Massively simplify this capturing in lambdas

Signed-off-by: TheSilkMiner <thesilkminer@outlook.com>

Author: TheSilkMiner

JavaBytecodeCompiler/src/main/java/org/openzen/zenscript/javabytecode/compiler/JavaExpressionVisitor.java

@@ -498,39 +498,41 @@ public Void visitFunction(FunctionExpression expression) {
 		final JavaClass thisClass = javaWriter.method.class_;
 		final String lambdaName = this.javaMangler.mangleLambdaMethod(javaWriter.method.compiled.name, interfaces[0]);
 		final LambdaClosureInfo closureInfo = LambdaClosureInfo.from(context, expression.closure, thisClass);
-		final String lambdaDescriptor = calcFunctionDescriptor(thisClass, closureInfo, expression.header);
+		final String lambdaDescriptor = calcFunctionDescriptor(closureInfo, expression.header);
 		final JavaNativeMethod lambdaMethod = JavaNativeMethod.getStatic(thisClass, lambdaName, lambdaDescriptor, Opcodes.ACC_PRIVATE | Opcodes.ACC_STATIC);
 		final JavaCompilingMethod lambdaMethodCompiling = JavaMemberVisitor.compileBridgeableMethodNoSideEffect(lambdaMethod, lambdaDescriptor); // TODO("Restore signatures")
 		final JavaWriter lambdaWriter = new JavaWriter(context.logger, expression.position, javaWriter.clazzVisitor, lambdaMethodCompiling, null);
 		final CapturedExpressionVisitor<Void> lambdaCapturesVisitor = new JavaCapturedExpressionVisitorLocalRedirectionVisitor(lambdaWriter, expression, closureInfo);
-		final JavaCompiledModule lambdaModule = new ShiftingJavaCompiledModule(module, closureInfo, context);
-		final JavaExpressionVisitor lambdaExpressionVisitor = new JavaExpressionVisitor(context, lambdaModule, lambdaWriter, javaMangler, lambdaCapturesVisitor);
+		final JavaExpressionVisitor lambdaExpressionVisitor = new JavaExpressionVisitor(context, module, lambdaWriter, javaMangler, lambdaCapturesVisitor);
 		final JavaStatementVisitor lambdaStatementVisitor = new JavaStatementVisitor(context, lambdaExpressionVisitor, javaMangler);
 
 		lambdaWriter.start();
 		expression.body.accept(lambdaStatementVisitor);
 		lambdaWriter.ret();
 		lambdaWriter.end();
 
-		if (java.lang.reflect.Modifier.isStatic(javaWriter.method.compiled.modifiers) || thisClass.kind == JavaClass.Kind.EXPANSION) {
-			javaWriter.aConstNull();
-		} else {
-			javaWriter.loadObject(0);
+		final JavaLoadThisOnIndyCapturedExpressionVisitor thisVisitor = new JavaLoadThisOnIndyCapturedExpressionVisitor(this);
+		final JavaLoadCapturesOnIndyCapturedExpressionVisitor othersVisitor = new JavaLoadCapturesOnIndyCapturedExpressionVisitor(this);
+
+		boolean hasLoadedThis = false;
+		for (final CapturedExpression capture : expression.closure.captures) {
+			// Note: we want this to be |= to ensure NO short-circuiting behavior
+			hasLoadedThis |= capture.accept(thisVisitor);
 		}
 
-		if (closureInfo.isDifferentThis()) {
-			for (final CapturedExpression capture : expression.closure.captures) {
-				capture.accept(new JavaCapturedExpressionVisitorLoadIndyCapturesVisitor(this, true));
-			}
+		// If no this was loaded, then we don't care about its value; just load null
+		if (!hasLoadedThis) {
+			javaWriter.aConstNull();
 		}
+
 		for (final CapturedExpression capture : expression.closure.captures) {
-			capture.accept(new JavaCapturedExpressionVisitorLoadIndyCapturesVisitor(this, false));
+			capture.accept(othersVisitor);
 		}
 
 		// TODO("Have this in JavaWriter")
 		javaWriter.getVisitor().visitInvokeDynamicInsn(
 				methodInfo.name,
-				calcIndyDescriptor(thisClass, closureInfo, interfaces[0]),
+				calcIndyDescriptor(closureInfo, interfaces[0]),
 				new org.objectweb.asm.Handle(
 						Opcodes.H_INVOKESTATIC,
 						Type.getInternalName(org.openzen.zenscript.javart.factory.LambdaFactory.class),
@@ -555,14 +557,14 @@ public Void visitFunction(FunctionExpression expression) {
 						false
 				),
 				Type.getMethodType(JavaMemberVisitor.compileBridgeableMethodNoSideEffect(methodInfo, context.getMethodDescriptor(expression.header)).compiled.descriptor),
-				org.openzen.zenscript.javart.factory.LambdaFactory.FLAG_GENERATE_BRIDGE | (closureInfo.isDifferentThis()? org.openzen.zenscript.javart.factory.LambdaFactory.FLAG_DIFFERENTIATE_RECEIVER : 0),
+				org.openzen.zenscript.javart.factory.LambdaFactory.FLAG_GENERATE_BRIDGE,
 				Type.getMethodType(methodInfo.descriptor)
 		);
 
 		return null;
 	}
 
-	private String calcFunctionDescriptor(final JavaClass thisClass, final LambdaClosureInfo closureInfo, final FunctionHeader header) {
+	private String calcFunctionDescriptor(final LambdaClosureInfo closureInfo, final FunctionHeader header) {
 		final StringJoiner joiner = new StringJoiner("");
 		for (final CapturedExpression capture : closureInfo.closure().captures) {
 			if (!(capture instanceof CapturedThisExpression)) {
@@ -571,19 +573,21 @@ private String calcFunctionDescriptor(final JavaClass thisClass, final LambdaClo
 			}
 		}
 
