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mercury/library/version_array2d.m
Zoltan Somogyi 4e50c5f634 Fix indentation.
2025-10-02 19:38:03 +10:00

249 lines
8.7 KiB
Mathematica

%---------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%---------------------------------------------------------------------------%
% Copyright (C) 2004-2006, 2011 The University of Melbourne.
% Copyright (C) 2013-2015, 2017-2019, 2022, 2024-2025 The Mercury team.
% This file is distributed under the terms specified in COPYING.LIB.
%---------------------------------------------------------------------------%
%
% File: version_array2d.m.
% Author: Ralph Becket <rafe@cs.mu.oz.au>.
% Stability: medium.
%
% Two-dimensional rectangular (i.e. not ragged) version arrays.
%
% See the header comments in version_array.m for more details about version
% structures.
%
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- module version_array2d.
:- interface.
:- import_module list.
%---------------------------------------------------------------------------%
% A version_array2d is a two-dimensional version array stored in row-major
% order (that is, the elements of the first row in left-to-right order,
% followed by the elements of the second row, and so on.)
%
:- type version_array2d(T).
% version_array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]]) constructs
% a 2d version array of size M * N, with the special case that
% bounds(version_array2d([]), 0, 0).
%
% An exception is thrown if the sublists are not all the same length.
%
:- func version_array2d(list(list(T))) = version_array2d(T).
% init(M, N, X) = version_array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]])
% where each XIJ = X.
%
% An exception is thrown if M < 0 or N < 0.
%
:- func init(int, int, T) = version_array2d(T).
% bounds(version_array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]), M, N)
%
:- pred bounds(version_array2d(T)::in, int::out, int::out) is det.
% in_bounds(version_array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]), I, J)
% succeeds if-and-only-if 0 =< I < M, 0 =< J < N.
%
:- pred in_bounds(version_array2d(T)::in, int::in, int::in) is semidet.
% lookup(VA2D, RowNum, ColNum, Value):
% VA2D ^ elem(RowNum, ColNum) = Value:
%
% Return the value at the given row and column numbers.
% Note that both row and column numbers start from zero.
%
% Throw an exception if either RowNum or ColNum is out of bounds.
%
:- pred lookup(version_array2d(T)::in, int::in, int::in, T::out) is det.
:- func elem(int, int, version_array2d(T)) = T.
% set(RowNum, ColNum, X, !VA2D):
% ( !.VA2D ^ elem(RowNum, ColNum) := X ) = !:VA2D:
%
% Return a version of the initial version_array2d that contains
% all the same values, with the exception that the element at the
% given row and column number is set to X.
%
% Throw an exception if either RowNum or ColNum is out of bounds.
%
:- pred set(int::in, int::in, T::in,
version_array2d(T)::in, version_array2d(T)::out) is det.
:- func 'elem :='(int, int, version_array2d(T), T) = version_array2d(T).
% lists(version_array2d([[X11, ..., X1N], ..., [XM1, ..., XMN])) =
% [[X11, ..., X1N], ..., [XM1, ..., XMN]]
%
:- func lists(version_array2d(T)) = list(list(T)).
% copy(VA2D) returns a copy of VA2D with O(1) access times.
%
:- func copy(version_array2d(T)) = version_array2d(T).
% resize(VA2D, M, N, X) returns a copy of VA2D resized to M * N.
% Items with coordinates in common are copied from VA2D; other
% items are initialised to X.
%
% An exception is thrown if M < 0 or N < 0.
%
:- func resize(version_array2d(T), int, int, T) = version_array2d(T).
% unsafe_rewind(VA2D) returns a new 2d version array with O(1) access
% times, at the cost of rendering VA2D and its descendants undefined.
% Only call this function if you are absolutely certain there are no
% remaining live references to VA2D or any descendent of VA2D.
%
:- func unsafe_rewind(version_array2d(T)) = version_array2d(T).
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- implementation.
:- import_module int.
:- import_module require.
:- import_module version_array.
%---------------------------------------------------------------------------%
% version_array2d(NumRows, NumCols, Array)
%
:- type version_array2d(T)
---> version_array2d(int, int, version_array(T)).
