peg can now be used for parsing words

db4
Sam Anklesaria 2009-03-09 20:36:35 -05:00
parent 895b1339f8
commit d95e515557
1 changed files with 53 additions and 0 deletions

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USING: hashtables assocs sequences locals math accessors multiline delegate strings
delegate.protocols kernel peg peg.ebnf lexer namespaces combinators parser words ;
IN: peg-lexer
TUPLE: lex-hash hash ;
CONSULT: assoc-protocol lex-hash hash>> ;
: <lex-hash> ( a -- lex-hash ) lex-hash boa ;
: pos-or-0 ( neg? -- pos/0 ) dup 0 < [ drop 0 ] when ;
:: store-pos ( v a -- )
[let | n [ input a at v head-slice ] |
v "\n" n last-index 0 or - lexer get (>>column)
n [ "\n" = ] filter length 1 + lexer get (>>line) ] ;
M: lex-hash set-at swap {
{ pos [ store-pos ] }
[ swap hash>> set-at ] } case ;
:: at-pos ( t l c -- p ) t l 1 - head-slice [ length ] map sum pos-or-0 c + ;
M: lex-hash at* swap {
{ input [ drop lexer get text>> "\n" join t ] }
{ pos [ drop lexer get [ text>> ] [ line>> ] [ column>> ] tri at-pos t ] }
[ swap hash>> at* ] } case ;
: with-global-lexer ( quot -- result )
[ f lrstack set
V{ } clone error-stack set H{ } clone \ heads set
H{ } clone \ packrat set ] f make-assoc <lex-hash>
swap bind ; inline
! Usage:
! ON-BNF: word expr= [1-9] ;ON-BNF
! << name parser create-bnf >>
: parse* ( parser -- ast ) compile
[ execute [ error-stack get first throw ] unless* ] with-global-lexer
ast>> ;
: create-bnf ( name parser -- ) [ lexer get skip-blank parse* dup V{ } = [ parsed ] unless ] curry
define POSTPONE: parsing ;
: ON-BNF: CREATE-WORD reset-tokenizer ";ON-BNF" parse-multiline-string parse-ebnf
main swap at reset-tokenizer create-bnf ; parsing
! Tokenizer like standard factor lexer
EBNF: factor
space = " " | "\n" | "\t"
spaces = space* => [[ drop ignore ]]
chunk = (!(space) .)+ => [[ >string ]]
expr = spaces chunk
;EBNF