allow to register for the same scheme twice. lifo behaviour

src/vs/workbench/common/editor/resourceEditorInput.ts

@@ -5,6 +5,7 @@
 'use strict';
 
 import {TPromise} from 'vs/base/common/winjs.base';
+import {sequence} from 'vs/base/common/async';
 import {EditorModel, EditorInput} from 'vs/workbench/common/editor';
 import {ResourceEditorModel} from 'vs/workbench/common/editor/resourceEditorModel';
 import {IModel} from 'vs/editor/common/editorCommon';
@@ -31,11 +32,28 @@ export class ResourceEditorInput extends EditorInput {
 	// todo@joh,ben this should maybe be a service that is in charge of loading/resolving a uri from a scheme
 
 	private static loadingModels: { [uri: string]: TPromise<IModel> } = Object.create(null);
-	private static registry: { [scheme: string]: IResourceEditorContentProvider } = Object.create(null);
+	private static registry: { [scheme: string]: IResourceEditorContentProvider[] } = Object.create(null);
 
 	public static registerResourceContentProvider(scheme: string, provider: IResourceEditorContentProvider): IDisposable {
-		ResourceEditorInput.registry[scheme] = provider;
-		return { dispose() { delete ResourceEditorInput.registry[scheme] } };
+		let array = ResourceEditorInput.registry[scheme];
+		if (!array) {
+			array = [provider];
+			ResourceEditorInput.registry[scheme] = array;
+		} else {
+			array.unshift(provider);
+		}
+		return {
+			dispose() {
+				let array = ResourceEditorInput.registry[scheme];
+				let idx = array.indexOf(provider);
+				if (idx >= 0) {
+					array.splice(idx, 1);
+					if (array.length === 0) {
+						delete ResourceEditorInput.registry[scheme];
+					}
+				}
+			}
+		};
 	}
 
 	private static getOrCreateModel(modelService: IModelService, resource: URI): TPromise<IModel> {
@@ -49,8 +67,8 @@ export class ResourceEditorInput extends EditorInput {
 
 			// make sure we have a provider this scheme
 			// the resource uses
-			const provider = ResourceEditorInput.registry[resource.scheme];
-			if (!provider) {
+			const array = ResourceEditorInput.registry[resource.scheme];
+			if (!array) {
 				return TPromise.wrapError(`No model with uri '${resource}' nor a resolver for the scheme '${resource.scheme}'.`);
 			}
 
@@ -59,7 +77,26 @@ export class ResourceEditorInput extends EditorInput {
 			// twice
 			ResourceEditorInput.loadingModels[resource.toString()] = loadingModel = new TPromise<IModel>((resolve, reject) => {
 
-				provider.provideTextContent(resource).then(resolve, reject);
+				let result: IModel;
+				let lastError: any;
+
+				sequence(array.map(provider => {
+					return () => {
+						if (!result) {
+							return provider.provideTextContent(resource).then(value => {
+								result = value;
+							}, err => {
+								lastError = err;
+							});
+						}
+					}
+				})).then(() => {
+					if (!result && lastError) {
+						reject(lastError);
+					} else {
+						resolve(result);
+					}
+				}, reject);
 
 			}, function() {
 				// no cancellation when caching promises