用 boost spirit x3 解析 SQL 类查询

Question

我正在尝试使用 boost spirit x3 解析一个简单的 SQL 类查询。之前的精灵版本有similar post。但是有了spirit x3，我们就不需要文法了
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returns:

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

results 包含提取的所有属性数据，除了保留在条件字符串中的 insideRule 属性数据。有什么线索可以让我的解析器正常工作吗？

Answer 1

这正在工作：

   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;
}

用 boost spirit x3 解析 SQL 类查询

Parse SQL like query with boost spirit x3

sql

dsl

c++14

boost-spirit-x3