Add negation as a unary operation

Author: jstrieb

src/formula.js

@@ -138,6 +138,7 @@ class UnaryOperation extends Expression {
   static operations = {
     "!": (x) => !x,
     "~": (x) => ~x,
+    "-": (x) => -x,
   };
 
   operator;
@@ -435,7 +436,7 @@ const unary = forwardDeclaration();
 unary.become(
   lex(
     alt(
-      seq(alt(lex("!"), lex("~")), unary).map(
+      seq(alt(...Object.keys(UnaryOperation.operations).map(lex)), unary).map(
         (args) => new UnaryOperation(...args),
       ),
       value,

test/sheet-and-formula.test.js

@@ -655,3 +655,14 @@ test("Single-quoted strings", async () => {
     ["test", "te'st\n\n", "te\\'st"],
   ]);
 });
+
+test("Negation as a unary operation", async () => {
+  const state = createSheet([
+    ["-5.0", "=-3.2", "=-(6)", "=---3"],
+    ["=3**-2", "=3**-(--2)", "=-AVERAGE(1, 2, 3)", "=---SUM(-3, -4, -5)"],
+  ]);
+  await expectSheet(state.currentSheet, [
+    [-5.0, -3.2, -6, -3],
+    [Math.pow(3, -2), Math.pow(3, -2), -2, 3 + 4 + 5],
+  ]);
+});