This closes #1469, fix cell resolver caused incorrect calculation result (#1470)

calc.go

@@ -198,7 +198,9 @@ var (
 type calcContext struct {
 	sync.Mutex
 	entry             string
+	maxCalcIterations uint
 	iterations        map[string]uint
+	iterationsCache   map[string]formulaArg
 }
 
 // cellRef defines the structure of a cell reference.
@@ -775,7 +777,9 @@ func (f *File) CalcCellValue(sheet, cell string, opts ...Options) (result string
 	)
 	if token, err = f.calcCellValue(&calcContext{
 		entry:             fmt.Sprintf("%s!%s", sheet, cell),
+		maxCalcIterations: getOptions(opts...).MaxCalcIterations,
 		iterations:        make(map[string]uint),
+		iterationsCache:   make(map[string]formulaArg),
 	}, sheet, cell); err != nil {
 		return
 	}
@@ -1527,17 +1531,6 @@ func (f *File) cellResolver(ctx *calcContext, sheet, cell string) (formulaArg, e
 		value string
 		err   error
 	)
-	ref := fmt.Sprintf("%s!%s", sheet, cell)
-	if formula, _ := f.GetCellFormula(sheet, cell); len(formula) != 0 {
-		ctx.Lock()
-		if ctx.entry != ref && ctx.iterations[ref] <= f.options.MaxCalcIterations {
-			ctx.iterations[ref]++
-			ctx.Unlock()
-			arg, _ = f.calcCellValue(ctx, sheet, cell)
-			return arg, nil
-		}
-		ctx.Unlock()
-	}
 	if value, err = f.GetCellValue(sheet, cell, Options{RawCellValue: true}); err != nil {
 		return arg, err
 	}
@@ -1551,8 +1544,25 @@ func (f *File) cellResolver(ctx *calcContext, sheet, cell string) (formulaArg, e
 			return newEmptyFormulaArg(), err
 		}
 		return arg.ToNumber(), err
-	default:
+	case CellTypeInlineString, CellTypeSharedString:
 		return arg, err
+	case CellTypeFormula:
+		ref := fmt.Sprintf("%s!%s", sheet, cell)
+		if ctx.entry != ref {
+			ctx.Lock()
+			if ctx.iterations[ref] <= ctx.maxCalcIterations {
+				ctx.iterations[ref]++
+				ctx.Unlock()
+				arg, _ = f.calcCellValue(ctx, sheet, cell)
+				ctx.iterationsCache[ref] = arg
+				return arg, nil
+			}
+			ctx.Unlock()
+			return ctx.iterationsCache[ref], nil
+		}
+		fallthrough
+	default:
+		return newEmptyFormulaArg(), err
 	}
 }
 
@@ -7746,7 +7756,7 @@ func (fn *formulaFuncs) COUNTBLANK(argsList *list.List) formulaArg {
 	}
 	var count float64
 	for _, cell := range argsList.Front().Value.(formulaArg).ToList() {
-		if cell.Value() == "" {
+		if cell.Type == ArgEmpty {
 			count++
 		}
 	}

calc_test.go

@@ -1023,7 +1023,7 @@ func TestCalcCellValue(t *testing.T) {
 		"=COUNTBLANK(MUNIT(1))": "0",
 		"=COUNTBLANK(1)":        "0",
 		"=COUNTBLANK(B1:C1)":    "1",
-		"=COUNTBLANK(C1)":       "1",
+		"=COUNTBLANK(C1)":       "0",
 		// COUNTIF
 		"=COUNTIF(D1:D9,\"Jan\")":     "4",
 		"=COUNTIF(D1:D9,\"<>Jan\")":   "5",
@@ -5871,3 +5871,20 @@ func TestCalcColRowQRDecomposition(t *testing.T) {
 	assert.False(t, calcRowQRDecomposition([][]float64{{0, 0}, {0, 0}}, []float64{0, 0}, 1, 0))
 	assert.False(t, calcColQRDecomposition([][]float64{{0, 0}, {0, 0}}, []float64{0, 0}, 1, 0))
 }
+
+func TestCalcCellResolver(t *testing.T) {
+	f := NewFile()
+	// Test reference a cell multiple times in a formula
+	assert.NoError(t, f.SetCellValue("Sheet1", "A1", "VALUE1"))
+	assert.NoError(t, f.SetCellFormula("Sheet1", "A2", "=A1"))
+	for formula, expected := range map[string]string{
+		"=CONCATENATE(A1,\"_\",A1)": "VALUE1_VALUE1",
+		"=CONCATENATE(A1,\"_\",A2)": "VALUE1_VALUE1",
+		"=CONCATENATE(A2,\"_\",A2)": "VALUE1_VALUE1",
+	} {
+		assert.NoError(t, f.SetCellFormula("Sheet1", "A3", formula))
+		result, err := f.CalcCellValue("Sheet1", "A3")
+		assert.NoError(t, err, formula)
+		assert.Equal(t, expected, result, formula)
+	}
+}