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Update peg.pl0 to use range pattern syntax 

This allows removing the words for ident and number, replacing them
with EBNF expressions.
db4
Chris Double 2008-03-20 14:22:14 +13:00
parent 68388fbed9
commit 39c228db6d
1 changed files with 4 additions and 9 deletions
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13
extra/peg/pl0/pl0.factor
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@ -1,18 +1,10 @@
! Copyright (C) 2007 Chris Double.
! See http://factorcode.org/license.txt for BSD license.
USING: kernel arrays strings math.parser sequences
peg peg.ebnf peg.parsers memoize namespaces ;
peg peg.ebnf peg.parsers memoize namespaces math ;
IN: peg.pl0
#! Grammar for PL/0 based on http://en.wikipedia.org/wiki/PL/0
MEMO: ident ( -- parser )
[
CHAR: a CHAR: z range ,
CHAR: A CHAR: Z range ,
] choice* repeat1 [ >string ] action ;
MEMO: number ( -- parser )
CHAR: 0 CHAR: 9 range repeat1 [ string>number ] action ;
<EBNF
program = block "."
@ -28,4 +20,7 @@ condition = "ODD" expression |
expression = ("+" | "-")? term (("+" | "-") term )*
term = factor (("*" | "/") factor )*
factor = ident | number | "(" expression ")"
ident = (([a-zA-Z])+) [[ >string ]]
digit = ([0-9]) [[ digit> ]]
number = ((digit)+) [[ unclip [ swap 10 * + ] reduce ]]
EBNF>