add .Save() to FileContext API

Author: TylerLeonhardt

src/features/ExtensionCommands.ts

@@ -140,6 +140,12 @@ export namespace CloseFileRequest {
             'editor/closeFile');
 }
 
+export namespace SaveFileRequest {
+    export const type =
+        new RequestType<string, EditorOperationResponse, void, void>(
+            'editor/saveFile');
+}
+
 export namespace ShowErrorMessageRequest {
     export const type =
         new RequestType<string, EditorOperationResponse, void, void>(
@@ -239,14 +245,18 @@ export class ExtensionCommandsFeature implements IFeature {
 		        NewFileRequest.type,
                 filePath => this.newFile());
 
-              this.languageClient.onRequest(
+            this.languageClient.onRequest(
                 OpenFileRequest.type,
                 filePath => this.openFile(filePath));
 
             this.languageClient.onRequest(
                 CloseFileRequest.type,
                 filePath => this.closeFile(filePath));
 
+            this.languageClient.onRequest(
+                SaveFileRequest.type,
+                filePath => this.saveFile(filePath));
+
             this.languageClient.onRequest(
                 ShowInformationMessageRequest.type,
                 message => this.showInformationMessage(message));
@@ -408,6 +418,36 @@ export class ExtensionCommandsFeature implements IFeature {
         return promise;
     }
 
+    private saveFile(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 => doc.save())
+                    .then(_ => EditorOperationResponse.Completed);
+        }
+        else
+        {
+            promise = Promise.resolve(EditorOperationResponse.Completed);
+        }
+
+        return promise;
+    }
+
     private setSelection(details: SetSelectionRequestArguments): EditorOperationResponse {
         vscode.window.activeTextEditor.selections = [
             new vscode.Selection(