eslint-plugin-flowtype & upgrade to eslint@4 (#849)

* Add eslint-plugin-flowtype. Fix #844

Using the recommended settings for plugin.
This involved adding some spaces to some existing union types.

* Upgrade to eslint@4, fix spotted bugs

Switched to indent-legacy to allow e.g. comments to have extra indents.

.eslintrc

@@ -1,5 +1,12 @@
 {
     "parser": "babel-eslint",
+    "plugins": [
+        "flowtype"
+    ],
+    "extends": [
+        "eslint:recommended",
+        "plugin:flowtype/recommended"
+    ],
     "rules": {
         "arrow-spacing": 2,
         "brace-style": [2, "1tbs", { "allowSingleLine": true }],
@@ -12,7 +19,8 @@
         "eol-last": 2,
         "eqeqeq": [2, "allow-null"],
         "guard-for-in": 2,
-        "indent": [2, 4, {"SwitchCase": 1}],
+        "indent": "off",
+        "indent-legacy": [2, 4, {"SwitchCase": 1}],
         "keyword-spacing": 2,
         "linebreak-style": [2, "unix"],
         "max-len": [2, 84, 4, { "ignoreUrls": true, "ignorePattern": "\\brequire\\([\"']|eslint-disable" }],
@@ -79,6 +87,5 @@
         "node": true,
         "browser": true
     },
-    "extends": "eslint:recommended",
     "root": true
 }

package.json

@@ -26,7 +26,8 @@
     "babelify": "^7.3.0",
     "browserify": "^13.3.0",
     "clean-css": "^3.4.23",
-    "eslint": "^3.13.0",
+    "eslint": "^4.6.1",
+    "eslint-plugin-flowtype": "^2.35.1",
     "express": "^4.14.0",
     "flow-bin": "^0.54.0",
     "glob": "^7.1.1",

src/ParseError.js

@@ -11,11 +11,12 @@ import {Token} from "./Token";
  * about where in the source string the problem occurred.
  */
 class ParseError {
-    position: number|void; // Error position based on passed-in Token or ParseNode.
+    position: number | void;
+        // Error position based on passed-in Token or ParseNode.
 
     constructor(
-        message: string,         // The error message
+        message: string,           // The error message
-        token?: Token|ParseNode, // An object providing position information
+        token?: Token | ParseNode, // An object providing position information
     ) {
         let error = "KaTeX parse error: " + message;
         let start;

src/ParseNode.js

@@ -16,9 +16,9 @@ export default class ParseNode {
     // TODO: We should combine these to ({lexer, start, end}|void) as they
     // should all exist together or not exist at all. That way, only a single
     // void check needs to be done to see if we have metadata.
-    lexer: LexerInterface|void;
+    lexer: LexerInterface | void;
-    start: number|void;
+    start: number | void;
-    end: number|void;
+    end: number | void;
 
     constructor(
         type: string,       // type of node, like e.g. "ordgroup"

src/Parser.js

@@ -847,7 +847,7 @@ class Parser {
             }
             return new ParseFuncOrArgument(
                 new ParseNode("ordgroup", expression, this.mode,
-                            firstToken, lastToken),
+                    firstToken, lastToken),
                 false);
         } else {
             // Otherwise, just return a nucleus, or nothing for an optional group

src/macros.js

@@ -216,7 +216,7 @@ defineMacro("\\dotsi", "\\!\\cdots");
 // amsmath doesn't actually define \dotsx, but \dots followed by a macro
 // starting with \DOTSX implies \dotso, and then \extra@ detects this case
 // and forces the added `\,`.
-defineMacro("\\dotsx", "\\ldots\,");
+defineMacro("\\dotsx", "\\ldots\\,");
 
 // \let\DOTSI\relax
 // \let\DOTSB\relax

test/errors-spec.js

@@ -286,7 +286,7 @@ describe("environments.js:", function() {
         });
         it("rejects incorrectly scoped \\end", function() {
             expect("{\\begin{matrix}1}\\end{matrix}").toFailWithParseError(
-                   "Expected & or \\\\\ or \\end at position 17:" +
+                   "Expected & or \\\\ or \\end at position 17:" +
                    " …\\begin{matrix}1}̲\\end{matrix}");
         });
     });

test/katex-spec.js

@@ -2384,8 +2384,8 @@ describe("A macro expander", function() {
 
     it("should expand the \\overset macro as expected", function() {
         expect("\\overset?=").toParseLike("\\mathop{=}\\limits^{?}");
-        expect("\\overset{x=y}{\sqrt{ab}}")
+        expect("\\overset{x=y}{\\sqrt{ab}}")
-            .toParseLike("\\mathop{\sqrt{ab}}\\limits^{x=y}");
+            .toParseLike("\\mathop{\\sqrt{ab}}\\limits^{x=y}");
         expect("\\overset {?} =").toParseLike("\\mathop{=}\\limits^{?}");
     });