victor_christov
asked on
Code Block
Hi experts,
I am trying to write a 'CodeBlock' function (or procedure) in Delphi 3.0, like one in CA-Clipper 5.2 / 5.3. That means I want to bo able to assign to a string variable a value like :
s := 'Writeln(a); writeln(2*a);'
and later to execute it in the same way as in Clipper :
eval(<parameter>,s)
where <parameter> are data, over which is evaluated the 'Code Block').
Is this possible in Delphi 3.0 and how can I achieve it ?
I am trying to write a 'CodeBlock' function (or procedure) in Delphi 3.0, like one in CA-Clipper 5.2 / 5.3. That means I want to bo able to assign to a string variable a value like :
s := 'Writeln(a); writeln(2*a);'
and later to execute it in the same way as in Clipper :
eval(<parameter>,s)
where <parameter> are data, over which is evaluated the 'Code Block').
Is this possible in Delphi 3.0 and how can I achieve it ?
No, this is not possible in Delphi, although there are some simple language interpreters that can be used in Delphi (take a look at Delphi Super Page http://sunsite.icm.edu.pl/delphi) - this has a couple of these engines on it.
One way you can approximate this is by using DLLs. If you would like more information on this let me know...
Cheers,
Raymond.
One way you can approximate this is by using DLLs. If you would like more information on this let me know...
Cheers,
Raymond.
Delphi is compiled. After your program is compiled, it has no clue what Pascal syntax means, or even what Pascal is, because the Pascal is no longer there.
What you're looking is called a "parser" under Pascal.
There are plenty of them in DSP: http://metalab.unc.edu/delphi
or
http://sunsite.unc.edu.pl/delphi
Alex
There are plenty of them in DSP: http://metalab.unc.edu/delphi
or
http://sunsite.unc.edu.pl/delphi
Alex
What you are looking for is lex and yacc,
where lex (lexical analyse) takes a string as input,
and you will get a lot of tookens back, depending on
what rules you have set up.....
And then you put these tookens into the yacc (yet another compiler compiler), wich also have a lot of rules on how the tookens are put together, and then yacc parse and makes up your source code for you....
This is a very huge task, you have to make your own compiler.....
you can find a lex/yacc program wich is called tply for delphi in www.torry.ru
I hope you this help... But good luck......
where lex (lexical analyse) takes a string as input,
and you will get a lot of tookens back, depending on
what rules you have set up.....
And then you put these tookens into the yacc (yet another compiler compiler), wich also have a lot of rules on how the tookens are put together, and then yacc parse and makes up your source code for you....
This is a very huge task, you have to make your own compiler.....
you can find a lex/yacc program wich is called tply for delphi in www.torry.ru
I hope you this help... But good luck......
Smilly:
lex and yacc will be about as useful to him as tits on a bull!
Even if he used them and wrote his compiler, he still can't insert the compiled code inline like he wants to do...
Cheers,
Raymond.
lex and yacc will be about as useful to him as tits on a bull!
Even if he used them and wrote his compiler, he still can't insert the compiled code inline like he wants to do...
Cheers,
Raymond.
Hi Raymond,
Sure he can, but it is a big task.
He can make a internal function rule EVAL and tell it to take [pascal] as
parameters.......It is not a big thing, the big thing is to make the compiler.
If it first works then its no big deal to force it to interprete the parameters inside
EVAL(.....).
And as I see it, it is the only way he can do this task.......
Sure he can, but it is a big task.
He can make a internal function rule EVAL and tell it to take [pascal] as
parameters.......It is not a big thing, the big thing is to make the compiler.
If it first works then its no big deal to force it to interprete the parameters inside
EVAL(.....).
And as I see it, it is the only way he can do this task.......
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Hello Vitor, any comment/question?
I don't think that it's possible in Delphi.