提振精神的队长问题 [英] Boost spirit skipper issues

问题描述

我有提振精神的船长麻烦。

I have trouble with boost spirit skippers.

我需要解析这样的文件：

I need to parse a file like that :

ROW int
int [int, int]
int [int, int]
...

我能够解析它没有问题（感谢StackOverflow的;）只有我的第一个INT后面加一个'_'。

I am able to parse it without problem (thanks to stackoverflow ;) only if I add an '_' after the first int.

其实，我觉得队长第一个吃INT后线的末端，所以第一和第二（在第二行）看起来像只有一个int值。我不明白如何保持停产，但吃的空间。我发现的例子使用像这里自定义解析器和这里。

In fact, I think the skipper eat the end of line after the first int, so the first and second (on second line) look as only one int. I don't understand how to keep eol but eat spaces. I've found examples to use a custom parser like here and here.

我试过气::空白，自定义分析器与一个单一的规则亮（''）
不管我用什么队长，空间和EOL总是吃。

I tried qi::blank, custom parser with one single rule lit(' ') No matter what skipper I use, space and eol are always eat.

我的语法是：

行：

struct rowType
{
    unsigned int number;
    std::list<unsigned int> list;
};

存储在一个结构的完整的问题：

the full problem stored in a structure :

struct problemType
{
    unsigned int ROW;
    std::vector<rowType> rows;
};

行解析器：

template<typename Iterator>
struct row_parser : qi::grammar<Iterator, rowType(), qi::space_type>
{
    row_parser() : row_parser::base_type(start)
    {

        list  = '[' >> -(qi::int_ % ',') >> ']';
        start = qi::int_ >> list;
    }

    qi::rule<Iterator, rowType(), qi::space_type> start;
    qi::rule<Iterator, std::list<unsigned int>(), qi::space_type> list;
};

和问题解析：

template<typename Iterator>
struct problem_parser : qi::grammar<Iterator,problemType(),qi::space_type>
{

    problem_parser() : problem_parser::base_type(start)
    {
        using boost::phoenix::bind;
        using qi::lit;

        start = qi::int_ >> lit('_') >> +(row);

        //BOOST_SPIRIT_DEBUG_NODE(start);
    }

    qi::rule<Iterator, problemType(),qi::space_type> start;
    row_parser<Iterator> row;
};

和我使用这样的：

main() {
static const problem_parser<spirit::multi_pass<base_iterator_type> > p;
...
spirit::qi::phrase_parse(first, last ,
            p,
            qi::space,
            pb);
}

当然，补气::空间是我的问题，并解决我的问题将不使用的队长一种方式，但phrase_parse需要一个，然后我的解析器要求之一。

Of course, the qi::space is my problem, and a way to solve my problem would be to don't use a skipper, but phrase_parse requires one, and then my parser requires one.

我现在因为几个小时卡住...
我认为这是显而易见的事我误解。

I'm stuck since some hours now... I think it's something obvious I have misunderstood.

感谢您的帮助。

推荐答案

在一般以下指令是用于抑制/开关船长中期语法帮助：

In general the following directives are helpful for inhibiting/switching skippers mid-grammar:

• <一个href=\"http://www.boost.org/doc/libs/1_53_0/libs/spirit/doc/html/spirit/qi/reference/directive/lexeme.html\"><$c$c>qi::lexeme [P]
  抑制一个队长，例如如果你想确保你解析没有内部跳过的标识符）

• qi::lexeme [ p ]
  which inhibits a skipper, e.g. if you want to be sure you parse an identifier without internal skips)

<一个href=\"http://www.boost.org/doc/libs/1_53_0/libs/spirit/doc/html/spirit/qi/reference/directive/raw.html\"><$c$c>qi::raw [P]
它解析像往常一样，包括跳跃，但返回匹配源序列的原始迭代器区间（包括跳过的位置）

qi::raw [ p ]
which parses like always, including skips, but returns the raw iterator range of the matched source sequence (including the skipped positions)

其中， P 是任何解析器前pression。

where p is any parser expression.

