factor/basis/peg/peg.factor

596 lines
15 KiB
Factor

! Copyright (C) 2007, 2008 Chris Double.
! See http://factorcode.org/license.txt for BSD license.
USING: accessors arrays assocs classes combinators
combinators.short-circuit compiler.units effects.parser fry
generalizations kernel locals make math math.order namespaces
quotations sequences sets splitting unicode vectors
vocabs.loader words ;
IN: peg
TUPLE: parse-result remaining ast ;
TUPLE: parse-error position got messages ;
TUPLE: parser peg compiled id ;
M: parser equal? { [ [ class-of ] same? ] [ [ id>> ] same? ] } 2&& ;
M: parser hashcode* id>> hashcode* ;
C: <parse-result> parse-result
C: <parse-error> parse-error
SYMBOL: error-stack
: merge-overlapping-errors ( a b -- c )
dupd [ messages>> ] bi@ union [ [ position>> ] [ got>> ] bi ] dip
<parse-error> ;
: (merge-errors) ( a b -- c )
{
{ [ over position>> not ] [ nip ] }
{ [ dup position>> not ] [ drop ] }
[
2dup [ position>> ] compare {
{ +lt+ [ nip ] }
{ +gt+ [ drop ] }
{ +eq+ [ merge-overlapping-errors ] }
} case
]
} cond ;
: merge-errors ( -- )
error-stack get dup length 1 > [
[ pop ] [ pop swap (merge-errors) ] [ ] tri push
] [
drop
] if ;
: add-error ( position got message -- )
<parse-error> error-stack get push ;
SYMBOL: ignore
: ignore? ( obj -- ? )
ignore = ;
: packrat ( id -- cache )
! The packrat cache is a mapping of parser-id->cache.
! For each parser it maps to a cache holding a mapping
! of position->result. The packrat cache therefore keeps
! track of all parses that have occurred at each position
! of the input string and the results obtained from that
! parser.
\ packrat get [ drop H{ } clone ] cache ;
SYMBOL: pos
SYMBOL: input
SYMBOL: fail
SYMBOL: lrstack
: heads ( -- cache )
! A mapping from position->peg-head. It maps a
! position in the input string being parsed to
! the head of the left recursion which is currently
! being grown. It is 'f' at any position where
! left recursion growth is not underway.
\ heads get ;
: failed? ( obj -- ? )
fail = ;
: peg-cache ( -- cache )
! Holds a hashtable mapping a peg tuple to
! the parser tuple for that peg. The parser tuple
! holds a unique id and the compiled form of that peg.
\ peg-cache get-global [
H{ } clone dup \ peg-cache set-global
] unless* ;
: reset-pegs ( -- )
H{ } clone \ peg-cache set-global ;
reset-pegs
! An entry in the table of memoized parse results
! ast = an AST produced from the parse
! or the symbol 'fail'
! or a left-recursion object
! pos = the position in the input string of this entry
TUPLE: memo-entry ans pos ;
TUPLE: left-recursion seed rule-id head next ;
TUPLE: peg-head rule-id involved-set eval-set ;
: rule-id ( word -- id )
! A rule is the parser compiled down to a word. It has
! a "peg-id" property containing the id of the original parser.
"peg-id" word-prop ;
: input-slice ( -- slice )
! Return a slice of the input from the current parse position
input get pos get tail-slice ;
: input-from ( input -- n )
! Return the index from the original string that the
! input slice is based on.
dup slice? [ from>> ] [ drop 0 ] if ;
: process-rule-result ( p result -- result )
[
nip [ ast>> ] [ remaining>> ] bi input-from pos namespaces:set
] [
pos namespaces:set fail
] if* ;
: eval-rule ( rule -- ast )
! Evaluate a rule, return an ast resulting from it.
