Boost C++ Libraries

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Escaped List Separator

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.

Example

// 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";
   }
}

Construction and Usage

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.

Template Parameters

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>

Model of

TokenizerFunction

Revised 25 December, 2006

Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)