! (c)2010 Joe Groff bsd license
USING: accessors arrays assocs combinators combinators.short-circuit
continuations effects fry kernel locals math namespaces
quotations sequences splitting
stack-checker.backend
stack-checker.errors
stack-checker.known-words
stack-checker.state
stack-checker.values
stack-checker.visitor ;
IN: stack-checker.row-polymorphism

<PRIVATE
SYMBOLS: current-effect-variables current-word-effect current-meta-d ;

: quotation-effect? ( in -- ? )
    dup pair? [ second effect? ] [ drop f ] if ;

SYMBOL: (unknown)

GENERIC: >error-quot ( known -- quot )

M: object >error-quot drop (unknown) ;
M: literal >error-quot value>> ;
M: composed >error-quot
    [ quot1>> known >error-quot ] [ quot2>> known >error-quot ] bi
    \ compose [ ] 3sequence ;
M: curried >error-quot
    [ obj>> known >error-quot ] [ quot>> known >error-quot ] bi
    \ curry [ ] 3sequence ;

: >error-branches-and-quots ( branch/values -- branches quots )
    [ [ second ] [ known >error-quot ] bi* ] assoc-map unzip ;

: abandon-check ( -- * )
    current-word get
    current-word-effect get in>> current-meta-d get zip
    [ first quotation-effect? ] filter
    >error-branches-and-quots
    invalid-quotation-input ;

:: check-variable ( actual-count declared-count variable -- difference )
    actual-count declared-count -
    variable [
        variable current-effect-variables get at* nip
        [ variable current-effect-variables get at -     ]
        [ variable current-effect-variables get set-at 0 ] if
    ] [
        dup [ abandon-check ] unless-zero
    ] if ;

: adjust-variable ( diff var -- )
    over 0 >=
    [ current-effect-variables get at+ ]
    [ 2drop ] if ; inline

:: (check-input) ( declared actual -- )
    actual terminated?>> [
        actual declared [ in>>  length ] bi@ declared in-var>>
            [ check-variable ] keep :> ( in-diff in-var ) 
        actual declared [ out>> length ] bi@ declared out-var>>
            [ check-variable ] keep :> ( out-diff out-var )
        { [ in-var not ] [ out-var not ] [ in-diff out-diff = ] } 0||
        [
            in-var  [ in-diff  swap adjust-variable ] when*
            out-var [ out-diff swap adjust-variable ] when*
        ] [
            abandon-check
        ] if
    ] unless ;

: infer-value ( value -- effect )
    dup known [ nest-visitor init-inference infer-call* current-effect ] with-scope ; inline

: check-input ( in value -- )
    over quotation-effect? [
        [ second ] dip infer-value (check-input)
    ] [ 2drop ] if ;

: normalize-variables ( -- variables' )
    current-effect-variables get dup values [
        infimum dup 0 <
        [ '[ _ - ] assoc-map ] [ drop ] if
    ] unless-empty ;

PRIVATE>

: infer-polymorphic-vars ( effect -- variables )
    H{ } clone current-effect-variables set
    dup current-word-effect set
    in>> dup length ensure-d dup current-meta-d set
    [ check-input ] 2each
    normalize-variables ;

: check-polymorphic-effect ( word -- )
    current-word get [
        dup current-word set
        stack-effect dup { [ in-var>> ] [ out-var>> ] } 1||
        [ infer-polymorphic-vars ] when drop
    ] dip current-word set ;

SYMBOL: infer-polymorphic?
infer-polymorphic? [ t ] initialize