一个行编辑器的实现
放假无聊，而且又不想学什么java，web编程等等。觉得自己oop思想还是不够，所以就打算把乔老的《数据结构与算法实验教程》的实验全部做完再说。下面就做了一个行编辑器：
Editor_H.h：
#ifndef Editor_H
#define Editor_H
#include <iostream>
#include <list>
#include <fstream>
#include <vector>
#include <string>
using namespace std;
class Editor
{
public:
//后置条件:编辑器为空。
Editor();
/* 如果line为合法命令，则该命令被执行，执行结果被返回。若line是插入的文本行，则该文本行被插入并返回结果；否则，返回非法命令错误。
*/
string parse(const string& line);
//protected:
/*后置条件：检查line是否有错误。如果不存在错误,则命令被执行,结果被返回；否则，一个错误信息被返回。
*/
string command_check(const string& line);
/*如果line不是很长,则将其插入编辑器，并返回一个空行；否则,返回错误信息。
*/
string insert_command(const string& line);
/*后置条件：如有可能,删除第k至第m行，并返回一个空行;否则，返回错误信息。
*/
string delete_command(const string& line);
/*后置条件：如有可能，第m行成为当前行,并返回一个空行;否则，返回错误信息。
*/
string line_command(int m);
/*后置条件：编辑器运行结束,并返回文本。
*/
string done_command();
/*后置条件：退出编辑器
*/
string quit_command();
/*后置条件：将在内存的文本文件存盘
*/
string save_command();
/*后置条件：打开一个新文件
*/
string open_command();
/*后置条件：输出命令的帮助信息
*/
string help_command();
/*后置条件：将文本中第k行至第m行输出至标准输出
*/
string print_command(const string& line);
/*后置条件：将文本中的所有字符串str1的出现替换成字符串str2
*/
string replace_command();
list<string> text; //文本
list<string>::iterator current; //指向当前行的指针
int currentLineNumber; //记录当前行的编号
bool inserting; //判断是否进入了insert操作
};
#endif
Editor.cpp：
#include "Editor_H.h"
Editor::Editor()
{
text.clear();
current = text.begin();
currentLineNumber = -1;
inserting = false;
}
string Editor::parse(const string &line)
{
if(line.substr(0,7) == "$Insert" && inserting == false)
{
inserting = true;
return " ";
}
else if(line.substr(0,7) == "$Delete" )
{
inserting = false;
return delete_command(line);
}
else if(line.substr(0,6) == "$Print")
{
inserting = false;
return print_command(line);
}
else if(line.substr(0,5) == "$Line" )
{
int a;
inserting = false;
if(line.substr(5,2) == "-1")
{
a = -1;
return line_command(a);
}
else
{
int i = 0,j,a = 0;
for(j = 6;(line[j] >= '0' && line[j] <= '9');j++)
{
a = 10 * a;
a += (line[j] - '0');
}
return line_command(a);
}
}
else if(line.substr(0,5) == "$Done" )
{
inserting = false;
return done_command();
}
else if(line.substr(0,5) == "$Quit")
{
inserting = false;
return quit_command();
}
else if(line.substr(0,5) == "$Save")
{
inserting = false;
return save_command();
}
else if(line.substr(0,5) == "$Open")
{
inserting = false;
return open_command();
}
else if(line.substr(0,5) == "$Help")
{
inserting = false;
return help_command();
}
else if(line.substr(0,8) == "$Replace")
{
inserting = false;
return replace_command();
}
else if(inserting == true)
return insert_command(line);
else
{
return "***Error:This is an illegal instruction.Please enter again.";
}
}
string Editor::insert_command(const string& line)
{
if(currentLineNumber == -1)
{
text.push_front(line);
currentLineNumber++;
current = text.begin();
current++;
}
//在当前行的下一位置插入
else
{
text.insert(current,line);
currentLineNumber++;
}
return " "; //返回一个空行，表示插入成功
}
string Editor::delete_command(const string &line)
{
int k = 0,m = 0,i = 0,j;
//捕获第一个参数
if(!((line[8] >= '0' && line[8] <= '9') || (line[8] == '-')))
return "***Error:The command is not followed by two integers.";
else if(line[8] == '-')
return "***Error:The first line number < 0.";
else
{
for(j = 8 ; (line[j] >= '0' && line[j] <= '9');j++)
{
k = k * 10;
k += (line[j] - '0');
}
while(line[j] == ' ')
j++;
for(;(line[j] >= '0' && line[j] <= '9');j++)
{
m = m * 10;
m += (line[j] - '0');
}
if(k > m)
return "***Error:The first line number > the second.";
else if(k < 0)
return "***Error:The first line number < 0.";
else if(m >= text.size())
return "***Error:The second line number > the last line number.";
else
{
list<string>::iterator temp = text.begin();
for(i = 0;i < k -1 ;i++)
temp++;
list<string>::iterator itr = temp;
for(i = k; i <= m;i++)
{
itr = text.erase(itr);
}
