Code clean (no functionality changes) (#31)

* Address code warnings

* Update to java 21 (LTS)

* Remove package-info.java in test area (conflict with main)

* Rename visitor members to avoid name hiding

Author: afs

README.md

@@ -20,8 +20,8 @@ subdirectory.
 
 # Requirements
 
-* Java 8+
-* Maven (v3.6.3 is known to work); not necessary for running the pre-built JAR
+* Java 21+
+* Maven (v3.9.9 is known to work); not necessary for running the pre-built JAR
 
 # Setup
 

pom.xml

@@ -34,8 +34,8 @@
 
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-		<maven.compiler.source>1.8</maven.compiler.source>
-		<maven.compiler.target>1.8</maven.compiler.target>
+		<maven.compiler.source>21</maven.compiler.source>
+		<maven.compiler.target>21</maven.compiler.target>
 	</properties>
 
 	<dependencies>

src/main/java/edu/harvard/seas/pl/abcdatalog/ast/PositiveAtom.java

@@ -127,6 +127,7 @@ public Substitution unify(PositiveAtom fact) {
    * @param subst the substitution
    * @return a new atom with the substitution applied
    */
+  @Override
   public PositiveAtom applySubst(Substitution subst) {
     return create(this.pred, subst.apply(this.args));
   }

src/main/java/edu/harvard/seas/pl/abcdatalog/ast/validation/DatalogValidationException.java

@@ -33,7 +33,6 @@
  * #L%
  */
 
-@SuppressWarnings("serial")
 public class DatalogValidationException extends Exception {
 
   public DatalogValidationException() {}

src/main/java/edu/harvard/seas/pl/abcdatalog/ast/validation/DatalogValidator.java

@@ -262,18 +262,22 @@ public Program(
       this.idbPredicateSymbols = idbPredicateSymbols;
     }
 
+    @Override
     public Set<ValidClause> getRules() {
       return this.rules;
     }
 
+    @Override
     public Set<PositiveAtom> getInitialFacts() {
       return this.initialFacts;
     }
 
+    @Override
     public Set<PredicateSym> getEdbPredicateSyms() {
       return this.edbPredicateSymbols;
     }
 
+    @Override
     public Set<PredicateSym> getIdbPredicateSyms() {
       return this.idbPredicateSymbols;
     }

src/main/java/edu/harvard/seas/pl/abcdatalog/ast/visitors/HeadVisitorBuilder.java

@@ -61,18 +61,18 @@ public HeadVisitor<I, O> orCrash() {
   }
 
   private class Visitor implements HeadVisitor<I, O> {
-    private final BiFunction<PositiveAtom, I, O> onPositiveAtom;
+    private final BiFunction<PositiveAtom, I, O> _onPositiveAtom;
     private final BiFunction<Head, I, O> otherwise;
 
     public Visitor(BiFunction<Head, I, O> otherwise) {
-      this.onPositiveAtom = HeadVisitorBuilder.this.onPositiveAtom;
+      this._onPositiveAtom = HeadVisitorBuilder.this.onPositiveAtom;
       this.otherwise = otherwise;
     }
 
     @Override
     public O visit(PositiveAtom atom, I state) {
-      if (this.onPositiveAtom != null) {
-        return this.onPositiveAtom.apply(atom, state);
+      if (this._onPositiveAtom != null) {
+        return this._onPositiveAtom.apply(atom, state);
       }
       return this.otherwise.apply(atom, state);
     }

src/main/java/edu/harvard/seas/pl/abcdatalog/ast/visitors/PremiseVisitorBuilder.java

@@ -92,58 +92,58 @@ public PremiseVisitor<I, O> orNull() {
   }
 
   private class Visitor implements PremiseVisitor<I, O> {
-    private final BiFunction<PositiveAtom, I, O> onPositiveAtom;
-    private final BiFunction<NegatedAtom, I, O> onNegatedAtom;
-    private final BiFunction<BinaryUnifier, I, O> onBinaryUnifier;
-    private final BiFunction<BinaryDisunifier, I, O> onBinaryDisunifier;
-    private BiFunction<AnnotatedAtom, I, O> onAnnotatedAtom;
+    private final BiFunction<PositiveAtom, I, O> _onPositiveAtom;
+    private final BiFunction<NegatedAtom, I, O> _onNegatedAtom;
+    private final BiFunction<BinaryUnifier, I, O> _onBinaryUnifier;
+    private final BiFunction<BinaryDisunifier, I, O> _onBinaryDisunifier;
+    private BiFunction<AnnotatedAtom, I, O> _onAnnotatedAtom;
     private final BiFunction<Premise, I, O> otherwise;
 
