escaped_list_separator<Char, Traits = std::char_traits<Char> >
The escaped_list_separator class is an implementation of the TokenizerFunction. The escaped_list_separator parses a superset of the csv (comma separated value) format. The examples of this formate are below. It is assumed that the default characters for separator, quote, and escape are used.
Field 1,Field 2,Field 3
Field 1,"Field 2, with comma",Field 3
Field 1,Field 2 with \"embedded quote\",Field 3
Field 1, Field 2 with \n new line,Field 3
Field 1, Field 2 with embedded \\ ,Field 3
Fields are normally separated by commas. If you want to put a comma in a field, you need to put quotes around it. Also 3 escape sequences are supported
Escape Sequence |
Result |
| <escape><quote> | <quote> |
| <escape>n | newline |
| <escape><escape> | <escape> |
Where <quote> is any character specified to be a quote and<escape> is any character specified to be an escape character.
// simple_example_2.cpp
#include<iostream>
#include<boost/tokenizer.hpp>
#include<string>
int main(){
using namespace std;
using namespace boost;
string s = "Field 1,\"putting quotes around fields, allows commas\",Field 3";
tokenizer<escaped_list_separator<char> > tok(s);
for(tokenizer<escaped_list_separator<char> >::iterator beg=tok.begin(); beg!=tok.end();++beg){
cout << *beg << "\n";
}
}
escaped_list_separator has 2 constructors. They are as follows
explicit escaped_list_separator(Char e = '\\', Char c = ',',Char q = '\"')
Parameter |
Description |
| e | Specifies the character to use for escape sequences. It defaults to the C style \ (backslash). However you can override by passing in a different character. An example of when you might want to do this is when you have many fields which are Windows style filenames. Instead of escaping out each \ in the path, you can change the escape to something else. |
| c | Specifies the character to use to separate the fields |
| q | Specifies the character to use for the quote. |
escaped_list_separator(string_type e, string_type c, string_type q):
Parameter |
Description |
| e | Any character in the string e, is considered to be an escape character. If an empty string is given, then there are no escape characters. |
| c | Any character in the string c, is considered to be a separator. If an empty string is given, then there are no separator characters. |
| q | Any character in the string q, is considered to be a quote. If an empty string is given, then there are no quote characters. |
To use this class, pass an object of it anywhere in the Tokenizer package where a TokenizerFunction is required.
| Parameter | Description |
|---|---|
| Char | The type of the elements within a token, typically char. |
| Traits | The traits class for the Char type. This is used for comparing Char's. It defaults to std::char_traits<Char> |
© Copyright John R. Bandela 2001. Permission to copy, use, modify, sell and distribute this document is granted provided this copyright notice appears in all copies. This document is provided "as is" without express or implied warranty, and with no claim as to its suitability for any purpose.