I have not released many blogs recently BUT I have been writing blogs in the background at the same rate as normal to release in the coming weeks as a series of articles around PL/SQL. I wrote back in 2022 about adding a scripting language to PL/SQL and now I have done this. I have created a simple language based on BASIC initially but it will change to be not BASIC as we go along. I have implemented an interpreter in PL/SQL for this simple version of BASIC and tested simple BASIC programs that work and are parsed and executed in PL/SQL. The next step is to complete the implementation of a VM in PL/SQL to simulate a simple CPU that will execute binaries for an assembly language I have designed. The interpreter will change into a compiler for the simple BASIC, it will output assembler for the machine I have created in the VM and assemble that to binary. Finally the binary is executed in the VM/CPU implemented in PL/SQL.
What do I mean with the title of this blog of Extreme PL/SQL?. Well, doing things with PL/SQL that you would not normally do and trying to write systems level code in PL/SQL. I have more things coming up but we will keep that quiet for now!!, ok, one for you now; PL/SQL does not have pointers in the same way that C does. You cannot create a pointer to a type such as char and then malloc memory for that char and access it using its location (pointer) and then retrieve the value. I have been looking at how we might do this in PL/SQL or simulate it more later.
Why? I have always been interested in PL/SQL and also from a security standpoint; there is always a security angle for me. I have some security ideas and things I want to talk about with PL/SQL and maybe with Apex. These ideas will become clearer soon. I might put forward some papers for conferences around this area of extreme PL/SQL and coding things that you would never do.
Watch out soon for the article series on "Extreme PL/SQL" and also compilers, interpreters, VMs, assemblers all in PL/SQL. I have 26 parts already, almost half of them complete and the others in a state of development with code to demonstrate.
Could we write an OS (Operating System) in PL/SQL? not Linux/Windows level of course but maybe at the level of a Monitor that were used to load and run programs in the old 8 bit days. I am focusing on the language layer as compilers, system programming, interpreters and more have interested me since the beginning of the 90s.
Here is a simple example of the interpreter loading and running a simple program with some trace output
-- -----------------------------------------------------------------------------
-- PFCL_int Interpreter - run examples code in a simple harness
-- -----------------------------------------------------------------------------
declare
lv_prog varchar2(32767):='PRINT var + 3+(7*66) END';
begin
-- initialise the interpreter
pfcl_int.init(true,1);
-- run the code
pfcl_int.run(lv_prog);
--
end;
/
sho err
And the output including trace:
TRACE: Trace Start [25-JUN-2024 08:55:25]
TRACE: [1] gv_source=[PRINT var + 3+(7*66) END]
TRACE: [1] gv_len=[24]
TRACE: [1] gv_posn=[0]
TRACE: [1] Token Type = [KEYWORD ] : Token is = [PRINT]
TRACE: [1] Token Type = [VARIABLE ] : Token is = [var]
TRACE: [1] Token Type = [DELIMETER] : Token is = [+]
TRACE: [1] Token Type = [NUMBER ] : Token is = [3]
TRACE: [1] Token Type = [DELIMETER] : Token is = [+]
TRACE: [1] Token Type = [DELIMETER] : Token is = [(]
TRACE: [1] Token Type = [NUMBER ] : Token is = [7]
TRACE: [1] Token Type = [DELIMETER] : Token is = [*]
TRACE: [1] Token Type = [NUMBER ] : Token is = [66]
TRACE: [1] Token Type = [DELIMETER] : Token is = [)]
TRACE: [1] Token Type = [KEYWORD ] : Token is = [END]
TRACE: [1] Symbol Table ==>
TRACE: [1] symbol name=[var],type=[NUMBER],value=[0]
TRACE: [1] Keyword table ==>
TRACE: [1] Keyword name=[REM],action=[]
TRACE: [1] Keyword name=[LET],action=[]
TRACE: [1] Keyword name=[PRINT],action=[]
TRACE: [1] Keyword name=[IF],action=[]
TRACE: [1] Keyword name=[THEN],action=[]
TRACE: [1] Keyword name=[GOTO],action=[]
TRACE: [1] Keyword name=[END],action=[]
465
TRACE: Trace End [25-JUN-2024 08:55:25]
===============================================================
No errors.
SQL>
Watch for the series detailing all of this work with PL/SQL
#oracleace #sym_42 #oracle #database #23c #23ai ##securecode #plsql #extreme #interpreter #compiler