-		final String thisDescriptor = closureInfo.isDifferentThis()? context.getDescriptor(closureInfo.thisType()) : "";
-
+		// TODO("Remove null check: the method should always return non-null")
+		final String thisType = closureInfo.thisType() == null? "Ljava/lang/Void;" : context.getDescriptor(closureInfo.thisType());
 		final StringBuilder builder = new StringBuilder(context.getMethodDescriptor(header));
-		builder.insert(builder.indexOf("(") + 1, 'L' + thisClass.internalName + ';' + thisDescriptor);
+		builder.insert(builder.indexOf("(") + 1, thisType);
 		builder.insert(builder.lastIndexOf(")"), joiner);
 		return builder.toString();
 	}
 
-	private String calcIndyDescriptor(final JavaClass thisClass, final LambdaClosureInfo closureInfo, final String targetInterface) {
-		final StringBuilder builder = new StringBuilder("(L");
-		builder.append(thisClass.internalName).append(';');
+	private String calcIndyDescriptor(final LambdaClosureInfo closureInfo, final String targetInterface) {
+		final StringBuilder builder = new StringBuilder("(");
 
-		if (closureInfo.isDifferentThis()) {
+		// TODO("Remove null check as this method should never return null")
+		if (closureInfo.thisType() == null) {
+			builder.append("Ljava/lang/Void;");
+		} else {
 			builder.append(context.getDescriptor(closureInfo.thisType()));
 		}
 

JavaBytecodeCompiler/src/main/java/org/openzen/zenscript/javabytecode/compiler/LambdaClosureInfo.java

@@ -3,19 +3,19 @@
 import org.openzen.zenscript.codemodel.expression.LambdaClosure;
 import org.openzen.zenscript.codemodel.expression.captured.CapturedExpression;
 import org.openzen.zenscript.codemodel.expression.captured.CapturedThisExpression;
+import org.openzen.zenscript.codemodel.type.BasicTypeID;
+import org.openzen.zenscript.codemodel.type.OptionalTypeID;
 import org.openzen.zenscript.codemodel.type.TypeID;
 import org.openzen.zenscript.javabytecode.JavaBytecodeContext;
 import org.openzen.zenscript.javashared.JavaClass;
 
 public final class LambdaClosureInfo {
 	private final LambdaClosure closure;
 	private final TypeID thisCapture;
-	private final boolean isDifferent;
 
-	private LambdaClosureInfo(final LambdaClosure closure, final TypeID thisCapture, final boolean isDifferent) {
+	private LambdaClosureInfo(final LambdaClosure closure, final TypeID thisCapture) {
 		this.closure = closure;
 		this.thisCapture = thisCapture;
-		this.isDifferent = isDifferent;
 	}
 
 	static LambdaClosureInfo from(final JavaBytecodeContext context, final LambdaClosure closure, final JavaClass thisClass) {
@@ -27,10 +27,17 @@ static LambdaClosureInfo from(final JavaBytecodeContext context, final LambdaClo
 			}
 		}
 
-		final TypeID thisType = capturedThis == null? null : capturedThis.type;
-		final boolean isDifferent = capturedThis != null && !thisClass.internalName.equals(context.getInternalName(capturedThis.type));
+		final TypeID thisType = computeCapturedThisType(capturedThis);
+		return new LambdaClosureInfo(closure, thisType);
+	}
+
+	private static TypeID computeCapturedThisType(final CapturedThisExpression expression) {
+		if (expression != null) {
+			return expression.type;
+		}
 
-		return new LambdaClosureInfo(closure, thisType, isDifferent);
+		// TODO("Make this default to void")
+		return null;
 	}
 
 	public LambdaClosure closure() {
@@ -40,8 +47,4 @@ public LambdaClosure closure() {
 	public TypeID thisType() {
 		return this.thisCapture;
 	}
-
-	public boolean isDifferentThis() {
-		return this.isDifferent;
-	}
 }

JavaBytecodeCompiler/src/main/java/org/openzen/zenscript/javabytecode/compiler/ShiftingJavaCompiledModule.java

@@ -39,9 +39,9 @@ public JavaCapturedExpressionVisitorLocalRedirectionVisitor(final JavaWriter jav
 
 	@Override
 	public Void visitCapturedThis(final CapturedThisExpression expression) {
-		return this.loadByMemberData(
-				this.closureInfo.isDifferentThis()? new MemberData(1, this.getTypeFrom(this.closureInfo.thisType())) : new MemberData(0, Type.getType(Object.class))
-		);
+		// TODO("Remove null-check as this method should never return null")
+		final Type type = this.closureInfo.thisType() == null? Type.getType(Void.class) : this.getTypeFrom(this.closureInfo.thisType());
+		return this.loadByMemberData(new MemberData(0, type));
 	}
 
 	@Override
@@ -109,11 +109,6 @@ private MemberData calculateMemberData(final FunctionExpression expression, fina
 
 	private int findFirstValidCaptureIndex(final FunctionExpression expression) {
 		int h = 1;
-
-		if (this.closureInfo.isDifferentThis()) {
-			h += this.getTypeFrom(this.closureInfo.thisType()).getSize();
-		}
-
 		for (final FunctionParameter parameter : expression.header.parameters) {
 			h += this.getTypeFrom(parameter.type).getSize();
 		}
@@ -142,6 +137,6 @@ private Type getTypeFrom(final TypeID type) {
 
 		// We don't care about the actual class contained in the type here, we only care that Java treats it as an
 		// object, so we simply grab a random Java class
-		return Type.getType(Object.class);
+		return Type.getType(Void.class);
 	}
 }