Files
mercury/library/array2d.m
Julien Fischer e0f5ac47db Make it easier for vi to jump past the initial comments
Estimated hours taken: 0.1
Branches: main

library/*.m:
	Make it easier for vi to jump past the initial comments
	at the head of a module.
2006-04-19 05:18:00 +00:00

219 lines
7.4 KiB
Mathematica

%-----------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et wm=0 tw=0
%-----------------------------------------------------------------------------%
% Copyright (C) 2003, 2005-2006 The University of Melbourne.
% This file may only be copied under the terms of the GNU Library General
% Public License - see the file COPYING.LIB in the Mercury distribution.
%-----------------------------------------------------------------------------%
%
% File: array2d.m.
% Author: Ralph Becket <rafe@cs.mu.oz.au>.
% Stability: medium-low.
%
% Two-dimensional rectangular (i.e. not ragged) array ADT.
%
% XXX The same caveats re: uniqueness of arrays apply to array2ds.
%
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%
:- module array2d.
:- interface.
:- import_module array.
:- import_module int.
:- import_module list.
%-----------------------------------------------------------------------------%
% A array2d is a two-dimensional 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 forth.)
%
:- type array2d(T).
:- inst array2d ---> array2d(ground, ground, array).
% XXX These are work-arounds until we get nested uniqueness working.
%
:- mode array2d_di == di(array2d).
:- mode array2d_ui == in(array2d).
:- mode array2d_uo == out(array2d).
% array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]]) constructs a array2d
% of size M * N, with the special case that bounds(array2d([]), 0, 0).
%
% An exception is thrown if the sublists are not all the same length.
%
:- func array2d(list(list(T))) = array2d(T).
:- mode array2d(in ) = array2d_uo is det.
% A synonym for the above.
%
:- func from_lists(list(list(T))) = array2d(T).
:- mode from_lists(in ) = array2d_uo is det.
% new(M, N, X) = array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]])
% where each XIJ = X. An exception is thrown if M < 0 or N < 0.
%
:- func new(int, int, T ) = array2d(T).
:- mode new(in, in, in) = array2d_uo is det.
% array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]]) ^ elem(I, J) = X
% where X is the J+1th element of the I+1th row (that is, indices
% start from zero.)
%
% An exception is thrown unless 0 =< I < M, 0 =< J < N.
%
:- func array2d(T) ^ elem(int, int) = T.
:- mode array2d_ui ^ elem(in, in ) = out is det.
:- mode in ^ elem(in, in ) = out is det.
% T ^ unsafe_elem(I, J) is the same as T ^ elem(I, J) except that
% behaviour is undefined if not in_bounds(T, I, J).
%
:- func array2d(T) ^ unsafe_elem(int, int) = T.
:- mode array2d_ui ^ unsafe_elem(in, in ) = out is det.
:- mode in ^ unsafe_elem(in, in ) = out is det.
% ( T0 ^ elem(I, J) := X ) = T
% where T ^ elem(II, JJ) = X if I = II, J = JJ
% and T ^ elem(II, JJ) = T0 ^ elem(II, JJ) otherwise.
%
% An exception is thrown unless 0 =< I < M, 0 =< J < N.
%
:- func ( array2d(T) ^ elem(int, int) := T ) = array2d(T).
:- mode ( array2d_di ^ elem(in, in) := in ) = array2d_uo is det.
% Pred version of the above.
%
:- pred set(int, int, T, array2d(T), array2d(T)).
:- mode set(in, in, in, array2d_di, array2d_uo) is det.
% T ^ unsafe_elem(I, J) := X is the same as T ^ elem(I, J) := X except
% that behaviour is undefined if not in_bounds(T, I, J).
%
