Thoughts on new heuristic

src/main/java/org/rairlab/planner/heuristics/DeletePrecondRelax.java

@@ -0,0 +1,66 @@
+package org.rairlab.planner.heuristics;
+
+import org.rairlab.planner.State;
+import org.rairlab.planner.Action;
+import org.rairlab.planner.State;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+/*
+ * IN PROGRESS
+
+ * Heuristic that returns the number of actions
+ * needed to perform to satisfy a goal where
+ * preconditions and deletes of actions are not
+ * taken into account.
+ *
+ * The difficult part here is how do we deal with effect computation?
+ * Since normally free variables are instantiated.
+ * I think in this case, we keep it as free variables.
+ * (Gotta make sure it's fresh and distinct wrt to the other formulae)
+ *
+ * Then for the goal condition check we see if the two
+ * formulas "unify" with each other...
+ */
+public class DeletePrecondRelax {
+
+    private List<Action> actions;
+    private State goal;
+    private Map<State, Integer> cache;
+    private Optional<Integer> bound = Optional.empty();
+
+    public DeletePrecondRelax(List<Action> actions, State goal) {
+        this.actions = actions;
+        this.goal = goal;
+        this.cache = new HashMap<State, Integer>();
+    }
+
+    public int h(State s) {
+        if (cache.containsKey(s)) {
+            return cache.get(s);
+        }
+        int ch = compute_h(s);
+        this.cache.put(s, ch);
+        return ch;
+    }
+
+    // TODO: Fill in...
+    public int compute_h(State s) {
+        return 0;
+    }
+
+    public Optional<Integer> getBound() {
+        return bound;
+    }
+
+    public void setBound(int b) {
+        bound = Optional.of(b);
+    }
+
+    public void clearBound() {
+        bound = Optional.empty();
+    }
+}