Class QueryParser

YACReaderLibrary/db/query_parser.h:47–111

* This class is used to generate an SQL query string from a search expression, * with a syntax very similar to that used by the Google search engine. * * The code herein is based upon the SearchQueryParser python class written by * Kovid Goyal as part of the Calibre eBook manager (https://calibre-ebook.com) * * Grammar: * prog ::= or_expression * or_expression ::= and_expression [ 'or'

 *    selectQuery.exec();
 */
class QueryParser
{
public:
    struct TreeNode {
        std::string t;
        std::vector<TreeNode> children;
        std::string expOperator;

        explicit TreeNode(std::string t, std::vector<TreeNode> children, std::string expOperator = "")
            : t(t), children(children), expOperator(expOperator)
        {
        }

        int buildSqlString(std::string &sqlString, int bindPosition = 0) const;
        int bindValues(QSqlQuery &selectQuery, int bindPosition = 0) const;
    };

    explicit QueryParser();
    TreeNode parse(const std::string &expr);

private:
    static std::string toLower(const std::string &string);

    std::string token(bool advance = false);
    std::string lcaseToken(bool advance = false);
    Token::Type tokenType();
    bool isEof() const;
    void advance();

    QueryLexer lexer = QueryLexer("");
    Token currentToken = Token(Token::Type::undefined);

    template<typename T>
    static bool isIn(const T &e, const std::list<T> &v)
    {
        return std::find(v.begin(), v.end(), e) != v.end();
    }

    bool isOperatorToken(Token::Type type);

    enum class FieldType { unknown,
                           numeric,
                           text,
                           boolean,
                           date,
                           dateFolder,
                           folder,
                           booleanFolder,
                           filename,
                           enumField,
                           enumFieldFolder };
    static FieldType fieldType(const std::string &str);

    static std::string join(const QStringList &strings, const std::string &delim);
    static QStringList split(const std::string &string, char delim);

    TreeNode orExpression();
    TreeNode andExpression();