doc/classes/Game.src/M000022.html

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   8   <title>apply_move (Game)</title>
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  13   <pre><span class="ruby-comment cmt"># File lib/libttc.rb, line 341</span>
  14   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">apply_move</span>(<span class="ruby-identifier">move</span>, <span class="ruby-identifier">player</span> = <span class="ruby-ivar">@current_player</span>)
  15     <span class="ruby-comment cmt"># Check the move is a valid one</span>
  16     <span class="ruby-identifier">raise</span>(<span class="ruby-constant">InvalidMoveError</span>, <span class="ruby-node">&quot;Piece #{move.piece} does not exist&quot;</span>) <span class="ruby-keyword kw">unless</span> <span class="ruby-ivar">@pieces</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">name</span>)
  17     <span class="ruby-identifier">raise</span>(<span class="ruby-constant">InvalidMoveError</span>, <span class="ruby-node">&quot;Player #{player} moving piece #{move.piece}&quot;</span>) <span class="ruby-keyword kw">unless</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">colour</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">player</span>
  18     <span class="ruby-identifier">raise</span>(<span class="ruby-constant">InvalidMoveError</span>, <span class="ruby-node">&quot;Attempting to move captured piece #{move.piece}&quot;</span>) <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">captured</span>
  19     <span class="ruby-identifier">raise</span>(<span class="ruby-constant">InvalidMoveError</span>, <span class="ruby-node">&quot;Attempting to move #{move.piece} onto or via base without captured pieces&quot;</span>) <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">via_base?</span> <span class="ruby-keyword kw">and</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">contains</span>.<span class="ruby-identifier">empty?</span>
  20     <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">destination</span>.<span class="ruby-identifier">safe?</span>
  21       <span class="ruby-keyword kw">if</span> (<span class="ruby-ivar">@pieces</span>.<span class="ruby-identifier">find_all</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>, <span class="ruby-identifier">p</span><span class="ruby-operator">|</span> <span class="ruby-identifier">p</span>.<span class="ruby-identifier">position</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">destination</span>}).<span class="ruby-identifier">length</span> <span class="ruby-operator">&gt;=</span> <span class="ruby-value">3</span>
  22         <span class="ruby-identifier">raise</span>(<span class="ruby-constant">InvalidMoveError</span>, <span class="ruby-node">&quot;Attempting to move #{move.piece} onto safe position #{move.destination} when there are already three or more pieces there&quot;</span>)
  23       <span class="ruby-keyword kw">end</span>
  24     <span class="ruby-keyword kw">end</span>
  25     <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">via_base?</span>
  26       <span class="ruby-identifier">moved_distance</span> = <span class="ruby-identifier">board</span>.<span class="ruby-identifier">distance_between</span>[<span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">position</span>.<span class="ruby-identifier">place</span>][<span class="ruby-identifier">player</span>] <span class="ruby-operator">+</span>
  27         <span class="ruby-identifier">board</span>.<span class="ruby-identifier">distance_between</span>[<span class="ruby-identifier">player</span>][<span class="ruby-identifier">move</span>.<span class="ruby-identifier">destination</span>.<span class="ruby-identifier">place</span>]
  28     <span class="ruby-keyword kw">else</span>
  29       <span class="ruby-identifier">moved_distance</span> = <span class="ruby-identifier">board</span>.<span class="ruby-identifier">distance_between</span>[<span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">position</span>.<span class="ruby-identifier">place</span>][<span class="ruby-identifier">move</span>.<span class="ruby-identifier">destination</span>.<span class="ruby-identifier">place</span>]
  30     <span class="ruby-keyword kw">end</span>
  31     <span class="ruby-identifier">raise</span>(<span class="ruby-constant">InvalidMoveError</span>, <span class="ruby-node">&quot;Attempting to move piece #{move.piece} #{moved_distance} places&quot;</span>) <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">moved_distance</span> <span class="ruby-operator">&lt;</span> <span class="ruby-value">1</span> <span class="ruby-keyword kw">or</span> <span class="ruby-identifier">moved_distance</span> <span class="ruby-operator">&gt;</span> <span class="ruby-value">6</span>
  32
  33     <span class="ruby-comment cmt"># Apply this move</span>
  34     <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">move_to</span>(<span class="ruby-identifier">move</span>.<span class="ruby-identifier">destination</span>)
  35
  36     <span class="ruby-comment cmt"># Capture anything already there (unless it's a safe place or a base, or our own colour)</span>
  37     <span class="ruby-keyword kw">unless</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">destination</span>.<span class="ruby-identifier">safe?</span> <span class="ruby-keyword kw">or</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">destination</span>.<span class="ruby-identifier">base?</span>
