Remove iterators from IDecorationService

They're too low performance for typical use cases

Fixes #4079

src/common/TestUtils.test.ts

@@ -161,8 +161,6 @@ export class MockDecorationService implements IDecorationService {
   public onDecorationRemoved = new EventEmitter<IInternalDecoration>().event;
   public registerDecoration(decorationOptions: IDecorationOptions): IDecoration | undefined { return undefined; }
   public reset(): void { }
-  public *getDecorationsAtLine(line: number): IterableIterator<IInternalDecoration> { }
-  public *getDecorationsAtCell(x: number, line: number): IterableIterator<IInternalDecoration> { }
   public forEachDecorationAtCell(x: number, line: number, layer: 'bottom' | 'top' | undefined, callback: (decoration: IInternalDecoration) => void): void { }
   public dispose(): void { }
 }

src/common/services/DecorationService.ts

@@ -62,10 +62,6 @@ export class DecorationService extends Disposable implements IDecorationService
     this._decorations.clear();
   }
 
-  public *getDecorationsAtLine(line: number): IterableIterator<IInternalDecoration> {
-    return this._decorations.getKeyIterator(line);
-  }
-
   public *getDecorationsAtCell(x: number, line: number, layer?: 'bottom' | 'top'): IterableIterator<IInternalDecoration> {
     let xmin = 0;
     let xmax = 0;

src/common/services/Services.ts

@@ -304,13 +304,9 @@ export interface IDecorationService extends IDisposable {
   readonly onDecorationRemoved: IEvent<IInternalDecoration>;
   registerDecoration(decorationOptions: IDecorationOptions): IDecoration | undefined;
   reset(): void;
-  /** Iterates over the decorations at a line (in no particular order). */
-  getDecorationsAtLine(line: number): IterableIterator<IInternalDecoration>;
-  /** Iterates over the decorations at a cell (in no particular order). */
-  getDecorationsAtCell(x: number, line: number, layer?: 'bottom' | 'top'): IterableIterator<IInternalDecoration>;
   /**
-   * Trigger a callback over the decoration at a cell (in no particular order). This is a high
-   * performance, but less ergonomic, version of {@link getDecorationsAtCell}.
+   * Trigger a callback over the decoration at a cell (in no particular order). This uses a callback
+   * instead of an iterator as it's typically used in hot code paths.
    */
   forEachDecorationAtCell(x: number, line: number, layer: 'bottom' | 'top' | undefined, callback: (decoration: IInternalDecoration) => void): void;
 }