像查询一样解析 SQL 与提升精神 x3

Question

我正在尝试使用boost spirit x3解析一个简单的SQL查询。以前版本的精神也有类似的帖子。但是有了精神x3，我们不需要语法。
所以这是我的尝试：

// SELECT chr, pos FROM table
// Select chr, pos FROM table WHERE a=5 and b = 6
// SELECT chr, pos FROM table WHERE a =5 and b=6 INSIDE region
// I would like to extract :
// vector<string> fields = {chr, pos}
// string tablename = "table"
// string where  = "a=5 and b=6"
// string region = "region"
string source ="SELECT chr,pos FROM table WHERE a=5 AND b=6 INSIDE region";
// varname = chr, pos, table, region
auto varname =  x3::rule<class varname, string>()
             =  x3::lexeme[(x3::alpha >> *(x3::alnum|'_'|'.'))];
// any character except "INSIDE" 
auto condition =  x3::rule<class condition, string>()
               =  x3::lexeme[*x3::char_]-"INSIDE";
// fields selection
auto selectRule = x3::rule<class fields, vector<string>> ()
                = "SELECT" >> varname % ",";
 //   table name 
auto fromRule   = x3::rule<class fromRule, string>()
                = "FROM" >> varname;
// where clause
auto whereRule  = x3::rule<class whereRule, vector<string>>()
                = "WHERE" >> condition ;
// inside clause
auto insideRule = x3::rule<class insideRule, string>()
                = "INSIDE" >> varname;
auto begin = source.begin();
auto end   = source.end();
vector<string> results;
x3::phrase_parse(begin,end,
                 selectRule >> fromRule >> -(whereRule >>-insideRule),
                 x3::space, results);
if (begin != end)
    cout<<"COULD NOT PARSE"<<endl;
else
    cout<<"parse succes"<<endl;
for (auto i : results)
    cout<<i<<endl;

它返回：

chr
pos
table
a=5 AND b=6 INSIDE region

结果包含提取的所有归因数据，但保留在条件字符串中的 InsideRule 归因数据除外。有什么线索可以让我的解析器工作吗？

Answer 1

这现在正在工作：

   struct VqlResult {
   std::vector<std::string> selectData;
   std::string fromData;
   std::string whereData;
   std::string insideData;
};
BOOST_FUSION_ADAPT_STRUCT
(
    VqlResult,
    selectData,
    fromData,
    whereData,
    insideData
);
 // Pseudo Sql parser
 // e.g : SELECT chr,pos FROM table WHERE a=5 AND b=6 INSIDE region
 bool parseSql(const std::string& sql)
{
    auto varnameRule =  x3::rule<class varname, string>()
            =  x3::lexeme[(x3::alpha >> *(x3::alnum|'_'|'.'))];

    auto columnsRule =  x3::rule<class varname, string>()
            =  x3::lexeme[*(x3::char_ - '"' - "FROM")];
    auto conditionRule =  x3::lexeme[*(x3::char_ - "INSIDE")];
    auto selectRule = x3::rule<class fields, vector<string>> ()
            = "SELECT" >> columnsRule % ",";
    auto fromRule   = "FROM" >> varnameRule;
    auto whereRule  = "WHERE" >> conditionRule;
    auto insideRule = "INSIDE" >> varnameRule;
    auto begin = sql.begin();
    auto end   = sql.end();
    VqlResult results;
    x3::phrase_parse(begin,end,
                     selectRule >> fromRule >> -whereRule >> -insideRule,
                     x3::space, results);
    // parse all
    if (begin != end){
        cout<<"cannot parse "<<endl;
        return false;
    }
    return true;
}