%---------------------------------------------------------------------------%
version_array2d(Rows) = VA2D :-
(
Rows = [],
VA2D = version_array2d(0, 0, version_array([]))
;
Rows = [FirstRow | _],
list.length(Rows, NumRows),
list.length(FirstRow, FirstRowNumCols),
( if
all [Row] (
list.member(Row, Rows)
=>
list.length(Row) = FirstRowNumCols
)
then
VA = version_array(list.condense(Rows)),
VA2D = version_array2d(NumRows, FirstRowNumCols, VA)
else
error($pred, "non-rectangular list of lists")
)
).
%---------------------------------------------------------------------------%
init(NumRows, NumCols, InitValue) = VA2D :-
( if NumRows >= 0, NumCols >= 0 then
VA = version_array.init(NumRows * NumCols, InitValue),
VA2D = version_array2d(NumRows, NumCols, VA)
else
error($pred, "bounds must be non-negative")
).
%---------------------------------------------------------------------------%
bounds(version_array2d(NumRows, NumCols, _A), NumRows, NumCols).
%---------------------------------------------------------------------------%
in_bounds(version_array2d(NumRows, NumCols, _A), RowNum, ColNum) :-
0 =< RowNum, RowNum < NumRows,
0 =< ColNum, ColNum < NumCols.
%---------------------------------------------------------------------------%
lookup(VA2D, RowNum, ColNum, Value) :-
VA2D = version_array2d(_NumRows, NumCols, VA),
version_array.lookup(VA, RowNum * NumCols + ColNum, Value).
elem(RowNum, ColNum, VA2D) = Value :-
lookup(VA2D, RowNum, ColNum, Value).
%---------------------------------------------------------------------------%
set(RowNum, ColNum, NewValue, !VA2D) :-
!.VA2D = version_array2d(NumRows, NumCols, VA0),
version_array.set(RowNum * NumCols + ColNum, NewValue, VA0, VA),
!:VA2D = version_array2d(NumRows, NumCols, VA).
'elem :='(RowNum, ColNum, !.VA2D, NewValue) = !:VA2D :-
set(RowNum, ColNum, NewValue, !VA2D).
%---------------------------------------------------------------------------%
lists(version_array2d(M, N, VA)) = lists_2((M * N) - 1, N - 1, N, VA, [], []).
% XXX This predicate should be replaced by two predicates.
% One should copy the elements of ONE row, looping over the columns,
% while the other should loop over all the rows.
%
:- func lists_2(int, int, int, version_array(T), list(T),
list(list(T))) = list(list(T)).
lists_2(IJ, J, N, VA, Xs, Xss) =
( if 0 =< IJ then
( if 0 =< J then
lists_2(IJ - 1, J - 1, N, VA, [VA ^ elem(IJ) | Xs], Xss )
else
lists_2(IJ, N - 1, N, VA, [], [Xs | Xss])
)
else
[Xs | Xss]
).
%---------------------------------------------------------------------------%
copy(VA2D) = CopyA2D :-
VA2D = version_array2d(NumRows, NumCols, VA),
CopyA2D = version_array2d(NumRows, NumCols, copy(VA)).
%---------------------------------------------------------------------------%
resize(VA2D0, M, N, X) = VA2D :-
VA2D1 = init(M, N, X),
bounds(VA2D0, M0, N0),
% XXX By allowing M1 != M and N1 != N, these calls to min *contradict*
% the documentation of resize.
M1 = min(M0, M),
N1 = min(N0, N),
VA2D = resize_2(0, 0, M1, N1, VA2D0, VA2D1).
% XXX This predicate should be replaced by two predicates.
% One should copy and resize ONE row, looping over the columns,
% while the other should copy and resize the rows themselves.
%
:- func resize_2(int, int, int, int, version_array2d(T),
version_array2d(T)) = version_array2d(T).
resize_2(I, J, M, N, SrcVA2D, DestVA2D) =
( if I >= M then
DestVA2D
else if J >= N then
resize_2(I + 1, 0, M, N, SrcVA2D, DestVA2D)
else
resize_2(I, J + 1, M, N, SrcVA2D,
DestVA2D ^ elem(I, J) := SrcVA2D ^ elem(I, J))
).
%---------------------------------------------------------------------------%
unsafe_rewind(version_array2d(M, N, VA)) =
version_array2d(M, N, unsafe_rewind(VA)).
%---------------------------------------------------------------------------%
:- end_module version_array2d.
%---------------------------------------------------------------------------%