精神齐序列解析问题 [英] Spirit Qi sequence parsing issues

问题描述

我有解析器写作与精神::齐2.4的一些问题。
我有一系列的键 - 值对的格式如下解析＆LT;键名称＆gt; = LT;价值方式＆gt;

I have some issues with parser writing with Spirit::Qi 2.4. I have a series of key-value pairs to parse in following format <key name>=<value>.

的键名称的可以是 [A-ZA-Z0-9] 键，总是跟着 = 与键名称和 = 符号之间没有空格符号。 键名称的也总是$ P $至少有一个空间pceded。

Key name can be [a-zA-Z0-9] and is always followed by = sign with no white-space between key name and = sign. Key name is also always preceded by at least one space.

的值的几乎可以是任何C EX pression（空格也是可能的），含恩pressions除外 = char和code块 {} 。

Value can be almost any C expression (spaces are possible as well), with the exception of the expressions containing = char and code blocks { }.

在键值对的序列的末端有一个 {标志。

At the end of the sequence of the key value pairs there's a { sign.

我奋斗了很多写作解析器这个前pression。由于密钥名称始终是由至少一个空格pceded其次为 = $ P $，并且不包含空格我把它定义为

I struggle a lot with writing parser for this expression. Since the key name always is preceded by at least one space and followed by = and contains no spaces I defined it as

  KeyName %= [+char_("a-zA-Z0-9_") >> lit("=")] ;

值几乎可以是任何东西，但它不能包含 = 也不 {字符，所以我把它定义为

Value can be almost anything, but it can not contain = nor { chars, so I defined it as:

  Value %=  +(char_ - char_("{=")) ;

我想过用前瞻的这样搭上了值：

I thought about using look-ahead's like this to catch the value:

ValueExpression 
    %= ( 
      Value  
      >> *space 
      >> &(KeyName | lit("{"))
    )
    ;

但它不会工作，出于某种原因（好像 ValueEx pression 贪婪上升到 = 号和不知道怎么从那里做）。我有限的LL解析器的知识，所以我真的不知道什么是烹调这里。有没有我可以解决这种序列的任何其他方式？

But it won't work, for some reason (seems like the ValueExpression greedily goes up to the = sign and "doesn't know" what to do from there). I have limited knowledge of LL parsers, so I'm not really sure what's cooking here. Is there any other way I could tackle this kind of sequence?

下面的例子系列：

EXP1=FunctionCall(A, B, C) TEST="Example String" \
AnotherArg=__FILENAME__ - 'BlahBlah' EXP2= a+ b+* {

其他信息：，因为这是一个更大的语法中的一部分，我不能真正解决这个问题不是由Spirit.Qi解析器（像'='和分裂做任何其他方式一些自定义的分析或类似的东西）。

Additional info: since this is a part of a much larger grammar I can't really solve this problem any other way than by a Spirit.Qi parser (like splitting by '=' and doing some custom parsing or something similar).

编辑：

我已经在这里创造最低工作例如： http://ideone.com/kgYD8 结果
（VS 2012在编译提升1.50，而应该是在旧的设置罚款以及）。

I've created minimum working example here: http://ideone.com/kgYD8
(compiled under VS 2012 with boost 1.50, but should be fine on older setups as well).

推荐答案

我建议你看看文章<一个href=\"http://boost-spirit.com/home/articles/qi-example/parsing-a-list-of-key-value-pairs-using-spirit-qi/\"相对=nofollow>解析键值对使用Spirit.Qi 的List。

I'd suggest you have a look at the article Parsing a List of Key-Value Pairs Using Spirit.Qi.

我的极大地的简化您的code，而

I've greatly simplified your code, while

• 添加属性处理


• 删除凤语义动作


• 规则调试

这，事不宜迟：

#define BOOST_SPIRIT_DEBUG

#include <boost/fusion/adapted.hpp>
#include <boost/spirit/include/qi.hpp>
#include <map>

namespace qi = boost::spirit::qi;
namespace fusion = boost::fusion;

typedef std::map<std::string, std::string> data_t;

template <typename It, typename Skipper>
struct grammar : qi::grammar<It, data_t(), Skipper>
{
    grammar() : grammar::base_type(Sequence)
    {
        using namespace qi;

        KeyName  = +char_("a-zA-Z0-9_") >> '=';
        Value    = qi::no_skip [+(~char_("={") - KeyName)];
        Sequence = +(KeyName > Value);

        BOOST_SPIRIT_DEBUG_NODE(KeyName);
        BOOST_SPIRIT_DEBUG_NODE(Value);
        BOOST_SPIRIT_DEBUG_NODE(Sequence);
    }
  private:
    qi::rule<It, data_t(), Skipper>      Sequence;
    qi::rule<It, std::string()>          KeyName; // no skipper, removes need for qi::lexeme
    qi::rule<It, std::string(), Skipper> Value;
};

template <typename Iterator>
data_t parse (Iterator begin, Iterator end)
{
    grammar<Iterator, qi::space_type> p;

    data_t data;

    if (qi::phrase_parse(begin, end, p, qi::space, data)) {
        std::cout << "parse ok\n";
        if (begin!=end) {
            std::cout << "remaining: " << std::string(begin,end) << '\n';
        }
    } else {
        std::cout << "failed: " << std::string(begin,end) << '\n';
    }

    return data;
}

int main ()
{
    std::string test(" ARG=Test still in first ARG ARG2=Zombie cat EXP2=FunctionCall(A, B C) {" );
    auto data = parse(test.begin(), test.end());

    for (auto& e : data)
        std::cout << e.first << "=" << e.second << '\n';
}

输出将是：

parse ok
remaining: {
ARG=Test still in first ARG 
ARG2=Zombie cat 
EXP2=FunctionCall(A, B C) 

如果你真的想要'{'是最后的价值的一部分，改变这一行：

If you really wanted '{' to be part of the last value, change this line:

Value    = qi::no_skip [+(char_ - KeyName)];

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