Fixed SharedValueManager to create separate empty instances in anticipation of instances becoming mutable.

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@893057 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/hssf/record/aggregates/RowRecordsAggregate.java

@@ -56,9 +56,12 @@ public final class RowRecordsAggregate extends RecordAggregate {
 
 	/** Creates a new instance of ValueRecordsAggregate */
 	public RowRecordsAggregate() {
-		this(SharedValueManager.EMPTY);
+		this(SharedValueManager.createEmpty());
 	}
 	private RowRecordsAggregate(SharedValueManager svm) {
+		if (svm == null) {
+			throw new IllegalArgumentException("SharedValueManager must be provided.");
+		}
 		_rowRecords = new TreeMap<Integer, RowRecord>();
 		_valuesAgg = new ValueRecordsAggregate();
 		_unknownRecords = new ArrayList<Record>();
@@ -68,6 +71,8 @@ public final class RowRecordsAggregate extends RecordAggregate {
 	/**
 	 * @param rs record stream with all {@link SharedFormulaRecord}
 	 * {@link ArrayRecord}, {@link TableRecord} {@link MergeCellsRecord} Records removed
+	 * @param svm an initialised {@link SharedValueManager} (from the shared formula, array
+	 * and table records of the current sheet).  Never <code>null</code>.
 	 */
 	public RowRecordsAggregate(RecordStream rs, SharedValueManager svm) {
 		this(svm);

src/java/org/apache/poi/hssf/record/aggregates/SharedValueManager.java

@@ -109,8 +109,14 @@ public final class SharedValueManager {
 		}
 	}
 
-	public static final SharedValueManager EMPTY = new SharedValueManager(
+	/**
+	 * @return a new empty {@link SharedValueManager}.
+	 */
+	public static final SharedValueManager createEmpty() {
+		// Note - must create distinct instances because they are assumed to be mutable.
+		return new SharedValueManager(
 			new SharedFormulaRecord[0], new CellReference[0], new ArrayRecord[0], new TableRecord[0]);
+	}
 	private final ArrayRecord[] _arrayRecords;
 	private final TableRecord[] _tableRecords;
 	private final Map<SharedFormulaRecord, SharedFormulaGroup> _groupsBySharedFormulaRecord;
@@ -144,7 +150,7 @@ public final class SharedValueManager {
 	public static SharedValueManager create(SharedFormulaRecord[] sharedFormulaRecords,
 			CellReference[] firstCells, ArrayRecord[] arrayRecords, TableRecord[] tableRecords) {
 		if (sharedFormulaRecords.length + firstCells.length + arrayRecords.length + tableRecords.length < 1) {
-			return EMPTY;
+			return createEmpty();
 		}
 		return new SharedValueManager(sharedFormulaRecords, firstCells, arrayRecords, tableRecords);
 	}

src/testcases/org/apache/poi/hssf/record/aggregates/TestFormulaRecordAggregate.java

@@ -37,7 +37,7 @@ public final class TestFormulaRecordAggregate extends TestCase {
 		f.setCachedResultTypeString();
 		StringRecord s = new StringRecord();
 		s.setString("abc");
-		FormulaRecordAggregate fagg = new FormulaRecordAggregate(f, s, SharedValueManager.EMPTY);
+		FormulaRecordAggregate fagg = new FormulaRecordAggregate(f, s, SharedValueManager.createEmpty());
 		assertEquals("abc", fagg.getStringValue());
 	}
 
@@ -54,7 +54,7 @@ public final class TestFormulaRecordAggregate extends TestCase {
 		fr.setValue(2.0);
 		StringRecord sr = new StringRecord();
 		sr.setString("NA");
-		SharedValueManager svm = SharedValueManager.EMPTY;
+		SharedValueManager svm = SharedValueManager.createEmpty();
 		FormulaRecordAggregate fra;
 
 		try {

src/testcases/org/apache/poi/hssf/record/aggregates/TestRowRecordsAggregate.java

@@ -140,7 +140,7 @@ public final class TestRowRecordsAggregate extends TestCase {
 		RecordStream rs = new RecordStream(Arrays.asList(inRecs), 0);
 		RowRecordsAggregate rra;
 		try {
-			rra = new RowRecordsAggregate(rs, SharedValueManager.EMPTY);
+			rra = new RowRecordsAggregate(rs, SharedValueManager.createEmpty());
 		} catch (RuntimeException e) {
 			if (e.getMessage().startsWith("Unexpected record type")) {
 				throw new AssertionFailedError("Identified bug 46280a");