Re: [boost] [RFC] string inserter/extractor "q u o t i n g"

Subject: Re: [boost] [RFC] string inserter/extractor "q u o t i n g"
From: Rob Stewart (robertstewart_at_[hidden])
Date: 2010-06-30 18:12:54

On 6/23/2010 9:59 PM, Rob Stewart wrote:
>
> When considered as the inverse of quote(), unquote() should
> simply strip leading and trailing delimiters and look for escaped
> delimiters and escaped escape characters within. To supply the
> extra semantics you've suggested, quote() must also be enhanced
> significantly.

I've attached a new version of unquote() (along with quote() and 
the updated test program) with that behavior.

As implemented, unquote() stops at the first delimiter it finds 
after the first character (whether the first is a delimiter or 
not).  Until then, it "unescapes" escaped characters.  Note the 
last test case:

    a = "embedded ";
    b = quote(a);
    b += "quotation mark\"";
    BOOST_ASSERT("\"embedded \"quotation mark\"" == b);
    b = unquote(b);
    BOOST_ASSERT(a == b);

In that test, "quotation mark\"" is ignored by unquote() because 
it stops writing to the output iterator up finding the quotation 
mark after the space following "embedded."

It is possible for unquote() to leave the embedded quotation 
mark, as if it had been escaped, but it would complicate the 
algorithm -- unless I assume random access iterators -- and its 
description.

This version doesn't care whether the first or last characters 
are delimiters, thus "muddling through" as Eric suggested.

I haven't taken the time to consider other reasonable ideas for 
delimiter support such as multiple character delimiters or 
distinct start and end delimiters.

___
Rob