! Return fail if the rule failed. The rule has
! stack effect ( -- parse-result )
pos get swap execute( -- parse-result ) process-rule-result ; inline
: memo ( pos id -- memo-entry )
! Return the result from the memo cache.
packrat at ;
: set-memo ( memo-entry pos id -- )
! Store an entry in the cache
packrat set-at ;
: update-m ( ast m -- )
swap >>ans pos get >>pos drop ;
: stop-growth? ( ast m -- ? )
[ failed? pos get ] dip pos>> <= or ;
: setup-growth ( h p -- )
pos namespaces:set dup involved-set>> clone >>eval-set drop ;
: (grow-lr) ( h p r: ( -- result ) m -- )
[ [ setup-growth ] 2keep ] 2dip
[ dup eval-rule ] dip swap
dup pick stop-growth? [
5drop
] [
over update-m
(grow-lr)
] if ; inline recursive
: grow-lr ( h p r m -- ast )
[ [ heads set-at ] 2keep ] 2dip
pick over [ (grow-lr) ] 2dip
swap heads delete-at
dup pos>> pos namespaces:set ans>>
; inline
:: (setup-lr) ( l s -- )
s [
s left-recursion? [ s throw ] unless
s head>> l head>> eq? [
l head>> s head<<
l head>> [ s rule-id>> suffix ] change-involved-set drop
l s next>> (setup-lr)
] unless
] when ;
:: setup-lr ( r l -- )
l head>> [
r rule-id V{ } clone V{ } clone peg-head boa l head<<
] unless
l lrstack get (setup-lr) ;
:: lr-answer ( r p m -- ast )
m ans>> head>> :> h
h rule-id>> r rule-id eq? [
m ans>> seed>> m ans<<
m ans>> failed? [
fail
] [
h p r m grow-lr
] if
] [
m ans>> seed>>
] if ; inline
:: recall ( r p -- memo-entry )
p r rule-id memo :> m
p heads at :> h
h [
m r rule-id h involved-set>> h rule-id>> suffix member? not and [
fail p memo-entry boa
] [
r rule-id h eval-set>> member? [
h [ r rule-id swap remove ] change-eval-set drop
r eval-rule
m update-m
m
] [
m
] if
] if
] [
m
] if ; inline
:: apply-non-memo-rule ( r p -- ast )
fail r rule-id f lrstack get left-recursion boa :> lr
lr lrstack namespaces:set lr p memo-entry boa dup p r rule-id set-memo :> m
r eval-rule :> ans
lrstack get next>> lrstack namespaces:set
pos get m pos<<
lr head>> [
m ans>> left-recursion? [
ans lr seed<<
r p m lr-answer
] [ ans ] if
] [
ans m ans<<
ans
] if ; inline
: apply-memo-rule ( r m -- ast )
[ ans>> ] [ pos>> ] bi pos namespaces:set
dup left-recursion? [
[ setup-lr ] keep seed>>
] [
nip
] if ;
: apply-rule ( r p -- ast )
2dup recall [
nip apply-memo-rule
] [
apply-non-memo-rule
] if* ; inline
: with-packrat ( input quot -- result )
! Run the quotation with a packrat cache active.
[
swap input ,,
0 pos ,,
f lrstack ,,
V{ } clone error-stack ,,
H{ } clone \ heads ,,
H{ } clone \ packrat ,,
] H{ } make swap with-variables ; inline
GENERIC: (compile) ( peg -- quot )
: process-parser-result ( result -- result )
dup failed? [
drop f
] [
input-slice swap <parse-result>
] if ;
: execute-parser ( word -- result )
pos get apply-rule process-parser-result ;
: preset-parser-word ( parser -- word parser )
gensym swap over >>compiled ;
: define-parser-word ( word parser -- )
! Return the body of the word that is the compiled version
! of the parser.
[ peg>> (compile) ( -- result ) define-declared ]
[ id>> "peg-id" set-word-prop ] 2bi ;
: compile-parser ( parser -- word )
! Look to see if the given parser has been compiled.
! If not, compile it to a temporary word, cache it,
! and return it. Otherwise return the existing one.
