Scripting

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

Marco Gerards wrote:

>I had a quick look at the patch for now.  Can you please explain in a
>new thread how the patch globally works?  I will reply about the other
>issues there as well.
>
>There are still some things I would like to know:
>
>- Why does everything happen with strings?
>
>  
>
Because environment variables are the strings and it's not really
needed to convert them (excluding the calculating)

>- Why are that many functions duplicated? (for example
>  grub_bash_dupstr).
>
>  
>
In this case I just forgot about grub_strdup. But some other functions
have (nerly) the same names that string function but are adapted for
scripting (ex: grub_bash_strchr)

>- What is that huge table with operators?  
>
It's used to determinate which operator to execute (see
grub_bash_find_oper and grub_bash_eval_arith)

>What kind of parser is it?
>  
>
It's a direct parser with aritmetic subparser. Main parser is
grub_bash_execute, arithmetic subparser is grub_bash_eval_arith.
grub_bash_execute determinates the special cases (loops,conditions,
functions,...) for other cases (commands,assignments, function calling)
it calls grub_bash_split_tokens, grub_bash_expand_braces and
grub_bash_expand_dollar

>  I have never seen this in a top-down or bottom-up parser I have
>  studied.
>
>  
>
I don't like to write the things reffering every time to algorithm.
Genereally I take some ideas and I write myself, at my own.

>- How does the parser in general work?  
>
grub_bash_execute parses a line. If it detectes that end of the line is
not the end of command it calls getline function

>So can you explain what
>  happens when executing a script?  First you load the file.  Do you
>  parse it, make pcode of it, run it directly?
>
For the files I use grub_bash_exec_file. Only thing it does is
reading a file line by line and calling grub_bash_execute

>  How about error
>  handling?
>
>  
>
For now the problem is that not all posiible syntax errors are handled
correctly and more return checks have to be written. But first I'll write
line counting (only grub_bash_execute, grub_bash_list_execute and
grub_command_execute are affected)

>Thanks,
>Marco
>
>
>
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