! Copyright (C) 2004, 2008 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: arrays generic assocs kernel math namespaces parser
sequences words vectors math.intervals effects classes
accessors combinators stack-checker.state stack-checker.visitor ;
IN: compiler.tree

! High-level tree SSA form.
!
! Invariants:
! 1) Each value has exactly one definition. A "definition" means
! the value appears in the out-d or out-r slot of a node, or the
! values slot of an #introduce node.
! 2) Each value appears only once in the inputs of a node, where
! the inputs are the concatenation of in-d and in-r, or in the
! case of a #phi node, the sequence of sequences in the phi-in-r
! and phi-in-d slots.
! 3) A value is never used in the same node where it is defined.
TUPLE: node < identity-tuple
in-d out-d in-r out-r info
successor children ;

M: node hashcode* drop node hashcode* ;

: node-child ( node -- child ) children>> first ;

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

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

TUPLE: #introduce < node values ;

: #introduce ( values -- node )
    \ #introduce new swap >>values ;

TUPLE: #call < node word history ;

: #call ( inputs outputs word -- node )
    \ #call new
        swap >>word
        swap >>out-d
        swap >>in-d ;

TUPLE: #call-recursive < node label ;

: #call-recursive ( inputs outputs label -- node )
    \ #call-recursive new
        swap >>label
        swap >>out-d
        swap >>in-d ;

TUPLE: #push < node literal ;

: #push ( literal value -- node )
    \ #push new
        swap 1array >>out-d
        swap >>literal ;

TUPLE: #shuffle < node mapping ;

: #shuffle ( inputs outputs mapping -- node )
    \ #shuffle new
        swap >>mapping
        swap >>out-d
        swap >>in-d ;

: #drop ( inputs -- node )
    { } { } #shuffle ;

TUPLE: #>r < node ;

: #>r ( inputs outputs -- node )
    \ #>r new
        swap >>out-r
        swap >>in-d ;

TUPLE: #r> < node ;

: #r> ( inputs outputs -- node )
    \ #r> new
        swap >>out-d
        swap >>in-r ;

TUPLE: #terminate < node ;

: #terminate ( stack -- node )
    \ #terminate new
        swap >>in-d ;

TUPLE: #branch < node ;

: new-branch ( value children class -- node )
    new
        swap >>children
        swap 1array >>in-d ; inline

TUPLE: #if < #branch ;

: #if ( ? true false -- node )
    2array \ #if new-branch ;

TUPLE: #dispatch < #branch ;

: #dispatch ( n branches -- node )
    \ #dispatch new-branch ;

TUPLE: #phi < node phi-in-d phi-in-r ;

: #phi ( d-phi-in d-phi-out r-phi-in r-phi-out -- node )
    \ #phi new
        swap >>out-r
        swap >>phi-in-r
        swap >>out-d
        swap >>phi-in-d ;

TUPLE: #declare < node declaration ;

: #declare ( declaration -- node )
    \ #declare new
        swap >>declaration ;

TUPLE: #return < node ;

: #return ( stack -- node )
    \ #return new
        swap >>in-d ;

TUPLE: #recursive < node word label loop? returns calls ;

: #recursive ( word label inputs child -- node )
    \ #recursive new
        swap 1array >>children
        swap >>in-d
        swap >>label
        swap >>word ;

TUPLE: #enter-recursive < node label ;

: #enter-recursive ( label inputs outputs -- node )
    \ #enter-recursive new
        swap >>out-d
        swap >>in-d
        swap >>label ;

TUPLE: #return-recursive < node label ;

: #return-recursive ( label inputs outputs -- node )
    \ #return-recursive new
        swap >>out-d
        swap >>in-d
        swap >>label ;

TUPLE: #copy < node ;

: #copy ( inputs outputs -- node )
    \ #copy new
        swap >>out-d
        swap >>in-d ;

DEFER: #tail?

PREDICATE: #tail-phi < #phi successor>> #tail? ;

UNION: #tail POSTPONE: f #return #tail-phi #terminate ;

TUPLE: node-list first last ;

: node, ( node -- )
    stack-visitor get swap
    over last>>
    [ [ [ last>> ] dip >>successor drop ] [ >>last drop ] 2bi ]
    [ [ >>first ] [ >>last ] bi drop ]
    if ;

M: node-list child-visitor node-list new ;
M: node-list #introduce, #introduce node, ;
M: node-list #call, #call node, ;
M: node-list #push, #push node, ;
M: node-list #shuffle, #shuffle node, ;
M: node-list #drop, #drop node, ;
M: node-list #>r, #>r node, ;
M: node-list #r>, #r> node, ;
M: node-list #return, #return node, ;
M: node-list #enter-recursive, #enter-recursive node, ;
M: node-list #return-recursive, #return-recursive [ node, ] [ dup label>> (>>return) ] bi ;
M: node-list #call-recursive, #call-recursive [ node, ] [ dup label>> calls>> push ] bi ;
M: node-list #terminate, #terminate node, ;
M: node-list #if, #if node, ;
M: node-list #dispatch, #dispatch node, ;
M: node-list #phi, #phi node, ;
M: node-list #declare, #declare node, ;
M: node-list #recursive, #recursive node, ;
M: node-list #copy, #copy node, ;