Add @Override annotations and clean up code

src/error/ErrorManager.java

@@ -50,32 +50,41 @@ public class ErrorManager {
     }
 
     public static enum Severity {
+
         WARNING {
 
+            @Override
             public String decorate(String warningOutput, RuntimeEnvironment environment) {
                 return environment.decorateWarningOutput(warningOutput);
             }
 
+            @Override
             public String toDisplayString() {
                 return "warning";
             }
         },
+
         ERROR {
 
+            @Override
             public String decorate(String errorOutput, RuntimeEnvironment environment) {
                 return environment.decorateErrorOutput(errorOutput);
             }
 
+            @Override
             public String toDisplayString() {
                 return "error";
             }
         },
+
         CRITICAL {
 
+            @Override
             public String decorate(String criticalOutput, RuntimeEnvironment environment) {
                 return environment.decorateCriticalOutput(criticalOutput);
             }
 
+            @Override
             public String toDisplayString() {
                 return "critical";
             }

src/function/UserDefinedFunction.java

@@ -81,6 +81,7 @@ public class UserDefinedFunction extends LispFunction {
             argumentValidator.setExactNumberOfArguments(this.formalParameters.size());
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/APPLY.java

@@ -21,6 +21,7 @@ public class APPLY extends LispFunction {
         this.argumentValidator.setTrailingArgumentExpectedType(Cons.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/EVAL.java

@@ -58,6 +58,7 @@ public class EVAL extends LispFunction {
         this.argumentValidator.setExactNumberOfArguments(1);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         SExpression argument = argumentList.getFirst();

src/function/builtin/EXIT.java

@@ -18,6 +18,7 @@ public class EXIT extends LispFunction {
         this.environment = RuntimeEnvironment.getInstance();
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         environment.terminateSuccessfully();

src/function/builtin/FUNCALL.java

@@ -16,6 +16,7 @@ public class FUNCALL extends LispFunction {
         this.argumentValidator.setMinimumNumberOfArguments(1);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         Cons applyArgs = new Cons(argumentList.getFirst(), makeList(argumentList.getRest()));

src/function/builtin/GENSYM.java

@@ -29,6 +29,7 @@ public class GENSYM extends LispFunction {
         this.argumentValidator.setMaximumNumberOfArguments(0);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/LOAD.java

@@ -29,6 +29,7 @@ public class LOAD extends LispFunction {
         this.environment = RuntimeEnvironment.getInstance();
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/PRINT.java

@@ -16,6 +16,7 @@ public class PRINT extends LispFunction {
         this.environment = RuntimeEnvironment.getInstance();
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         SExpression argument = argumentList.getFirst();

src/function/builtin/SET.java

@@ -23,6 +23,7 @@ public class SET extends LispFunction {
         this.executionContext = ExecutionContext.getInstance();
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/SYMBOL_FUNCTION.java

@@ -19,6 +19,7 @@ public class SYMBOL_FUNCTION extends LispFunction {
         this.argumentValidator.setEveryArgumentExpectedType(Symbol.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/cons/CONS.java

@@ -13,6 +13,7 @@ public class CONS extends LispFunction {
         this.argumentValidator.setExactNumberOfArguments(2);
     }
 
+    @Override
     public Cons call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/cons/FIRST.java

@@ -14,6 +14,7 @@ public class FIRST extends LispFunction {
         this.argumentValidator.setEveryArgumentExpectedType(Cons.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         Cons argument = (Cons) argumentList.getFirst();

src/function/builtin/cons/LENGTH.java

@@ -25,6 +25,7 @@ public class LENGTH extends LispFunction {
         this.argumentValidator.setEveryArgumentExpectedType(Cons.class);
     }
 
+    @Override
     public LispNumber call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/cons/LIST.java

@@ -18,6 +18,7 @@ public class LIST extends LispFunction {
         this.argumentValidator = new ArgumentValidator(name);
     }
 
+    @Override
     public Cons call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/cons/REST.java

@@ -14,6 +14,7 @@ public class REST extends LispFunction {
         this.argumentValidator.setEveryArgumentExpectedType(Cons.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         Cons argument = (Cons) argumentList.getFirst();

src/function/builtin/math/DIVIDE.java

@@ -18,6 +18,7 @@ public class DIVIDE extends LispFunction {
         this.mathFunction = new MathFunction(this::getReciprocal, this::divide);
     }
 
+    @Override
     public LispNumber call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/math/MINUS.java

@@ -18,6 +18,7 @@ public class MINUS extends LispFunction {
         this.mathFunction = new MathFunction(this::additiveInverse, this::subtract);
     }
 
+    @Override
     public LispNumber call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/math/MULTIPLY.java

