implement pretty print visitor

src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java

@@ -0,0 +1,134 @@
+package de.hsrm.compiler.Klang.visitors;
+
+import java.io.*;
+import de.hsrm.compiler.Klang.nodes.Block;
+import de.hsrm.compiler.Klang.nodes.expressions.AdditiveExpression;
+import de.hsrm.compiler.Klang.nodes.expressions.IntegerExpression;
+import de.hsrm.compiler.Klang.nodes.expressions.ModuloExpression;
+import de.hsrm.compiler.Klang.nodes.expressions.MultiplicativeExpression;
+import de.hsrm.compiler.Klang.nodes.expressions.NegateExpression;
+import de.hsrm.compiler.Klang.nodes.statements.IfStatement;
+import de.hsrm.compiler.Klang.nodes.statements.PrintStatement;
+import de.hsrm.compiler.Klang.nodes.statements.Statement;;
+
+public class PrettyPrintVisitor implements Visitor<Void> {
+
+    public static class ExWriter {
+        Writer w;
+        String indent = "";
+
+        void addIndent() {
+            indent = indent + "  ";
+        }
+
+        void subIndent() {
+            indent = indent.substring(2);
+        }
+
+        void nl() {
+            write("\n" + indent);
+        }
+
+        int lbl = 0;
+
+        int next() {
+            return lbl++;
+        }
+
+        public ExWriter(Writer w) {
+            this.w = w;
+        }
+
+        void lnwrite(Object o) {
+            nl();
+            write(o);
+        }
+
+        void write(Object o) {
+            try {
+                w.write(o + "");
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        }
+    }
+
+    public ExWriter ex;
+
+    public PrettyPrintVisitor(ExWriter ex) {
+        this.ex = ex;
+    }
+
+    @Override
+    public Void visit(IntegerExpression e) {
+        ex.write(e.value);
+        return null;
+    }
+
+    @Override
+    public Void visit(MultiplicativeExpression e) {
+        e.lhs.welcome(this);
+        ex.write(" * ");
+        e.rhs.welcome(this);
+        return null;
+    }
+
+    @Override
+    public Void visit(AdditiveExpression e) {
+        e.lhs.welcome(this);
+        ex.write(" + ");
+        e.rhs.welcome(this);
+        return null;
+    }
+
+    @Override
+    public Void visit(NegateExpression e) {
+        ex.write(" - ");
+        e.lhs.welcome(this);
+        return null;
+    }
+
+    @Override
+    public Void visit(ModuloExpression e) {
+        e.lhs.welcome(this);
+        ex.write(" % ");
+        e.rhs.welcome(this);
+        return null;
+    }
+
+    @Override
+    public Void visit(IfStatement e) {
+        ex.write("if (");
+        e.cond.welcome(this);
+        ex.write(") ");
+        e.then.welcome(this);
+        if (e.alt != null) {
+            ex.write(" else ");
+            e.alt.welcome(this);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visit(PrintStatement e) {
+        ex.write("print ");
+        e.expression.welcome(this);
+        ex.write(";");
+        return null;
+    }
+
+    @Override
+    public Void visit(Block e) {
+        ex.write("{");
+        ex.addIndent();
+        for (Statement stmt : e.statements) {
+            ex.nl();
+            stmt.welcome(this);
+        }
+        ex.subIndent();
+        ex.nl();
+        ex.write("}");
+        return null;
+    }
+
+}