Checkpoint

src/prolog/ast/Database.kt

@@ -0,0 +1,76 @@
+package prolog.ast
+
+import io.Logger
+import prolog.Program
+import prolog.Answers
+import prolog.Substitutions
+import prolog.ast.logic.Clause
+import prolog.ast.logic.Predicate
+import prolog.ast.logic.Resolvent
+import prolog.ast.terms.Functor
+import prolog.ast.terms.Goal
+
+/**
+ * Prolog Program or Database
+ */
+class Database(val sourceFile: String): Resolvent {
+    private var predicates: Map<Functor, Predicate> = emptyMap()
+
+    fun initialize() {
+        Logger.info("Initializing database from $sourceFile")
+        if (predicates.contains("/_")) {
+            Logger.debug("Loading clauses from /_ predicate")
+            predicates["/_"]?.clauses?.forEach {
+                Logger.debug("Loading clause $it")
+                val goal = it.body as Goal
+                goal.satisfy(emptyMap()).toList()
+            }
+        }
+    }
+
+    override fun solve(goal: Goal, subs: Substitutions): Answers {
+        val functor = goal.functor
+        // If the predicate does not exist, return false
+        val predicate = predicates[functor] ?: return emptySequence()
+        // If the predicate exists, evaluate the goal against it
+        return predicate.solve(goal, subs)
+    }
+
+    /**
+     * Loads a list of clauses into the program.
+     */
+    fun load(clauses: List<Clause>) {
+        for (clause in clauses) {
+            val functor = clause.functor
+            val predicate = predicates[functor]
+
+            if (predicate != null) {
+                // If the predicate already exists, add the clause to it
+                predicate.add(clause)
+            } else {
+                // If the predicate does not exist, create a new one
+                predicates += Pair(functor, Predicate(listOf(clause)))
+            }
+
+            Logger.debug("Loaded clause $clause into predicate $functor")
+        }
+    }
+
+    fun load(predicate: Predicate) {
+        val functor = predicate.functor
+        val existingPredicate = predicates[functor]
+
+        if (existingPredicate != null) {
+            // If the predicate already exists, add the clauses to it
+            existingPredicate.addAll(predicate.clauses)
+        } else {
+            // If the predicate does not exist, create a new one
+            predicates += Pair(functor, predicate)
+        }
+    }
+
+    fun clear() {
+        Logger.debug("Clearing ${this::class.java.simpleName}")
+        predicates = emptyMap()
+    }
+}