initial commit

Author: cjihrig

.travis.yml

@@ -0,0 +1,10 @@
+sudo: false
+language: node_js
+node_js:
+  - "0.10"
+  - "0.12"
+  - "4"
+  - "5"
+  - "iojs"
+  - "iojs-v1"
+  - "iojs-v2"

README.md

@@ -1,2 +1,24 @@
 # hapi-for-you
-hapi style guide ESLint rule dealing with for loops
+
+[![Current Version](https://img.shields.io/npm/v/hapi-for-you.svg)](https://www.npmjs.org/package/hapi-for-you)
+[![Build Status via Travis CI](https://travis-ci.org/continuationlabs/hapi-for-you.svg?branch=master)](https://travis-ci.org/continuationlabs/hapi-for-you)
+![Dependencies](http://img.shields.io/david/continuationlabs/hapi-for-you.svg)
+
+hapi style guide ESLint rule dealing with for loops. This rule enforces the following:
+
+- Restrict iterator variable names. `for` loop iterator variables should be named `i`. Nested loops should use the variables `j`, `k`, and so on.
+- Restrict loop nesting.  You can restrict the maximum nesting of `for` loops. By default, this limit is three.
+- Prevent postfix increment and decrement operators. The hapi style guide does not allow postfix increment and decrement operators in `for` loop updates. The prefix version of these operators should be used instead.
+- Single variable declaration in initialization section. A single `var i = 0;` is allowed in the initialization section. This only applies to variable declarations, not assignments to existing variables. This means that `for (i = 0, j = 0)` is allowed if `i` and `j` are existing variables. Variable declarations involving destructuring are not allowed.
+
+## Rule options
+
+This rule can be configured by providing a single options object. The object supports the following keys.
+
+### `maxDepth`
+
+A number representing the maximum allowed nesting of `for` loops. Defaults to three.
+
+### `startIterator`
+
+The first variable iterator name to use. This defaults to `'i'`.

lib/index.js

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+'use strict';
+
+module.exports = function (context) {
+  var options = context.options[0] || {};
+  var maxDepth = options.maxDepth || 3;
+  var startIterator = options.startIterator || 'i';
+  var stack = [];
+
+  function check (node) {
+    stack.push(node);
+
+    // Make sure that for loops are not nested excessively
+    if (stack.length > maxDepth) {
+      context.report(node, 'Too many nested for loops.');
+    }
+
+    var init = node.init;
+
+    if (init !== null && init.type === 'VariableDeclaration') {
+      // Verify that there is 1 initialized variable at most
+      if (init.declarations.length > 1) {
+        context.report(node, 'Only one variable can be initialized per loop.');
+      }
+
+      var declaration = init.declarations[0];
+
+      // Verify that this is a normal variable declaration, not destructuring
+      if (declaration.id.type !== 'Identifier') {
+        context.report(node, 'Left hand side of initializer must be a single variable.');
+      } else {
+        var iteratorVar = declaration.id.name;
+        var designatedIter = getIteratorVariable(stack.length - 1);
+
+        // Verify that the iterator variable has the expected value
+        if (iteratorVar !== designatedIter) {
+          context.report(node, 'Expected iterator \'' + designatedIter + '\', but got \'' + iteratorVar + '\'.');
+        }
+      }
+    }
+
+    var update = node.update;
+
+    // Verify that postfix increment/decrement are not used
+    if (update && update.type === 'UpdateExpression' && !update.prefix) {
+      context.report(node, 'Update to iterator should use prefix operator.');
+    }
+  }
+
+  function getIteratorVariable (offset) {
+    return String.fromCharCode(startIterator.charCodeAt(0) + offset);
+  }
+
+  function popStack () {
+    stack.pop();
+  }
+
+  return {
+    'ForStatement': check,
+    'ForStatement:exit': popStack
+  };
+};
+
+module.exports.esLintRuleName = 'hapi-for-you';

package.json

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+{
+  "name": "hapi-for-you",
+  "version": "1.0.0",
+  "description": "hapi style guide ESLint rule dealing with for loops",
+  "author": "Continuation Labs <contact@continuation.io> (http://continuation.io/)",
+  "main": "lib/index.js",
+  "scripts": {
+    "test": "belly-button && lab -v -t 100 -a code"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/continuationlabs/hapi-for-you.git"
+  },
+  "keywords": [
+    "eslint",
+    "rule",
+    "for",
+    "loop",
+    "for loop"
+  ],
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/continuationlabs/hapi-for-you/issues"
+  },
+  "homepage": "https://github.com/continuationlabs/hapi-for-you",
+  "devDependencies": {
+    "belly-button": "1.x.x",
+    "code": "1.x.x",
+    "eslint": "1.x.x",
+    "lab": "6.x.x"
+  }
+}

