52 lines
1.7 KiB
Plaintext
52 lines
1.7 KiB
Plaintext
[/==============================================================================
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Copyright (C) 2001-2011 Joel de Guzman
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Copyright (C) 2001-2011 Hartmut Kaiser
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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===============================================================================/]
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[section Number List Attribute - one more, with style]
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You've seen that the `double_` parser has a `double` attribute. All parsers have
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an attribute, even complex parsers. Those that are composed from primitives
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using operators, like the list parser, also have an attribute. It so happens that
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the attribute of a list parser:
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p % d
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is a `std::vector` of the attribute of `p`. So, for our parser:
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double_ % ','
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we'll have an attribute of:
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std::vector<double>
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So, what does this give us? Well, we can simply pass in a `std::vector<double>`
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to our number list parser and it will happily churn out our result in our
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vector. For that to happen, we'll use a variation of the `phrase_parse` with
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an additional argument: the parser's attribute. With the following arguments
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passed to `phrase_parse`
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# An iterator pointing to the start of the input
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# An iterator pointing to one past the end of the input
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# The parser object
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# Another parser called the skip parser
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# The parser's attribute
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our parser now is further simplified to:
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[import ../../example/qi/num_list4.cpp]
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[tutorial_numlist4]
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The full cpp file for this example can be found here: [@../../example/qi/num_list4.cpp]
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[*Hey, no more actions!!!] Now we're entering the realm of attribute grammars.
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Cool eh?
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[endsect]
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