1 files changed, 90 insertions, 0 deletions
diff --git a/devtools/client/debugger/src/actions/utils/middleware/context.js b/devtools/client/debugger/src/actions/utils/middleware/context.js
new file mode 100644
index 0000000000..00711a8c3f
--- /dev/null
+++ b/devtools/client/debugger/src/actions/utils/middleware/context.js
@@ -0,0 +1,90 @@
+/* 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/>. */
+
+import {
+  validateNavigateContext,
+  validateContext,
+  validateSelectedFrame,
+  validateBreakpoint,
+  validateSource,
+  validateSourceActor,
+  validateThreadFrames,
+  validateFrame,
+} from "../../../utils/context";
+
+function validateActionContext(getState, action) {
+  if (action.type == "COMMAND" && action.status == "done") {
+    // The thread will have resumed execution since the action was initiated,
+    // so just make sure we haven't navigated.
+    validateNavigateContext(getState(), action.cx);
+    return;
+  }
+
+  // Validate using all available information in the context.
+  validateContext(getState(), action.cx);
+}
+
+// Middleware which looks for actions that have a cx property and ignores
+// them if the context is no longer valid.
+function context({ dispatch, getState }) {
+  return next => action => {
+    if ("cx" in action) {
+      validateActionContext(getState, action);
+    }
+
+    // Validate actions specific to a Source object.
+    // This will throw if the source has been removed,
+    // i.e. when the source has been removed from all the threads where it existed.
+    if ("source" in action) {
+      validateSource(getState(), action.source);
+    }
+
+    // Validate actions specific to a Source Actor object.
+    // This will throw if the source actor has been removed,
+    // i.e. when the source actor's thread has been removed.
+    if ("sourceActor" in action) {
+      validateSourceActor(getState(), action.sourceActor);
+    }
+
+    // Similar to sourceActor assertion, but with a distinct attribute name
+    if ("generatedSourceActor" in action) {
+      validateSourceActor(getState(), action.generatedSourceActor);
+    }
+
+    // Validate actions specific to a given breakpoint.
+    // This will throw if the breakpoint's location is obsolete.
+    // i.e. when the related source has been removed.
+    if ("breakpoint" in action) {
+      validateBreakpoint(getState(), action.breakpoint);
+    }
+
+    // Validate actions specific to the currently selected paused frame.
+    // It will throw if we resumed or moved to another frame in the call stack.
+    //
+    // Ignore falsy selectedFrame as sometimes it can be null
+    // for expression actions.
+    if (action.selectedFrame) {
+      validateSelectedFrame(getState(), action.selectedFrame);
+    }
+
+    // Validate actions specific to a given pause location.
+    // This will throw if we resumed or paused in another location.
+    // Compared to selected frame, this would not throw if we moved to another frame in the call stack.
+    if ("thread" in action && "frames" in action) {
+      validateThreadFrames(getState(), action.thread, action.frames);
+    }
+
+    // Validate actions specific to a given frame while being paused.
+    // This will throw if we resumed or paused in another location.
+    // But compared to selected frame, this would not throw if we moved to another frame in the call stack.
+    // This ends up being similar to "pause location" case, but with different arguments.
+    if ("frame" in action) {
+      validateFrame(getState(), action.frame);
+    }
+
+    return next(action);
+  };
+}
+
+export { context };