Controlled instantiation of BoolPtg (made consistent with ErrPtg)

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@887477 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/hssf/record/formula/BoolPtg.java

@@ -22,22 +22,29 @@ import org.apache.poi.util.LittleEndianOutput;
 
 /**
  * Boolean (boolean) Stores a (java) boolean value in a formula.
- * 
+ *
  * @author Paul Krause (pkrause at soundbite dot com)
  * @author Andrew C. Oliver (acoliver at apache dot org)
  * @author Jason Height (jheight at chariot dot net dot au)
  */
 public final class BoolPtg extends ScalarConstantPtg {
-	public final static int SIZE = 2;
-	public final static byte sid = 0x1D;
+	public static final int SIZE = 2;
+	public static final byte sid = 0x1D;
+
+	private static final BoolPtg FALSE = new BoolPtg(false);
+	private static final BoolPtg TRUE = new BoolPtg(true);
+
 	private final boolean _value;
 
-	public BoolPtg(LittleEndianInput in)  {
-		_value = (in.readByte() == 1);
+	private BoolPtg(boolean b) {
+		_value = b;
 	}
 
-	public BoolPtg(String formulaToken) {
-		_value = (formulaToken.equalsIgnoreCase("TRUE"));
+	public static BoolPtg valueOf(boolean b) {
+		return b ? TRUE : FALSE;
+	}
+	public static BoolPtg read(LittleEndianInput in)  {
+		return valueOf(in.readByte() == 1);
 	}
 
 	public boolean getValue() {

src/java/org/apache/poi/hssf/record/formula/Ptg.java

@@ -152,7 +152,7 @@ public abstract class Ptg {
 			case StringPtg.sid:       return new StringPtg(in);       // 0x17
 			case AttrPtg.sid:         return new AttrPtg(in);         // 0x19
 			case ErrPtg.sid:          return ErrPtg.read(in);         // 0x1c
-			case BoolPtg.sid:         return new BoolPtg(in);         // 0x1d
+			case BoolPtg.sid:         return BoolPtg.read(in);        // 0x1d
 			case IntPtg.sid:          return new IntPtg(in);          // 0x1e
 			case NumberPtg.sid:       return new NumberPtg(in);       // 0x1f
 		}

src/java/org/apache/poi/ss/formula/FormulaParser.java

@@ -551,7 +551,7 @@ public final class FormulaParser {
 			return function(name);
 		}
 		if (name.equalsIgnoreCase("TRUE") || name.equalsIgnoreCase("FALSE")) {
-			return  new ParseNode(new BoolPtg(name.toUpperCase()));
+			return  new ParseNode(BoolPtg.valueOf(name.equalsIgnoreCase("TRUE")));
 		}
 		if (_book == null) {
 			// Only test cases omit the book (expecting it not to be needed)