Count implementation from ooxml branch

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@642737 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/hssf/record/formula/functions/Count.java

@@ -20,6 +20,99 @@
  */
 package org.apache.poi.hssf.record.formula.functions;
 
-public class Count extends NotImplementedFunction {
+import org.apache.poi.hssf.record.formula.eval.AreaEval;
+import org.apache.poi.hssf.record.formula.eval.BlankEval;
+import org.apache.poi.hssf.record.formula.eval.ErrorEval;
+import org.apache.poi.hssf.record.formula.eval.Eval;
+import org.apache.poi.hssf.record.formula.eval.NumberEval;
+import org.apache.poi.hssf.record.formula.eval.RefEval;
+import org.apache.poi.hssf.record.formula.eval.ValueEval;
 
+/**
+ * Counts the number of cells that contain numeric data within
+ *  the list of arguments. 
+ *
+ * Excel Syntax
+ * COUNT(value1,value2,...)
+ * Value1, value2, ...   are 1 to 30 arguments representing the values or ranges to be counted.
+ * 
+ * TODO: Check this properly matches excel on edge cases
+ *  like formula cells, error cells etc
+ */
+public class Count implements Function {
+
+	public Eval evaluate(Eval[] args, int srcCellRow, short srcCellCol) {
+		int nArgs = args.length;
+		if (nArgs < 1) {
+			// too few arguments
+			return ErrorEval.VALUE_INVALID;
+		}
+
+		if (nArgs > 30) {
+			// too many arguments
+			return ErrorEval.VALUE_INVALID;
+		}
+		
+		int temp = 0;
+		
+		for(int i=0; i<nArgs; i++) {
+			temp += countArg(args[i]);
+			
+		}
+		return new NumberEval(temp);
+	}
+
+	private static int countArg(Eval eval) {
+        if (eval instanceof AreaEval) {
+            AreaEval ae = (AreaEval) eval;
+            return countAreaEval(ae);
+        }
+        if (eval instanceof RefEval) {
+            RefEval refEval = (RefEval)eval;
+			return countValue(refEval.getInnerValueEval());
+        }
+        if (eval instanceof NumberEval) {
+            return 1;
+        }
+		
+		throw new RuntimeException("Unexpected eval type (" + eval.getClass().getName() + ")");
+	}
+
+	private static int countAreaEval(AreaEval ae) {
+		
+		int temp = 0;
+		ValueEval[] values = ae.getValues();
+		for (int i = 0; i < values.length; i++) {
+			ValueEval val = values[i];
+			if(val == null) {
+				// seems to occur.  Really we would have expected BlankEval
+				continue;
+			}
+			temp += countValue(val);
+			
+		}
+		return temp;
+	}
+
+	private static int countValue(ValueEval valueEval) {
+		
+		if(valueEval == BlankEval.INSTANCE) {
+			return 0;
+		}
+		
+		if(valueEval instanceof BlankEval) {
+			// wouldn't need this if BlankEval was final
+			return 0;
+		}
+
+		if(valueEval instanceof ErrorEval) {
+			// note - error values not counted
+			return 0;
+		}
+		
+		if(valueEval instanceof NumberEval)
+			return 1;
+
+		return 0;
+	}
 }