Move query result helper class to maxsql

Added some asserts to ensure the class is used correctly.

maxutils/maxsql/include/maxsql/mariadb.hh

@@ -14,6 +14,7 @@
 
 #include <maxsql/ccdefs.hh>
 #include <string>
+#include <unordered_map>
 #include <mysql.h>
 
 namespace maxsql
@@ -51,4 +52,91 @@ void mysql_set_log_statements(bool enable);
  * @return True, if statements are logged, false otherwise.
  */
 bool mysql_get_log_statements();
+
+/**
+ * Helper class for simplifying working with resultsets.
+ */
+class QueryResult
+{
+    QueryResult(const QueryResult&) = delete;
+    QueryResult& operator=(const QueryResult&) = delete;
+
+public:
+    /**
+     * Construct a new resultset.
+     *
+     * @param resultset The results from mysql_query(). Must not be NULL.
+     */
+    QueryResult(MYSQL_RES* resultset);
+
+    ~QueryResult();
+
+    /**
+     * Advance to next row. Affects all result returning functions.
+     *
+     * @return True if the next row has data, false if the current row was the last one.
+     */
+    bool next_row();
+
+    /**
+     * Get the index of the current row.
+     *
+     * @return Current row index, or -1 if next_row() has not been called yet or all rows have been processed.
+     */
+    int64_t get_current_row_index() const;
+
+    /**
+     * How many columns the result set has.
+     *
+     * @return Column count
+     */
+    int64_t get_col_count() const;
+
+    /**
+     * How many rows does the result set have?
+     *
+     * @return The number of rows
+     */
+    int64_t get_row_count() const;
+
+    /**
+     * Get a numeric index for a column name. May give wrong results if column names are not unique.
+     *
+     * @param col_name Column name
+     * @return Index or -1 if not found
+     */
+    int64_t get_col_index(const std::string& col_name) const;
+
+    /**
+     * Read a string value from the current row and given column. Empty string and (null) are both interpreted
+     * as the empty string.
+     *
+     * @param column_ind Column index
+     * @return Value as string
+     */
+    std::string get_string(int64_t column_ind) const;
+
+    /**
+     * Read a non-negative integer value from the current row and given column.
+     *
+     * @param column_ind Column index
+     * @return Value as integer. 0 or greater indicates success, -1 is returned if the data
+     * could not be parsed or the result was negative.
+     */
+    int64_t get_uint(int64_t column_ind) const;
+
+    /**
+     * Read a boolean value from the current row and given column.
+     *
+     * @param column_ind Column index
+     * @return Value as boolean. Returns true if the text is either 'Y' or '1'.
+     */
+    bool get_bool(int64_t column_ind) const;
+
+private:
+    MYSQL_RES*                               m_resultset = NULL;    // Underlying result set, freed at dtor.
+    std::unordered_map<std::string, int64_t> m_col_indexes;         // Map of column name -> index
+    MYSQL_ROW                                m_rowdata = NULL;      // Data for current row
+    int64_t                                  m_current_row_ind = -1;// Index of current row
+};
 }