! Copyright (C) 2004, 2006 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
IN: inference
USING: arrays generic hashtables interpreter kernel math
namespaces parser sequences words ;

! The dataflow IR is the first of the two intermediate
! representations used by Factor. It annotates concatenative
! code with stack flow information and types.

TUPLE: node param shuffle
       classes literals history
       successor children ;

M: node = eq? ;

: make-node ( param in-d out-d in-r out-r node -- node )
    [ >r swapd <shuffle> f f f f f <node> r> set-delegate ] keep ;

: node-in-d  node-shuffle shuffle-in-d  ;
: node-in-r  node-shuffle shuffle-in-r  ;
: node-out-d node-shuffle shuffle-out-d ;
: node-out-r node-shuffle shuffle-out-r ;

: set-node-in-d  node-shuffle set-shuffle-in-d  ;
: set-node-in-r  node-shuffle set-shuffle-in-r  ;
: set-node-out-d node-shuffle set-shuffle-out-d ;
: set-node-out-r node-shuffle set-shuffle-out-r ;

: empty-node f { } { } { } { } ;
: param-node ( label) { } { } { } { } ;
: in-node ( inputs) >r f r> { } { } { } ;
: out-node ( outputs) >r f { } r> { } { } ;
: meta-d-node meta-d get clone in-node ;

: d-tail ( n -- list ) meta-d get tail* ;
: r-tail ( n -- list ) meta-r get tail* ;

: node-child node-children first ;

TUPLE: #label ;
C: #label make-node ;
: #label ( label -- node ) param-node <#label> ;

TUPLE: #entry ;
C: #entry make-node ;

: #entry ( -- node ) meta-d-node <#entry> ;

TUPLE: #call ;
C: #call make-node ;
: #call ( word -- node ) param-node <#call> ;

TUPLE: #call-label ;
C: #call-label make-node ;
: #call-label ( label -- node ) param-node <#call-label> ;

TUPLE: #push ;
C: #push make-node ;
: #push ( -- node ) peek-d 1array out-node <#push> ;
: >#push< ( node -- seq ) node-out-d [ value-literal ] map ;

TUPLE: #shuffle ;
C: #shuffle make-node ;
: #shuffle ( -- node ) empty-node <#shuffle> ;

TUPLE: #values ;
C: #values make-node ;
: #values ( -- node ) meta-d-node <#values> ;

TUPLE: #return ;
C: #return make-node ;
: #return ( label -- node )
    #! The parameter is the label we are returning from, or if
    #! f, this is a top-level return.
    meta-d-node <#return> [ set-node-param ] keep ;

TUPLE: #if ;
C: #if make-node ;
: #if ( in -- node ) peek-d 1array in-node <#if> ;

TUPLE: #dispatch ;
C: #dispatch make-node ;
: #dispatch ( in -- node ) peek-d 1array in-node <#dispatch> ;

TUPLE: #merge ;
C: #merge make-node ;
: #merge ( -- node ) meta-d get clone out-node <#merge> ;

TUPLE: #terminate ;
C: #terminate make-node ;
: #terminate ( -- node ) empty-node <#terminate> ;

TUPLE: #declare ;
C: #declare make-node ;
: #declare ( classes -- node ) param-node <#declare> ;

: node-inputs ( d-count r-count node -- )
    tuck
    >r r-tail r> set-node-in-r
    >r d-tail r> set-node-in-d ;

: node-outputs ( d-count r-count node -- )
    tuck
    >r r-tail r> set-node-out-r
    >r d-tail r> set-node-out-d ;

! Variable holding dataflow graph being built.
SYMBOL: dataflow-graph
! The most recently added node.
SYMBOL: current-node

: node, ( node -- )
    dataflow-graph get [
        dup current-node [ set-node-successor ] change
    ] [
        ! first node
        dup dataflow-graph set  current-node set
    ] if ;

: node-values ( node -- values )
    [
        dup node-in-d % dup node-out-d %
        dup node-in-r % node-out-r %
    ] { } make ;

