Re: Pre-alpha scripting engine

[Serbinenko Vladimir <serbinenko.vova@list.ru>]

Marco Gerards wrote:

>Can you please explain how the parser itself works?  What kind of
>parser is it, something about the scanner perhaps, etc?
>
>  
>
It's two times parser. First time it removes comments and creates 
function list.Then it launches "script_load" function. Real script 
execution is in script_execute. This function detects what structure is 
used. IF it's a loop it makes a recursive call. If it's  return, 
brake,... if return value and status(why exited?) for expressions it 
uses recursive function script_eval_expr. It checks the type of first 
token(string,function, variable,...) ,calculates it and stores to cur, 
then it repeats until end of expression. If it's an operator it can be 
unary operator only if cur==NULL. Then it determines the part of 
expression that must be passed as right argument
Ex: $a+$b*$c When it finds+ cur contains $a so it's binary+ right part 
is $b*$c as priority of * is bigger than binary+.
Then it invokes corresponding function(in that case script_arith). There 
are some special operators like ?:, ||, &&,... that control execution so 
they must be calculated directly in script_eval_expr and so .func_do=NULL
Function script_parse_args converts script-like argument to internal 
format. Function import_args imports arguments to local environment. 
script_exec_* are made to call different functions. For information 
about other functions just mail me or wait alpha-beta version where I'll 
add some comments

>>For now all script files must be made of functions and nothing except
>>functions. All other will be ignored. Function must be declared as:
>>function [global] <function
>>name>([$arg1[=defval1]][,$arg2[=defval2]][,...]){
>>    <function body here>
>>}
>>    
>>
>
>How about grub.cfg?  It would be nice if it would be possible to embed
>code there.
>
>  
>
You can just write in grub.cfg
insmod script
script <file>
And there is no mess between  scripts and shell(however shell functions 
can be used by scripts...will in alpha)

>>Notes:
>>    
>>
>[...]
>  
>
>>Spaces in (type) are not supported,
>>    
>>
>
>Sorry, I don't understand this one.
>
>  
>
in PHP you can write (   int   ), (   int),  (int   ),  (int
),... and so on but  current version supports only (int), (bool) and (str)

>Thanks,
>Marco
>
>
>
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>  
>