refactoring

Author: fxnn

src/main/java/de/fxnn/brainfuck/interpreter/TddBrainfuckInstructionSet.java

@@ -0,0 +1,44 @@
+package de.fxnn.brainfuck.interpreter.tdd;
+
+import de.fxnn.brainfuck.interpreter.InterpreterException;
+import de.fxnn.brainfuck.interpreter.tdd.MostRecentLabel.Known;
+import de.fxnn.brainfuck.interpreter.tdd.MostRecentLabel.NoneYet;
+import de.fxnn.brainfuck.interpreter.tdd.MostRecentLabel.StartOfLabelKnown;
+import de.fxnn.brainfuck.program.InstructionPointer;
+
+class LabelMachine {
+
+  private MostRecentLabel mostRecentLabel = new MostRecentLabel.NoneYet();
+
+  String getLabelName() {
+    return ((Known) mostRecentLabel).name();
+  }
+
+  void startOfTest(InstructionPointer instructionPointer) throws InterpreterException {
+    switch (mostRecentLabel) {
+      case NoneYet ignored ->
+          throw new InterpreterException("'{' without preceding '#' instruction");
+      case StartOfLabelKnown l -> {
+        var name = extractName(l.startPointer(), instructionPointer);
+        mostRecentLabel = new Known(name, l.startPointer());
+      }
+      case Known ignored -> {
+        // nothing to do
+      }
+    }
+  }
+
+  void startOfLabel(InstructionPointer instructionPointer) {
+    mostRecentLabel = new StartOfLabelKnown(instructionPointer);
+  }
+
+  private String extractName(InstructionPointer start, InstructionPointer max) {
+    var nameBuilder = new StringBuilder();
+    var current = start;
+    while (nameBuilder.length() < 20 && !current.equals(max)) {
+      nameBuilder.append(current.getInstruction());
+      current = current.forward();
+    }
+    return nameBuilder.toString();
+  }
+}

src/main/java/de/fxnn/brainfuck/interpreter/tdd/LabelMachine.java

@@ -1,4 +1,4 @@
-package de.fxnn.brainfuck.interpreter;
+package de.fxnn.brainfuck.interpreter.tdd;
 
 import de.fxnn.brainfuck.program.InstructionPointer;
 

src/main/java/de/fxnn/brainfuck/interpreter/MostRecentLabel.java renamed to src/main/java/de/fxnn/brainfuck/interpreter/tdd/MostRecentLabel.java

@@ -0,0 +1,43 @@
+package de.fxnn.brainfuck.interpreter.tdd;
+
+import de.fxnn.brainfuck.interpreter.InstructionSet;
+import de.fxnn.brainfuck.interpreter.InterpreterException;
+import de.fxnn.brainfuck.program.InstructionPointer;
+import java.io.PrintWriter;
+
+class TddBrainfuckInstructionSet implements InstructionSet {
+
+  private final PrintWriter output;
+  private final LabelMachine labelMachine = new LabelMachine();
+  private boolean withinTest = false;
+  private InstructionPointer lastInstructionPointer;
+
+  public TddBrainfuckInstructionSet(PrintWriter output) {
+    this.output = output;
+  }
+
+  public InstructionPointer step(InstructionPointer instructionPointer)
+      throws InterpreterException {
+    switch (instructionPointer.getInstruction()) {
+      case '#' -> {
+        if (lastInstructionPointer == null || lastInstructionPointer.getInstruction() != '#') {
+          labelMachine.startOfLabel(instructionPointer);
+        }
+      }
+      case '{' -> {
+        labelMachine.startOfTest(instructionPointer);
+        withinTest = true;
+      }
+      case '}' -> {
+        if (!withinTest) {
+          throw new InterpreterException("'}' without preceding '{' instruction");
+        }
+        withinTest = false;
+        output.println("PASSED " + labelMachine.getLabelName());
+      }
+    }
+    lastInstructionPointer = instructionPointer;
+    return instructionPointer.forward();
+  }
+
+}

src/main/java/de/fxnn/brainfuck/interpreter/tdd/TddBrainfuckInstructionSet.java

@@ -1,11 +1,13 @@
-package de.fxnn.brainfuck.interpreter;
+package de.fxnn.brainfuck.interpreter.tdd;
 
+import de.fxnn.brainfuck.interpreter.InterpreterException;
 import de.fxnn.brainfuck.program.InstructionPointer;
 import de.fxnn.brainfuck.program.StringInstructionPointer;
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import org.junit.Assert;
 import org.junit.Before;
+import org.junit.Ignore;
 import org.junit.Test;
 
 public class TddBrainfuckInstructionSetTest {
@@ -49,7 +51,7 @@ public void step__endOfTestWithoutBeginOfTest__throws() {
   }
 
   @Test
-  public void step__labelBeginEnd__passes() throws InterpreterException {
+  public void step__labelBeginEnd__passed() throws InterpreterException {
     var underTest = createUnderTest();
     stepUntilEndOfProgram(underTest, "#{}");
     Assert.assertEquals("PASSED #\n", output.toString());
@@ -77,6 +79,14 @@ public void step__labelBeginEnd__forward() throws InterpreterException {
     Assert.assertTrue(result.isEndOfProgram());
   }
 
+  @Ignore
+  @Test
+  public void step__tapeOutputDiffersFromInput__failed() throws InterpreterException {
+    var underTest = createUnderTest();
+    stepUntilEndOfProgram(underTest, "#{0~1}");
+    Assert.assertEquals("FAILED #\n", output.toString());
+  }
+
   private void stepUntilEndOfProgram(TddBrainfuckInstructionSet underTest,
       String stringProgram) throws InterpreterException {
     InstructionPointer instructionPointer = new StringInstructionPointer(stringProgram, 0);