Core object-literal-key-quotes rule (#1364)

* Core quote-props rule

* Tweaks for code review

* rename

src/ruleLoader.ts

@@ -59,6 +59,7 @@ export function loadRules(ruleConfiguration: {[name: string]: any},
             Try upgrading TSLint and/or ensuring that you have all necessary custom rules installed.
             If TSLint was recently upgraded, you may have old rules configured which need to be cleaned up.
         `;
+
         throw new Error(ERROR_MESSAGE);
     } else {
         return rules;

src/rules/objectLiteralKeyQuotesRule.ts

@@ -0,0 +1,95 @@
+import * as Lint from "../lint";
+import * as ts from "typescript";
+
+export class Rule extends Lint.Rules.AbstractRule {
+    /* tslint:disable:object-literal-sort-keys */
+    public static metadata: Lint.IRuleMetadata = {
+        ruleName: "object-literal-key-quotes",
+        description: "Enforces consistent object literal property quote style.",
+        descriptionDetails: Lint.Utils.dedent`
+            Object literal property names can be defined in two ways: using literals or using strings.
+            For example, these two objects are equivalent:
+
+            var object1 = {
+                property: true
+            };
+
+            var object2 = {
+                "property": true
+            };
+
+            In many cases, it doesn’t matter if you choose to use an identifier instead of a string
+            or vice-versa. Even so, you might decide to enforce a consistent style in your code.
+
+            This rules lets you enforce consistent quoting of property names. Either they should always
+            be quoted (default behavior) or quoted only as needed ("as-needed").`,
+        optionsDescription: Lint.Utils.dedent`
+            Possible settings are:
+
+            * \`"always"\`: Property names should always be quoted. (This is the default.)
+            * \`"as-needed"\`: Only property names which require quotes may be quoted (e.g. those with spaces in them).
+
+            For ES6, computed property names (\`{[name]: value}\`) and methods (\`{foo() {}}\`) never need
+            to be quoted.`,
+        options: {
+            type: "string",
+            enum: ["always", "as-needed"],
+            // TODO: eslint also supports "consistent", "consistent-as-needed" modes.
+            // TODO: eslint supports "keywords", "unnecessary" and "numbers" options.
+        },
+        optionExamples: ["[true, \"as-needed\"]", "[true, \"always\"]"],
+        type: "style",
+    };
+    /* tslint:enable:object-literal-sort-keys */
+
+    public static UNNEEDED_QUOTES = (name: string) => `Unnecessarily quoted property '${name}' found.`;
+    public static UNQUOTED_PROPERTY = (name: string) => `Unquoted property '${name}' found.`;
+
+    public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+        const objectLiteralKeyQuotesWalker = new ObjectLiteralKeyQuotesWalker(sourceFile, this.getOptions());
+        return this.applyWithWalker(objectLiteralKeyQuotesWalker);
+    }
+}
+
+// This is simplistic. See https://mothereff.in/js-properties for the gorey details.
+const IDENTIFIER_NAME_REGEX = /^(?:[\$A-Z_a-z])*$/;
+
+const NUMBER_REGEX = /^[0-9]+$/;
+
+type QuotesMode = "always" | "as-needed";
+
+class ObjectLiteralKeyQuotesWalker extends Lint.RuleWalker {
+    private mode: QuotesMode;
+
+    constructor(sourceFile: ts.SourceFile, options: Lint.IOptions) {
+        super(sourceFile, options);
+
+        this.mode = this.getOptions()[0] || "always";
+    }
+
+    public visitPropertyAssignment(node: ts.PropertyAssignment) {
+        const name = node.name;
+        if (this.mode === "always") {
+            if (name.kind !== ts.SyntaxKind.StringLiteral &&
+                name.kind !== ts.SyntaxKind.ComputedPropertyName) {
+                this.addFailure(this.createFailure(name.getStart(), name.getWidth(),
+                                                   Rule.UNQUOTED_PROPERTY(name.getText())));
+            }
+        } else if (this.mode === "as-needed") {
+            if (name.kind === ts.SyntaxKind.StringLiteral) {
+                // Check if the quoting is necessary.
+                const stringNode = name as ts.StringLiteral;
+                const property = stringNode.text;
+
+                const isIdentifier = IDENTIFIER_NAME_REGEX.test(property);
+                const isNumber = NUMBER_REGEX.test(property);
+                if (isIdentifier || (isNumber && Number(property).toString() === property)) {
+                    this.addFailure(this.createFailure(stringNode.getStart(), stringNode.getWidth(),
+                                                    Rule.UNNEEDED_QUOTES(property)));
+                }
+            }
+        }
+
+        super.visitPropertyAssignment(node);
+    }
+}

src/tsconfig.json

@@ -120,6 +120,7 @@
         "rules/noUseBeforeDeclareRule.ts",
         "rules/noVarKeywordRule.ts",
         "rules/noVarRequiresRule.ts",
+        "rules/objectLiteralKeyQuotesRule.ts",
         "rules/objectLiteralSortKeysRule.ts",
         "rules/oneLineRule.ts",
         "rules/oneVariablePerDeclarationRule.ts",

test/rules/object-literal-key-quotes/always/test.ts.lint

@@ -0,0 +1,23 @@
+const o = {
+  'hello': 123,
+  goodbye: 234, // failure
+  ~~~~~~~  [Unquoted property 'goodbye' found.]
+  "quote": 345,
+  "needs quote": 789,
+  "hyphens-need-quotes": null,
+  [computed]: 456,
+  123: "hello", // failure
+  ~~~  [Unquoted property '123' found.]
+  1e4: "something", // failure
+  ~~~  [Unquoted property '1e4' found.]
+  .123: "float", // failure
+  ~~~~  [Unquoted property '.123' found.]
+  '123': 'numbers do not need quotes',
+  '010': 'but this one does.',
+  '.123': 'as does this one',
+  fn() { return },
+  true: 0, // failure
+  ~~~~  [Unquoted property 'true' found.]
+  "0x0": 0,
+  "true": 0,
+};

test/rules/object-literal-key-quotes/always/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "object-literal-key-quotes": [true, "always"]
+  }
+}

test/rules/object-literal-key-quotes/as-needed/test.ts.lint

@@ -0,0 +1,22 @@
+const o = {
+  'hello': 123, // failure
+  ~~~~~~~  [Unnecessarily quoted property 'hello' found.]
+  goodbye: 234,
+  "quote": 345, // failure
+  ~~~~~~~  [Unnecessarily quoted property 'quote' found.]
+  "needs quote": 789,
+  "hyphens-need-quotes": null,
+  [computed]: 456,
+  123: "hello",
+  1e4: "something",
+  .123: "float",
+  '123': 'numbers do not need quotes', // failure
+  ~~~~~  [Unnecessarily quoted property '123' found.]
+  '010': 'but this one does.',
+  '.123': 'as does this one',
+  fn() { return },
+  true: 0,
+  "0x0": 0,
+  "true": 0, // failure
+  ~~~~~~  [Unnecessarily quoted property 'true' found.]
+};

test/rules/object-literal-key-quotes/as-needed/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "object-literal-key-quotes": [true, "as-needed"]
+  }
+}

test/tsconfig.json

@@ -116,6 +116,7 @@
         "../src/rules/noUseBeforeDeclareRule.ts",
         "../src/rules/noVarKeywordRule.ts",
         "../src/rules/noVarRequiresRule.ts",
+        "../src/rules/objectLiteralKeyQuotesRule.ts",
         "../src/rules/objectLiteralSortKeysRule.ts",
         "../src/rules/oneLineRule.ts",
         "../src/rules/oneVariablePerDeclarationRule.ts",