1 files changed, 96 insertions, 0 deletions
diff --git a/tools/eslint/lib/rules/no-space-before-semi.js b/tools/eslint/lib/rules/no-space-before-semi.js
new file mode 100644
index 0000000000..33926741e0
--- /dev/null
+++ b/tools/eslint/lib/rules/no-space-before-semi.js
@@ -0,0 +1,96 @@
+/**
+ * @fileoverview Rule to disallow whitespace before the semicolon
+ * @author Jonathan Kingston
+ * @copyright 2015 Mathias Schreck
+ * @copyright 2014 Jonathan Kingston
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+
+    /**
+     * Determines whether two adjacent tokens are have whitespace between them.
+     * @param {Object} left - The left token object.
+     * @param {Object} right - The right token object.
+     * @returns {boolean} Whether or not there is space between the tokens.
+     */
+    function isSpaced(left, right) {
+        return left.range[1] < right.range[0];
+    }
+
+    /**
+     * Checks whether two tokens are on the same line.
+     * @param {Object} left The leftmost token.
+     * @param {Object} right The rightmost token.
+     * @returns {boolean} True if the tokens are on the same line, false if not.
+     * @private
+     */
+    function isSameLine(left, right) {
+        return left.loc.end.line === right.loc.start.line;
+    }
+
+    /**
+     * Checks if a given token has leading whitespace.
+     * @param {Object} token The token to check.
+     * @returns {boolean} True if the given token has leading space, false if not.
+     */
+    function hasLeadingSpace(token) {
+        var tokenBefore = context.getTokenBefore(token);
+        return isSameLine(tokenBefore, token) && isSpaced(tokenBefore, token);
+    }
+
+    /**
+     * Checks if the given token is a semicolon.
+     * @param {Token} token The token to check.
+     * @returns {boolean} Whether or not the given token is a semicolon.
+     */
+    function isSemicolon(token) {
+        return token.type === "Punctuator" && token.value === ";";
+    }
+
+    /**
+     * Reports if the given token has leading space.
+     * @param {Token} token The semicolon token to check.
+     * @param {ASTNode} node The corresponding node of the token.
+     * @returns {void}
+     */
+    function checkSemiTokenForLeadingSpace(token, node) {
+        if (isSemicolon(token) && hasLeadingSpace(token)) {
+            context.report(node, token.loc.start, "Unexpected whitespace before semicolon.");
+        }
+    }
+
+    /**
+     * Checks leading space before the semicolon with the assumption that the last token is the semicolon.
+     * @param {ASTNode} node The node to check.
+     * @returns {void}
+     */
+    function checkNode(node) {
+        var token = context.getLastToken(node);
+        checkSemiTokenForLeadingSpace(token, node);
+    }
+
+    return {
+        "VariableDeclaration": checkNode,
+        "ExpressionStatement": checkNode,
+        "BreakStatement": checkNode,
+        "ContinueStatement": checkNode,
+        "DebuggerStatement": checkNode,
+        "ReturnStatement": checkNode,
+        "ThrowStatement": checkNode,
+        "ForStatement": function (node) {
+            if (node.init) {
+                checkSemiTokenForLeadingSpace(context.getTokenAfter(node.init), node);
+            }
+
+            if (node.test) {
+                checkSemiTokenForLeadingSpace(context.getTokenAfter(node.test), node);
+            }
+        }
+    };
+};