Add handler for editor/closeFile request

This change adds a handler for the editor/closeFile request which is part
of the editor extensibility model of PowerShell Editor Services.  This
request currently gets fired when the user exits a remote debugging
session where a remote file had been opened.  It will later be exposed
through the $psEditor API.

Author: daviwil

src/features/ExtensionCommands.ts

@@ -122,6 +122,11 @@ export namespace OpenFileRequest {
         { get method() { return 'editor/openFile'; } };
 }
 
+export namespace CloseFileRequest {
+    export const type: RequestType<string, EditorOperationResponse, void> =
+        { get method() { return 'editor/closeFile'; } };
+}
+
 export namespace ShowErrorMessageRequest {
     export const type: RequestType<string, EditorOperationResponse, void> =
         { get method() { return 'editor/showErrorMessage'; } };
@@ -198,6 +203,10 @@ export class ExtensionCommandsFeature implements IFeature {
                 OpenFileRequest.type,
                 filePath => this.openFile(filePath));
 
+            this.languageClient.onRequest(
+                CloseFileRequest.type,
+                filePath => this.closeFile(filePath));
+
             this.languageClient.onRequest(
                 ShowInformationMessageRequest.type,
                 message => this.showInformationMessage(message));
@@ -317,6 +326,37 @@ export class ExtensionCommandsFeature implements IFeature {
         return promise;
     }
 
+    private closeFile(filePath: string): Thenable<EditorOperationResponse> {
+
+        var promise: Thenable<EditorOperationResponse>;
+
+        // Make sure the file path is absolute
+        if (!path.win32.isAbsolute(filePath))
+        {
+            filePath = path.win32.resolve(
+                vscode.workspace.rootPath,
+                filePath);
+        }
+
+        // Normalize file path case for comparison
+        var normalizedFilePath = filePath.toLowerCase();
+
+        if (vscode.workspace.textDocuments.find(doc => doc.fileName.toLowerCase() == normalizedFilePath))
+        {
+            promise =
+                vscode.workspace.openTextDocument(filePath)
+                    .then(doc => vscode.window.showTextDocument(doc))
+                    .then(editor => vscode.commands.executeCommand("workbench.action.closeActiveEditor"))
+                    .then(_ => EditorOperationResponse.Completed);
+        }
+        else
+        {
+            promise = Promise.resolve(EditorOperationResponse.Completed);
+        }
+
+        return promise;
+    }
+
     private setSelection(details: SetSelectionRequestArguments): EditorOperationResponse {
         vscode.window.activeTextEditor.selections = [
             new vscode.Selection(