bundles/org.simantics.scl.runtime/src/org/simantics/scl/runtime/chr/FactActivationQueue.java

   1 package org.simantics.scl.runtime.chr;\r
   2 \r
   3 import java.util.Arrays;\r
   4 \r
   5 public class FactActivationQueue {\r
   6     public static final boolean TRACE = false;\r
   7     \r
   8     private final PriorityContainer[] containers;\r
   9     private PriorityContainer[] activeContainers = new PriorityContainer[8];\r
  10     private int activeContainerCount; \r
  11 \r
  12     public FactActivationQueue(int priorityCount) {\r
  13         if(TRACE)\r
  14             System.out.println("priorityCount = " + priorityCount);\r
  15         containers = new PriorityContainer[priorityCount];\r
  16         for(int i=0;i<priorityCount;++i)\r
  17             containers[i] = new PriorityContainer(i); \r
  18     }\r
  19     \r
  20     /**\r
  21      * Adds a new fact with a given priority\r
  22      */\r
  23     public void add(int priority, Fact item) {\r
  24         if(TRACE)\r
  25             System.out.println("FactActivationQueue.add " + priority + "@" + item);\r
  26         PriorityContainer container = containers[priority];\r
  27         if(container.size == 0)\r
  28             activateContainer(container);\r
  29         container.push(item);\r
  30     }\r
  31     \r
  32     private void activateContainer(PriorityContainer container) {\r
  33         if(TRACE)\r
  34             System.out.println("FactActivationQueue.activate priority " + container.priority);\r
  35         if(activeContainers.length == activeContainerCount)\r
  36             activeContainers = Arrays.copyOf(activeContainers, activeContainerCount*2);\r
  37         adjustUpwards(activeContainerCount, container);\r
  38         ++activeContainerCount;\r
  39     }\r
  40 \r
  41     private void deactivateContainer() {\r
  42         --activeContainerCount;\r
  43         adjustDownwards(0, activeContainers[activeContainerCount]);\r
  44         activeContainers[activeContainerCount] = null;\r
  45     }\r
  46 \r
  47     private void adjustDownwards(int pos, PriorityContainer item) {\r
  48         int priority = item.priority;\r
  49         while(true) {\r
  50             int npos = 2*pos+1;\r
  51             if(npos+1 >= activeContainerCount) {\r
  52                 if(npos >= activeContainerCount)\r
  53                     break;\r
  54                 PriorityContainer item1 = activeContainers[npos];\r
  55                 if(priority > item1.priority) {\r
  56                     activeContainers[pos] = item1;\r
  57                     activeContainers[npos] = item;\r
  58                     return;\r
  59                 }\r
  60                 else\r
  61                     break;\r
  62             }\r
  63             PriorityContainer item1 = activeContainers[npos];\r
  64             PriorityContainer item2 = activeContainers[npos+1];\r
  65             if(priority < item1.priority) {\r
  66                 if(priority < item2.priority)\r
  67                     break;\r
  68             }\r
  69             else {\r
  70                 if(item1.priority < item2.priority) {\r
  71                     activeContainers[pos] = item1;\r
  72                     pos = npos;\r
  73                     continue;\r
  74                 }\r
  75             }\r
  76             activeContainers[pos] = item2;\r
  77             pos = npos+1;\r
  78         }\r
  79         activeContainers[pos] = item;\r
  80     }\r
  81 \r
  82     private void adjustUpwards(int pos, PriorityContainer item) {\r
  83         int priority = item.priority;\r
  84         while(pos > 0) {\r
  85             int npos = (pos-1)/2;\r
  86             PriorityContainer item1 = activeContainers[npos];\r
  87             if(item1.priority > priority) {\r
  88                 activeContainers[pos] = item1;\r
  89                 pos = npos;\r
  90             }\r
  91             else\r
  92                 break;\r
  93         }\r
  94         activeContainers[pos] = item;\r
  95     }\r
  96     \r
  97     /**\r
  98      * Activates all facts with priority less than the current priority\r
  99      */\r
 100     public void activate(Object context, int currentPriority) {\r
 101         if(TRACE)\r
 102             System.out.println("FactActivationQueue.activate " + currentPriority);\r
 103         while(activeContainerCount > 0) {\r
 104             PriorityContainer topContainer = activeContainers[0];\r
 105             int priority = topContainer.priority;\r
 106             if(priority >= currentPriority)\r
 107                 return;\r
 108             \r
 109             Fact fact = topContainer.pop();\r
 110             if(topContainer.size == 0)\r
 111                 deactivateContainer();\r
 112             \r
 113             int newPriority = fact.activate(context, priority);\r
 114             if(TRACE)\r
 115                 System.out.println("    [" + currentPriority + "] " + fact + " oldPriority=" + priority + ", newPriority=" + newPriority);\r
 116             if(newPriority >= 0)\r
 117                 add(newPriority, fact);\r
 118         }\r
 119     }\r
 120 }\r