current = temp;
currentLineNumber = k -1;
return " "; //删除成功，返回一个空行
}
}
}
string Editor::print_command(const string& line)
{
int k = 0,m = 0,i = 0,j;
//捕获第一个参数
if(!((line[7] >= '0' && line[7] <= '9') || (line[7] == '-')))
return "***Error:The command is not followed by two integers.";
else if(line[7] == '-')
return "***Error:The first line number < 0.";
else
{
for(j = 7 ; (line[j] >= '0' && line[j] <= '9');j++)
{
k = k * 10;
k += (line[j] - '0');
}
while(line[j] == ' ')
j++;
for(;(line[j] >= '0' && line[j] <= '9');j++)
{
m = m * 10;
m += (line[j] - '0');
}
if(k > m)
return "***Error:The first line number > the second.";
else if(k < 0)
return "***Error:The first line number < 0.";
else if(m >= text.size())
return "***Error:The second line number > the last line number.";
else
{
list<string>::iterator temp = text.begin();
for(i = 0;i < k -1 ;i++)
temp++;
list<string>::iterator itr = temp;
for(i = k; i <= m;i++)
{
cout << i << " " << *itr << endl;
itr++;
}
return " "; //删除成功，返回一个空行
}
}
}
string Editor::line_command(int m)
{
int i;
if(m >= text.size() && m >= 0)
return "***Error:the line number is greater than the last line number.";
else if(m == -1)
{
current = text.begin();
currentLineNumber = -1;
return " "; //操作成功，返回一个空行。
}
else
{
currentLineNumber = m;
list<string>::iterator temp = text.begin();
for(i = 0;i < m ;i++)
temp++;
current = temp;
current++;
return " "; //操作成功，返回一个空行。
}
}
string Editor::done_command()
{
if(text.empty())
{
cout << "The text is empty." << endl ;
return " "; //表示文本为空
}
else
{
cout << "Here is the final text:" << endl << endl;
list<string>::iterator itr = text.begin();
while(itr != text.end())
{
cout << *itr << endl;
itr++;
}
return " "; //操作成功，返回一个空行。
}
}
string Editor::quit_command()
{
return "Please press the Enter key to close this output window.";
}
string Editor::save_command()
{
cout << "Please enter the name of the document:" << endl;
ofstream output;
string name;
vector<string> file;
list<string>::iterator qq = text.begin();
cin >> name;
file.push_back(name);
vector<string>::const_iterator temp = file.begin();
output.open(temp->c_str());
while(qq != text.end())
{
output << *qq << endl;
qq++;
}
output.close();
return "***Finish.";
}
string Editor::open_command()
{
text.clear();
current = text.begin();
currentLineNumber = -1;
return "***Finish.";
}
string Editor::help_command()
{
cout << "*** $Insert -- 插入命令 ***" << endl;
cout << "*** $Delete k m -- 删除第k~第m行 ***" << endl;
cout << "*** $Line m -- 使第m行变成当前行 ***" << endl;
cout << "*** $Print k m -- 输出第k~第m行 ***" << endl;
cout << "*** $Done -- 完成编辑,打印文本 ***" << endl;
cout << "*** $Quit -- 退出编辑器 ***" << endl;
cout << "*** $Save -- 在内存文本文件存盘***" << endl;
cout << "*** $Open -- 打开一个新文件 ***" << endl;
cout << "*** $Replace -- 替换命令 ***" << endl;
cout << "*** $Help -- 输出命令帮助信息 ***" << endl;
return "";
}
string Editor::replace_command()
{
string str1,str2;
cout<< "***Please enter the string1:" << endl;
getline(cin,str1);
cout<< "***Please enter the string2:" << endl;
getline(cin,str2);
list<string>::iterator itr = text.begin();
while(itr!=text.end())
{
if(*itr == str1)
*itr = str2;
itr++;
}
return ""; //操作完成，返回空行
}
text.cpp：
#include <iostream>
#include "Editor_H.h"
using namespace std;
int main()
{
const string PROMPT = "Please enter a line: ";
const string COMMAND_START = "$";
const string DONE_COMMAND = "$Done";
const string CLOSE_WINDOW_PROMPT = "Please press the Enter key to close this output window.";
Editor editor;
string result;
string line;
int i = 100;
do
{
cout << PROMPT << endl;
getline(cin,line);
if(line == "")
result = "***Save is finished.";
else
result = editor.parse(line);
cout << result << endl;
list<string>::iterator ss = editor.text.begin();
}while(result != CLOSE_WINDOW_PROMPT); //使行编辑器退出
return 0;
}
效果自己看吧：
