Merge branch 'dominicsbranch' into 'main'

Dominicsbranch

See merge request !10

expressions.txt

+1 + x*y^2 - (31 * x)-y
+1 + x^2 - (3 * x)
+2-x + 0.5*x^2 - 1
 (5*2-(5^2)+3*(201.01-15))
\ No newline at end of file

src/ASTPrinter.java

+public class ASTPrinter implements  Visitor<String>{
+    @Override
+    public String visit(final Parser.BinaryOperation binaryOP) {
+        StringBuffer sb = new StringBuffer();
+        if(binaryOP.capsuled) {
+            sb.append("(");
+        }
+        sb.append(binaryOP.leftExpression.accept(this));
+        sb.append(binaryOP.operator);
+        sb.append(binaryOP.rightExpression.accept(this));
+        if(binaryOP.capsuled) {
+            sb.append(")");
+        }
+        return sb.toString();
+    }
+
+    @Override
+    public String visit(Parser.Variable variable) {
+        return variable.variableName;
+    }
+
+    @Override
+    public String visit(Parser.Number number) {
+        return number.digits;
+    }
+
+    @Override
+    public String visit(Parser.Decimal decimal) {
+        return decimal.beforeDot.digits + "." + decimal.afterDot.digits;
+    }
+
+    public String visit(final Parser.Expression ast) {
+        if(ast==null) {
+            throw new RuntimeException("AST is null");
+        }
+        return ast.accept(this);
+    }
+}

src/Application.java

@@ -40,7 +40,8 @@ public class Application {
             Parser parser = new Parser();
             try {
                 Parser.Expression exp = parser.parse(tokens);
-                System.out.println(exp.toString());
+                ASTPrinter printer = new ASTPrinter();
+                System.out.println("Printing: '" + printer.visit(exp) + "'");
             }
             catch (ParserException e) {
                 System.out.println(e.getMessage());

src/Evaluator.java

+public class Evaluator {
+}

src/Parser.java

@@ -3,14 +3,11 @@ import java.util.List;
 
 public class Parser {
 
-    public static class Expression {
-        @Override
-        public String toString() {
-            return "";
-        }
+    public abstract class Expression {
+        public abstract <T> T accept(Visitor<T> visitor);
     }
 
-    private class BinaryOperation extends Expression {
+    public class BinaryOperation extends Expression {
         Expression leftExpression;
         String operator;
         Expression rightExpression;
@@ -21,23 +18,18 @@ public class Parser {
             this.rightExpression = rightExpression;
             this.capsuled = capsuled;
         }
-        @Override
-        public String toString() {
-            if(capsuled) {
-                return "("+ leftExpression.toString() + operator + rightExpression.toString() + ")";
-            }
-            return leftExpression.toString() + operator + rightExpression.toString();
+        public <T> T accept(Visitor<T> visitor) {
+            return visitor.visit(this);
         }
     }
 
-    private class Variable extends Expression {
+    public class Variable extends Expression {
         String variableName;
         public Variable(String i, Boolean capsuled) {
             this.variableName = i;
         }
-        @Override
-        public String toString() {
-            return variableName;
+        public <T> T accept(Visitor<T> visitor) {
+            return visitor.visit(this);
         }
     }
 
@@ -45,18 +37,17 @@ public class Parser {
 
     }
 
-    private class Number extends Value {
+    public class Number extends Value {
         public String digits;
         public Number(String i) {
             this.digits = i;
         }
-        @Override
-        public String toString() {
-            return digits;
+        public <T> T accept(Visitor<T> visitor) {
+            return visitor.visit(this);
         }
     }
 
-    private class Decimal extends Value {
+    public class Decimal extends Value {
         public Number beforeDot;
         public Number afterDot;
 
@@ -64,9 +55,8 @@ public class Parser {
             this.beforeDot = i1;
             this.afterDot = i2;
         }
-        @Override
-        public String toString() {
-            return beforeDot.toString() + "." + afterDot.toString();
+        public <T> T accept(Visitor<T> visitor) {
+            return visitor.visit(this);
         }
     }
 

src/Visitor.java

+public interface Visitor<T>{
+    public T visit(final Parser.BinaryOperation binOp);
+    public T visit(final Parser.Variable variable);
+    public T visit(final Parser.Number number);
+    public T visit(final Parser.Decimal decimal);
+}

to-do.txt

+2. Testklassen
+
+3. Visitor pattern
+4. plot function
+5. Überarbeiten
+-> Dokumentation
+-> Exceptions
+-> Kommentare
+-> Code strukturieren
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