tools: replace closure-linter with eslint

PR-URL: https://github.com/iojs/io.js/pull/1539
Fixes: https://github.com/iojs/io.js/issues/1253
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/tools/eslint/lib/rules/no-unreachable.js b/tools/eslint/lib/rules/no-unreachable.js
new file mode 100644
index 0000000000..6606b6adae
--- /dev/null
+++ b/tools/eslint/lib/rules/no-unreachable.js
@@ -0,0 +1,96 @@
+/**
+ * @fileoverview Checks for unreachable code due to return, throws, break, and continue.
+ * @author Joel Feenstra
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+
+function report(context, node, unreachableType) {
+    var keyword;
+    switch (unreachableType) {
+        case "BreakStatement":
+            keyword = "break";
+            break;
+        case "ContinueStatement":
+            keyword = "continue";
+            break;
+        case "ReturnStatement":
+            keyword = "return";
+            break;
+        case "ThrowStatement":
+            keyword = "throw";
+            break;
+        default:
+            return;
+    }
+    context.report(node, "Found unexpected statement after a {{type}}.", { type: keyword });
+}
+
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+
+    /**
+     * Checks if a node is an exception for no-unreachable because of variable/function hoisting
+     * @param {ASTNode} node The AST node to check.
+     * @returns {boolean} if the node doesn't trigger unreachable
+     * @private
+     */
+    function isUnreachableAllowed(node) {
+        return node.type === "FunctionDeclaration" ||
+            node.type === "VariableDeclaration" &&
+            node.declarations.every(function(declaration) {
+                return declaration.type === "VariableDeclarator" && declaration.init === null;
+            });
+    }
+
+    /*
+     * Verifies that the given node is the last node or followed exclusively by
+     * hoisted declarations
+     * @param {ASTNode} node Node that should be the last node
+     * @returns {void}
+     * @private
+     */
+    function checkNode(node) {
+        var parent = context.getAncestors().pop();
+        var field, i, sibling;
+
+        switch (parent.type) {
+            case "SwitchCase":
+                field = "consequent";
+                break;
+            case "Program":
+            case "BlockStatement":
+                field = "body";
+                break;
+            default:
+                return;
+        }
+
+        for (i = parent[field].length - 1; i >= 0; i--) {
+            sibling = parent[field][i];
+            if (sibling === node) {
+                return; // Found the last reachable statement, all done
+            }
+
+            if (!isUnreachableAllowed(sibling)) {
+                report(context, sibling, node.type);
+            }
+        }
+    }
+
+    return {
+        "ReturnStatement": checkNode,
+        "ThrowStatement": checkNode,
+        "ContinueStatement": checkNode,
+        "BreakStatement": checkNode
+    };
+
+};