Modified calculate to allow for string concatenation

cell.go

@@ -93,6 +93,7 @@ func (c *cell) Update(val string) bool {
 		c.num  = num
 		c.mask = strconv.FormatFloat(num, 'f', -1, 64)
 	} else if strings.HasPrefix(val, "\"") && strings.HasSuffix(val, "\"") {
+		c.rawVal = strings.Replace(c.rawVal, " ", "\\_", -1)
 		c.kind = Text
 		c.mask = strings.Replace(val[1:len(val)-1], "\\_", " ", -1)
 	} else {
@@ -106,10 +107,6 @@ func (c *cell) Calculate() {
 	if c.kind != Expr {
 		return
 	}
-	if len(c.expr) < 2 {
-		c.mask = "#Err"
-		return
-	}
 	insideString := false
 	s := makeStack()
 
@@ -117,7 +114,7 @@ func (c *cell) Calculate() {
 		if IsAddr(v) {
 			c, err := GetCell(Addr2Point(v))
 			if err != nil {
-				c.mask = "#Err"
+				c.mask = "#Err: Invalid Cell"
 				return
 			}
 			if c.kind == Text {
@@ -129,27 +126,14 @@ func (c *cell) Calculate() {
 			// TODO Apply range
 		}
 
-		if s.ptr >= 0 && s.text {
-			c.mask = "#Err"
-			return
-		}
-
 		switch true {
 		case strings.HasPrefix(v, "\""):
-			if s.ptr >= 0 {
-				c.mask = "#Err"
-				return
-			}
 			if !strings.HasSuffix(v, "\"") {
 				insideString = true
 			}
 			s.str.WriteString(strings.Replace(v, "\"", "", -1))
 			s.text = true
 		case insideString:
-			if s.ptr >= 0 {
-				c.mask = "#Err"
-				return
-			}
 			if strings.HasSuffix(v, "\"") {
 				insideString = false
 				v = strings.Replace(v, "\"", "", -1)
@@ -157,22 +141,32 @@ func (c *cell) Calculate() {
 			s.str.WriteRune(' ')
 			s.str.WriteString(v)
 		case IsFunc(v):
-			if s.text {
-				c.mask = "#Err"
-				return
-			} else if v == "+" {
+			v = strings.ToUpper(v)
+			if v == "SPC" {
+				s.str.WriteRune(' ')
+				s.text = true
+			}
+			if v == "+" {
 				s.Add()
-			} else if v == "-" {
+			}
+			if v == "-" {
 				s.Subtract()
-			} else if v == "/" {
+			}
+			if v == "/" {
 				s.Divide()
-			} else if v == "*" {
+			}
+			if v == "*" {
 				s.Multiply()
 			}
+			if v == "." {
+				num := s.Pop()
+				s.str.WriteString(strconv.FormatFloat(num, 'f', -1, 64))
+				s.text = true
+			}
 		default:
 			v, err := strconv.ParseFloat(v, 64)
 			if err != nil {
-				c.mask = "#Err"
+				c.mask = "#Err: Cannot parse float"
 				return
 			}
 			s.Push(v)
@@ -180,11 +174,17 @@ func (c *cell) Calculate() {
 	}
 
 	if s.text {
+		if s.ptr != -1 {
+			for s.Len() > 0 {
+				num := s.Pop()
+				s.str.WriteString(strconv.FormatFloat(num, 'f', -1, 64))
+			}
+		}
 		c.mask = strings.Replace(s.str.String(), "\\_", " ", -1)
 	} else if s.ptr == 0 {
 		c.mask = strconv.FormatFloat(s.data[0], 'f', -1, 64)
 	} else {
-		c.mask = "Err"
+		c.mask = "#Err: Invalid Formula"
 	}
 }
 
@@ -215,6 +215,10 @@ func (s *stack) Pop() float64 {
 	return s.data[s.ptr+1]
 }
 
+func (s stack) Len() int {
+	return s.ptr + 1
+}
+
 func (s *stack) Add() {
 	if s.text {
 		val := strconv.FormatFloat(s.Pop(), 'f', -1, 64)

main.go

@@ -151,7 +151,7 @@ func IsRange(addr string) bool {
 func IsFunc(val string) bool {
 	switch strings.ToUpper(val) {
 	case "+", "-", "/", "*", "^", "MIN", "MAX", "SQRT",
-		"ROUND", "SUBSTR", "UPPER", "LOWER", "SUM":
+		"ROUND", "SUBSTR", "UPPER", "LOWER", "SUM", "SPC", ".":
 		return true
 	default:
 		return false

workbook.go

@@ -65,7 +65,7 @@ func (w *workbook) Run() {
 			w.sheets[w.sheet].moveSelection(input, w.termRows)
 		case Quit:
 			if modified {
-				fmt.Print("There are unsaved changes. Quit? [y/n]")
+				fmt.Print("There are unsaved changes. Quit anyway? [y/n]")
 				answer := Getch()
 				if answer == 'n' || answer == 'N' {
 					continue