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This repository was archived by the owner on Apr 21, 2024. It is now read-only.

Commit 414708e

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Finish Chapter 12
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‎README.md‎

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@@ -471,6 +471,21 @@ Lambda expression provides a wrapping for functions to make it takes the require
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- `bind`
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## Forward Declaration
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The *forward declration* `class StrBlob;` introduces the name `StrBlob` into the program and indicates that it's a class type. **After the declaration and before a definition is seen, the class is a incomplete type:** it is know that `StrBlob` is a class type but what members the type contains is unknown.
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We can use a incomplete type only in limited ways:
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1. we can define pointers or references to such type.
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2. We can declare, but not define, functions using the incomplete type as return or parameter type.
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A class must be defined before:
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1. we can create object of that type, otherwise the compiler does not know how much memory to allocate for the object.
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2. we can access the members of the class.
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3. Being used as the member of another class.
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‎ch12/ex12_1.h‎

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#include "headers.h"
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class StrBlob {
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public:
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using size_type = vector<string>::size_type;
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StrBlob();
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StrBlob(initializer_list<string> il);
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size_type size() { return data->size(); }
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bool empty() { return data->empty(); }
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void push_back(const string & s) { data -> push_back(s); }
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string &front();
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const string &front() const;
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string &back();
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const string &back() const;
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private:
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shared_ptr<vector<string>> data;
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void check(size_type i, const string &msg) const;
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};
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StrBlob::StrBlob() : data(make_shared<vector<string>>()) {}
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StrBlob::StrBlob(initializer_list<string> il) : data(make_shared<vector<string>>(il)) {}
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void StrBlob::check(StrBlob::size_type i, const string &msg) const {
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if ( i >= data->size()){
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throw out_of_range(msg);
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}
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}
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string & StrBlob::front(){
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check(0, "front at empty StrBlob");
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return data -> front();
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}
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const string & StrBlob::front() const{
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check(0, "front at empty StrBlob");
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return data -> front();
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}
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string & StrBlob::back(){
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check(0, "back at empty StrBlob");
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return data -> back();
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}
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const string & StrBlob::back() const{
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check(0, "back at empty StrBlob");
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return data -> back();
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}

‎ch12/ex12_14.cpp‎

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#include "headers.h"
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class Connection {
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public:
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Connection(string dst) {
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cout << "Connection to " << dst << " created!" << endl;
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}
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};
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Connection connect(string dst) {
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Connection &c = *(new Connection(dst));
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cout << "Connection to " << dst << " conncted!" << endl;
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return c;
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}
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void end_connection(Connection * pc){
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delete pc;
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pc = nullptr;
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cout << "Connection ended!" << endl;
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}
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void fn() {
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Connection c = connect("USA");
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shared_ptr<Connection> spc(&c, end_connection);
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}
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int main() {
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fn();
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}

‎ch12/ex12_15.cpp‎

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#include "headers.h"
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class Connection {
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public:
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Connection(string dst) {
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cout << "Connection to " << dst << " created!" << endl;
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}
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};
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Connection connect(string dst) {
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Connection &c = *(new Connection(dst));
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cout << "Connection to " << dst << " conncted!" << endl;
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return c;
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}
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void fn() {
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Connection c = connect("USA");
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shared_ptr<Connection> spc(&c,
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[](Connection *pc) -> void {delete pc; pc = nullptr; cout << "Connection ended!" << endl; });
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}
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int main() {
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fn();
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}

‎ch12/ex12_16.cpp‎

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#include "headers.h"
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int main() {
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unique_ptr<string> ups1(new string("Kobe"));
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// unique_ptr<string> ups2(ups1);
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// unique_ptr<string> ups3 = ups1;
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}

‎ch12/ex12_19.cpp‎

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#include "headers.h"
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// #include "ex12_19_StrBlob.h"
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// #include "ex12_19_StrBlobPtr.h"
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#include "ex12_19_combined.h"
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int main() {
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StrBlob sb{"hu", "jdkf"};
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StrBlobPtr sbp(sb, 0);
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sb.push_back("fhdj");
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cout << sbp.deref() << endl;
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cout << sbp.incre().deref() << endl;
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}

