From a747b382336717478cd77f50bbd55e0a101d05c6 Mon Sep 17 00:00:00 2001
From: Brandon Rozek <brozek@brandonrozek.com>
Date: Mon, 20 Nov 2023 17:20:48 -0500
Subject: [PATCH] Handling edge cases in precondition -> formula

---
 src/main/java/org/rairlab/planner/Action.java | 9 ++++++++-
 src/main/java/org/rairlab/planner/State.java  | 3 +++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/rairlab/planner/Action.java b/src/main/java/org/rairlab/planner/Action.java
index 7d4d0f0..057de89 100644
--- a/src/main/java/org/rairlab/planner/Action.java
+++ b/src/main/java/org/rairlab/planner/Action.java
@@ -49,7 +49,14 @@ public class Action {
 
         this.freeVariables = freeVariables;
 
-        this.precondition = new And(preconditions.stream().collect(Collectors.toList()));
+        if (preconditions.size() > 1) {
+            this.precondition = new And(preconditions.stream().collect(Collectors.toList()));
+        } else if (preconditions.size() == 1) {
+            this.precondition = preconditions.iterator().next();
+        } else {
+            this.precondition = State.TRUE;
+        }
+
 
         this.weight = preconditions.stream().mapToInt(Formula::getWeight).sum() +
                 additions.stream().mapToInt(Formula::getWeight).sum() +
diff --git a/src/main/java/org/rairlab/planner/State.java b/src/main/java/org/rairlab/planner/State.java
index 38de048..cbc9697 100644
--- a/src/main/java/org/rairlab/planner/State.java
+++ b/src/main/java/org/rairlab/planner/State.java
@@ -12,14 +12,17 @@ import java.util.Set;
 public class State {
 
     final Set<Formula> formulae;
+    static Formula TRUE;
     static Formula FALSE;
 
     static{
 
         try {
+            TRUE = Reader.readFormulaFromString("(or P (not P))");
             FALSE = Reader.readFormulaFromString("(and P (not P))");
         } catch (Reader.ParsingException e) {
             e.printStackTrace();
+            TRUE = null;
             FALSE  = null;
         }