{@code
+ * guardWithCatch=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L,a6:L,a7:L)=>{
+ * t8:L=MethodHandle.invokeBasic(a4:L,a6:L,a7:L);
+ * t9:L=MethodHandleImpl.guardWithCatch(a1:L,a2:L,a3:L,t8:L);
+ * t10:I=MethodHandle.invokeBasic(a5:L,t9:L);t10:I}
+ * }
+ *
+ * It is compiled into bytecode equivalent of the following code:
+ * {@code
+ * try {
+ * return a1.invokeBasic(a6, a7);
+ * } catch (Throwable e) {
+ * if (!a2.isInstance(e)) throw e;
+ * return a3.invokeBasic(ex, a6, a7);
+ * }}
+ */
+ private void emitGuardWithCatch(int pos) {
+ Name args = lambdaForm.names[pos];
+ Name invoker = lambdaForm.names[pos+1];
+ Name result = lambdaForm.names[pos+2];
+
+ Label L_startBlock = new Label();
+ Label L_endBlock = new Label();
+ Label L_handler = new Label();
+ Label L_done = new Label();
+
+ Class returnType = result.function.resolvedHandle.type().returnType();
+ MethodType type = args.function.resolvedHandle.type()
+ .dropParameterTypes(0,1)
+ .changeReturnType(returnType);
+
+ mv.visitTryCatchBlock(L_startBlock, L_endBlock, L_handler, "java/lang/Throwable");
+
+ // Normal case
+ mv.visitLabel(L_startBlock);
+ // load target
+ emitPushArgument(invoker, 0);
+ emitPushArguments(args, 1); // skip 1st argument: method handle
+ mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
+ mv.visitLabel(L_endBlock);
+ mv.visitJumpInsn(Opcodes.GOTO, L_done);
+
+ // Exceptional case
+ mv.visitLabel(L_handler);
+
+ // Check exception's type
+ mv.visitInsn(Opcodes.DUP);
+ // load exception class
+ emitPushArgument(invoker, 1);
+ mv.visitInsn(Opcodes.SWAP);
+ mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Class", "isInstance", "(Ljava/lang/Object;)Z", false);
+ Label L_rethrow = new Label();
+ mv.visitJumpInsn(Opcodes.IFEQ, L_rethrow);
+
+ // Invoke catcher
+ // load catcher
+ emitPushArgument(invoker, 2);
+ mv.visitInsn(Opcodes.SWAP);
+ emitPushArguments(args, 1); // skip 1st argument: method handle
+ MethodType catcherType = type.insertParameterTypes(0, Throwable.class);
+ mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", catcherType.basicType().toMethodDescriptorString(), false);
+ mv.visitJumpInsn(Opcodes.GOTO, L_done);
+
+ mv.visitLabel(L_rethrow);
+ mv.visitInsn(Opcodes.ATHROW);
+
+ mv.visitLabel(L_done);
+ }
+
+ private void emitPushArguments(Name args, int start) {
+ for (int i = start; i < args.arguments.length; i++) {
+ emitPushArgument(args, i);
+ }
+ }
+
private void emitPushArgument(Name name, int paramIndex) {
Object arg = name.arguments[paramIndex];
char ptype = name.function.parameterType(paramIndex);