Add API Documentation in core package

* Document 'BackendContribution'
* Document 'MessageService' and related message interfaces
* Extend documentation of MenuContribution and related menu interfaces
and classes
* Document 'PreferenceService', 'PreferenceProxy' and related
interfaces, classes and functions

Signed-off-by: Stefan Dirix <sdirix@eclipsesource.com>
Contributed on behalf of STMicroelectronics

packages/core/src/browser/preferences/preference-proxy.ts

@@ -33,21 +33,104 @@ export interface PreferenceEventEmitter<T> {
     readonly ready: Promise<void>;
 }
 
+/**
+ * Generic interface to declare a typesafe get function based on the given
+ * configuration type.
+ * 
+ * ### Example
+ * 
+ * ```typescript
+ * interface PreferenceConfiguration {
+ *  'myext.decorations.enabled': boolean,
+ *  'myext.debug': boolean,
+ *  'myext.editor.previewtype': string
+ * }
+ * const prefs : PreferenceRetrieval<PreferenceConfiguration> = createPreferenceProxy(...);
+ * const enabled : boolean = prefs.get('myext.decorations.enabled'); // valid
+ * const debug : string = prefs.get('myext.debug'); // invalid
+ * prefs.get('foobar'); // invalid
+ * ```
+ */
 export interface PreferenceRetrieval<T> {
     get<K extends keyof T>(preferenceName: K | {
         preferenceName: K,
         overrideIdentifier?: string
     }, defaultValue?: T[K], resourceUri?: string): T[K];
 }
 
+/**
+ * Typesafe schema-based preferences utility based on the {@link PreferenceService}.
+ * 
+ * Can be used to set and get preferences as well as listen to preference changes.
+ * 
+ * ### Example usage
+ * 
+ * ``` typescript
+ * const MyPreferencesSchema: PreferenceSchema = {
+ *   'type': 'object',
+ *   'properties': {
+ *       'myext.decorations.enabled': {
+ *           'type': 'boolean',
+ *           'description': 'Show file status',
+ *           'default': true
+ *       },
+ *       // [...]
+ *    }
+ * }
+ * 
+ * interface MyPrefConfiguration {
+ *   'myext.decorations.enabled': boolean;
+ * }
+ * 
+ * type MyPreferences = PreferenceProxy<MyPrefConfiguration>;
+ * 
+ * const preferences : MyPreferences = createPreferenceProxy(preferenceService, MyPreferenceSchema);
+ * 
+ * preferences.onPreferenceChanged(({ preferenceName, newValue }) => { console.log(preferenceName, newValue) });
+ * const enabled = preferences['myext.decorations.enabled'];
+ * ```
+ * 
+ */
 export type PreferenceProxy<T> = Readonly<T> & Disposable & PreferenceEventEmitter<T> & PreferenceRetrieval<T>;
+/**
+ * Proxy configuration parameters.
+ */
 export interface PreferenceProxyOptions {
+    /**
+     * Prefix which is transparently added to all preference identifiers.
+     */
     prefix?: string;
+    /**
+     * The default resourceUri to use if none was specified when calling "set" or "get".
+     */
     resourceUri?: string;
+    /**
+     * The overrideIdentifier to use with the underlying preferenceService.
+     * Useful to potentially override existing values while keeping both values in store.
+     * 
+     * For example to store different editor settings, e.g. "[markdown].editor.autoIndent",
+     * "[json].editor.autoIndent" and "editor.autoIndent" 
+     */
     overrideIdentifier?: string;
+    /**
+     * Indicates whether '.' in schema properties shall be interpreted as regular names (flat),
+     * as declaring nested objects (deep) or both. Default is flat.
+     * 
+     * When 'deep' or 'both' is given, nested preference proxies can be retrieved.
+     */
     style?: 'flat' | 'deep' | 'both';
 }
 
+/**
+ * Creates a preference proxy for typesafe preference handling.
+ * 
+ * @param preferences the underlying preference service to use for preference handling. 
+ * @param schema the JSON Schema which describes which preferences are available including types and descriptions.
+ * @param options configuration options.
+ * 
+ * @returns the created preference proxy.
+ * 
+ */
 export function createPreferenceProxy<T>(preferences: PreferenceService, schema: PreferenceSchema, options?: PreferenceProxyOptions): PreferenceProxy<T> {
     const opts = options || {};
     const prefix = opts.prefix || '';

