Урок 13. Шаблон проектирования «Посетитель»

src/com/annimon/ownlang/Main.java

@@ -4,6 +4,9 @@ import com.annimon.ownlang.parser.Lexer;
 import com.annimon.ownlang.parser.Parser;
 import com.annimon.ownlang.parser.Token;
 import com.annimon.ownlang.parser.ast.Statement;
+import com.annimon.ownlang.parser.visitors.AssignValidator;
+import com.annimon.ownlang.parser.visitors.FunctionAdder;
+import com.annimon.ownlang.parser.visitors.VariablePrinter;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
@@ -15,7 +18,7 @@ import java.util.List;
 public final class Main {
 
     public static void main(String[] args) throws IOException {
-        final String input = new String( Files.readAllBytes(Paths.get("program.own")), "UTF-8");
+        final String input = new String( Files.readAllBytes(Paths.get("visitor.own")), "UTF-8");
         final List<Token> tokens = new Lexer(input).tokenize();
         for (Token token : tokens) {
             System.out.println(token);
@@ -23,6 +26,9 @@ public final class Main {
         
         final Statement program = new Parser(tokens).parse();
         System.out.println(program.toString());
+        program.accept(new FunctionAdder());
+        program.accept(new VariablePrinter());
+        program.accept(new AssignValidator());
         program.execute();
     }
 }

src/com/annimon/ownlang/parser/ast/ArrayAccessExpression.java

@@ -11,8 +11,8 @@ import java.util.List;
  */
 public final class ArrayAccessExpression implements Expression {
     
-    private final String variable;
+    public final String variable;
-    private final List<Expression> indices;
+    public final List<Expression> indices;
 
     public ArrayAccessExpression(String variable, List<Expression> indices) {
         this.variable = variable;
@@ -48,6 +48,11 @@ public final class ArrayAccessExpression implements Expression {
             throw new RuntimeException("Array expected");
         }
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/ArrayAssignmentStatement.java

@@ -6,8 +6,8 @@ package com.annimon.ownlang.parser.ast;
  */
 public final class ArrayAssignmentStatement implements Statement {
     
-    private final ArrayAccessExpression array;
+    public final ArrayAccessExpression array;
-    private final Expression expression;
+    public final Expression expression;
 
     public ArrayAssignmentStatement(ArrayAccessExpression array, Expression expression) {
         this.array = array;
@@ -18,6 +18,11 @@ public final class ArrayAssignmentStatement implements Statement {
     public void execute() {
         array.getArray().set(array.lastIndex(), expression.eval());
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/ArrayExpression.java

@@ -10,7 +10,7 @@ import java.util.List;
  */
 public final class ArrayExpression implements Expression {
     
-    private final List<Expression> elements;
+    public final List<Expression> elements;
 
     public ArrayExpression(List<Expression> arguments) {
         this.elements = arguments;
@@ -25,6 +25,11 @@ public final class ArrayExpression implements Expression {
         }
         return array;
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/AssignmentStatement.java

@@ -9,8 +9,8 @@ import com.annimon.ownlang.lib.Variables;
  */
 public final class AssignmentStatement implements Statement {
 
-    private final String variable;
+    public final String variable;
-    private final Expression expression;
+    public final Expression expression;
 
     public AssignmentStatement(String variable, Expression expression) {
         this.variable = variable;
@@ -22,6 +22,11 @@ public final class AssignmentStatement implements Statement {
         final Value result = expression.eval();
         Variables.set(variable, result);
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/BinaryExpression.java

@@ -11,8 +11,8 @@ import com.annimon.ownlang.lib.Value;
  */
 public final class BinaryExpression implements Expression {
     
-    private final Expression expr1, expr2;
+    public final Expression expr1, expr2;
-    private final char operation;
+    public final char operation;
 
     public BinaryExpression(char operation, Expression expr1, Expression expr2) {
         this.operation = operation;
@@ -52,6 +52,11 @@ public final class BinaryExpression implements Expression {
                 return new NumberValue(number1 + number2);
         }
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/BlockStatement.java

@@ -9,7 +9,7 @@ import java.util.List;
  */
 public final class BlockStatement implements Statement {
     
-    private final List<Statement> statements;
+    public final List<Statement> statements;
 
     public BlockStatement() {
         statements = new ArrayList<>();
@@ -25,6 +25,11 @@ public final class BlockStatement implements Statement {
             statement.execute();
         }
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/BreakStatement.java

@@ -10,6 +10,11 @@ public final class BreakStatement extends RuntimeException implements Statement
     public void execute() {
         throw this;
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/ConditionalExpression.java

