SQLExec.h

/**
 * @file SQLExec.h - SQLExec class 
 * @author Kevin Lundeen
 * @see "Seattle University, CPSC5300, Summer 2018"
 */
#pragma once

#include <exception>
#include <string>
#include "SQLParser.h"
#include "schema_tables.h"

/**
 * @class SQLExecError - exception for SQLExec methods
 */
class SQLExecError : public std::runtime_error {
public:
    explicit SQLExecError(std::string s) : runtime_error(s) {}
};


/**
 * @class QueryResult - data structure to hold all the returned data for a query execution
 */
class QueryResult {
public:
    QueryResult() : column_names(nullptr), column_attributes(nullptr), rows(nullptr), message("") {}

    QueryResult(std::string message) : column_names(nullptr), column_attributes(nullptr), rows(nullptr),
                                       message(message) {}

    QueryResult(ColumnNames *column_names, ColumnAttributes *column_attributes, ValueDicts *rows, std::string message)
            : column_names(column_names), column_attributes(column_attributes), rows(rows), message(message) {}

    virtual ~QueryResult();

    ColumnNames *get_column_names() const { return column_names; }
    ColumnAttributes *get_column_attributes() const { return column_attributes; }
    ValueDicts *get_rows() const { return rows; }
    const std::string &get_message() const { return message; }
    friend std::ostream &operator<<(std::ostream &stream, const QueryResult &qres);

protected:
    ColumnNames *column_names;
    ColumnAttributes *column_attributes;
    ValueDicts *rows;
    std::string message;
};


/**
 * @class SQLExec - execution engine
 */
class SQLExec {
public:
	/**
	 * Execute the given SQL statement.
	 * @param statement   the Hyrise AST of the SQL statement to execute
	 * @returns           the query result (freed by caller)
	 */
    static QueryResult *execute(const hsql::SQLStatement *statement) throw(SQLExecError);

protected:
	// the one place in the system that holds the _tables table and _indices table
    static Tables *tables;
	static Indices *indices;

	// recursive decent into the AST
    static QueryResult *create(const hsql::CreateStatement *statement);
    static QueryResult *create_table(const hsql::CreateStatement *statement);
    static QueryResult *create_index(const hsql::CreateStatement *statement);

    static QueryResult *drop(const hsql::DropStatement *statement);
    static QueryResult *drop_table(const hsql::DropStatement *statement);
    static QueryResult *drop_index(const hsql::DropStatement *statement);

    static QueryResult *show(const hsql::ShowStatement *statement);
    static QueryResult *show_tables();
    static QueryResult *show_columns(const hsql::ShowStatement *statement);
    static QueryResult *show_index(const hsql::ShowStatement *statement);

	static QueryResult *insert(const hsql::InsertStatement *statement);
	static QueryResult *del(const hsql::DeleteStatement *statement);
	static QueryResult *select(const hsql::SelectStatement *statement);


	/**
	 * Pull out column name and attributes from AST's column definition clause
	 * @param col                AST column definition
	 * @param column_name        returned by reference
	 * @param column_attributes  returned by reference
	 */
	static ValueDict* get_where_conjunction(const hsql::Expr *expr);
    static void column_definition(const hsql::ColumnDefinition *col, Identifier &column_name, ColumnAttribute &column_attribute);
};