boost :: spirit :: qi ::解析语法不能按预期工作 [英] boost::spirit::qi::parse grammar not working as expected
问题描述
我尝试编写语法来解析以下语法:
// - command
// - 命令value0 ... valueN
// - 命令-arg0 ... -argN
// - 命令-arg0 value0 ... valueN ... -argN value0 ... valueN
- 每个元素都应解释为字符串
-
- 一个参数总是以 - 开始。 / li>
-
结果应存储在结构中:
struct Data
{
std :: string m_command;
std :: map< std :: string,std :: vector< std :: string> m_arg;
}
- m_command将存储已解析的命令
- m_arg应将解析的参数和相应的值存储在向量中
我在一个简短示例中添加了我当前的语法这里
我的问题:
向量包含比可用值更多的条目,因为空格也被解释为值
这不是很清楚你想要的语法函数¹,但从目标数据结构,我得到的印象可以大大简化
- 使用船长(请参阅 Boost精灵船长问题作为背景)
-
使用自动属性传播而不是phoenix(另请参阅 Boost Spirit:Semantic actions are evil?)。
code> token = +〜char _(\r\\\
- );
values = + token;
//
entry =(lexeme [' - '>> token]> --values | attr(empty)>>值);
args = * entry;
//
data = skip(qi :: blank)[token>> args]
适用于启用自动属性传播(可立即使用
#define BOOST_SPIRIT_DEBUG
//#define BOOST_SPIRIT_DEBUG
#include< boost / fusion / adapted.hpp>
#include< boost / spirit / include / qi.hpp>
#include< map>
#include< ; string>
#include< vector>
//结构存储已解析的命令行信息:
struct CmdData
{
typedef std :: string Name;
typedef std :: string ArgName;
typedef std :: string Value;
typedef std :: vector< Value> Values; // Type定义值列表:
typedef std :: map< ArgName,Values> Args; // Type定义一个存储参数和相应值之间关系的映射:
Name cmd; //将命令名存储为字符串。
Args arg; //将参数和相应的值存储为字符串。
};
BOOST_FUSION_ADAPT_STRUCT(CmdData,(CmdData :: Name,cmd)(CmdData :: Args,arg))
命名空间语法
{
namespace qi = boost :: spirit :: qi;
//此类实现用于解析命令行的语法。
//预期的格式如下:
// - command
// - command value0 ... valueN
// - command -arg0 ... -argN
// - command -arg0 value0 ... valueN ... -argN value0 ... valueN
template< typename It>
struct decode:qi :: grammar< It,CmdData()>
{
decode():decode :: base_type(data)
{
使用命名空间qi;
token = +〜char _(\r\\\
- );
values = + token;
//
entry =(lexeme [' - '>> token]> --values | attr(empty)>>值);
args = * entry;
//
data = skip(qi :: blank)[token>> args];
BOOST_SPIRIT_DEBUG_NODES((token)(values)(entry)(args)(data))
}
private:
qi :: rule< It,CmdData()>数据;
//以下变量定义了此语法中使用的规则:
typedef std :: pair< CmdData :: ArgName,CmdData :: Values>条目;
qi :: rule< It,CmdData :: Values(),qi :: blank_type>值;
qi :: rule< It,Entry(),qi :: blank_type>条目;
qi :: rules< It,CmdData :: Args(),qi :: blank_type> args;
// lexemes
qi :: rule< It,std :: string()>令牌
};
} //命名空间
bool parse(const std :: string& in)
{
CmdData data;
//创建一个使用语法的实例:
Grammar :: decode< std :: string :: const_iterator> gr;
//尝试根据语法解析存储在流中的数据,并将结果存储在标记变量中:
bool b = boost :: spirit :: qi :: parse(in .begin(),in.end(),gr,data);
std :: cout<< Parsing:'<<在<< 'ok:<< std :: boolalpha< b<< \\\
;
if(b)
std :: cout<< 条目解析:< data.arg.size()< \\\
;
return b;
}
int main()
{
parse(cmd0)
parse(cmd0 -23.0 value0 value1 value2);
parse(cmd0 -arg0 -arg1 -arg2);
parse(cmd0 -arg0 value0 -arg1 value0 value1 -arg2 value0 value1 value2);
}
列印
解析:'cmd0'ok:true
解析的条目:0
解析:'cmd0 -23.0 value0 value1 value2'ok:true
解析的条目:1
解析:'cmd0 -arg0 -arg1 -arg2'ok:true
解析的条目:3
解析:'cmd0 -arg0 value0 -arg1 value0 value1 -arg2 value0 value1 value2'ok:true
条目解析:3
(禁用调试输出)
¹(例如 -23.0
明确表示某个选项)
I try to write a grammar to parse the following syntax:
// - command
// - command value0 ... valueN
// - command -arg0 ... -argN
// - command -arg0 value0 ... valueN ... -argN value0 ... valueN
- Each element shall be interpreted as a string
- Within a string all symbols are allowed
- Between command, argument and value multiple blanks shall be allowed
- An argument starts always with '-'
The results shall be stored in a struct:
struct Data { std::string m_command; std::map< std::string, std::vector< std::string > m_arg; }
- m_command shall store the parsed command
- m_arg shall store the parsed argument and the corresponding values within a vector
I added my current grammar within a short example here
My problem:
The vector contains more entries than available values because blanks are also interpreted as values
It's not exactly clear how you want the grammer to function¹, but from the target data structure I get the impression things could be simplified vastly by
- using a skipper (see Boost spirit skipper issues for background)
using automatic attribute propagation instead of phoenix (see also Boost Spirit: "Semantic actions are evil"?).