  38       <span class="ruby-ivar">@pieces</span>.<span class="ruby-identifier">each</span> <span class="ruby-keyword kw">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">name</span>, <span class="ruby-identifier">target_piece</span><span class="ruby-operator">|</span>
  39         <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">target_piece</span>.<span class="ruby-identifier">position</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">destination</span> <span class="ruby-keyword kw">and</span>
  40             <span class="ruby-identifier">target_piece</span> <span class="ruby-operator">!=</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span> <span class="ruby-keyword kw">and</span>
  41             <span class="ruby-keyword kw">not</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">contains</span>.<span class="ruby-identifier">member?</span>(<span class="ruby-identifier">target_piece</span>) <span class="ruby-keyword kw">and</span>
  42             <span class="ruby-identifier">target_piece</span>.<span class="ruby-identifier">colour</span> <span class="ruby-operator">!=</span> <span class="ruby-identifier">player</span>
  43           <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">capture</span>(<span class="ruby-identifier">target_piece</span>)
  44         <span class="ruby-keyword kw">end</span>
  45       <span class="ruby-keyword kw">end</span>
  46     <span class="ruby-keyword kw">end</span>
  47
  48     <span class="ruby-comment cmt"># If the move was via our base, drop all captured pieces</span>
  49     <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">via_base?</span>
  50       <span class="ruby-identifier">capturers_base</span> = <span class="ruby-identifier">board</span>.<span class="ruby-identifier">positions</span>[<span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">colour</span>]
  51       <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">contains</span>.<span class="ruby-identifier">each</span> <span class="ruby-keyword kw">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">captured_piece</span><span class="ruby-operator">|</span>
  52         <span class="ruby-identifier">captured_piece</span>.<span class="ruby-identifier">move_to</span> <span class="ruby-identifier">capturers_base</span>
  53         <span class="ruby-identifier">captured_piece</span>.<span class="ruby-identifier">captured</span> = <span class="ruby-keyword kw">false</span> <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">captured_piece</span>.<span class="ruby-identifier">colour</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">colour</span>
  54       <span class="ruby-keyword kw">end</span>
  55       <span class="ruby-identifier">move</span>.<span class="ruby-identifier">piece</span>.<span class="ruby-identifier">contains</span> = []
  56     <span class="ruby-keyword kw">end</span>
  57
  58     <span class="ruby-comment cmt"># Record the new stae</span>
  59     <span class="ruby-identifier">this_game_state</span> = <span class="ruby-constant">GameState</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">move</span>, <span class="ruby-identifier">player</span>, <span class="ruby-ivar">@pieces</span>)
  60     <span class="ruby-ivar">@history</span> <span class="ruby-operator">&lt;&lt;</span> <span class="ruby-identifier">this_game_state</span>
  61
  62     <span class="ruby-comment cmt"># If there's only one player with uncaptured pieces, declare a win</span>
  63     <span class="ruby-identifier">potential_players</span> = []
  64     <span class="ruby-ivar">@players</span>.<span class="ruby-identifier">each</span> <span class="ruby-keyword kw">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">p</span><span class="ruby-operator">|</span>
  65       <span class="ruby-identifier">potential_players</span> <span class="ruby-operator">&lt;&lt;</span> <span class="ruby-identifier">p</span> <span class="ruby-keyword kw">if</span> (<span class="ruby-ivar">@pieces</span>.<span class="ruby-identifier">values</span>.<span class="ruby-identifier">select</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">p</span><span class="ruby-operator">|</span> <span class="ruby-identifier">p</span>.<span class="ruby-identifier">colour</span> <span class="ruby-operator">==</span> <span class="ruby-ivar">@current_player</span>}).<span class="ruby-identifier">any?</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">p</span><span class="ruby-operator">|</span> <span class="ruby-keyword kw">not</span> <span class="ruby-identifier">p</span>.<span class="ruby-identifier">captured</span>}
  66     <span class="ruby-keyword kw">end</span>
  67     <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">potential_players</span>.<span class="ruby-identifier">length</span> <span class="ruby-operator">&lt;=</span> <span class="ruby-value">1</span>
  68       <span class="ruby-identifier">raise</span>(<span class="ruby-constant">GameWonNotice</span>, <span class="ruby-node">&quot;Game won by #{potential_players[0]}&quot;</span>)
  69     <span class="ruby-keyword kw">end</span>
  70   <span class="ruby-keyword kw">end</span></pre>
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