2015-4-30 improved StrVec

Author: tthhee

C++PrimerTest/exercise13.5StrVec

@@ -0,0 +1,151 @@
+#include "exercise13.5StrVec.h"
+
+void StrVec::push_back(const string& s)
+{
+	chk_n_alloc();  //确保有足够空间容纳新元素
+	alloc.construct(firstfree++, s);  //构造新元素
+}
+
+pair<string*, string*> StrVec::alloc_n_copy(const string* s1, const string* s2)
+{
+	auto data = alloc.allocate(s2-s1);
+	return {data, uninitialized_copy(s1, s2, data)};
+}
+
+/**
+*free()
+*首先销毁元素， 然后释放所有内存
+*/
+void StrVec::free()
+{
+	if(elements)
+	{
+		// for(auto p = firstfree; p!=elements;)
+		// 	alloc.destroy(--p);
+		for_each(elements, firstfree, [this](string& str){alloc.destroy(&str);});
+		alloc.deallocate(elements, cap-elements);
+	}
+}
+StrVec::StrVec(const StrVec& str)
+{
+	auto temp = alloc_n_copy(str.begin(), str.end());
+	elements = temp.first;
+	firstfree = cap = temp.second;
+}
+
+/**
+*StrVec(initializer_list<string> strlist)
+*使用初始化列表的构造函数
+*/
+StrVec::StrVec(initializer_list<string> strlist)
+{
+	auto newcapacity = strlist.size()*2;
+	auto data = alloc.allocate(newcapacity);
+	auto fisfree = uninitialized_copy(strlist.begin(), strlist.end(), data);
+	elements = data;
+	firstfree = fisfree;
+	cap = elements + newcapacity;
+}
+StrVec& StrVec::operator=(const StrVec& rhs)
+{
+	auto data = alloc_n_copy(rhs.begin(), rhs.end());
+	free();
+	elements = data.first;
+	firstfree = cap = data.second;
+	return *this;
+}
+StrVec::~StrVec()
+{
+	free();
+}
+/**
+*reallocate()
+*
+*/
+void StrVec::reallocate()
+{
+	auto newcapacity = size() ? size()*2:1;
+	auto newdata = alloc.allocate(newcapacity);
+
+	auto dest = newdata;
+	auto elem = elements;
+	for(size_t i=0; i<size(); i++)
+	{
+		alloc.construct(dest++, std::move(*elem++));
+	}
+
+	free();
+	elements = newdata;
+	firstfree = dest;
+	cap = elements + newcapacity;
+	
+}
+
+void StrVec::reserve(size_t n)
+{
+	size_t old_capacity = capacity();
+	if(n > old_capacity)
+	{
+		auto newcapacity = n;
+		auto newdata = alloc.allocate(newcapacity);
+
+		auto dest = newdata;
+		auto elem = elements;
+		for(size_t i=0; i<size(); i++)
+		{
+			alloc.construct(dest++, std::move(*elem++));
+		}
+
+		free();
+		elements = newdata;
+		firstfree = dest;
+		cap = elements + newcapacity;
+	}
+}
+
+void StrVec::resize(size_t n)
+{
+	if(n > capacity())
+	{
+		
+		throw out_of_range("out of range!");
+		return;
+		
+	}
+
+	else if(n>size())
+	{
+		auto count = n - size();
+		uninitialized_fill_n(firstfree, count, "");
+	}
+}
+
+void StrVec::resize(size_t n, string str)
+{
+	if(n > capacity())
+	{
+	
+		throw out_of_range("out of range!");
+		return;
+	}
+
+	else if(n>size())
+	{
+		auto count = n - size();
+		uninitialized_fill_n(firstfree, count, str);
+	}
+}
+
+int main()
+{
+	StrVec test{"xianguy", "love", "liuchang"};
+	test.push_back("xiangyu");
+	 test.push_back("liuchang");
+	 cout << "capacity: " << test.capacity() << endl;
+	 cout << "size: " << test.size() << endl;
+	 for(auto it=test.begin(); it !=test.end(); it++)
+	 {
+	 	cout << *it << endl;
+	 }
+	return 0;
+}

C++PrimerTest/exercise13.5StrVec.cpp

@@ -0,0 +1,51 @@
+#include <iostream>
+#include <string>
+#include <memory>
+#include <utility>
+#include <stdexcept>
+#include <initializer_list>
+#include <algorithm>
+
+using namespace std;
+//allocator<string> alloc; 
+class StrVec
+{
+private:
+	string* elements;  //指向分配内存中的首元素
+	string* firstfree; //指向最后一个实际元素之后的位置
+	string* cap;	   //指向分配的内存末尾之后的位置
+	allocator<string> alloc;   //分配元素
+	void chk_n_alloc()
+	{
+		if(size() == capacity()) 
+			reallocate();
+	}
+	pair<string*, string*> alloc_n_copy(const string*, const string*);
+	void free();
+	void reallocate();
+public:
+	StrVec():
+		elements(nullptr), firstfree(nullptr), cap(nullptr) {}
+	StrVec(initializer_list<string> strlist);
+	StrVec(const StrVec&);  //拷贝构造函数
+	StrVec& operator=(const StrVec&); //赋值构造函数
+	~StrVec();
+	void push_back(const string&);
+	size_t size()
+	{return (firstfree - elements);}
+	size_t capacity()
+	{return (cap - elements);}
+	string* begin() const
+	{
+		return elements;
+	}
+	string* end() const
+	{
+		return firstfree;
+	}
+	void reserve(size_t n);
+	void resize(size_t n);
+	void resize(size_t n, string str);
+
+
+};