Merge pull request #73 from iancmyers/rule-one-true-brace

Rule: One True Brace Style

conf/eslint.json

@@ -17,6 +17,7 @@
         "no-new": 1,
 
         "smarter-eqeqeq": 0,
+        "brace-style": 0,
         "camelcase": 1,
         "curly": 1,
         "eqeqeq": 1,

docs/brace-style.md

@@ -0,0 +1,63 @@
+# brace style
+
+One true brace style is a common coding style in JavaScript, in which the opening curly brace of a block is placed on the same line as its corresponding statement or declaration.
+
+```js
+function foo()
+{
+  return true;
+}
+
+if (foo)
+{
+  bar();
+}
+```
+
+## Rule Details
+
+This rule is aimed at enforcing one true brace style across your JavaScript. As such, it warns whenever it sees a statement or declaration that does not adhere to the one true brace style.
+
+The following patterns are considered warnings:
+
+```js
+function foo()
+{
+  return true;
+}
+
+if (foo)
+{
+  bar();
+}
+
+try
+{
+  somethingRisky();
+} catch(e)
+{
+  handleError();
+}
+```
+
+The following patterns adhere to one true brace style and do not cause warnings:
+
+```js
+function foo() {
+  return true;
+}
+
+if (foo) {
+  bar();
+}
+
+try {
+  somethingRisky();
+} catch(e) {
+  handleError();
+}
+```
+
+## When Not To Use It
+
+If your project will not be using the one true brace style, turn this rule off.

lib/rules/brace-style.js

@@ -0,0 +1,57 @@
+/**
+ * @fileoverview Rule to flag block statements that do not use the one true brace style
+ * @author Ian Christian Myers
+ */
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+
+    //--------------------------------------------------------------------------
+    // Helpers
+    //--------------------------------------------------------------------------
+
+    function checkBlockStartsAtIdentifier(node) {
+        var startLine = node.loc.start.line;
+
+        // Checks for opening curly brace on FunctionDeclarations.
+        if (node.body && startLine !== node.body.loc.start.line) {
+            context.report(node, "Opening curly brace does not appear on the same line as the block identifier.");
+        }
+
+        // Checks for opening curly brace on IfStatement, DoWhileStatement,
+        // WhileStatement, WithStatement, ForStatement, and ForInStatement.
+        if (node.consequent && startLine !== node.consequent.loc.start.line) {
+            context.report(node, "Opening curly brace does not appear on the same line as the block identifier.");
+        }
+
+        // Checks for opening curly brace on TryStatement.
+        if (node.block && startLine !== node.block.loc.start.line) {
+            context.report(node, "Opening curly brace does not appear on the same line as the block identifier.");
+        }
+
+        // Checks for opening curly on SwitchStatement.
+        if (node.discriminant && startLine !== node.cases[0].loc.start.line - 1) {
+            context.report(node, "Opening curly brace does not appear on the same line as the block identifier.");
+        }
+    }
+
+    //--------------------------------------------------------------------------
+    // Public API
+    //--------------------------------------------------------------------------
+
+    return {
+        "FunctionDeclaration": checkBlockStartsAtIdentifier,
+        "IfStatement": checkBlockStartsAtIdentifier,
+        "SwitchStatement": checkBlockStartsAtIdentifier,
+        "TryStatement": checkBlockStartsAtIdentifier,
+        "DoWhileStatement": checkBlockStartsAtIdentifier,
+        "WhileStatement": checkBlockStartsAtIdentifier,
+        "WithStatement": checkBlockStartsAtIdentifier,
+        "ForStatement": checkBlockStartsAtIdentifier,
+        "ForInStatement": checkBlockStartsAtIdentifier
+    };
+
+};