Minor code improvements, fixed comments

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@723146 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 39 insertions, 15 deletions

diff --git a/src/java/org/apache/poi/ss/formula/Formula.java b/src/java/org/apache/poi/ss/formula/Formula.java
index eaf73cd637..f2cef2cb42 100644
--- a/src/java/org/apache/poi/ss/formula/Formula.java
+++ b/src/java/org/apache/poi/ss/formula/Formula.java
@@ -1,3 +1,20 @@
+/* ====================================================================

+   Licensed to the Apache Software Foundation (ASF) under one or more

+   contributor license agreements.  See the NOTICE file distributed with

+   this work for additional information regarding copyright ownership.

+   The ASF licenses this file to You under the Apache License, Version 2.0

+   (the "License"); you may not use this file except in compliance with

+   the License.  You may obtain a copy of the License at

+

+       http://www.apache.org/licenses/LICENSE-2.0

+

+   Unless required by applicable law or agreed to in writing, software

+   distributed under the License is distributed on an "AS IS" BASIS,

+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

+   See the License for the specific language governing permissions and

+   limitations under the License.

+==================================================================== */

+

 package org.apache.poi.ss.formula;

 

 import java.util.Arrays;

@@ -14,9 +31,16 @@ import org.apache.poi.util.LittleEndianByteArrayInputStream;
 import org.apache.poi.util.LittleEndianInput;

 import org.apache.poi.util.LittleEndianOutput;

 

+/**

+ * Encapsulates an encoded formula token array. 

+ * 

+ * @author Josh Micich

+ */

 public class Formula {

 

-	private static final byte[] EMPTY_BYTE_ARRAY = { };

+	private static final Formula EMPTY = new Formula(new byte[0], 0);

+

+	/** immutable */

 	private final byte[] _byteEncoding;

 	private final int _encodedTokenLen;

 	

@@ -24,17 +48,17 @@ public class Formula {
 		_byteEncoding = byteEncoding;

 		_encodedTokenLen = encodedTokenLen;

 		if (false) { // set to true to eagerly check Ptg decoding 

-    		LittleEndianByteArrayInputStream in = new LittleEndianByteArrayInputStream(byteEncoding);

-    		Ptg.readTokens(encodedTokenLen, in);

-    		int nUnusedBytes = _byteEncoding.length - in.getReadIndex();

-    		if (nUnusedBytes > 0) {

-    			// TODO - this seems to occur when IntersectionPtg is present

-        		// This example file "IntersectionPtg.xls"

-        		// used by test: TestIntersectionPtg.testReading()

-        		// has 10 bytes unused at the end of the formula

-    			// 10 extra bytes are just 0x01 and 0x00

-    			System.out.println(nUnusedBytes + " unused bytes at end of formula");

-    		}

+			LittleEndianByteArrayInputStream in = new LittleEndianByteArrayInputStream(byteEncoding);

+			Ptg.readTokens(encodedTokenLen, in);

+			int nUnusedBytes = _byteEncoding.length - in.getReadIndex();

+			if (nUnusedBytes > 0) {

+				// TODO - this seems to occur when IntersectionPtg is present

+				// This example file "IntersectionPtg.xls"

+				// used by test: TestIntersectionPtg.testReading()

+				// has 10 bytes unused at the end of the formula

+				// 10 extra bytes are just 0x01 and 0x00

+				System.out.println(nUnusedBytes + " unused bytes at end of formula");

+			}

 		}

 	}

 	/**

@@ -112,8 +136,8 @@ public class Formula {
 	 * @return Never <code>null</code> (Possibly empty if the supplied <tt>ptgs</tt> is <code>null</code>)

 	 */

 	public static Formula create(Ptg[] ptgs) {

-		if (ptgs == null) {

-			return new Formula(EMPTY_BYTE_ARRAY, 0);

+		if (ptgs == null || ptgs.length < 1) {

+			return EMPTY;

 		}

 		int totalSize = Ptg.getEncodedSize(ptgs);

 		byte[] encodedData = new byte[totalSize];

@@ -136,7 +160,7 @@ public class Formula {
 	}

 	

 	public Formula copy() {

-		// OK to return this for the moment because currently immutable

+		// OK to return this because immutable

 		return this;

 	}