Remove jison-gho dependency

.eslintignore

@@ -1,3 +1,4 @@
 .coverage
 flow-typed
 lib/vendor
+lib/utils/parseCalcExpression/parser.js

.prettierignore

@@ -1,2 +1,3 @@
 .coverage
 flow-typed
+lib/utils/parseCalcExpression/parser.js

lib/utils/__tests__/parseCalcExpression.test.js → lib/utils/parseCalcExpression/__tests__/parseCalcExpression.test.js

@@ -1,6 +1,6 @@
 "use strict";
 
-const parse = require("../parseCalcExpression");
+const parse = require("..");
 
 it("parseCalcExpression parse to ast", () => {
   expect(parse("calc(100% - 80px)")).toEqual({

lib/utils/parseCalcExpression/index.js

@@ -1,19 +1,11 @@
 "use strict";
 
-const fs = require("fs");
-const jison = require("jison-gho");
+// To generate parser.js run the following command in the current directory:
+//
+// npx jison-gho parser.jison -o parser.js
 
-let parser;
+const parse = require("./parser").parse;
 
-module.exports = function(exp) {
-  if (!parser) {
-    const parserConfig = fs.readFileSync(
-      require.resolve("./parser.jison"),
-      "utf8"
-    );
-
-    parser = new jison.Parser(parserConfig);
-  }
-
-  return parser.parse(exp);
+module.exports = function parseCalcExpression(exp) {
+  return parse(exp);
 };