@@ -17,6 +17,7 @@ public class MULTIPLY extends LispFunction {
         this.mathFunction = new MathFunction(number -> number, this::multiply);
     }
 
+    @Override
     public LispNumber call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/math/PLUS.java

@@ -17,6 +17,7 @@ public class PLUS extends LispFunction {
         this.mathFunction = new MathFunction(number -> number, this::add);
     }
 
+    @Override
     public LispNumber call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/predicate/ATOM.java

@@ -16,6 +16,7 @@ public class ATOM extends LispFunction {
         this.argumentValidator.setExactNumberOfArguments(1);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         SExpression argument = argumentList.getFirst();

src/function/builtin/predicate/EQ.java

@@ -16,6 +16,7 @@ public class EQ extends LispFunction {
         this.argumentValidator.setExactNumberOfArguments(2);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/predicate/EQUAL.java

@@ -20,6 +20,7 @@ public class EQUAL extends LispFunction {
         this.argumentValidator.setExactNumberOfArguments(2);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/predicate/LISTP.java

@@ -16,6 +16,7 @@ public class LISTP extends LispFunction {
         this.argumentValidator.setExactNumberOfArguments(1);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/predicate/NULL.java

@@ -16,6 +16,7 @@ public class NULL extends LispFunction {
         this.argumentValidator.setExactNumberOfArguments(1);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/predicate/NUMERIC_EQUAL.java

@@ -17,6 +17,7 @@ public class NUMERIC_EQUAL extends LispFunction {
         this.argumentValidator.setEveryArgumentExpectedType(LispNumber.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/predicate/NUMERIC_GREATER.java

@@ -17,6 +17,7 @@ public class NUMERIC_GREATER extends LispFunction {
         this.argumentValidator.setEveryArgumentExpectedType(LispNumber.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/predicate/NUMERIC_LESS.java

@@ -17,6 +17,7 @@ public class NUMERIC_LESS extends LispFunction {
         this.argumentValidator.setEveryArgumentExpectedType(LispNumber.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/AND.java

@@ -15,6 +15,7 @@ public class AND extends LispSpecialFunction {
         this.argumentValidator = new ArgumentValidator(name);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/CASE.java

@@ -20,6 +20,7 @@ public class CASE extends LispSpecialFunction {
         this.argumentValidator.setTrailingArgumentExcludedType(Nil.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         SExpression key = eval(argumentList.getFirst());

src/function/builtin/special/COND.java

@@ -17,6 +17,7 @@ public class COND extends LispSpecialFunction {
         this.argumentValidator.setEveryArgumentExcludedType(Nil.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/Define.java

@@ -31,6 +31,7 @@ public abstract class Define extends LispSpecialFunction {
         this.environment = RuntimeEnvironment.getInstance();
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/IF.java

@@ -16,6 +16,7 @@ public class IF extends LispSpecialFunction {
         this.argumentValidator.setMaximumNumberOfArguments(3);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/LAMBDA.java

@@ -42,6 +42,7 @@ public class LAMBDA extends LispSpecialFunction {
         this.lambdaListValidator.setEveryArgumentExpectedType(Symbol.class);
     }
 
+    @Override
     public LambdaExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/LET.java

@@ -31,6 +31,7 @@ public class LET extends LispSpecialFunction {
         this.executionContext = ExecutionContext.getInstance();
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
         Cons variableDefinitions = (Cons) argumentList.getFirst();

src/function/builtin/special/LET_STAR.java

@@ -11,6 +11,7 @@ public class LET_STAR extends LET {
         super(name);
     }
 
+    @Override
     protected SymbolTable createLocalScope(Cons variableDefinitions) {
         SymbolTable localScope = new SymbolTable(executionContext.getScope());
         executionContext.setScope(localScope);

src/function/builtin/special/OR.java

@@ -14,6 +14,7 @@ public class OR extends LispSpecialFunction {
         this.argumentValidator = new ArgumentValidator(name);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/PROGN.java

@@ -15,6 +15,7 @@ public class PROGN extends LispSpecialFunction {
         this.argumentValidator = new ArgumentValidator(name);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/QUOTE.java

@@ -13,6 +13,7 @@ public class QUOTE extends LispSpecialFunction {
         this.argumentValidator.setExactNumberOfArguments(1);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/function/builtin/special/SETQ.java

@@ -18,6 +18,7 @@ public class SETQ extends LispSpecialFunction {
         this.argumentValidator.setFirstArgumentExpectedType(Symbol.class);
     }
 
+    @Override
     public SExpression call(Cons argumentList) {
         argumentValidator.validate(argumentList);
 

src/sexpression/AtSignExpression.java

@@ -12,10 +12,12 @@ public class AtSignExpression extends SExpression {
         return expression;
     }
 