@@ -38,8 +38,8 @@ public final class ConditionalExpression implements Expression {
         }
     }
     
-    private final Expression expr1, expr2;
+    public final Expression expr1, expr2;
-    private final Operator operation;
+    public final Operator operation;
 
     public ConditionalExpression(Operator operation, Expression expr1, Expression expr2) {
         this.operation = operation;
@@ -78,6 +78,11 @@ public final class ConditionalExpression implements Expression {
         }
         return new NumberValue(result);
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/ContinueStatement.java

@@ -10,6 +10,11 @@ public final class ContinueStatement extends RuntimeException implements Stateme
     public void execute() {
         throw this;
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/DoWhileStatement.java

@@ -6,8 +6,8 @@ package com.annimon.ownlang.parser.ast;
  */
 public final class DoWhileStatement implements Statement {
     
-    private final Expression condition;
+    public final Expression condition;
-    private final Statement statement;
+    public final Statement statement;
 
     public DoWhileStatement(Expression condition, Statement statement) {
         this.condition = condition;
@@ -27,6 +27,11 @@ public final class DoWhileStatement implements Statement {
         }
         while (condition.eval().asNumber() != 0);
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/Expression.java

@@ -6,7 +6,7 @@ import com.annimon.ownlang.lib.Value;
  *
  * @author aNNiMON
  */
-public interface Expression {
+public interface Expression extends Node {
     
     Value eval();
 }

src/com/annimon/ownlang/parser/ast/ForStatement.java

@@ -6,10 +6,10 @@ package com.annimon.ownlang.parser.ast;
  */
 public final class ForStatement implements Statement {
     
-    private final Statement initialization;
+    public final Statement initialization;
-    private final Expression termination;
+    public final Expression termination;
-    private final Statement increment;
+    public final Statement increment;
-    private final Statement statement;
+    public final Statement statement;
 
     public ForStatement(Statement initialization, Expression termination, Statement increment, Statement block) {
         this.initialization = initialization;
@@ -30,6 +30,11 @@ public final class ForStatement implements Statement {
             }
         }
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/FunctionDefineStatement.java

@@ -10,9 +10,9 @@ import java.util.List;
  */
 public final class FunctionDefineStatement implements Statement {
     
-    private final String name;
+    public final String name;
-    private final List<String> argNames;
+    public final List<String> argNames;
-    private final Statement body;
+    public final Statement body;
     
     public FunctionDefineStatement(String name, List<String> argNames, Statement body) {
         this.name = name;
@@ -24,6 +24,11 @@ public final class FunctionDefineStatement implements Statement {
     public void execute() {
         Functions.set(name, new UserDefinedFunction(argNames, body));
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/FunctionStatement.java

@@ -6,7 +6,7 @@ package com.annimon.ownlang.parser.ast;
  */
 public final class FunctionStatement implements Statement {
     
-    private final FunctionalExpression function;
+    public final FunctionalExpression function;
     
     public FunctionStatement(FunctionalExpression function) {
         this.function = function;
@@ -16,6 +16,11 @@ public final class FunctionStatement implements Statement {
     public void execute() {
         function.eval();
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/FunctionalExpression.java

@@ -14,8 +14,8 @@ import java.util.List;
  */
 public final class FunctionalExpression implements Expression {
     
-    private final String name;
+    public final String name;
-    private final List<Expression> arguments;
+    public final List<Expression> arguments;
     
     public FunctionalExpression(String name) {
         this.name = name;
@@ -30,7 +30,7 @@ public final class FunctionalExpression implements Expression {
     public void addArgument(Expression arg) {
         arguments.add(arg);
     }
-
+    
     @Override
     public Value eval() {
         final int size = arguments.size();
@@ -54,6 +54,11 @@ public final class FunctionalExpression implements Expression {
         }
         return function.execute(values);
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/IfStatement.java

@@ -6,8 +6,8 @@ package com.annimon.ownlang.parser.ast;
  */
 public final class IfStatement implements Statement {
     
-    private final Expression expression;
+    public final Expression expression;
-    private final Statement ifStatement, elseStatement;
+    public final Statement ifStatement, elseStatement;
 
     public IfStatement(Expression expression, Statement ifStatement, Statement elseStatement) {
         this.expression = expression;
@@ -24,6 +24,11 @@ public final class IfStatement implements Statement {
             elseStatement.execute();
         }
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/Node.java

@@ -0,0 +1,10 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public interface Node {
+    
+    void accept(Visitor visitor);
+}

src/com/annimon/ownlang/parser/ast/PrintStatement.java

@@ -6,7 +6,7 @@ package com.annimon.ownlang.parser.ast;
  */
 public final class PrintStatement implements Statement {
     