test/index.js

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+'use strict';
+
+var Code = require('code');
+var ESLint = require('eslint');
+var Lab = require('lab');
+var HapiForYou = require('../lib');
+
+var lab = exports.lab = Lab.script();
+var describe = lab.describe;
+var it = lab.it;
+var RuleTester = ESLint.RuleTester;
+
+Code.settings.truncateMessages = false;
+
+describe('ESLint Rule', function () {
+  it('enforces iterator variable naming', function (done) {
+    var ruleTester = new RuleTester();
+    var valids = [
+      {
+        code: 'for (var i = 0; i < a.length; ++i) { for (var j = 0; j < b.length; ++j) {} }'
+      },
+      {
+        code: 'for (var j = 0; j < a.length; ++j) { for (var k = 0; k < b.length; ++k) {} }',
+        options: [{startIterator: 'j'}]
+      },
+      {
+        code: 'for (var i = 0; i < a.length; ++i) {}; for (var i = 0; i < a.length; ++i) {}'
+      },
+      {
+        code: 'for (;;) {}'
+      }
+    ];
+    var invalids = [
+      {
+        code: 'for (var j = 0; j < a.length; ++j) {}',
+        errors: [{message: 'Expected iterator \'i\', but got \'j\'.'}]
+      },
+      {
+        code: 'for (var i = 0; i < a.length; ++i) {}',
+        options: [{startIterator: 'j'}],
+        errors: [{message: 'Expected iterator \'j\', but got \'i\'.'}]
+      }
+    ];
+
+    ruleTester.run(HapiForYou.esLintRuleName, HapiForYou, {
+      valid: valids,
+      invalid: invalids
+    });
+    done();
+  });
+
+  it('enforces a maximum of one variable initialized per loop', function (done) {
+    var ruleTester = new RuleTester();
+    var valids = [
+      {
+        code: 'for (var i = 0; i < a.length; ++i) {}'
+      },
+      {
+        code: 'for (i = 0, j = 1; i < a.length; ++i) {}'
+      },
+      {
+        code: 'for (; i < a.length; ++i) {}'
+      }
+    ];
+    var invalids = [
+      {
+        code: 'for (var i = 0, j; i < a.length; ++i) {}',
+        errors: [{message: 'Only one variable can be initialized per loop.'}]
+      },
+      {
+        code: 'for (var [i] = [0]; i < a.length; ++i) {}',
+        ecmaFeatures: {destructuring: true},
+        errors: [{message: 'Left hand side of initializer must be a single variable.'}]
+      }
+    ];
+
+    ruleTester.run(HapiForYou.esLintRuleName, HapiForYou, {
+      valid: valids,
+      invalid: invalids
+    });
+    done();
+  });
+
+  it('enforces the maximum number of nested for loops', function (done) {
+    var ruleTester = new RuleTester();
+    var valids = [
+      {
+        code: 'for (var i = 0; i < a.length; ++i) {}'
+      },
+      {
+        code: 'for (var i = 0; i < a.length; ++i) { for (var j = 0; j < b.length; ++j) { for (var k = 0; k < c.length; ++k) { for (var l = 0; l < d.length; ++l) {} } } }',
+        options: [{maxDepth: 4}]
+      }
+    ];
+    var invalids = [
+      {
+        code: 'for (var i = 0; i < a.length; ++i) { for (var j = 0; j < b.length; ++j) { for (var k = 0; k < c.length; ++k) { for (var l = 0; l < d.length; ++l) {} } } }',
+        errors: [{message: 'Too many nested for loops.'}]
+      },
+      {
+        code: 'for (var i = 0; i < a.length; ++i) { for (var j = 0; j < b.length; ++j) {} }',
+        options: [{maxDepth: 1}],
+        errors: [{message: 'Too many nested for loops.'}]
+      }
+    ];
+
+    ruleTester.run(HapiForYou.esLintRuleName, HapiForYou, {
+      valid: valids,
+      invalid: invalids
+    });
+    done();
+  });
+
+  it('prevents post-increment and post-decrement', function (done) {
+    var ruleTester = new RuleTester();
+    var valids = [
+      {
+        code: 'for (var i = 0; i < a.length; ++i) {}'
+      },
+      {
+        code: 'for (var i = 0; i < a.length; --i) {}'
+      },
+      {
+        code: 'for (var i = 0; i < a.length; i += 1) {}'
+      },
+      {
+        code: 'for (var i = 0; i < a.length; i = i + 1) {}'
+      },
+      {
+        code: 'for (var i = 0; i < a.length;) {}'
+      }
+    ];
+    var invalids = [
+      {
+        code: 'for (var i = 0; i < a.length; i++) {}',
+        errors: [{message: 'Update to iterator should use prefix operator.'}]
+      },
+      {
+        code: 'for (var i = 0; i < a.length; i--) {}',
+        errors: [{message: 'Update to iterator should use prefix operator.'}]
+      }
+    ];
+
+    ruleTester.run(HapiForYou.esLintRuleName, HapiForYou, {
+      valid: valids,
+      invalid: invalids
+    });
+    done();
+  });
+});