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Add support for & syntax in ebnf

db4
Chris Double 2008-03-20 17:25:27 +13:00
parent dbd0583044
commit d1e7ede35d
1 changed files with 16 additions and 0 deletions
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16
extra/peg/ebnf/ebnf.factor
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@ -10,6 +10,7 @@ TUPLE: ebnf-non-terminal symbol ;
TUPLE: ebnf-terminal symbol ; TUPLE: ebnf-terminal symbol ;
TUPLE: ebnf-any-character ; TUPLE: ebnf-any-character ;
TUPLE: ebnf-range pattern ; TUPLE: ebnf-range pattern ;
TUPLE: ebnf-ensure group ;
TUPLE: ebnf-ensure-not group ; TUPLE: ebnf-ensure-not group ;
TUPLE: ebnf-choice options ; TUPLE: ebnf-choice options ;
TUPLE: ebnf-sequence elements ; TUPLE: ebnf-sequence elements ;
@ -24,6 +25,7 @@ C: <ebnf-non-terminal> ebnf-non-terminal
C: <ebnf-terminal> ebnf-terminal C: <ebnf-terminal> ebnf-terminal
C: <ebnf-any-character> ebnf-any-character C: <ebnf-any-character> ebnf-any-character
C: <ebnf-range> ebnf-range C: <ebnf-range> ebnf-range
C: <ebnf-ensure> ebnf-ensure
C: <ebnf-ensure-not> ebnf-ensure-not C: <ebnf-ensure-not> ebnf-ensure-not
C: <ebnf-choice> ebnf-choice C: <ebnf-choice> ebnf-choice
C: <ebnf-sequence> ebnf-sequence C: <ebnf-sequence> ebnf-sequence
@ -73,6 +75,7 @@ C: <ebnf> ebnf
[ dup CHAR: [ = ] [ dup CHAR: [ = ]
[ dup CHAR: . = ] [ dup CHAR: . = ]
[ dup CHAR: ! = ] [ dup CHAR: ! = ]
[ dup CHAR: & = ]
[ dup CHAR: * = ] [ dup CHAR: * = ]
[ dup CHAR: + = ] [ dup CHAR: + = ]
[ dup CHAR: ? = ] [ dup CHAR: ? = ]
@ -153,11 +156,21 @@ DEFER: 'choice'
'group' sp , 'group' sp ,
] seq* [ first <ebnf-ensure-not> ] action ; ] seq* [ first <ebnf-ensure-not> ] action ;
: 'ensure' ( -- parser )
#! Parses the '&' syntax to ensure that
#! something that matches the following elements does
#! exist in the parse stream.
[
"&" syntax ,
'group' sp ,
] seq* [ first <ebnf-ensure> ] action ;
: ('sequence') ( -- parser ) : ('sequence') ( -- parser )
#! A sequence of terminals and non-terminals, including #! A sequence of terminals and non-terminals, including
#! groupings of those. #! groupings of those.
[ [
'ensure-not' sp , 'ensure-not' sp ,
'ensure' sp ,
'element' sp , 'element' sp ,
'group' sp , 'group' sp ,
'repeat0' sp , 'repeat0' sp ,
@ -221,6 +234,9 @@ M: ebnf-any-character (transform) ( ast -- parser )
M: ebnf-range (transform) ( ast -- parser ) M: ebnf-range (transform) ( ast -- parser )
ebnf-range-pattern range-pattern ; ebnf-range-pattern range-pattern ;
M: ebnf-ensure (transform) ( ast -- parser )
ebnf-ensure-group (transform) ensure ;
M: ebnf-ensure-not (transform) ( ast -- parser ) M: ebnf-ensure-not (transform) ( ast -- parser )
ebnf-ensure-not-group (transform) ensure-not ; ebnf-ensure-not-group (transform) ensure-not ;