Re: [Boost-users] Can Regex callback function arguments be modified?

Subject: Re: [Boost-users] Can Regex callback function arguments be modified?
From: Ramon F Herrera (ramon_at_[hidden])
Date: 2009-09-20 10:53:54

Great! This certainly helps.

Thanks a lot, John.

-Ramon

John Maddock wrote:
>> My data is structured like this:
>>
>> [Unique ID1]
>> Variable Name = Variable Value
>> Variable Name = Variable Value
>> Variable Name = Variable Value
>>
>> [Unique ID2]
>> Variable Name = Variable Value
>> Variable Name = Variable Value
>> Variable Name = Variable Value
>> Variable Name = Variable Value
>>
>> All I need to do is to extract the different parts, to be saved in a
>> map. In my first callback, I divide every section into (a) Unique ID,
>> and (b) rest of the (multiline) block. Once I have the latter, I make a
>> call to a second callback to break the LHS and the RHS of each
>> assignment expression.
>>
>> So you say that the callback is really not required?
> 
> How about nested for-loops (caution untested code!!):
> 
> std::string text = get_text_from_file();
> regex block_extractor("\\[(\\w+)\\]([^\\[]+)");
> regex variable_extractor("(\\w+)\\s*=\\s*(\\w+)");
> 
> for(regex_iterator<std::string::const_iterator> i = 
> make_regex_iterator(text, block_extractor);
>        i != regex_iterator<std::string::const_iterator>(); ++i)
> {
>   std::string block_name = i->str(1);
>   std::string block_contents = i->str(2);
>   std::map<std::string, std::string> param_list;
> 
>  for(regex_iterator<std::string::const_iterator> j = 
> make_regex_iterator(block_contents, variable_extractor);
>        j != regex_iterator<std::string::const_iterator>(); ++j)
>  {
>      param_list[j->str(1)] = j->str(2);
>  }
> }
> 
> Obviously the regexes used may vary depending upon the exact data 
> format, but hopefully this should give you the general idea?
> 
> John.