>
  8 #include <vector>
  9 #include <stdexcept>
 10 #include <fstream>
 11 #include <sstream>
 12 using namespace std;
 13 
 14 #ifndef STRBLOB_H_
 15 #define STRBLOB_H_
 16 
 17 class StrBlobPtr;
 18 
 22 class StrBlob
 23 {
 24 public:
 25     friend class StrBlobPtr;
 26     friend void inp(StrBlob& str, ifstream& input);
 27     typedef std::vector<std::string>::size_type size_type;
 28     StrBlob();
 29     StrBlob(std::initializer_list<std::string> il);
 30     size_type size() const { return data->size(); }
 31     bool empty() const { return data->empty(); }
 32     void push_back(const std::string& t) { data->push_back(t); }
 33     void pop_back();
 34     std::string& front();
 35     std::string& back();
 36     const std::string& front() const;
 37     const std::string& back() const;
 38     StrBlobPtr begin();
 39     StrBlobPtr end();
 40 private:
 41     std::shared_ptr<std::vector<std::string>> data;
 42     void check(size_type i, const std::string& msg) const;
 43 };
 44 
 45 class StrBlobPtr
 46 {
 47 public:
 48     friend void inp(StrBlob& str, ifstream& input);
 49     StrBlobPtr() : curr(0) {};
 50     StrBlobPtr(StrBlob& a, size_t sz = 0) : wptr(a.data), curr(sz) {}
 51     std::string& deref() const;
 52     StrBlobPtr& incr();
 53     friend bool eq(const StrBlobPtr& lhs, const StrBlobPtr& rhs);
 54 private:
 55     std::shared_ptr<std::vector<std::string>> check(std::size_t, const std::string&) const;
 56     std::weak_ptr<std::vector<std::string>> wptr;
 57     std::size_t curr;
 58 };
 59 
 60 std::shared_ptr<std::vector<std::string>> StrBlobPtr::check(std::size_t i, const std::string& msg) const
 61 {
 62     auto ret = wptr.lock();
 63     if (!ret)
 64         throw std::runtime_error("unbound StrBlobPtr");
 65     if (i >= ret->size())
 66         throw std::out_of_range(msg);
 67     return ret;
 68 }
 69 
 70 std::string& StrBlobPtr::deref() const
 71 {
 72     auto p = check(curr, "dereference past end");
 73     return (*p)[curr];
 74 }
 75 
 76 StrBlobPtr& StrBlobPtr::incr()
 77 {
 78     check(curr, "increment past end of StrBlobPtr");
 79     ++curr;
 80     return *this;
 81 }
 82 
 83 StrBlob::StrBlob() : data(std::make_shared<std::vector<std::string>>()) {}
 84 StrBlob::StrBlob(std::initializer_list<std::string> il) : data(std::make_shared<std::vector<std::string>>(il)) {}
 85 
 86 void StrBlob::check(size_type i, const std::string& msg) const
 87 {
 88     if (i >= data->size())
 89         throw std::out_of_range(msg);
 90 }
 91 
 92 std::string& StrBlob::front()
 93 {
 94     check(0, "front on empty StrBlob");
 95     return data->front();
 96 }
 97 
 98 std::string& StrBlob::back()
 99 {
100     check(0, "back on empty StrBlob");
101     return data->back();
102 }
103 
104 const std::string& StrBlob::front() const
105 {
106     check(0, "front on empty StrBlob");
107     return data->front();
108 }
109 
110 const std::string& StrBlob::back() const
111 {
112     check(0, "back on empty StrBlob");
113     return data->back();
114 }
115 
116 void StrBlob::pop_back()
117 {
118     check(0, "pop_back on empty StrBlob");
119     data->pop_back();
120 }
121 
122 StrBlobPtr StrBlob::begin() { return StrBlobPtr(*this); }
123 
124 StrBlobPtr StrBlob::end()
125 {
126     auto ret = StrBlobPtr(*this, data->size());
127     return ret;
128 }
129 
130 #endif
131 
132 bool eq(const StrBlobPtr& lhs, const StrBlobPtr& rhs) {
133     auto lp = lhs.wptr.lock(), rp = rhs.wptr.lock();
134     if (lp == rp) {
135         return (!lp || lhs.curr == rhs.curr);
136     }
137     else {
138         return false;
139     }
140 }
141 
142 void inp(StrBlob &str, ifstream &input)
143 {
144     //存入类中
145     string text;
146     while (getline(input, text))
147     {
148         istringstream stream(text);
149         string word;
150         while (stream >> word)
151         {
152             str.push_back(word);
153         }
154     }
155     //打印类中元素
156     for (StrBlobPtr cur = str.begin(); !eq(cur,str.end()); cur.incr())
157     {
158         string out = cur.deref();
159         cout << out << "";
160     }
161     
162 }