refactor task running on save (#2384)

Author: rchl

plugin/save_command.py

@@ -1,7 +1,8 @@
 from .core.registry import LspTextCommand
 from .core.settings import userprefs
-from .core.typing import Any, Callable, Dict, List, Type
+from .core.typing import Any, Callable, Dict, List, Optional, Type
 from abc import ABCMeta, abstractmethod
+from functools import partial
 import sublime
 import sublime_plugin
 
@@ -60,6 +61,47 @@ def _purge_changes_async(self) -> None:
                 break
 
 
+class SaveTasksRunner:
+    def __init__(
+        self, text_command: LspTextCommand, tasks: List[Type[SaveTask]], on_complete: Callable[[], None]
+    ) -> None:
+        self._text_command = text_command
+        self._tasks = tasks
+        self._on_tasks_completed = on_complete
+        self._pending_tasks = []  # type: List[SaveTask]
+        self._canceled = False
+
+    def run(self) -> None:
+        for task in self._tasks:
+            if task.is_applicable(self._text_command.view):
+                self._pending_tasks.append(task(self._text_command, self._on_task_completed_async))
+        self._process_next_task()
+
+    def cancel(self) -> None:
+        for task in self._pending_tasks:
+            task.cancel()
+        self._pending_tasks = []
+        self._canceled = True
+
+    def _process_next_task(self) -> None:
+        if self._pending_tasks:
+            # Even though we might be on an async thread already, we want to give ST a chance to notify us about
+            # potential document changes.
+            sublime.set_timeout_async(self._run_next_task_async)
+        else:
+            self._on_tasks_completed()
+
+    def _run_next_task_async(self) -> None:
+        if self._canceled:
+            return
+        current_task = self._pending_tasks[0]
+        current_task.run_async()
+
+    def _on_task_completed_async(self) -> None:
+        self._pending_tasks.pop(0)
+        self._process_next_task()
+
+
 class LspSaveCommand(LspTextCommand):
     """
     A command used as a substitute for native save command. Runs code actions and document
@@ -74,23 +116,14 @@ def register_task(cls, task: Type[SaveTask]) -> None:
 
     def __init__(self, view: sublime.View) -> None:
         super().__init__(view)
-        self._pending_tasks = []  # type: List[SaveTask]
-        self._kwargs = {}  # type: Dict[str, Any]
+        self._save_tasks_runner = None  # type: Optional[SaveTasksRunner]
 
     def run(self, edit: sublime.Edit, **kwargs: Dict[str, Any]) -> None:
-        if self._pending_tasks:
-            for task in self._pending_tasks:
-                task.cancel()
-            self._pending_tasks = []
-        self._kwargs = kwargs
+        if self._save_tasks_runner:
+            self._save_tasks_runner.cancel()
         sublime.set_timeout_async(self._trigger_on_pre_save_async)
-        for Task in self._tasks:
-            if Task.is_applicable(self.view):
-                self._pending_tasks.append(Task(self, self._on_task_completed_async))
-        if self._pending_tasks:
-            sublime.set_timeout_async(self._run_next_task_async)
-        else:
-            self._trigger_native_save()
+        self._save_tasks_runner = SaveTasksRunner(self, self._tasks, partial(self._on_tasks_completed, kwargs))
+        self._save_tasks_runner.run()
 
     def _trigger_on_pre_save_async(self) -> None:
         # Supermassive hack that will go away later.
@@ -100,22 +133,10 @@ def _trigger_on_pre_save_async(self) -> None:
                 listener.trigger_on_pre_save_async()  # type: ignore
                 break
 
-    def _run_next_task_async(self) -> None:
-        current_task = self._pending_tasks[0]
-        current_task.run_async()
-
-    def _on_task_completed_async(self) -> None:
-        self._pending_tasks.pop(0)
-        if self._pending_tasks:
-            # Even though we are on the async thread already, we want to give ST a chance to notify us about
-            # potential document changes.
-            sublime.set_timeout_async(self._run_next_task_async)
-        else:
-            self._trigger_native_save()
-
-    def _trigger_native_save(self) -> None:
+    def _on_tasks_completed(self, kwargs: Dict[str, Any]) -> None:
+        self._save_tasks_runner = None
         # Triggered from set_timeout to preserve original semantics of on_pre_save handling
-        sublime.set_timeout(lambda: self.view.run_command('save', self._kwargs))
+        sublime.set_timeout(lambda: self.view.run_command('save', kwargs))
 
 
 class LspSaveAllCommand(sublime_plugin.WindowCommand):