Adds support for early step out of macro invocations that expand to s…

…treams.

src/main/java/com/amazon/ion/impl/IonReaderContinuableCoreBinary.java

@@ -2045,11 +2045,18 @@ public Event stepIntoContainer() {
     @Override
     public Event stepOutOfContainer() {
         if (isEvaluatingEExpression) {
-            // TODO step out of the macro evaluator only if it's in a container. Otherwise, finish the evaluation early
-            //  and step out of the parent.
-            macroEvaluatorIonReader.stepOut();
-            event = Event.NEEDS_INSTRUCTION;
-            return event;
+            if (macroEvaluatorIonReader.getDepth() > 0) {
+                // The user has stepped into a container produced by the evaluator. Therefore, this stepOut() call
+                // must step out of that evaluated container.
+                macroEvaluatorIonReader.stepOut();
+                event = Event.NEEDS_INSTRUCTION;
+                return event;
+            } else {
+                // The evaluator is not producing a container value. Therefore, the user intends for this stepOut() call
+                // to step out of the parent container of the e-expression being evaluated. This terminates e-expression
+                // evaluation.
+                isEvaluatingEExpression = false;
+            }
         }
         return super.stepOutOfContainer();
     }

src/test/java/com/amazon/ion/impl/IonReaderContinuableTopLevelBinaryTest.java

@@ -6309,8 +6309,35 @@ public void earlyStepOutDelimitedStructThatContainsMacroInvocationWithTaggedExpr
         closeAndCount();
     }
 
-    // TODO add a test that modifies the above to step out after beginning macro evaluation but before exhausting it.
-    //  This should end evaluation early and step out of the struct.
+    @ParameterizedTest(name = "constructFromBytes={0}")
+    @ValueSource(booleans = {true, false})
+    public void partialEvaluationOfMacroInvocationInDelimitedContainer(boolean constructFromBytes) throws Exception {
+        reader = readerForIon11(bytes(
+                0xF3, // Delimited struct start
+                0xFF, 'a', // FlexSym field name 'a'
+                0x06, 0x02, // Macro invocation 6 (delta), AEB 2 (group)
+                0x0D, // 6-byte expression group
+                0x61, 0x01, // 1
+                0x61, 0x02, // 2
+                0x61, 0x03, // 3
+                0x01, 0xF0, // Delimited struct end
+                0x93, 'a', 'b', 'c'
+            ),
+            constructFromBytes
+        );
+        assertSequence(
+            next(IonType.STRUCT),
+            STEP_IN,
+            next(IonType.INT),
+            bigIntegerValue(BigInteger.ONE),
+            // Step out before exhausting all values produced by the 'delta' invocation.
+            STEP_OUT,
+            next(IonType.STRING),
+            stringValue("abc"),
+            next(null)
+        );
+        closeAndCount();
+    }
 
     @ParameterizedTest(name = "constructFromBytes={0}")
     @ValueSource(booleans = {true, false})
@@ -6452,6 +6479,69 @@ public void fillMultipleNestedDelimitedLists() throws Exception {
         closeAndCount();
     }
 
+    @ParameterizedTest(name = "constructFromBytes={0}")
+    @ValueSource(booleans = {true, false})
+    public void partialEvaluationOfMacroInvocationInPrefixedContainer(boolean constructFromBytes) throws Exception {
+        reader = readerForIon11(bytes(
+                0xB9, // List length 9
+                0x06, 0x02, // Macro invocation 6 (delta), AEB 2 (group)
+                0x0D, // 6-byte expression group
+                0x61, 0x01, // 1
+                0x61, 0x02, // 2
+                0x61, 0x03, // 3
+                0x01, 0x02, // Macro invocation 1 (values), AEB 2 (group)
+                0x09, // 4-byte expression group
+                0x93, 'a', 'b', 'c'
+            ),
+            constructFromBytes
+        );
+        assertSequence(
+            next(IonType.LIST),
+            STEP_IN,
+            next(IonType.INT),
+            bigIntegerValue(BigInteger.ONE),
+            // Step out before exhausting all values produced by the 'delta' invocation.
+            STEP_OUT,
+            next(IonType.STRING),
+            stringValue("abc"),
+            next(null)
+        );
+        closeAndCount();
+    }
+
+    @ParameterizedTest(name = "constructFromBytes={0}")
+    @ValueSource(booleans = {true, false})
+    public void earlyStepOutOfContainerInMacroInvocation(boolean constructFromBytes) throws Exception {
+        reader = readerForIon11(bytes(
+                0x01, 0x02, // Macro invocation 1 (values), AEB 2 (group)
+                0x0F, // 7-byte expression group
+                0xB4, // 4-byte list
+                0x61, 0x01, // 1
+                0x61, 0x02, // 2
+                0x61, 0x03, // 3
+                0x01, 0x02, // Macro invocation 1 (values), AEB 2 (group)
+                0x09, // 4-byte expression group
+                0x93, 'a', 'b', 'c'
+            ),
+            constructFromBytes
+        );
+        assertSequence(
+            next(IonType.LIST),
+            STEP_IN,
+            next(IonType.INT),
+            bigIntegerValue(BigInteger.ONE),
+            // Step out before exhausting all values in the list.
+            STEP_OUT,
+            next(IonType.INT),
+            bigIntegerValue(BigInteger.valueOf(3)),
+            // This ends the 'values' invocation.
+            next(IonType.STRING),
+            stringValue("abc"),
+            next(null)
+        );
+        closeAndCount();
+    }
+
     // TODO test continuable reading and skipping of non-prefixed macro invocations.
     // TODO test skipping macro invocations (especially length-prefixed ones) that expand to system values.
     // TODO Ion 1.1 symbol tables with all kinds of annotation encodings (opcodes E4 - E9, inline and SID)