loopwhilecom. now works

Triangle.Compiler/src/main/java/triangle/codeGenerator/Encoder.java

@@ -181,10 +181,28 @@ public final class Encoder implements ActualParameterVisitor<Frame, Integer>,
 		var loopAddr = emitter.getNextInstrAddr();
 		ast.C.visit(this, frame);
 		emitter.patch(jumpAddr);
+		
 		ast.E.visit(this, frame);
 		emitter.emit(OpCode.JUMPIF, Machine.trueRep, Register.CB, loopAddr);
 		return null;
 	}
+	
+	@Override
+	public Void visitLoopWhile(LoopWhile ast, Frame frame) {
+		var loopAddr = emitter.getNextInstrAddr();
+		ast.C1.visit(this, frame); //(LOOP = C1)
+		
+		ast.E.visit(this, frame); //check if the while is false first (WHILE = E)
+		var jumpIfAddr = emitter.emit(OpCode.JUMPIF, Machine.falseRep, Register.CB, 0);
+								  //store this address
+		
+		ast.C2.visit(this, frame); // visit the do section now (DO = C2)
+		emitter.emit(OpCode.JUMP, Machine.trueRep, Register.CB, loopAddr); //jump back to C1
+		
+		emitter.patch(jumpIfAddr); //patch the jmpIfAddr to go back to the while section
+	
+		return null;
+	}
 
 	// Expressions
 	@Override
@@ -794,10 +812,4 @@ public final class Encoder implements ActualParameterVisitor<Frame, Integer>,
 		var baseObject = (AddressableEntity) V.visit(this, frame);
 		baseObject.encodeFetchAddress(emitter, frame, V);
 	}
-
-	@Override
-	public Void visitLoopWhile(LoopWhile loopWhile, Frame arg) {
-		// TODO Auto-generated method stub
-		return null;
-	}
 }

Triangle.Compiler/src/main/java/triangle/optimiser/ConstantFolder.java

@@ -496,6 +496,17 @@ public class ConstantFolder implements ActualParameterVisitor<Void, AbstractSynt
 		}
 		return null;
 	}
+	
+	@Override
+	public AbstractSyntaxTree visitLoopWhile(LoopWhile ast, Void arg) {
+		ast.C1.visit(this);
+		AbstractSyntaxTree replacement = ast.E.visit(this);
+		if (replacement != null) {
+			ast.E = (Expression) replacement;
+		}
+		ast.C2.visit(this);
+		return null;
+	}
 
 	// TODO uncomment if you've implemented the repeat command
 //	@Override
@@ -596,11 +607,4 @@ public class ConstantFolder implements ActualParameterVisitor<Void, AbstractSynt
 		// any unhandled situation (i.e., not foldable) is ignored
 		return null;
 	}
-
-	@Override
-	public AbstractSyntaxTree visitLoopWhile(LoopWhile loopWhile, Void arg) {
-		// TODO Auto-generated method stub
-		return null;
-	}
-
 }

Triangle.Compiler/src/main/java/triangle/syntacticAnalyzer/Parser.java

@@ -386,7 +386,6 @@ public class Parser {
 		case Token.IN:
 		case Token.EOT:
 		case Token.RCURLY:
-
 			finish(commandPos);
 			commandAST = new EmptyCommand(commandPos);
 			break;

Triangle.Compiler/src/main/java/triangle/treeDrawer/LayoutVisitor.java

@@ -169,7 +169,7 @@ public class LayoutVisitor implements ActualParameterVisitor<Void, DrawingTree>,
 		var d1 = ast.C1.visit(this);
 		var d2 = ast.E.visit(this);
 		var d3 = ast.C2.visit(this);
-		return layoutTernary("LoopWhile.", d1, d2, d3);
+		return layoutTernary("LoopWhileCom.", d1, d2, d3);
 	}
 	
 	

Triangle.Compiler/src/test/java/triangle/syntacticAnalyser/TestScanner.java

@@ -53,6 +53,11 @@ public class TestScanner {
 		compileExpectSuccess("/while-curly.tri");
 	}
 	
+	@Test
+	public void testLoopWhileDoCommand() {
+		compileExpectSuccess("/loopwhile.tri");
+	}
+	
 	private void compileExpectSuccess(String filename) {
 		// build.gradle has a line sourceSets.test.resources.srcDir file("$rootDir/programs")
 		// which adds the programs directory to the list of places Java can easily find files