! Circular parsers are supported by getting the word
! name and storing it in the cache, before compiling,
! so it is picked up when re-entered.
dup compiled>> [
nip
] [
preset-parser-word dupd define-parser-word
] if* ;
: compile-parser-quot ( parser -- quot )
compile-parser '[ _ execute-parser ] ;
: compile-parsers-quots ( parsers -- quots )
[ compile-parser-quot ] map dup rest-slice
[ '[ @ merge-errors ] ] map! drop ;
SYMBOL: delayed
: fixup-delayed ( -- )
! Work through all delayed parsers and recompile their
! words to have the correct bodies.
delayed get [
call( -- parser ) compile-parser-quot ( -- result ) define-declared
] assoc-each ;
: compile ( parser -- word )
[
H{ } clone delayed [
compile-parser-quot ( -- result ) define-temp fixup-delayed
] with-variable
] with-compilation-unit ;
: compiled-parse ( state word -- result )
swap [
execute( -- result )
[ error-stack get ?first [ throw ]
[ pos get input get f <parse-error> throw ] if* ] unless*
] with-packrat ;
: (parse) ( input parser -- result )
dup word? [ compile ] unless compiled-parse ;
: parse ( input parser -- ast )
(parse) ast>> ;
<PRIVATE
: next-id ( -- n )
! Return the next unique id for a parser
\ next-id counter ;
: wrap-peg ( peg -- parser )
! Wrap a parser tuple around the peg object.
! Look for an existing parser tuple for that
! peg object.
peg-cache [ f next-id parser boa ] cache ;
TUPLE: token-parser symbol ;
: parse-token ( input string -- result )
! Parse the string, returning a parse result
[ ?head-slice ] keep swap [
<parse-result>
] [
[ seq>> pos get swap ] dip "'" "'" surround 1vector add-error f
] if ;
M: token-parser (compile) ( peg -- quot )
symbol>> '[ input-slice _ parse-token ] ;
TUPLE: satisfy-parser quot ;
:: parse-satisfy ( input quot -- result/f )
input [ f ] [
unclip-slice dup quot call [
<parse-result>
] [
2drop f
] if
] if-empty ; inline
M: satisfy-parser (compile)
quot>> '[ input-slice _ parse-satisfy ] ;
TUPLE: range-parser min max ;
:: parse-range ( input min max -- result/f )
input [ f ] [
dup first min max between? [
unclip-slice <parse-result>
] [
drop f
] if
] if-empty ;
M: range-parser (compile)
[ min>> ] [ max>> ] bi '[ input-slice _ _ parse-range ] ;
TUPLE: seq-parser parsers ;
: calc-seq-result ( prev-result current-result -- next-result )
[
[ remaining>> >>remaining ] [ ast>> ] bi
dup ignore? [ drop ] [ over ast>> push ] if
] [
drop f
] if* ;
: parse-seq-element ( result quot -- result )
'[ @ calc-seq-result ] [ f ] if* ; inline
M: seq-parser (compile)
parsers>> compile-parsers-quots
[ '[ _ parse-seq-element ] ] map
'[ input-slice V{ } clone <parse-result> _ 1&& ] ;
TUPLE: choice-parser parsers ;
M: choice-parser (compile)
parsers>> compile-parsers-quots '[ _ 0|| ] ;
TUPLE: repeat0-parser parser ;
: (repeat) ( quot: ( -- result ) result -- result )
over call [
[ remaining>> >>remaining ] [ ast>> ] bi
over ast>> push (repeat)
] [
nip
] if* ; inline recursive
M: repeat0-parser (compile)
parser>> compile-parser-quot '[
input-slice V{ } clone <parse-result> _ swap (repeat)
] ;
TUPLE: repeat1-parser parser ;
: repeat1-empty-check ( result -- result )
[ dup ast>> empty? [ drop f ] when ] [ f ] if* ;
M: repeat1-parser (compile)
parser>> compile-parser-quot '[
input-slice V{ } clone <parse-result> _ swap (repeat)
repeat1-empty-check
] ;
TUPLE: optional-parser parser ;
: check-optional ( result -- result )
[ input-slice f <parse-result> ] unless* ;
M: optional-parser (compile)
parser>> compile-parser-quot '[ @ check-optional ] ;
TUPLE: semantic-parser parser quot ;
: check-semantic ( result quot -- result )
dupd '[ dup ast>> @ [ drop f ] unless ] when ; inline
M: semantic-parser (compile)
[ parser>> compile-parser-quot ] [ quot>> ] bi
'[ @ _ check-semantic ] ;
TUPLE: ensure-parser parser ;
: check-ensure ( old-input result -- result )
[ ignore <parse-result> ] [ drop f ] if ;
M: ensure-parser (compile)
parser>> compile-parser-quot '[ input-slice @ check-ensure ] ;
TUPLE: ensure-not-parser parser ;
: check-ensure-not ( old-input result -- result )
[ drop f ] [ ignore <parse-result> ] if ;
M: ensure-not-parser (compile)
parser>> compile-parser-quot '[ input-slice @ check-ensure-not ] ;
TUPLE: action-parser parser quot ;
: check-action ( result quot -- result )
dupd '[ [ _ call( ast -- ast ) ] change-ast ] when ;
M: action-parser (compile)
[ parser>> compile-parser-quot ] [ quot>> ] bi
'[ @ _ check-action ] ;
TUPLE: sp-parser parser ;
M: sp-parser (compile)
parser>> compile-parser-quot '[
input-slice [ blank? ] trim-head-slice input-from pos namespaces:set @
] ;
TUPLE: delay-parser quot ;
M: delay-parser (compile)
! For efficiency we memoize the quotation.
