ClickHouse/src/Interpreters/QueryParameterVisitor.cpp

#include <Interpreters/QueryParameterVisitor.h>
#include <Parsers/IAST.h>
#include <Parsers/ASTQueryParameter.h>
#include <Parsers/ParserQuery.h>
#include <Parsers/parseQuery.h>


namespace DB
{

class QueryParameterVisitor
{
public:
    explicit QueryParameterVisitor(NameSet & parameters_name)
        : query_parameters(parameters_name)
    {
    }

    void visit(const ASTPtr & ast)
    {
        for (const auto & child : ast->children)
        {
            if (const auto & query_parameter = child->as<ASTQueryParameter>())
                visitQueryParameter(*query_parameter);
            else
                visit(child);
        }
    }

private:
    NameSet & query_parameters;

    void visitQueryParameter(const ASTQueryParameter & query_parameter)
    {
        query_parameters.insert(query_parameter.name);
    }
};


NameSet analyzeReceiveQueryParams(const std::string & query)
{
    NameSet query_params;
    const char * query_begin = query.data();
    const char * query_end = query.data() + query.size();

    ParserQuery parser(query_end);
    ASTPtr extract_query_ast = parseQuery(parser, query_begin, query_end, "analyzeReceiveQueryParams", 0, 0);
    QueryParameterVisitor(query_params).visit(extract_query_ast);
    return query_params;
}

}