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CCF 201509-3 template generation system

2022-07-25 09:57:00 【Tobi_ Obito】

subject

Problem description

　　 Cheng Cheng is building a website recently , Part of the content of some of these pages comes from different data records in the database , But the basic structure of the page is the same . for example , For pages that display user information , When the user is Tom when , The source code of the web page is

　　 And when the user is Jerry when , The source code of the web page is

　　 There are many more examples of this in websites with dynamic content . In order to simplify the generation of web pages , Cheng Cheng thinks he needs to introduce a template generation system .
　　 Templates are text that contains special tags . The template used in Chengcheng contains only one special tag , The format is { { VAR }}, among VAR It's a variable . This tag will be changed when the template is generated VAR The value of . for example , If the variable name = "Tom", be { { name }} Will generate Tom. The specific rules are as follows ：
　　· Variable names are made up of uppercase and lowercase letters 、 Numbers and underscores (_) constitute , And the first character is not a number , Length not exceeding 16 Characters .
　　· Variable names are case sensitive ,Name and name It's two different variables .
　　· The value of a variable is a string .
　　· If the variable in the tag is not defined , Then an empty string will be generated , It's equivalent to removing the tag from the template .
　　· Templates are not generated recursively . in other words , If the value of a variable contains a shape like { { VAR }} The content of , No further replacement .

Input format

　　 The first line of input contains two integers m, n, It represents the number of lines of the template and the number of variables given when the template is generated .
　　 Next m That's ok , Each line is a string , Presentation template .
　　 Next n That's ok , Each line represents a variable and its value , Separated by a space . The value is a string , Use double quotes (") Cover up , Content can contain any printable... Except for double quotes ASCII character （ASCII Code range 32, 33, 35-126）.

Output format

　　 The output contains several lines , Represents the result of template generation .

The sample input

11 2
<!DOCTYPE html>
<html>
<head>
<title>User { { name }}</title>
</head>
<body>
<h1>{ { name }}</h1>
<p>Email: <a href="mailto:{ { email }}">{ { email }}</a></p>
<p>Address: { { address }}</p>
</body>
</html>
name "David Beckham"
email "[email protected]"

Sample output

<!DOCTYPE html>
<html>
<head>
<title>User David Beckham</title>
</head>
<body>
<h1>David Beckham</h1>
<p>Email: <a href="mailto:[email protected]">[email protected]</a></p>
<p>Address: </p>
</body>
</html>

Evaluate use case size and conventions

　　0 ≤ m ≤ 100
　　0 ≤ n ≤ 100
　　 The length of each line of the input template does not exceed 80 Characters （ Does not contain line breaks ）.
　　 Type in all of the guarantee templates to { { The first substring is a legal token , It starts with two left braces and a space , And then the variable name , It ends with a space and two closing braces .
　　 The value string length of all variables in the input does not exceed 100 Characters （ Do not include double quotes ）.
　　 Make sure that the names of all the variables you enter are different .

Problem analysis

This problem looks a little messy at a glance , Do not know how to start , It is a topic that needs to be analyzed systematically . First, input the template first, and then input （ Variable , value ）, So you must store the template first . Besides , We can focus on each line of the template , Because the processing of each line is similar and does not affect each other . For each line , Make the following analysis ：

First of all, we need location marks { { xxx }} The location of , Because the title tells us “ Type in all of the guarantee templates to { { The first substring is a legal token ”, So the starting position of the mark can be found by 2 A continuous '{' complete , Then we start from this position 、 Mark the required spaces with '}'、 Variable name length to calculate the end position of the tag '}'. In subsequent processing, you only need to replace all tags with the values of the corresponding variables .

Analyze and process each line , Let's consider the whole template . Each line may have multiple tags , So each line needs a record mark position （ The starting position , End position ） Array of , And a numeric variable to record the number of marks in each line .

Finally, the problem of mapping variables to values , This obviously works map To complete , It is worth mentioning that , Because when using map[new] And new Not before map As defined in , This will be right map[new] Default initialization , Because the mapping type in this topic is (string,string), So it will initialize by default map[new]= Empty string , In this way, there is no need to deal with the situation that there is no variable name in the tag . Don't forget to ignore the double quotation marks in the value in the details .

The easiest thing to mess up is the location of the mark , So be sure to know how the location of the mark is recorded , What I recorded was [ The starting position , End position next position ). Here's the code .

Code

#include<iostream>
#include<vector>
#include<map>
#include<algorithm>
using namespace std;

const int MAX = 100;

void scan(const string &s,int *num,vector<string> &vars,vector<pair<int,int> > &pos){
	int i,j,len = s.length();
	for(i=1;i<len-4;i++){// Legal mark {
   { At least 4 Characters  "_ _ } }"
		if(s[i] == '{' && s[i-1] == '{'){
			*num = *num + 1;
			j = i + 2;
			while(s[j]!=' ') j++;
			vars.push_back(string(s.begin()+i+2,s.begin()+j));
			pos.push_back(make_pair(i-1,j+3));
		}
	}
}

void print(const string &s,int num,const vector<string> &vars,const vector<pair<int,int> > &pos,map<string,string> &f){
	if(num==0){// This line is unmarked  
		cout<<s<<endl;
		return;
	}
	int from = 0,to;
	string t = "";
	for(int i=0;i<num;i++){
		to = pos[i].first;
		t += string(s.begin()+from,s.begin()+to);// Connect the unmarked part to t after  
		t += f[string(s.begin()+pos[i].first+3, s.begin()+pos[i].second-3)];// Replace the marked part with the corresponding value of the variable , Then connect to t after  
		from = pos[i].second;
	}
	t += string(s.begin()+from,s.end());// The unmarked part at the end is connected to t after  
	cout<<t<<endl;
}

int main(){
	int m,n;
	map<string,string> f;
	int row_num[MAX] = {0};// Count how many variables need to be replaced in each line  
	
	cin>>m>>n;
	getchar();// Absorption enter  
	vector<vector<string> > vars(m);// Record the variables to be replaced in each line  
	vector<string> text(m);// Store the entire template  
	vector<vector<pair<int,int> > > pos(m);// Record the... Of each template to be replaced in each line [ Start , end ) Location  
	
	for(int i=0;i<m;i++){
		getline(cin,text[i]);
		scan(text[i],&row_num[i],vars[i],pos[i]);// Process each row , Find the number of tags 、 Position and record  
	}
	string name,value,t;
	string::iterator it;
	for(int i=0;i<n;i++){
		getline(cin,t);
		it = find(t.begin(),t.end(),' ');// Find the space after the variable name , Separate variable names from values （algorithm Functions in header file ） 
		name = string(t.begin(),it);
		value = string(it+1,t.end());
		f[name] = string(value.begin()+1,value.end()-1);
	}
	
	for(int i=0;i<m;i++){
		print(text[i],row_num[i],vars[i],pos[i],f);// Process and output each line  
	}
	return 0;
}

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