! :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
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IN: vectors
USE: generic
USE: kernel
USE: lists
USE: math

BUILTIN: vector  11

: empty-vector ( len -- vec )
    #! Creates a vector with 'len' elements set to f. Unlike
    #! <vector>, which gives an empty vector with a certain
    #! capacity.
    dup <vector> dup >r set-vector-length r> ;

: vector-empty? ( obj -- ? )
    vector-length 0 = ;

: vector-push ( obj vector -- )
    #! Push a value on the end of a vector.
    dup vector-length swap set-vector-nth ;

: vector-pop ( vector -- obj )
    #! Get value at end of vector and remove it.
    dup vector-length pred ( vector top )
    2dup swap vector-nth >r swap set-vector-length r> ;

: >pop> ( stack -- stack )
    dup vector-pop drop ;

: vector-each ( vector code -- )
    #! Execute the code, with each element of the vector
    #! pushed onto the stack.
    over vector-length [
        -rot 2dup >r >r >r vector-nth r> call r> r>
    ] times* 2drop ; inline

: vector-map ( vector code -- vector )
    #! Applies code to each element of the vector, return a new
    #! vector with the results. The code must have stack effect
    #! ( obj -- obj ).
    over vector-length <vector> rot [
        swap >r apply r> tuck vector-push
    ] vector-each nip ; inline

: vector-and ( vector -- ? )
    #! Logical and of all elements in the vector.
    t swap [ and ] vector-each ;

: vector-all? ( vector pred -- ? )
    vector-map vector-and ; inline

: vector-append ( v1 v2 -- )
    #! Destructively append v2 to v1.
    [ over vector-push ] vector-each drop ;

: vector-project ( n quot -- accum )
    #! Execute the quotation n times, passing the loop counter
    #! the quotation as it ranges from 0..n-1. Collect results
    #! in a new vector.
    over <vector> rot [
        -rot 2dup >r >r slip vector-push r> r>
    ] times* nip ; inline

: vector-zip ( v1 v2 -- v )
    #! Make a new vector with each pair of elements from the
    #! first two in a pair.
    over vector-length [
        pick pick >r over >r vector-nth r> r> vector-nth cons
    ] vector-project nip nip ;

: vector-2map ( v1 v2 quot -- v )
    #! Apply a quotation with stack effect ( obj obj -- obj ) to
    #! each pair of elements from v1 and v2, collecting them
    #! into a new list. Behavior is undefined if vector lengths
    #! differ.
    -rot vector-zip [
        swap dup >r >r uncons r> call r> swap
    ] vector-map nip ; inline

: vector-clone ( vector -- vector )
    #! Shallow copy of a vector.
    [ ] vector-map ;

: list>vector ( list -- vector )
    dup length <vector> swap [ over vector-push ] each ;

: stack>list ( vector -- list )
    [ ] swap [ swons ] vector-each ;

: vector>list ( vector -- list )
    stack>list reverse ;

: vector-length= ( vec vec -- ? )
    vector-length swap vector-length number= ;

M: vector = ( obj vec -- ? )
    #! Check if two vectors are equal. Two vectors are
    #! considered equal if they have the same length and contain
    #! equal elements.
    2dup eq? [
        2drop t
    ] [
        over vector? [
            2dup vector-length= [
                swap vector>list swap vector>list =
            ] [
                2drop f
            ] ifte
        ] [
            2drop f
        ] ifte
    ] ifte ;

: ?vector-nth ( n vec -- obj/f )
    2dup vector-length >= [ 2drop f ] [ vector-nth ] ifte ;

M: vector hashcode ( vec -- n )
    0 swap 4 [
        over ?vector-nth hashcode rot bitxor swap
    ] times* drop ;

: vector-tail ( n vector -- list )
    #! Return a new vector, with all elements from the nth
    #! index upwards.
    2dup vector-length swap - [
        pick + over vector-nth
    ] project nip nip ;

: vector-tail* ( n vector -- list )
    #! Unlike vector-tail, n is an index from the end of the
    #! vector. For example, if n=1, this returns a vector of
    #! one element.
    [ vector-length swap - ] keep vector-tail ;