! :folding=indent:collapseFolds=1:

! $Id$
!
! Copyright (C) 2004 Slava Pestov.
! 
! Redistribution and use in source and binary forms, with or without
! modification, are permitted provided that the following conditions are met:
! 
! 1. Redistributions of source code must retain the above copyright notice,
!    this list of conditions and the following disclaimer.
! 
! 2. Redistributions in binary form must reproduce the above copyright notice,
!    this list of conditions and the following disclaimer in the documentation
!    and/or other materials provided with the distribution.
! 
! THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
! INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
! FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
! DEVELOPERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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! PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
! OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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IN: compiler
USE: inference
USE: errors
USE: hashtables
USE: kernel
USE: lists
USE: math
USE: namespaces
USE: parser
USE: prettyprint
USE: stdio
USE: strings
USE: unparser
USE: vectors
USE: words

! We use a hashtable "compiled-xts" that maps words to
! xt's that are currently being compiled. The commit-xt's word
! sets the xt of each word in the hashtable to the value in the
! hastable.
!
! This has the advantage that we can compile a word before the
! words it depends on and perform a fixup later; among other
! things this enables mutually recursive words.

SYMBOL: compiled-xts

: save-xt ( word -- )
    compiled-offset swap compiled-xts [ acons ] change ;

: commit-xt ( xt word -- )
    dup t "compiled" set-word-property  set-word-xt ;

: commit-xts ( -- )
    compiled-xts get [ unswons commit-xt ] each
    compiled-xts off ;

: compiled-xt ( word -- xt )
    dup compiled-xts get assoc [ nip ] [ word-xt ] ifte* ;

! "deferred-xts" is a list of [ where word relative ] pairs; the
! xt of word when its done compiling will be written to the
! offset, relative to the offset.

SYMBOL: deferred-xts

! Words being compiled are consed onto this list. When a word
! is encountered that has not been previously compiled, it is
! consed onto this list. Compilation stops when the list is
! empty.

SYMBOL: compile-words

: defer-xt ( word where relative -- )
    #! After word is compiled, put its XT at where, relative.
    3list deferred-xts cons@ ;

: compiling? ( word -- ? )
    #! A word that is compiling or already compiled will not be
    #! added to the list of words to be compiled.
    dup compiled? [
        drop t
    ] [
        dup compile-words get contains? [
            drop t
        ] [
            compiled-xts get assoc
        ] ifte
    ] ifte ;

: fixup-deferred-xt ( word where relative -- )
    rot dup compiling? [
        compiled-xt swap - swap set-compiled-cell
    ] [
        "Not compiled: " swap word-name cat2 throw
    ] ifte ;

: fixup-deferred-xts ( -- )
    deferred-xts get [
        uncons uncons car fixup-deferred-xt
    ] each
    deferred-xts off ;

: with-compiler ( quot -- )
    [ call  fixup-deferred-xts  commit-xts ] with-scope ;

: postpone-word ( word -- )
    dup compiling? [ drop ] [ compile-words unique@ ] ifte ;