+    @Override
     public boolean isAtSign() {
         return true;
     }
 
+    @Override
     public String toString() {
         return "@" + expression;
     }

src/sexpression/Atom.java

@@ -9,10 +9,12 @@ public abstract class Atom extends SExpression {
         this.text = text;
     }
 
+    @Override
     public boolean isAtom() {
         return true;
     }
 
+    @Override
     public String toString() {
         return text;
     }

src/sexpression/BackquoteExpression.java

@@ -12,10 +12,12 @@ public class BackquoteExpression extends SExpression {
         return expression;
     }
 
+    @Override
     public boolean isBackquote() {
         return true;
     }
 
+    @Override
     public String toString() {
         return "`" + expression;
     }

src/sexpression/CommaExpression.java

@@ -12,10 +12,12 @@ public class CommaExpression extends SExpression {
         return expression;
     }
 
+    @Override
     public boolean isComma() {
         return true;
     }
 
+    @Override
     public String toString() {
         return "," + expression;
     }

src/sexpression/Cons.java

@@ -27,10 +27,12 @@ public class Cons extends SExpression {
         this.rest = rest;
     }
 
+    @Override
     public boolean isCons() {
         return true;
     }
 
+    @Override
     public String toString() {
         return ("(" + toStringAux());
     }

src/sexpression/LambdaExpression.java

@@ -13,6 +13,7 @@ public class LambdaExpression extends SExpression {
         this.function = function;
     }
 
+    @Override
     public boolean isFunction() {
         return true;
     }
@@ -25,6 +26,7 @@ public class LambdaExpression extends SExpression {
         return function;
     }
 
+    @Override
     public String toString() {
         return lambdaExpression.toString();
     }

src/sexpression/LispNumber.java

@@ -29,6 +29,7 @@ public class LispNumber extends Atom {
         this.value = value;
     }
 
+    @Override
     public boolean isNumber() {
         return true;
     }

src/sexpression/LispString.java

@@ -7,6 +7,7 @@ public class LispString extends Atom {
         super(text);
     }
 
+    @Override
     public boolean isString() {
         return true;
     }

src/sexpression/Nil.java

@@ -12,18 +12,22 @@ public class Nil extends Cons {
         super.setRest(this);
     }
 
+    @Override
     public boolean isNull() {
         return true;
     }
 
+    @Override
     public boolean isAtom() {
         return true;
     }
 
+    @Override
     public boolean isCons() {
         return false;
     }
 
+    @Override
     public boolean isSymbol() {
         return true;
     }
@@ -31,13 +35,16 @@ public class Nil extends Cons {
     /**
      * The first of NIL can not be changed.
      */
+    @Override
     public void setFirst(SExpression first) {}
 
     /**
      * The rest of NIL can not be changed.
      */
+    @Override
     public void setRest(SExpression rest) {}
 
+    @Override
     public String toString() {
         return "NIL";
     }

src/sexpression/Symbol.java

@@ -13,6 +13,7 @@ public class Symbol extends Atom {
         super(text.toUpperCase());
     }
 
+    @Override
     public boolean isSymbol() {
         return true;
     }

src/token/Eof.java

@@ -25,6 +25,7 @@ public class Eof extends Token {
             super(position);
         }
 
+        @Override
         public String getMessagePrefix() {
             return "end-of-file encountered";
         }

src/token/RightParenthesis.java

@@ -32,6 +32,7 @@ public class RightParenthesis extends Token {
             super(position);
         }
 
+        @Override
         public String getMessagePrefix() {
             return "expression begins with ')'";
         }

src/token/TokenFactoryImpl.java

@@ -7,6 +7,7 @@ import file.FilePosition;
 
 public class TokenFactoryImpl implements TokenFactory {
 
+    @Override
     public Token createToken(String text, FilePosition position) {
         if (text.length() == 0)
             throw new EmptyTokenTextException(position);
@@ -51,6 +52,7 @@ public class TokenFactoryImpl implements TokenFactory {
         return (text.length() > 1) && isDigit(text.charAt(1));
     }
 
+    @Override
     public Token createEofToken(FilePosition position) {
         return new Eof("EOF", position);
     }

test/interpreter/LispInterpreterBuilderTester.java

@@ -13,6 +13,7 @@ public class LispInterpreterBuilderTester {
 
     private LispInterpreterBuilder builder = new LispInterpreterBuilderImpl() {
 
+        @Override
         public void reset() {
             this.isBuilt = false;
         }

test/testutil/TestUtilities.java

@@ -21,6 +21,7 @@ public final class TestUtilities {
     public static InputStream createIOExceptionThrowingInputStream() {
         return new InputStream() {
 
+            @Override
             public int read() throws IOException {
                 throw new IOException("test IOException");
             }