tests/ctags/maze.erl

   1 -module(maze).
   2 -vsn('2002.0317').
   3 -author('cpressey@catseye.mb.ca').
   4 -copyright('Copyright (c)2002 Cat`s Eye Technologies. All rights reserved.').
   5
   6 %%% Redistribution and use in source and binary forms, with or without
   7 %%% modification, are permitted provided that the following conditions
   8 %%% are met:
   9 %%%
  10 %%%   Redistributions of source code must retain the above copyright
  11 %%%   notice, this list of conditions and the following disclaimer.
  12 %%%
  13 %%%   Redistributions in binary form must reproduce the above copyright
  14 %%%   notice, this list of conditions and the following disclaimer in
  15 %%%   the documentation and/or other materials provided with the
  16 %%%   distribution.
  17 %%%
  18 %%%   Neither the name of Cat's Eye Technologies nor the names of its
  19 %%%   contributors may be used to endorse or promote products derived
  20 %%%   from this software without specific prior written permission.
  21 %%%
  22 %%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  23 %%% CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  24 %%% INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  25 %%% MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  26 %%% DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
  27 %%% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  28 %%% OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  29 %%% PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
  30 %%% OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  31 %%% ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  32 %%% OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33 %%% OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34 %%% POSSIBILITY OF SUCH DAMAGE.
  35
  36 -include("maze.hrl").
  37
  38 -export([build/0, generate/1]).
  39
  40
  41 %%% BEGIN maze.erl %%%
  42
  43 %%% A simple maze-drawing program.
  44
  45 %% Driver function -----------------------------------------------------
  46
  47 build() ->
  48   Tot = generate(#maze{}),
  49   tot_print(Tot).
  50
  51 %% Maze generation function --------------------------------------------
  52
  53 generate(#maze{}=M) ->
  54   seed(),
  55   {X, Y} = {random:uniform(M#maze.width div 2) * 2, random:uniform(M#maze.height div 2) * 2},
  56
  57   R2 = tot_put(X, Y, tot_new(M#maze.width, M#maze.height, M#maze.wall), M#maze.space),
  58   generate(M, R2, X, Y).
  59
  60 generate(#maze{}=M, R, X, Y) ->
  61   lists:foldl(fun({DX, DY}, A) ->
  62                 NX = X + DX * 2, NY = Y + DY * 2,
  63                 W = M#maze.wall,
  64                 case catch tot_get(NX, NY, A) of
  65                    W ->
  66                     M1 = tot_put(X + DX, Y + DY, A, M#maze.space),
  67                     M2 = tot_put(NX, NY, M1, M#maze.space),
  68                     generate(M, M2, NX, NY);
  69                   _ -> A
  70                 end
  71               end, R, scramble([{-1,0}, {1,0}, {0,-1}, {0,1}])).
  72
  73 %%% ToT (Tuple-of-Tuples) Utilities ------------------------------------
  74
  75 tot_new(W, H, Cell) ->
  76   erlang:make_tuple(H, erlang:make_tuple(W, Cell)).
  77
  78 tot_get(X, Y, Tot) ->
  79   element(X, element(Y, Tot)).
  80
  81 tot_put(X, Y, Tot, V) ->
  82   setelement(Y, Tot, setelement(X, element(Y, Tot), V)).
  83
  84 tot_print(ToT) ->
  85   tot_print(1, ToT).
  86 tot_print(Y, ToT) when Y =< size(ToT) ->
  87   tot_print_tuple(element(Y, ToT)),
  88   io:fwrite("~n"),
  89   tot_print(Y+1, ToT);
  90 tot_print(Y, ToT) -> ok.
  91 tot_print_tuple(T) ->
  92   tot_print_tuple(1, T).
  93 tot_print_tuple(X, T) when X =< size(T) ->
  94   io:fwrite("~s", [[element(X, T)]]),
  95   tot_print_tuple(X+1, T);
  96 tot_print_tuple(X, T) -> ok.
  97
  98 %%% Randomness Functions -----------------------------------------------
  99
 100 %% Seed the random number generator so that it will produce unpredictable
 101 %% values.  Should be called once at startup, before using random numbers.
 102
 103 seed() ->
 104   {H,M,S} = time(),
 105   random:seed(S,M,H),
 106   random:uniform(23).  % prime the pump - first number can be iffy
 107
 108 %% Pick a random element from a tuple or a list (equal chance for every
 109 %% element.)
 110
 111 pick(Tuple) when tuple(Tuple) ->
 112   pick(tuple_to_list(Tuple));
 113 pick(List) ->
 114   lists:nth(random:uniform(length(List)), List).
 115
 116 %% Mix up the order (shuffle or scramble) a tuple or list.
 117
 118 scramble(Tuple) when tuple(Tuple) ->
 119   list_to_tuple(scramble(tuple_to_list(Tuple)));
 120 scramble(List) ->
 121   scramble(List, []).
 122 scramble([], Acc) -> Acc;
 123 scramble(List, Acc) ->
 124   S = pick(List),
 125   scramble(List -- [S], Acc ++ [S]).
 126
 127 %%% END of maze.erl %%%