     public Visitor(BiFunction<Premise, I, O> otherwise) {
-      this.onPositiveAtom = PremiseVisitorBuilder.this.onPositiveAtom;
-      this.onNegatedAtom = PremiseVisitorBuilder.this.onNegatedAtom;
-      this.onBinaryUnifier = PremiseVisitorBuilder.this.onBinaryUnifier;
-      this.onBinaryDisunifier = PremiseVisitorBuilder.this.onBinaryDisunifier;
-      this.onAnnotatedAtom = PremiseVisitorBuilder.this.onAnnotatedAtom;
+      this._onPositiveAtom = PremiseVisitorBuilder.this.onPositiveAtom;
+      this._onNegatedAtom = PremiseVisitorBuilder.this.onNegatedAtom;
+      this._onBinaryUnifier = PremiseVisitorBuilder.this.onBinaryUnifier;
+      this._onBinaryDisunifier = PremiseVisitorBuilder.this.onBinaryDisunifier;
+      this._onAnnotatedAtom = PremiseVisitorBuilder.this.onAnnotatedAtom;
       this.otherwise = otherwise;
     }
 
     @Override
     public O visit(PositiveAtom atom, I state) {
-      if (this.onPositiveAtom != null) {
-        return this.onPositiveAtom.apply(atom, state);
+      if (this._onPositiveAtom != null) {
+        return this._onPositiveAtom.apply(atom, state);
       }
       return this.otherwise.apply(atom, state);
     }
 
     @Override
     public O visit(BinaryUnifier u, I state) {
-      if (this.onBinaryUnifier != null) {
-        return this.onBinaryUnifier.apply(u, state);
+      if (this._onBinaryUnifier != null) {
+        return this._onBinaryUnifier.apply(u, state);
       }
       return this.otherwise.apply(u, state);
     }
 
     @Override
     public O visit(BinaryDisunifier u, I state) {
-      if (this.onBinaryDisunifier != null) {
-        return this.onBinaryDisunifier.apply(u, state);
+      if (this._onBinaryDisunifier != null) {
+        return this._onBinaryDisunifier.apply(u, state);
       }
       return this.otherwise.apply(u, state);
     }
 
     @Override
     public O visit(NegatedAtom atom, I state) {
-      if (this.onNegatedAtom != null) {
-        return this.onNegatedAtom.apply(atom, state);
+      if (this._onNegatedAtom != null) {
+        return this._onNegatedAtom.apply(atom, state);
       }
       return this.otherwise.apply(atom, state);
     }
 
     @Override
     public O visit(AnnotatedAtom atom, I state) {
-      if (this.onAnnotatedAtom != null) {
-        return this.onAnnotatedAtom.apply(atom, state);
+      if (this._onAnnotatedAtom != null) {
+        return this._onAnnotatedAtom.apply(atom, state);
       }
       return this.otherwise.apply(atom, state);
     }

src/main/java/edu/harvard/seas/pl/abcdatalog/ast/visitors/TermVisitorBuilder.java

@@ -68,28 +68,28 @@ public TermVisitor<I, O> orCrash() {
   }
 
   private class Visitor implements TermVisitor<I, O> {
-    private final BiFunction<Variable, I, O> onVariable;
-    private final BiFunction<Constant, I, O> onConstant;
+    private final BiFunction<Variable, I, O> _onVariable;
+    private final BiFunction<Constant, I, O> _onConstant;
     private final BiFunction<Term, I, O> otherwise;
 
     public Visitor(BiFunction<Term, I, O> otherwise) {
-      this.onVariable = TermVisitorBuilder.this.onVariable;
-      this.onConstant = TermVisitorBuilder.this.onConstant;
+      this._onVariable = TermVisitorBuilder.this.onVariable;
+      this._onConstant = TermVisitorBuilder.this.onConstant;
       this.otherwise = otherwise;
     }
 
     @Override
     public O visit(Variable t, I state) {
-      if (onVariable != null) {
-        return onVariable.apply(t, state);
+      if (_onVariable != null) {
+        return _onVariable.apply(t, state);
       }
       return otherwise.apply(t, state);
     }
 
     @Override
     public O visit(Constant t, I state) {
-      if (onConstant != null) {
-        return onConstant.apply(t, state);
+      if (_onConstant != null) {
+        return _onConstant.apply(t, state);
       }
       return otherwise.apply(t, state);
     }

src/main/java/edu/harvard/seas/pl/abcdatalog/gui/DatalogGui.java

@@ -67,7 +67,6 @@
 import javax.swing.undo.UndoManager;
 
 /** A GUI with a Datalog editor and interpreter. */
-@SuppressWarnings("serial")
 public class DatalogGui extends JFrame {
   private final TextEditor program;
   private final JTextArea results;

src/main/java/edu/harvard/seas/pl/abcdatalog/gui/TextEditor.java

@@ -38,7 +38,6 @@
 import javax.swing.JTextArea;
 import javax.swing.text.BadLocationException;
 
-@SuppressWarnings("serial")
 public class TextEditor extends JTextArea {
   TextEditor(int rows, int columns) {
     this.setRows(rows);