Checkpoint web parity through Chromium input tasks

web/protocol/ime-composition.ts

@@ -0,0 +1,34 @@
+export const IME_COMPOSITION_SCHEMA_VERSION = 1 as const;
+
+export interface IMECompositionState {
+  schemaVersion: typeof IME_COMPOSITION_SCHEMA_VERSION;
+  composing: boolean;
+  revision: number;
+  pendingText: string;
+  lastEvent: "IDLE" | "START" | "UPDATE" | "END";
+}
+
+export type IMECompositionEvent =
+  | { type: "compositionstart"; data?: string }
+  | { type: "compositionupdate"; data?: string }
+  | { type: "compositionend"; data?: string };
+
+export function createIMECompositionState(): IMECompositionState {
+  return { schemaVersion: IME_COMPOSITION_SCHEMA_VERSION, composing: false, revision: 0, pendingText: "", lastEvent: "IDLE" };
+}
+
+export function reduceIMEComposition(state: IMECompositionState, event: IMECompositionEvent): IMECompositionState {
+  if (!state || state.schemaVersion !== IME_COMPOSITION_SCHEMA_VERSION) throw new Error("IME_STATE_INVALID");
+  const text = typeof event.data === "string" ? event.data : "";
+  if (event.type === "compositionstart") return { schemaVersion: 1, composing: true, revision: state.revision + 1, pendingText: text, lastEvent: "START" };
+  if (event.type === "compositionupdate") {
+    if (!state.composing) return state;
+    return { schemaVersion: 1, composing: true, revision: state.revision + 1, pendingText: text, lastEvent: "UPDATE" };
+  }
+  return { schemaVersion: 1, composing: false, revision: state.revision + 1, pendingText: text, lastEvent: "END" };
+}
+
+export function shouldBlockOperatorShortcuts(state: IMECompositionState, eventIsComposing = false): boolean {
+  if (!state || state.schemaVersion !== IME_COMPOSITION_SCHEMA_VERSION) throw new Error("IME_STATE_INVALID");
+  return state.composing || eventIsComposing;
+}