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Use choice* and seq* in ebnf

db4
Chris Double 2008-03-19 17:00:53 +13:00
parent 4b37c9098e
commit cc9a17b551
1 changed files with 45 additions and 25 deletions
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70
extra/peg/ebnf/ebnf.factor
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@ -100,33 +100,46 @@ M: ebnf (generate-parser) ( ast -- id )
DEFER: 'rhs'
: 'non-terminal' ( -- parser )
CHAR: a CHAR: z range "-" token [ first ] action 2array choice repeat1 [ >string <ebnf-non-terminal> ] action ;
[
CHAR: a CHAR: z range ,
"-" token [ first ] action ,
] choice* repeat1 [ >string <ebnf-non-terminal> ] action ;
: 'terminal' ( -- parser )
"'" token hide [ CHAR: ' = not ] satisfy repeat1 "'" token hide 3array seq [ first >string <ebnf-terminal> ] action ;
[
"'" token hide ,
[ CHAR: ' = not ] satisfy repeat1 ,
"'" token hide ,
] seq* [ first >string <ebnf-terminal> ] action ;
: 'element' ( -- parser )
'non-terminal' 'terminal' 2array choice ;
[
'non-terminal' ,
'terminal' ,
] choice* ;
DEFER: 'choice'
: 'group' ( -- parser )
"(" token sp hide
[ 'choice' sp ] delay
")" token sp hide
3array seq [ first ] action ;
[
"(" token sp hide ,
[ 'choice' sp ] delay ,
")" token sp hide ,
] seq* [ first ] action ;
: 'repeat0' ( -- parser )
"{" token sp hide
[ 'choice' sp ] delay
"}" token sp hide
3array seq [ first <ebnf-repeat0> ] action ;
[
"{" token sp hide ,
[ 'choice' sp ] delay ,
"}" token sp hide ,
] seq* [ first <ebnf-repeat0> ] action ;
: 'optional' ( -- parser )
"[" token sp hide
[ 'choice' sp ] delay
"]" token sp hide
3array seq [ first <ebnf-optional> ] action ;
[
"[" token sp hide ,
[ 'choice' sp ] delay ,
"]" token sp hide ,
] seq* [ first <ebnf-optional> ] action ;
: 'sequence' ( -- parser )
[
@ -134,8 +147,7 @@ DEFER: 'choice'
'group' sp ,
'repeat0' sp ,
'optional' sp ,
] { } make choice
repeat1 [
] choice* repeat1 [
dup length 1 = [ first ] [ <ebnf-sequence> ] if
] action ;
@ -145,18 +157,26 @@ DEFER: 'choice'
] action ;
: 'action' ( -- parser )
"=>" token hide
[ blank? ] satisfy ensure-not [ drop t ] satisfy 2array seq [ first ] action repeat1 [ >string ] action sp
2array seq [ first <ebnf-action> ] action ;
[
"=>" token hide ,
[
[ blank? ] satisfy ensure-not ,
[ drop t ] satisfy ,
] seq* [ first ] action repeat1 [ >string ] action sp ,
] seq* [ first <ebnf-action> ] action ;
: 'rhs' ( -- parser )
'choice' 'action' sp optional 2array seq ;
[
'choice' ,
'action' sp optional ,
] seq* ;
: 'rule' ( -- parser )
'non-terminal' [ ebnf-non-terminal-symbol ] action
"=" token sp hide
'rhs'
3array seq [ first2 <ebnf-rule> ] action ;
[
'non-terminal' [ ebnf-non-terminal-symbol ] action ,
"=" token sp hide ,
'rhs' ,
] seq* [ first2 <ebnf-rule> ] action ;
: 'ebnf' ( -- parser )
'rule' sp "." token sp hide list-of [ <ebnf> ] action ;