: last-node ( node -- last )
    dup node-successor [ last-node ] [ ] ?if ;

: penultimate-node ( node -- penultimate )
    dup node-successor dup [
        dup node-successor
        [ nip penultimate-node ] [ drop ] if
    ] [
        2drop f
    ] if ;

: drop-inputs ( node -- #shuffle )
    node-in-d clone in-node <#shuffle> ;

: #drop ( n -- #shuffle )
    d-tail in-node <#shuffle> ;

: each-node ( node quot -- | quot: node -- )
    over [
        [ call ] 2keep swap
        [ node-children [ swap each-node ] each-with ] 2keep
        node-successor swap each-node
    ] [
        2drop
    ] if ; inline

: each-node-with ( obj node quot -- | quot: obj node -- )
    swap [ with ] each-node 2drop ; inline

: all-nodes? ( node quot -- ? | quot: node -- ? )
    over [
        [ call ] 2keep rot [
            [
                swap node-children [ swap all-nodes? ] all-with?
            ] 2keep rot [
                >r node-successor r> all-nodes?
            ] [
                2drop f
            ] if
        ] [
            2drop f
        ] if
    ] [
        2drop t
    ] if ; inline

: all-nodes-with? ( obj node quot -- ? | quot: obj node -- ? )
    swap [ with rot ] all-nodes? 2nip ; inline

: remember-node ( word node -- )
    #! Annotate each node with the fact it was inlined from
    #! 'word'.
    [
        dup #call?
        [ [ node-history ?push ] keep set-node-history ]
        [ 2drop ] if
    ] each-node-with ;

GENERIC: calls-label* ( label node -- ? )

M: node calls-label* 2drop f ;

M: #call-label calls-label* node-param eq? ;

: calls-label? ( label node -- ? )
    [ calls-label* not ] all-nodes-with? not ;

: recursive-label? ( node -- ? )
    dup node-param swap calls-label? ;

SYMBOL: node-stack

: >node node-stack get push ;
: node> node-stack get pop ;
: node@ node-stack get peek ;

DEFER: iterate-nodes

: iterate-children ( quot -- )
    node@ node-children [ swap iterate-nodes ] each-with ;
    inline

: iterate-next ( -- node ) node@ node-successor ;

: iterate-nodes ( node quot -- )
    over [
        [ swap >node call node> drop ] keep
        over [ iterate-nodes ] [ 2drop ] if
    ] [
        2drop
    ] if ; inline

: ?set-node-successor ( next prev -- )
    [ set-node-successor ] [ drop ] if* ;

: map-node ( prev quot -- )
    swap >r node@ swap call dup r> ?set-node-successor
    node> drop >node ; inline

DEFER: map-children
DEFER: (map-nodes)

: map-next ( quot -- )
    node@ [
        swap [ map-children ] keep
        node> node-successor >node (map-nodes)
    ] [
        drop
    ] if* ; inline

: (map-nodes) ( prev quot -- | quot: node -- node )
    node@
    [ [ map-node ] keep map-next ]
    [ drop f swap ?set-node-successor ] if ; inline

: map-first ( node quot -- node | quot: node -- node )
    call node> drop dup >node ; inline

: map-nodes ( node quot -- node | quot: node -- node )
    over [
        over >node [ map-first ] keep map-next node>
    ] when drop ; inline

: map-children ( quot -- | quot: node -- node )
    node@ [ node-children [ swap map-nodes ] map-with ] keep
    set-node-children ; inline

: with-node-iterator ( quot -- )
    [ V{ } clone node-stack set call ] with-scope ; inline

: (subst-values) ( new old node -- )
    [
        [ node-in-d subst ] 3keep [ node-in-r subst ] 3keep
        [ node-out-d subst ] 3keep [ node-out-r subst ] 3keep
        drop
    ] each-node 2drop ;

: subst-values ( new old node -- )
    #! Mutates nodes.
    1 node-stack get head* swap add
    [ >r 2dup r> node-successor (subst-values) ] each 2drop ;