Add initial implementation

.editorconfig

@@ -0,0 +1,21 @@
+# EditorConfig helps developers define and maintain consistent
+# coding styles between different editors and IDEs
+# editorconfig.org
+
+root = true
+
+
+[*]
+
+# Change these settings to your own preference
+indent_style = space
+indent_size = 2
+
+# We recommend you to keep these unchanged
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false

.gitignore

@@ -59,3 +59,15 @@ typings/
 
 # next.js build output
 .next
+
+# System files
+.DS_Store
+Thumbs.db
+[Dd]esktop.ini
+
+# Lock files
+package-lock.json
+yarn.lock
+
+# Release
+dist

.npmignore

@@ -0,0 +1,10 @@
+.vscode
+.idea
+node_modules
+src
+.editorconfig
+.gitignore
+.npmignore
+.travis.yml
+tsconfig.json
+tslint.json

README.md

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+# TSLint Rule: whitespace-before-colon
+
+TSLint provides no means of controlling spaces before colon in object literals and destructuring assignments. `whitespace.check-type` checks only for space after colon, and `typedef-whitespace` works only for type definitions.
+
+This rules determines if a space is required or not before the colon in object literals and destructuring assignments.
+
+Related to [palantir/tslint#991](https://github.com/palantir/tslint/issues/991).
+
+## Usage
+
+Install with NPM or Yarn to your dev dependencies:
+
+```
+npm install --save-dev tslint-whitespace-before-colon
+```
+
+and enable it in your project's `tslint.json` file:
+
+```json
+{
+  "extends": [
+    "tslint-whitespace-before-colon"
+  ],
+  "rules": {
+    "whitespace-before-colon": [true, "nospace"]
+  }
+}
+```
+
+## Configuration
+
+Rule expects a single string option indicating the required number of spaces before colon:
+
+* `"nospace"` requires no space
+* `"onespace"` requires exactly one space
+* `"space"` requires one or more spaces
+
+If none of the above is provided, the rule will have no effect.
+
+If a newline character (`"\n"`) is present, the rule validates regardless of the configured option, just as `typedef-whitespace` rule does.
+
+## License
+
+MIT

index.js

@@ -0,0 +1,3 @@
+module.exports = {
+  rulesDirectory: "./dist",
+};

package.json

@@ -0,0 +1,40 @@
+{
+  "name": "tslint-whitespace-before-colon",
+  "version": "0.1.0",
+  "description": "TSLint rule for determining if a space is required or not before the colon in object literals and destructuring assignments",
+  "main": "index.js",
+  "scripts": {
+    "build": "tsc --project tsconfig.json --outDir dist",
+    "prepublish": "npm run build",
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "lint": "tslint --project tsconfig.json"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/xemlock/tslint-whitespace-before-colon.git"
+  },
+  "author": "xemlock <[email protected]>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/xemlock/tslint-whitespace-before-colon/issues"
+  },
+  "homepage": "https://github.com/xemlock/tslint-whitespace-before-colon#readme",
+  "keywords": [
+    "tslint",
+    "tslint-plugin",
+    "custom-rules",
+    "rules",
+    "lint",
+    "linter",
+    "linting"
+  ],
+  "devDependencies": {
+    "@types/node": "^8.10.40",
+    "tslint": "^5.12.1",
+    "typescript": "^2.9.2"
+  },
+  "peerDependencies": {
+    "tslint": "^5.0.0",
+    "typescript": "^2.2.0 || ^3.0.0"
+  }
+}

src/whitespaceBeforeColonRule.ts

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+import * as ts from 'typescript';
+import * as Lint from 'tslint';
+
+type Option = 'nospace' | 'onespace' | 'space';
+
+export class Rule extends Lint.Rules.AbstractRule {
+  public static metadata: Lint.IRuleMetadata = {
+    ruleName: 'whitespace-before-colon',
+    description: Lint.Utils.dedent`
+      Determines if a space is required or not before the colon in object literals
+      and destructuring assignments.
+
+      If a newline character (\`"\\n"\`) is present, the rule validates regardless
+      of the configured option, just as \`typedef-whitespace\` rule does.
+    `,
+    rationale: Lint.Utils.dedent`
+      TSLint provides no means of controlling spaces before colon in object literals
+      and destructuring assignments. \`whitespace.check-type\` checks only for space
+      after colon, and \`typedef-whitespace\` works only for type definitions.
+
+      Related to [palantir/tslint#991](https://github.com/palantir/tslint/issues/991).
+    `,
+    optionsDescription: Lint.Utils.dedent`
+      An option indicating the required number of spaces before colon must be provided:
+
+      * \`"nospace"\` requires no space
+      * \`"onespace"\` requires exactly one space
+      * \`"space"\` requires one or more spaces
+    `,
+    options: {
+      type: 'string',
+      enum: ['nospace', 'onespace', 'space'],
+    },
+    optionExamples: [
+      [true, 'onespace'],
+    ],
+    type: 'style',
+    typescriptOnly: false,
+    hasFix: true,
+  };
+
+  public static FAILURE_STRING(option: string) {
+    return `expected ${option} before colon`;
+  }
+
+  public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+    const walker = new RuleWalker(sourceFile, this.getOptions());
+    return this.applyWithWalker(walker);
+  }
+}
+
+class RuleWalker extends Lint.RuleWalker {
+  private option?: Option;
+
+  constructor(sourceFile: ts.SourceFile, options: Lint.IOptions) {
+    super(sourceFile, options);
+
+    const [option] = this.getOptions();
+
+    if (['nospace', 'onespace', 'space'].indexOf(option) !== -1) {
+      this.option = option;
+    }
+  }
+
+  public visitNode(node: ts.Node) {
+    if (
+      node.kind === ts.SyntaxKind.PropertyAssignment ||
+      node.kind === ts.SyntaxKind.BindingElement
+    ) {
+      for (const child of node.getChildren()) {
+        if (child.kind === ts.SyntaxKind.ColonToken) {
+          this.checkWhitespace(child);
+        }
+      }
+    }
+    super.visitNode(node);
+  }
+
+  private checkWhitespace(colon: ts.Node) {
+    const start = colon.pos; // position of whitespace before ':' in ColonToken
+    const end = colon.end; // position of ':'
+    const text = this.getSourceFile().text.substring(start, end);
+
+    const match = text.match(/^(\s+)/);
+    const whitespace = match && match[1] || '';
+
+    if (whitespace.includes('\n')) {
+      return;
+    }
+
+    const { option } = this;
+
+    if (!option || option === 'space' && whitespace.length) {
+      return;
+    }
+
+    const requiredLength = option === 'nospace' ? 0 : 1;
+
+    if (whitespace.length !== requiredLength) {
+      this.addFailureAt(
+        start,
+        whitespace.length,
+        Rule.FAILURE_STRING(option),
+        Lint.Replacement.replaceFromTo(start, start + whitespace.length, ' '.repeat(requiredLength))
+      );
+    }
+  }
+}

tsconfig.json

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+{
+  "compileOnSave": false,
+  "compilerOptions": {
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "baseUrl": "src",
+    "removeComments": true,
+    "sourceMap": false,
+    "target": "es5",
+    "typeRoots": [
+      "node_modules/@types",
+    ],
+    "lib": [
+      "es2017"
+    ],
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noEmitOnError": true,
+    "strictNullChecks": true,
+    "strictFunctionTypes": true,
+    "strictPropertyInitialization": true
+  },
+  "exclude": [
+    "node_modules"
+  ]
+}