-    private final Expression expression;
+    public final Expression expression;
 
     public PrintStatement(Expression expression) {
         this.expression = expression;
@@ -16,6 +16,11 @@ public final class PrintStatement implements Statement {
     public void execute() {
         System.out.print(expression.eval());
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/ReturnStatement.java

@@ -8,7 +8,7 @@ import com.annimon.ownlang.lib.Value;
  */
 public final class ReturnStatement extends RuntimeException implements Statement {
 
-    private final Expression expression;
+    public final Expression expression;
     private Value result;
     
     public ReturnStatement(Expression expression) {
@@ -24,6 +24,11 @@ public final class ReturnStatement extends RuntimeException implements Statement
         result = expression.eval();
         throw this;
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/Statement.java

@@ -4,7 +4,7 @@ package com.annimon.ownlang.parser.ast;
  *
  * @author aNNiMON
  */
-public interface Statement {
+public interface Statement extends Node {
     
     void execute();
 }

src/com/annimon/ownlang/parser/ast/UnaryExpression.java

@@ -9,14 +9,14 @@ import com.annimon.ownlang.lib.Value;
  */
 public final class UnaryExpression implements Expression {
     
-    private final Expression expr1;
+    public final Expression expr1;
-    private final char operation;
+    public final char operation;
 
     public UnaryExpression(char operation, Expression expr1) {
         this.operation = operation;
         this.expr1 = expr1;
     }
-
+    
     @Override
     public Value eval() {
         switch (operation) {
@@ -27,6 +27,11 @@ public final class UnaryExpression implements Expression {
         }
     }
     
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
+    
     @Override
     public String toString() {
         return String.format("%c %s", operation, expr1);

src/com/annimon/ownlang/parser/ast/ValueExpression.java

@@ -10,7 +10,7 @@ import com.annimon.ownlang.lib.Value;
  */
 public final class ValueExpression implements Expression {
     
-    private final Value value;
+    public final Value value;
     
     public ValueExpression(double value) {
         this.value = new NumberValue(value);
@@ -24,6 +24,11 @@ public final class ValueExpression implements Expression {
     public Value eval() {
         return value;
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/VariableExpression.java

@@ -9,7 +9,7 @@ import com.annimon.ownlang.lib.Variables;
  */
 public final class VariableExpression implements Expression {
     
-    private final String name;
+    public final String name;
     
     public VariableExpression(String name) {
         this.name = name;
@@ -20,6 +20,11 @@ public final class VariableExpression implements Expression {
         if (!Variables.isExists(name)) throw new RuntimeException("Variable does not exists");
         return Variables.get(name);
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/ast/Visitor.java

@@ -0,0 +1,30 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public interface Visitor {
+    
+    void visit(ArrayAccessExpression s);
+    void visit(ArrayAssignmentStatement s);
+    void visit(ArrayExpression s);
+    void visit(AssignmentStatement s);
+    void visit(BinaryExpression s);
+    void visit(BlockStatement s);
+    void visit(BreakStatement s);
+    void visit(ConditionalExpression s);
+    void visit(ContinueStatement s);
+    void visit(DoWhileStatement s);
+    void visit(ForStatement s);
+    void visit(FunctionDefineStatement s);
+    void visit(FunctionStatement s);
+    void visit(FunctionalExpression s);
+    void visit(IfStatement s);
+    void visit(PrintStatement s);
+    void visit(ReturnStatement s);
+    void visit(UnaryExpression s);
+    void visit(ValueExpression s);
+    void visit(VariableExpression s);
+    void visit(WhileStatement st);
+}

src/com/annimon/ownlang/parser/ast/WhileStatement.java

@@ -6,8 +6,8 @@ package com.annimon.ownlang.parser.ast;
  */
 public final class WhileStatement implements Statement {
     
-    private final Expression condition;
+    public final Expression condition;
-    private final Statement statement;
+    public final Statement statement;
 
     public WhileStatement(Expression condition, Statement statement) {
         this.condition = condition;
@@ -26,6 +26,11 @@ public final class WhileStatement implements Statement {
             }
         }
     }
+    
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
 
