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+---- Thread: Another Recursive Descent Parser (/showthread.php?tid=3592)
Another Recursive Descent Parser - eoredson - 04-07-2025
Find attached is a file with Whatis.bas which is a Recursive Descent Parser..
Wat is a recursive descent parser you ask?
Well, basically the parser reads tokens in a stream such as: +-*/^ then
the descent is from highest precedence to lowest where
when the parser detects an opening ( it calls the parser recursively until a closing ) is detected.
Therefore a stream such as: 8*(10-1) can be parsed..
This parser I am releasing also parses more tokens such as ++ and -- and others.
Erik.
Ok, so the parser starts at the > prompt where equations can be entered
which also support simple variables like: X=10 and then X+10 could be calculated.
Parser also calculates string variables A$ to Z$ and arrays A(n) to Z(n).
Additional multi-character variables can be specified as:
X0 to X9, and A0(n) to A9(n), and A0$ to A9$.
What64X6.zip is v1.4a of the parser.
LOC: 3,994
Code: (Select All)
update v1.1a: 04/08/2025:
adds custom getCommand$ function.
modifies true/false constants.
extends array subscript for A(n) to any value.
update v1.2a: 05/05/2025:
fixes shell to DOS.
update v1.3a: 07/25/2025:
adds multichar variables.
update v1.4a: 12/05/2025:
adds constant function.