您的问题，因为你已经知道了，可能是齐::空间吃所有的空白。我不可能知道什么是错在你的语法（因为你不显示为完整的语法，或相关的输入）。

Your problem, as you already know, might be that qi::space eats all whitespace. I can't possibly know what is wrong in your grammar (since you don't show either the full grammar, or relevant input).

因此​​，这里是我会写。注意

Therefore, here's what I'd write. Note

• 使用 齐:: EOL 到明确地的要求在特定的地点换行


• 使用齐::空白作为队长（不包括 EOL ）
的

• 为简单起见我结合语法

• the use of qi::eol to explicitely require linebreaks at specific locations
• the use of qi::blank as a skipper (not including eol)
• for brevity I combined the grammars

code：

#define BOOST_SPIRIT_DEBUG
#include <boost/fusion/adapted.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>

namespace qi = boost::spirit::qi;
namespace phx = boost::phoenix;

struct rowType {
    unsigned int number;
    std::list<unsigned int> list;
};

struct problemType {
    unsigned int ROW;
    std::vector<rowType> rows;
};

BOOST_FUSION_ADAPT_STRUCT(rowType, (unsigned int, number)(std::list<unsigned int>, list))
BOOST_FUSION_ADAPT_STRUCT(problemType, (unsigned int, ROW)(std::vector<rowType>, rows))

template<typename Iterator>
struct problem_parser : qi::grammar<Iterator,problemType(),qi::blank_type>
{
    problem_parser() : problem_parser::base_type(problem)
    {
        using namespace qi;
        list    = '[' >> -(int_ % ',') >> ']';
        row     = int_ >> list >> eol;
        problem = "ROW" >> int_ >> eol >> +row;

        BOOST_SPIRIT_DEBUG_NODES((problem)(row)(list));
    }

    qi::rule<Iterator, problemType()            , qi::blank_type> problem;
    qi::rule<Iterator, rowType()                , qi::blank_type> row;
    qi::rule<Iterator, std::list<unsigned int>(), qi::blank_type> list;
};

int main()
{
    const std::string input = 
        "ROW 1\n"
        "2 [3, 4]\n"
        "5 [6, 7]\n";

    auto f = begin(input), l = end(input);

    problem_parser<std::string::const_iterator> p;
    problemType data;

    bool ok = qi::phrase_parse(f, l, p, qi::blank, data);

    if (ok) std::cout << "success\n";
    else    std::cout << "failed\n";

    if (f!=l)
        std::cout << "Remaining unparsed: '" << std::string(f,l) << "'\n";
}

如果你真的不想要求换行：

If you really didn't want to require line breaks:

template<typename Iterator>
struct problem_parser : qi::grammar<Iterator,problemType(),qi::space_type>
{
    problem_parser() : problem_parser::base_type(problem)
    {
        using namespace qi;
        list    = '[' >> -(int_ % ',') >> ']';
        row     = int_ >> list;
        problem = "ROW" >> int_ >> +row;

        BOOST_SPIRIT_DEBUG_NODES((problem)(row)(list));
    }

    qi::rule<Iterator, problemType()            , qi::space_type> problem;
    qi::rule<Iterator, rowType()                , qi::space_type> row;
    qi::rule<Iterator, std::list<unsigned int>(), qi::space_type> list;
};

int main()
{
    const std::string input = 
        "ROW 1 " // NOTE whitespace, obviously required!
        "2 [3, 4]"
        "5 [6, 7]";

    auto f = begin(input), l = end(input);

    problem_parser<std::string::const_iterator> p;
    problemType data;

    bool ok = qi::phrase_parse(f, l, p, qi::space, data);

    if (ok) std::cout << "success\n";
    else    std::cout << "failed\n";

    if (f!=l)
        std::cout << "Remaining unparsed: '" << std::string(f,l) << "'\n";
}

更新

在回应评论：这里是一个片段，展示了如何从文件中读取输入。这是测试和对我工作得很好：

Update

In response to the comment: here is a snippet that shows how to read the input from a file. This was tested and works fine for me:

std::ifstream ifs("input.txt"/*, std::ios::binary*/);
ifs.unsetf(std::ios::skipws);

boost::spirit::istream_iterator f(ifs), l;

problem_parser<boost::spirit::istream_iterator> p;

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