Re: [Boost-users] Boost.Xpressive

On 8/15/14, 8:09 AM, Jeff Flinn wrote:

On 8/13/14 8:16 PM, Nat Goodspeed wrote:

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On Wed, Aug 13, 2014 at 7:18 PM, Eric Niebler wrote:

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On 8/11/2014 5:27 AM, Goran wrote:

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So, how can I open a CSV file in text mode, get bidirectional iterators and hand them over to Xpressive?

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The hard part is implementing a bidirectional iterator that pages in sections of a text file on demand.

I'm not aware of such a beast in Boost. If I were to implement one, I'd probably start by looking at the existing support for memory mapped files in Boost.Interprocess.

You might also take a look at multi-pass iterators from Spirit: http://www.boost.org/doc/libs/1_56_0/libs/spirit/doc/html/spirit/support/mul...

Unless used with spirit's expectation points, multi-pass will suffer the same issue raised by the OP as the data is stored in memory as it's read from file via a std::vector IIRC.

A little known utility in spirit classic is the file_iterator: http://www.boost.org/doc/libs/1_39_0/boost/spirit/home/classic/iterator/file... It uses memmap whenever available. Regards, -- Joel de Guzman http://www.ciere.com http://boost-spirit.com http://www.cycfi.com/