Negate before exponentiation, as Sheets does

Dami committed Sep 26ff6486e

-2^2 is 4 in Sheets and Excel: unary minus binds tighter than ^. The
excelize oracle caught it.

commit: ff6486e58d7d15f4b5f2964883228a15e68c1163
parent: 26a76be2d39047f8dd170966bffb08162e6720b5
author: Dami <dami.etoile@gmail.com>

2 files changed, +5 -2wrap lines

M	internal/sheet/parse.go	3	++-
M	internal/sheet/sheet_test.go	4	+++-

M internal/sheet/parse.go +2 -1

@@ -167,9 +167,10 @@ var infixPower = map[string]int{
167167 	"^": 70,168168 }169169 170+// Negation binds tighter than ^, so -2^2 is 4 as in Sheets and Excel.170171 const (171172 	notPower     = 20172-	unaryPower   = 60173+	unaryPower   = 75173174 	percentPower = 80174175 )175176 

M internal/sheet/sheet_test.go +3 -1

@@ -73,7 +73,9 @@ func TestFormulas(t *testing.T) {
7373 	}{7474 		{"=A1+A2*2", num(50)},7575 		{"=(A1+A2)*2", num(60)},76-		{"=-2^2", num(-4)},76+		{"=-2^2", num(4)}, // negation first, as in Sheets77+		{"=2^-1", num(0.5)},78+		{"=-A1^2", num(100)},7779 		{"=A1/4", num(2.5)},7880 		{"+A1*2", num(20)}, // Sheets accepts a leading +7981 		{"=SUM(A1:A3)", num(60)},