Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 121 insertions, 0 deletions

diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/balanced-observers.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/balanced-observers.js
new file mode 100644
index 0000000000..854fbc9a63
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/balanced-observers.js
@@ -0,0 +1,121 @@
+/**
+ * @fileoverview Check that there's a Services.(prefs|obs).removeObserver for
+ * each addObserver.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+"use strict";
+
+module.exports = {
+  meta: {
+    docs: {
+      url: "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/rules/balanced-observers.html",
+    },
+    messages: {
+      noCorresponding:
+        "No corresponding 'removeObserver(\"{{observable}}\")' was found.",
+    },
+    schema: [],
+    type: "problem",
+  },
+
+  create(context) {
+    var addedObservers = [];
+    var removedObservers = [];
+
+    function getObserverAPI(node) {
+      const object = node.callee.object;
+      if (
+        object.type == "MemberExpression" &&
+        object.property.type == "Identifier"
+      ) {
+        return object.property.name;
+      }
+      return null;
+    }
+
+    function isServicesObserver(api) {
+      return api == "obs" || api == "prefs";
+    }
+
+    function getObservableName(node, api) {
+      if (api === "obs") {
+        return node.arguments[1].value;
+      }
+      return node.arguments[0].value;
+    }
+
+    function addAddedObserver(node) {
+      const api = getObserverAPI(node);
+      if (!isServicesObserver(api)) {
+        return;
+      }
+
+      addedObservers.push({
+        functionName: node.callee.property.name,
+        observable: getObservableName(node, api),
+        node: node.callee.property,
+      });
+    }
+
+    function addRemovedObserver(node) {
+      const api = getObserverAPI(node);
+      if (!isServicesObserver(api)) {
+        return;
+      }
+
+      removedObservers.push({
+        functionName: node.callee.property.name,
+        observable: getObservableName(node, api),
+      });
+    }
+
+    function getUnbalancedObservers() {
+      const unbalanced = addedObservers.filter(
+        observer => !hasRemovedObserver(observer)
+      );
+      addedObservers = removedObservers = [];
+
+      return unbalanced;
+    }
+
+    function hasRemovedObserver(addedObserver) {
+      return removedObservers.some(
+        observer => addedObserver.observable === observer.observable
+      );
+    }
+
+    return {
+      CallExpression(node) {
+        if (node.arguments.length === 0) {
+          return;
+        }
+
+        if (node.callee.type === "MemberExpression") {
+          var methodName = node.callee.property.name;
+
+          if (methodName === "addObserver") {
+            addAddedObserver(node);
+          } else if (methodName === "removeObserver") {
+            addRemovedObserver(node);
+          }
+        }
+      },
+
+      "Program:exit": function () {
+        getUnbalancedObservers().forEach(function (observer) {
+          context.report({
+            node: observer.node,
+            messageId: "noCorresponding",
+            data: {
+              observable: observer.observable,
+            },
+          });
+        });
+      },
+    };
+  },
+};