-- ABSTRACT:
--
--	This module is the first in a series of two that demonstrates the
--	dynamic interface of SQL using SQL module language and Ada.  The 
--      second Ada module is named sql_dynamic.
--
--	This module accepts a string that contains an SQL statement
--	and then calls the other module to process it.
--
--	You can adapt the modules to your own needs.  For example, you can 
--	substitute your own module for this driver. Instead of prompting
--	the user for an SQL statement, your module could use 
--	other methods to generate SQL statements to pass to sql_dynamic:
--
--	   - Construct an SQL statement from parameters passed by a 
--               calling module.
--         - Parse a non-SQL statement from a calling module and 
--	         build an SQL statement from it.
--	
--	However the module generates an SQL statement, it can be passed to
--	a module similar to sql_dynamic for processing. 



with CONDITION_HANDLING;
with TEXT_IO; use TEXT_IO;

procedure SQL_DYNAMIC_DRIVER is

-- Declare the parameters for the SQL statement input by the user.

    MAX_STRLNG : constant integer := 1024;
    subtype ST is string(1..max_strlng);
    STMT : st := (others => ' ');

-- Parameters for parsing the statement:

    PART_STMT : string (1..64) := (others => ' ');
    BEGIN_POS,END_POS,POS : integer;
    LAST : natural;

-- Declare the subunit that will handle the statement processing.

    procedure sql_dynamic(sql_stmt : in st) is separate;

-------------------------------------------------------------------------------
-- Main program for SQL_DYNAMIC_DRIVER
-------------------------------------------------------------------------------
begin

-- Prompt the user to enter an SQL statement.  

new_line(24);
put("Enter any valid dynamic SQL statement, ");
put_line("continuing it on successive lines.");
put_line("Terminate the statement with a semicolon.");
put_line("Use <F10> or <CTRL/Z> to exit.");
new_line;

-- The main loop.  It executes until the user enters <CTRL/Z>.
-- <CTRL/Z> in the get_line call generates an end_error that
-- will be handled by a null exception.

loop
    begin_pos := 1;
    stmt := (others => ' ');
    put("SQL_STATEMENT> ");

-- This inner loop accepts partial lines and prompts for continuation until
-- the user enters a semicolon.

    loop
	get_line(part_stmt,last);
	if last > 0 then
	    end_pos := (begin_pos + last) - 1;
	    stmt(begin_pos..end_pos) := part_stmt(1..last);
	    stmt(end_pos + 1) := ' ';
	    begin_pos := (begin_pos + last) + 1;
	    if part_stmt(last) = ascii.semicolon then
		stmt(end_pos) := ' ';
		exit;
	    end if;
	end if;
	put("Cont>          ");
    end loop;



-- Pass the STMT parameter containing the SQL statement to 
-- the SQL_DYNAMIC procedure in the sql_dynamic module for processing.

    sql_dynamic(stmt);

end loop;

exception
	when end_error => null;

end SQL_DYNAMIC_DRIVER;