‎ch12/ex12_19_StrBlob.h‎

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#include "headers.h"
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class StrBlobPtr;
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class StrBlob {
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friend class StrBlobPtr;
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public:
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using size_type = vector<string>::size_type;
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StrBlob();
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StrBlob(initializer_list<string> il);
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size_type size() { return data->size(); }
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bool empty() { return data->empty(); }
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void push_back(const string &s) { data->push_back(s); }
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string &front();
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const string &front() const;
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string &back();
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const string &back() const;
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StrBlobPtr begin();
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StrBlobPtr end();
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private:
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shared_ptr<vector<string>> data;
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void check(size_type i, const string &msg) const;
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};
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StrBlob::StrBlob() : data(make_shared<vector<string>>()) {}
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StrBlob::StrBlob(initializer_list<string> il) : data(make_shared<vector<string>>(il)) {}
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void StrBlob::check(StrBlob::size_type i, const string &msg) const {
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if (i >= data->size()) {
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throw out_of_range(msg);
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}
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}
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string &StrBlob::front() {
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check(0, "front at empty StrBlob");
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return data->front();
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}
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const string &StrBlob::front() const {
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check(0, "front at empty StrBlob");
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return data->front();
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}
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string &StrBlob::back() {
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check(0, "back at empty StrBlob");
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return data->back();
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}
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const string &StrBlob::back() const {
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check(0, "back at empty StrBlob");
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return data->back();
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}

‎ch12/ex12_19_StrBlobPtr.h‎

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#include "headers.h"
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class StrBlob;
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// StrBlobPtr is a class provided for
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// user of StrBlob class to access
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// string elements stored in the StrBlob object
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class StrBlobPtr {
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public:
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StrBlobPtr() : curr(0) {}
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StrBlobPtr(StrBlob &sb, size_t init_idx = 0) : wptr(sb.data), curr(init_idx) {}
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string &deref();
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StrBlobPtr &incre();
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private:
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shared_ptr<vector<string>> check(size_t i, const string &msg) const;
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weak_ptr<vector<string>> wptr;
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size_t curr;
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};
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shared_ptr<vector<string>> StrBlobPtr::check(size_t i, const string &msg) const {
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auto sp = wptr.lock();
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if (!sp) {
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throw runtime_error("Memory already freed!");
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}
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if (i >= sp->size()) {
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throw out_of_range(msg);
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}
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return sp;
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}
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string &StrBlobPtr::deref() {
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auto p = check(curr, "dereference past the end");
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return (*p)[curr];
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}
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StrBlobPtr &StrBlobPtr::incre() {
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check(curr, "increment past end of StrBlob");
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++curr;
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return *this;
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}

‎ch12/ex12_19_combined.h‎

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#ifndef STRBLOB_STRBLOBPTR_COMBINED
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#define STRBLOB_STRBLOBPTR_COMBINED
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#include "headers.h"
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class StrBlobPtr;
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class StrBlob {
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friend class StrBlobPtr;
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public:
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using size_type = vector<string>::size_type;
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StrBlob();
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StrBlob(initializer_list<string> il);
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size_type size() { return data->size(); }
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bool empty() { return data->empty(); }
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void push_back(const string &s) { data->push_back(s); }
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string &front();
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const string &front() const;
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string &back();
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const string &back() const;
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StrBlobPtr begin();
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StrBlobPtr end();
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private:
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shared_ptr<vector<string>> data;
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void check(size_type i, const string &msg) const;
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};
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StrBlob::StrBlob() : data(make_shared<vector<string>>()) {}
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StrBlob::StrBlob(initializer_list<string> il) : data(make_shared<vector<string>>(il)) {}
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void StrBlob::check(StrBlob::size_type i, const string &msg) const {
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if (i >= data->size()) {
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throw out_of_range(msg);
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}
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}
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string &StrBlob::front() {
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check(0, "front at empty StrBlob");
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return data->front();
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}
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const string &StrBlob::front() const {
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check(0, "front at empty StrBlob");
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return data->front();
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}
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string &StrBlob::back() {
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check(0, "back at empty StrBlob");
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return data->back();
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}
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const string &StrBlob::back() const {
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check(0, "back at empty StrBlob");
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return data->back();
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}
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class StrBlobPtr {
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public:
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StrBlobPtr() : curr(0) {}
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StrBlobPtr(StrBlob &sb, size_t init_idx = 0) : wptr(sb.data), curr(init_idx) {}
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string &deref();
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StrBlobPtr &incre();
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private:
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shared_ptr<vector<string>> check(size_t i, const string &msg) const;
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weak_ptr<vector<string>> wptr;
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size_t curr;
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};
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shared_ptr<vector<string>> StrBlobPtr::check(size_t i, const string &msg) const {
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auto sp = wptr.lock();
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if (!sp) {
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throw runtime_error("Memory already freed!");
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}
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if (i >= sp->size()) {
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throw out_of_range(msg);
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}
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return sp;
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}
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string &StrBlobPtr::deref() {
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auto p = check(curr, "dereference past the end");
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return (*p)[curr];
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}
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StrBlobPtr &StrBlobPtr::incre() {
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check(curr, "increment past end of StrBlob");
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++curr;
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return *this;
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}
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StrBlobPtr StrBlob::begin() {
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return StrBlobPtr(*this);
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}
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StrBlobPtr StrBlob::end() {
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return StrBlobPtr(*this, data->size());
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}
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#endif

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