Sync

src/prolog/builtins/controlOperators.kt

@@ -9,12 +9,14 @@ import prolog.ast.terms.Body
 import prolog.ast.terms.Goal
 import prolog.ast.terms.Structure
 import prolog.flags.AppliedCut
+import prolog.logic.applySubstitution
 
 /**
  * Always fail.
  */
 object Fail : Atom("fail"), Body {
     override fun satisfy(subs: Substitutions): Answers = emptySequence()
+    override fun applySubstitution(subs: Substitutions): Fail = Fail
 }
 
 /**
@@ -27,6 +29,7 @@ typealias False = Fail
  */
 object True : Atom("true"), Body {
     override fun satisfy(subs: Substitutions): Answers = sequenceOf(Result.success(emptyMap()))
+    override fun applySubstitution(subs: Substitutions): True = True
 }
 
 // TODO Repeat/0
@@ -99,8 +102,8 @@ class Conjunction(val left: LogicOperand, private val right: LogicOperand) :
     }
 
     override fun applySubstitution(subs: Substitutions): Conjunction = Conjunction(
-        left.applySubstitution(subs) as LogicOperand,
-        right.applySubstitution(subs) as LogicOperand
+        applySubstitution(left, subs) as LogicOperand,
+        applySubstitution(right, subs) as LogicOperand
     )
 }
 
@@ -114,10 +117,9 @@ open class Disjunction(private val left: LogicOperand, private val right: LogicO
         yieldAll(right.satisfy(subs))
     }
 
-    override fun clone(): Disjunction = Disjunction(left.clone() as LogicOperand, right.clone() as LogicOperand)
     override fun applySubstitution(subs: Substitutions): Disjunction = Disjunction(
-        left.applySubstitution(subs) as LogicOperand,
-        right.applySubstitution(subs) as LogicOperand
+        applySubstitution(left, subs) as LogicOperand,
+        applySubstitution(right, subs) as LogicOperand
     )
 }
 
@@ -141,4 +143,6 @@ class Not(private val goal: Goal) : LogicOperator(Atom("\\+"), rightOperand = go
         // If the goal cannot be proven, return a sequence with an empty map
         return sequenceOf(Result.success(emptyMap()))
     }
+
+    override fun applySubstitution(subs: Substitutions): Not = Not(applySubstitution(goal, subs) as Goal)
 }