Stub for DocumentPaste proposed API.

The immediate goal was for for the vscode built-in extension
`markdown-language-features` v1.72.2 (and a few prevgious I think),
to work again (minus the real "DocumentPaste" benefits.

Fixes eclipse-theia#12430

Signed-off-by: Marc Dumais <marc.dumais@ericsson.com>

packages/plugin-ext/src/plugin/languages.ts

@@ -999,6 +999,13 @@ export class LanguagesExtImpl implements LanguagesExt {
         return result;
     }
     // #endregion
+
+    // Stub implementation
+    registerDocumentPasteEditProvider(
+        extension: Plugin, selector: theia.DocumentSelector, provider: theia.DocumentPasteEditProvider, metadata: theia.DocumentPasteProviderMetadata
+    ): theia.Disposable {
+        return Disposable.NULL;
+    }
 }
 
 function getPluginLabel(pluginInfo: PluginInfo): string {

packages/plugin-ext/src/plugin/plugin-context.ts

@@ -191,7 +191,8 @@ import {
     TerminalEditorTabInput,
     TextDiffTabInput,
     TextMergeTabInput,
-    WebviewEditorTabInput
+    WebviewEditorTabInput,
+    DocumentPasteEdit
 } from './types-impl';
 import { AuthenticationExtImpl } from './authentication-ext';
 import { SymbolKind } from '../common/plugin-api-rpc-model';
@@ -918,6 +919,11 @@ export function createAPIFactory(
             },
             createLanguageStatusItem(id: string, selector: theia.DocumentSelector): theia.LanguageStatusItem {
                 return languagesExt.createLanguageStatusItem(plugin, id, selector);
+            },
+            registerDocumentPasteEditProvider(
+                selector: theia.DocumentSelector, provider: theia.DocumentPasteEditProvider, metadata: theia.DocumentPasteProviderMetadata
+            ): theia.Disposable {
+                return languagesExt.registerDocumentPasteEditProvider(plugin, selector, provider, metadata);
             }
         };
 
@@ -1336,7 +1342,8 @@ export function createAPIFactory(
             TabInputWebview: WebviewEditorTabInput,
             TabInputTerminal: TerminalEditorTabInput,
             TerminalLocation,
-            TerminalExitReason
+            TerminalExitReason,
+            DocumentPasteEdit
         };
     };
 }

packages/plugin-ext/src/plugin/types-impl.ts

@@ -3429,3 +3429,14 @@ export class InteractiveWindowInput {
 }
 
 // #endregion
+
+// #region DocumentPaste
+@es5ClassCompat
+export class DocumentPasteEdit {
+    constructor(insertText: string | SnippetString) {
+        this.insertText = insertText;
+    }
+    insertText: string | SnippetString;
+    additionalEdit?: WorkspaceEdit;
+}
+// #endregion

packages/plugin/src/theia-proposed.d.ts

@@ -613,6 +613,78 @@ export module '@theia/plugin' {
 
     }
 
+    // https://github.com/microsoft/vscode/issues/30066/
+
+    /**
+     * Provider invoked when the user copies and pastes code.
+     */
+    export interface DocumentPasteEditProvider {
+
+        /**
+         * Optional method invoked after the user copies text in a file.
+         *
+         * During {@link prepareDocumentPaste}, an extension can compute metadata that is attached to
+         * a {@link DataTransfer} and is passed back to the provider in {@link provideDocumentPasteEdits}.
+         *
+         * @param document Document where the copy took place.
+         * @param ranges Ranges being copied in the `document`.
+         * @param dataTransfer The data transfer associated with the copy. You can store additional values on this for later use in  {@link provideDocumentPasteEdits}.
+         * @param token A cancellation token.
+         */
+        prepareDocumentPaste?(document: TextDocument, ranges: readonly Range[], dataTransfer: DataTransfer, token: CancellationToken): void | Thenable<void>;
+
+        /**
+         * Invoked before the user pastes into a document.
+         *
+         * In this method, extensions can return a workspace edit that replaces the standard pasting behavior.
+         *
+         * @param document Document being pasted into
+         * @param ranges Currently selected ranges in the document.
+         * @param dataTransfer The data transfer associated with the paste.
+         * @param token A cancellation token.
+         *
+         * @return Optional workspace edit that applies the paste. Return undefined to use standard pasting.
+         */
+        provideDocumentPasteEdits(document: TextDocument, ranges: readonly Range[], dataTransfer: DataTransfer, token: CancellationToken): ProviderResult<DocumentPasteEdit>;
+    }
+
+    /**
+     * An operation applied on paste
+     */
+    class DocumentPasteEdit {
+        /**
+         * The text or snippet to insert at the pasted locations.
+         */
+        insertText: string | SnippetString;
+
+        /**
+         * An optional additional edit to apply on paste.
+         */
+        additionalEdit?: WorkspaceEdit;
+
+        /**
+         * @param insertText The text or snippet to insert at the pasted locations.
+         */
+        constructor(insertText: string | SnippetString);
+    }
+
+    interface DocumentPasteProviderMetadata {
+        /**
+         * Mime types that `provideDocumentPasteEdits` should be invoked for.
+         *
+         * Use the special `files` mimetype to indicate the provider should be invoked if any files are present in the `DataTransfer`.
+         */
+        readonly pasteMimeTypes: readonly string[];
+    }
+
+    namespace languages {
+        export function registerDocumentPasteEditProvider(selector: DocumentSelector, provider: DocumentPasteEditProvider, metadata: DocumentPasteProviderMetadata): Disposable;
+    }
+
+    // export namespace languages {
+    //     export function registerDocumentPasteEditProvider(selector: DocumentSelector, provider: DocumentPasteEditProvider, metadata: DocumentPasteProviderMetadata): Disposable;
+    // }
+
     // #endregion
 }