! This way it is run only once and the
! parser constructed once at run time.
quot>> gensym [ delayed get set-at ] keep 1quotation ;
TUPLE: box-parser quot ;
M: box-parser (compile)
! Calls the quotation at compile time
! to produce the parser to be compiled.
! This differs from 'delay' which calls
! it at run time.
quot>> call( -- parser ) compile-parser-quot ;
PRIVATE>
: token ( string -- parser )
token-parser boa wrap-peg ;
: satisfy ( quot -- parser )
satisfy-parser boa wrap-peg ;
: range ( min max -- parser )
range-parser boa wrap-peg ;
: seq ( seq -- parser )
seq-parser boa wrap-peg ;
: 2seq ( parser1 parser2 -- parser )
2array seq ;
: 3seq ( parser1 parser2 parser3 -- parser )
3array seq ;
: 4seq ( parser1 parser2 parser3 parser4 -- parser )
4array seq ;
: seq* ( quot -- paser )
{ } make seq ; inline
: choice ( seq -- parser )
choice-parser boa wrap-peg ;
: 2choice ( parser1 parser2 -- parser )
2array choice ;
: 3choice ( parser1 parser2 parser3 -- parser )
3array choice ;
: 4choice ( parser1 parser2 parser3 parser4 -- parser )
4array choice ;
: choice* ( quot -- paser )
{ } make choice ; inline
: repeat0 ( parser -- parser )
repeat0-parser boa wrap-peg ;
: repeat1 ( parser -- parser )
repeat1-parser boa wrap-peg ;
: optional ( parser -- parser )
optional-parser boa wrap-peg ;
: semantic ( parser quot -- parser )
semantic-parser boa wrap-peg ;
: ensure ( parser -- parser )
ensure-parser boa wrap-peg ;
: ensure-not ( parser -- parser )
ensure-not-parser boa wrap-peg ;
: action ( parser quot -- parser )
action-parser boa wrap-peg ;
: sp ( parser -- parser )
sp-parser boa wrap-peg ;
: hide ( parser -- parser )
[ drop ignore ] action ;
: delay ( quot -- parser )
delay-parser boa wrap-peg ;
: box ( quot -- parser )
! because a box has its quotation run at compile time
! it must always have a new parser wrapper created,
! not a cached one. This is because the same box,
! compiled twice can have a different compiled word
! due to running at compile time.
! Why the [ ] action at the end? Box parsers don't get
! memoized during parsing due to all box parsers being
! unique. This breaks left recursion detection during the
! parse. The action adds an indirection with a parser type
! that gets memoized and fixes this. Need to rethink how
! to fix boxes so this isn't needed...
box-parser boa f next-id parser boa [ ] action ;
ERROR: parse-failed input word ;
SYNTAX: PEG:
[let
(:) :> ( word def effect )
[
[
def call compile :> compiled-def
word [
dup compiled-def compiled-parse
[ ast>> ] [ word parse-failed ] ?if
] effect define-declared
] with-compilation-unit
] append!
] ;
{ "debugger" "peg" } "peg.debugger" require-when