token = +~char_("\r\n -"); values = +token; // entry = (lexeme['-' >> token] >> -values | attr("empty") >> values); args = *entry; // data = skip(qi::blank) [ token >> args ];
In the sample below I've used Fusion adaptation to enable automatic attribute propagation (which, at once, enables debug output with
#define BOOST_SPIRIT_DEBUG
//#define BOOST_SPIRIT_DEBUG
#include <boost/fusion/adapted.hpp>
#include <boost/spirit/include/qi.hpp>
#include <map>
#include <string>
#include <vector>
// Structure stores the parsed command line information:
struct CmdData
{
typedef std::string Name;
typedef std::string ArgName;
typedef std::string Value;
typedef std::vector<Value> Values; // Type defines a list of values:
typedef std::map<ArgName, Values> Args; // Type defines a map storing the relation between a argument and the corresponding values:
Name cmd; // Stores the command name as a string.
Args arg; // Stores the arguments and the corresponding values as strings.
};
BOOST_FUSION_ADAPT_STRUCT(CmdData, (CmdData::Name, cmd)(CmdData::Args, arg))
namespace Grammar
{
namespace qi = boost::spirit::qi;
// This class implements the grammar used to parse a command line.
// The expected format is as follows:
// - command
// - command value0 ... valueN
// - command -arg0 ... -argN
// - command -arg0 value0 ... valueN ... -argN value0 ... valueN
template <typename It>
struct decode : qi::grammar<It, CmdData()>
{
decode() : decode::base_type(data)
{
using namespace qi;
token = +~char_("\r\n -");
values = +token;
//
entry = (lexeme['-' >> token] >> -values | attr("empty") >> values);
args = *entry;
//
data = skip(qi::blank) [ token >> args ];
BOOST_SPIRIT_DEBUG_NODES( (token)(values)(entry)(args)(data) )
}
private:
qi::rule<It, CmdData()> data;
// The following variables define the rules used within this grammar:
typedef std::pair<CmdData::ArgName, CmdData::Values> Entry;
qi::rule<It, CmdData::Values(), qi::blank_type> values;
qi::rule<It, Entry(), qi::blank_type> entry;
qi::rule<It, CmdData::Args(), qi::blank_type> args;
// lexemes
qi::rule<It, std::string()> token;
};
} // namespace
bool parse(const std::string& in)
{
CmdData data;
// Create an instance of the used grammar:
Grammar::decode<std::string::const_iterator> gr;
// Try to parse the data stored within the stream according the grammar and store the result in the tag variable:
bool b = boost::spirit::qi::parse(in.begin(), in.end(), gr, data);
std::cout << "Parsing: '" << in << "' ok: " << std::boolalpha << b << "\n";
if (b)
std::cout << "Entries parsed: " << data.arg.size() << "\n";
return b;
}
int main()
{
parse(" cmd0");
parse(" cmd0 -23.0 value0 value1 value2");
parse(" cmd0 -arg0 -arg1 -arg2");
parse(" cmd0 -arg0 value0 -arg1 value0 value1 -arg2 value0 value1 value2");
}
Prints
Parsing: ' cmd0' ok: true
Entries parsed: 0
Parsing: ' cmd0 -23.0 value0 value1 value2' ok: true
Entries parsed: 1
Parsing: ' cmd0 -arg0 -arg1 -arg2' ok: true
Entries parsed: 3
Parsing: ' cmd0 -arg0 value0 -arg1 value0 value1 -arg2 value0 value1 value2' ok: true
Entries parsed: 3
(with debug output disabled)
¹ (e.g. is -23.0
expressly an option or not)
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