     @Override
     public String toString() {

src/com/annimon/ownlang/parser/visitors/AbstractVisitor.java

@@ -0,0 +1,132 @@
+package com.annimon.ownlang.parser.visitors;
+
+import com.annimon.ownlang.parser.ast.*;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public abstract class AbstractVisitor implements Visitor {
+
+    @Override
+    public void visit(ArrayAccessExpression s) {
+        for (Expression index : s.indices) {
+            index.accept(this);
+        }
+    }
+
+    @Override
+    public void visit(ArrayAssignmentStatement s) {
+        s.array.accept(this);
+        s.expression.accept(this);
+    }
+
+    @Override
+    public void visit(ArrayExpression s) {
+        for (Expression index : s.elements) {
+            index.accept(this);
+        }
+    }
+
+    @Override
+    public void visit(AssignmentStatement s) {
+        s.expression.accept(this);
+    }
+
+    @Override
+    public void visit(BinaryExpression s) {
+        s.expr1.accept(this);
+        s.expr2.accept(this);
+    }
+
+    @Override
+    public void visit(BlockStatement s) {
+        for (Statement statement : s.statements) {
+            statement.accept(this);
+        }
+    }
+
+    @Override
+    public void visit(BreakStatement s) {
+    }
+
+    @Override
+    public void visit(ConditionalExpression s) {
+        s.expr1.accept(this);
+        s.expr2.accept(this);
+    }
+
+    @Override
+    public void visit(ContinueStatement s) {
+    }
+
+    @Override
+    public void visit(DoWhileStatement s) {
+        s.condition.accept(this);
+        s.statement.accept(this);
+    }
+
+    @Override
+    public void visit(ForStatement s) {
+        s.initialization.accept(this);
+        s.termination.accept(this);
+        s.increment.accept(this);
+        s.statement.accept(this);
+    }
+
+    @Override
+    public void visit(FunctionDefineStatement s) {
+        s.body.accept(this);
+    }
+
+    @Override
+    public void visit(FunctionStatement s) {
+        s.function.accept(this);
+    }
+
+    @Override
+    public void visit(FunctionalExpression s) {
+        for (Expression argument : s.arguments) {
+            argument.accept(this);
+        }
+    }
+
+    @Override
+    public void visit(IfStatement s) {
+        s.expression.accept(this);
+        s.ifStatement.accept(this);
+        if (s.elseStatement != null) {
+            s.elseStatement.accept(this);
+        }
+    }
+
+    @Override
+    public void visit(PrintStatement s) {
+        s.expression.accept(this);
+    }
+
+    @Override
+    public void visit(ReturnStatement s) {
+        s.expression.accept(this);
+    }
+
+    @Override
+    public void visit(UnaryExpression s) {
+        s.expr1.accept(this);
+    }
+
+    @Override
+    public void visit(ValueExpression s) {
+    }
+
+    @Override
+    public void visit(VariableExpression s) {
+    }
+
+    @Override
+    public void visit(WhileStatement st) {
+        st.condition.accept(this);
+        st.statement.accept(this);
+    }
+
+}

src/com/annimon/ownlang/parser/visitors/AssignValidator.java

@@ -0,0 +1,19 @@
+package com.annimon.ownlang.parser.visitors;
+
+import com.annimon.ownlang.lib.Variables;
+import com.annimon.ownlang.parser.ast.*;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class AssignValidator extends AbstractVisitor {
+
+    @Override
+    public void visit(AssignmentStatement s) {
+        super.visit(s);
+        if (Variables.isExists(s.variable)) {
+            throw new RuntimeException("Cannot assign value to constant");
+        }
+    }
+}

src/com/annimon/ownlang/parser/visitors/FunctionAdder.java

@@ -0,0 +1,16 @@
+package com.annimon.ownlang.parser.visitors;
+
+import com.annimon.ownlang.parser.ast.*;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class FunctionAdder extends AbstractVisitor {
+
+    @Override
+    public void visit(FunctionDefineStatement s) {
+        super.visit(s);
+        s.execute();
+    }
+}

src/com/annimon/ownlang/parser/visitors/VariablePrinter.java

@@ -0,0 +1,28 @@
+package com.annimon.ownlang.parser.visitors;
+
+import com.annimon.ownlang.parser.ast.*;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class VariablePrinter extends AbstractVisitor {
+
+    @Override
+    public void visit(ArrayAccessExpression s) {
+        super.visit(s);
+        System.out.println(s.variable);
+    }
+    
+    @Override
+    public void visit(AssignmentStatement s) {
+        super.visit(s);
+        System.out.println(s.variable);
+    }
+
+    @Override
+    public void visit(VariableExpression s) {
+        super.visit(s);
+        System.out.println(s.name);
+    }
+}

visitor.own

@@ -0,0 +1,5 @@
+func()
+def func() print "function\n"
+
+a = 2 + 3 * 4
+print a