(refs #7250) Refactoring CHR implementation

[simantics/platform.git] / bundles / org.simantics.scl.runtime / src / org / simantics / scl / runtime / chr / CHRPriorityFactContainer.java

diff --git a/bundles/org.simantics.scl.runtime/src/org/simantics/scl/runtime/chr/CHRPriorityFactContainer.java b/bundles/org.simantics.scl.runtime/src/org/simantics/scl/runtime/chr/CHRPriorityFactContainer.java
new file mode 100644 (file)
index 0000000..bedb8e0
--- /dev/null
+++ b/bundles/org.simantics.scl.runtime/src/org/simantics/scl/runtime/chr/CHRPriorityFactContainer.java
@@ -0,0 +1,59 @@
+package org.simantics.scl.runtime.chr;
+
+import java.util.Arrays;
+
+import org.simantics.scl.runtime.reporting.SCLReporting;
+
+public abstract class CHRPriorityFactContainer extends CHRPriority {
+    private static final boolean CLEANUP_ENABLED = true;
+    private static final int INITIAL_FACT_ARRAY_SIZE = 4;
+    
+    private CHRFact[] facts = new CHRFact[INITIAL_FACT_ARRAY_SIZE];
+    private int size;
+
+    public CHRPriorityFactContainer(int priority) {
+        super(priority);
+    }
+
+    public boolean isEmpty() {
+        return size == 0;
+    }
+
+    public void addFact(CHRContext context, CHRFact item) {
+        //SCLReporting.print("added " + item + " to " + this);
+        ensureInContext(context);
+        if(size == facts.length)
+            increaseCapacity();
+        facts[size++] = item;
+    }
+    
+    private void increaseCapacity() {
+        if(CLEANUP_ENABLED) {
+            // Cleanup dead facts
+            int j=0;
+            for(int i=0;i<size;++i) {
+                CHRFact fact = facts[i];
+                if(fact.id >= 0)
+                    facts[j++] = fact;
+            }
+            size = j;
+        }
+        
+        // Resize if necessary
+        if(size >= facts.length*3/4)
+            facts = Arrays.copyOf(facts, size*2);
+    }
+
+    @Override
+    public void activate(CHRContext context) {
+        while(size > 0) {
+            --size;
+            CHRFact fact = facts[size];
+            facts[size] = null;
+            if(fact.id >= 0)
+                activate(context, fact);
+        }
+    }
+
+    protected abstract void activate(CHRContext context, CHRFact fact);
+}