The standard interfaces have their own approaches to getting and
dealing with user input. Sometimes though it'd be nicer to have a
way of evaluating code from within RETRO itself. This provides an
evaluate word.
{{
First, create a buffer for the string to be evaluated. This is sized to allow for a standard FORTH block to fit, or to easily fit a RETRO style 512 character block. It's also long enough for most source lines I expect to encounter when working with files.
'Current-Line d:create
#1025 allot
To make use of this, we need to know how many tokens are in the input
string. The count-tokens word will do this, by filtering out anything
other than spaces and getting the size of the remaining string.
:count-tokens (s-n)
[ ASCII:SPACE eq? ] s:filter s:length ;
The next-token word splits the remainimg string on SPACE and returns
both parts.
:next-token (s-ss)
ASCII:SPACE s:split ;
And then the process-tokens uses next-token and interpret to go
through the string, processing each token in turn. Using the standard
interpret word allows for proper handling of the prefixes and classes
so everything works just as if entered directly.
:process-tokens (sn-)
[ next-token swap [ interpret ] dip n:inc ] times interpret ;
---reveal---
And finally, tie it all together into the single exposed word
evaluate.
:evaluate (s-...)
&Current-Line s:copy
&Current-Line dup count-tokens process-tokens ;
}}