:- func ( array2d(T) ^ unsafe_elem(int, int) := T ) = array2d(T).
:- mode ( array2d_di ^ unsafe_elem(in, in) := in ) = array2d_uo is det.
% Pred version of the above.
%
:- pred unsafe_set(int, int, T, array2d(T), array2d(T)).
:- mode unsafe_set(in, in, in, array2d_di, array2d_uo) is det.
% bounds(array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]), M, N)
%
:- pred bounds(array2d(T), int, int).
:- mode bounds(array2d_ui, out, out) is det.
:- mode bounds(in, out, out) is det.
% in_bounds(array2d([[X11, ..., X1N], ..., [XM1, ..., XMN]), I, J)
% succeeds iff 0 =< I < M, 0 =< J < N.
%
:- pred in_bounds(array2d(T), int, int).
:- mode in_bounds(array2d_ui, in, in ) is semidet.
:- mode in_bounds(in, in, in ) is semidet.
% lists(array2d([[X11, ..., X1N], ..., [XM1, ..., XMN])) =
% [[X11, ..., X1N], ..., [XM1, ..., XMN]]
%
:- func lists(array2d(T)) = list(list(T)).
:- mode lists(array2d_ui) = out is det.
:- mode lists(in ) = out is det.
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%
:- implementation.
:- import_module array.
:- import_module require.
% array2d(Rows, Cols, Array)
%
:- type array2d(T) ---> array2d(int, int, array(T)).
%-----------------------------------------------------------------------------%
array2d( [] ) = array2d(0, 0, make_empty_array).
array2d(Xss @ [Xs | _]) = T :-
M = length(Xss),
N = length(Xs),
A = array(condense(Xss)),
T = ( if all [Ys] ( member(Ys, Xss) => length(Ys) = N )
then array2d(M, N, A)
else func_error("array2d.array2d/1: non-rectangular list of lists")
).
from_lists(Xss) = array2d(Xss).
%-----------------------------------------------------------------------------%
new(M, N, X) =
( if M >= 0, N >= 0
then array2d(M, N, array.init(M * N, X))
else func_error("array2d.new: bounds must be non-negative")
).
%-----------------------------------------------------------------------------%
bounds(array2d(M, N, _A), M, N).
%-----------------------------------------------------------------------------%
in_bounds(array2d(M, N, _A), I, J) :-
0 =< I, I < M,
0 =< J, J < N.
%-----------------------------------------------------------------------------%
T ^ elem(I, J) =
( if in_bounds(T, I, J)
then T ^ unsafe_elem(I, J)
else func_error("array2d.elem: indices out of bounds")
).
%-----------------------------------------------------------------------------%
array2d(_M, N, A) ^ unsafe_elem(I, J) = A ^ elem(I * N + J).
%-----------------------------------------------------------------------------%
( T ^ elem(I, J) := X ) =
( if in_bounds(T, I, J)
then T ^ unsafe_elem(I, J) := X
else func_error("array2d.'elem :=': indices out of bounds")
).
set(I, J, X, A, A ^ elem(I, J) := X).
%-----------------------------------------------------------------------------%
( array2d(M, N, A) ^ unsafe_elem(I, J) := X ) =
array2d(M, N, A ^ elem(I * N + J) := X).
unsafe_set(I, J, X, A, A ^ unsafe_elem(I, J) := X).
%-----------------------------------------------------------------------------%
lists(array2d(M, N, A)) = lists_2((M * N) - 1, N - 1, N, A, [], []).
:- func lists_2(int, int, int, array(T), list(T), list(list(T))) =
list(list(T)).
:- mode lists_2(in, in, in, array_ui, in, in ) = out is det.
:- mode lists_2(in, in, in, in, in, in ) = out is det.
lists_2(IJ, J, N, A, Xs, Xss) =
( if 0 =< IJ then
( if 0 =< J
then lists_2(IJ - 1, J - 1, N, A, [A ^ elem(IJ) | Xs], Xss )
else lists_2(IJ, N - 1, N, A, [], [Xs | Xss])
)
else
[Xs | Xss]
).
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%