packages/core/src/browser/preferences/preference-service.ts

@@ -66,34 +66,163 @@ export interface PreferenceChanges {
 }
 
 export const PreferenceService = Symbol('PreferenceService');
+/**
+ * Service to store and retrieve preference values.
+ * 
+ * Depending on your use case you might also want to look at `createPreferenceProxy` with which
+ * you can easily create a typesafe schema-based interface for your preferences. Internally the proxy
+ * uses the PreferenceService so both approaches are compatible.
+ */
 export interface PreferenceService extends Disposable {
     readonly ready: Promise<void>;
+    /**
+     * Retrieve the stored value for the given preference.
+     * 
+     * @param preferenceName the preference identifier.
+     * 
+     * @returns the value stored for the given preference when it exists, `undefined` otherwise.
+     */
     get<T>(preferenceName: string): T | undefined;
+    /**
+     * Retrieve the stored value for the given preference.
+     * 
+     * @param preferenceName the preference identifier.
+     * @param defaultValue the value to return when no value for the given preference is stored.
+     * 
+     * @returns the value stored for the given preference when it exists, otherwise the given default value.
+     */
     get<T>(preferenceName: string, defaultValue: T): T;
+    /**
+     * Retrieve the stored value for the given preference and resourceUri.
+     * 
+     * @param preferenceName the preference identifier.
+     * @param defaultValue the value to return when no value for the given preference is stored.
+     * @param resourceUri the uri of the resource for which the preference is stored. This used to retrieve
+     * a potentially different value for the same preference for different resources, for example `files.encoding`.
+     * 
+     * @returns the value stored for the given preference and resourceUri when it exists, otherwise the given
+     * default value.
+     */
     get<T>(preferenceName: string, defaultValue: T, resourceUri?: string): T;
+    /**
+     * Retrieve the stored value for the given preference and resourceUri.
+     * 
+     * @param preferenceName the preference identifier.
+     * @param defaultValue the value to return when no value for the given preference is stored.
+     * @param resourceUri the uri of the resource for which the preference is stored. This used to retrieve
+     * a potentially different value for the same preference for different resources, for example `files.encoding`.
+     * 
+     * @returns the value stored for the given preference and resourceUri when it exists, otherwise the given
+     * default value.
+     */
     get<T>(preferenceName: string, defaultValue?: T, resourceUri?: string): T | undefined;
+    /**
+     * Sets the given preference to the given value.
+     * 
+     * @param preferenceName the preference identifier.
+     * @param value the new value of the preference.
+     * @param scope the scope for which the value shall be set, i.e. user, workspace etc.
+     * When the folder scope is specified a resourceUri must be provided.
+     * @param resourceUri the uri of the resource for which the preference is stored. This used to store
+     * a potentially different value for the same preference for different resources, for example `files.encoding`.
+     *
+     * @returns a promise which resolves to `undefined` when setting the preference was successful. Otherwise it rejects
+     * with an error.
+     */
     set(preferenceName: string, value: any, scope?: PreferenceScope, resourceUri?: string): Promise<void>;
+    /**
+     * Registers a callback which will be called whenever a preference is changed.
+     */
     onPreferenceChanged: Event<PreferenceChange>;
+    /**
+     * Registers a callback which will be called whenever one or more preferences are changed.
+     */
     onPreferencesChanged: Event<PreferenceChanges>;
-
-    inspect<T>(preferenceName: string, resourceUri?: string): {
-        preferenceName: string,
-        defaultValue: T | undefined,
-        globalValue: T | undefined, // User Preference
-        workspaceValue: T | undefined, // Workspace Preference
-        workspaceFolderValue: T | undefined // Folder Preference
-    } | undefined;
-
+    /**
+     * Retrieve the stored value for the given preference and resourceUri in all available scopes.
+     * 
+     * @param preferenceName the preference identifier.
+     * @param resourceUri the uri of the resource for which the preference is stored.
+     * 
+     * @return an object containing the value of the given preference for all scopes.
+     */
+    inspect<T>(preferenceName: string, resourceUri?: string): PreferenceInspection<T> | undefined;
+    /**
+     * Returns a new preference identifier based on the given OverridePreferenceName.
+     * 
+     * @param options the override specification.
+     * 
+     * @returns the calculated string based on the given OverridePreferenceName.
+     */
     overridePreferenceName(options: OverridePreferenceName): string;
+    /**
+     * Tries to split the given preference identifier into the original OverridePreferenceName attributes
+     * with which this identifier was created. Returns `undefined` if this is not possible, for example
+     * when the given preference identifier was not generated by `overridePreferenceName`.
+     * 
+     * This method is checked when resolving preferences. Therefore together with "overridePreferenceName"
+     * this can be used to handle specialized preferences, e.g. "[markdown].editor.autoIndent" and "editor.autoIndent".
+     * 
+     * @param preferenceName the preferenceName which might have been created via {@link PreferenceService.overridePreferenceName}.
+     * 
+     * @returns the OverridePreferenceName which was used to create the given `preferenceName` if this was the case,
+     * `undefined` otherwise.
+     */
     overriddenPreferenceName(preferenceName: string): OverridePreferenceName | undefined;
-
+    /**
+     * Retrieve the stored value for the given preference and resourceUri.
+     * 
+     * @param preferenceName the preference identifier.
+     * @param defaultValue the value to return when no value for the given preference is stored.
+     * @param resourceUri the uri of the resource for which the preference is stored. This used to retrieve
+     * a potentially different value for the same preference for different resources, for example `files.encoding`.
+     * 
+     * @returns an object containing the value stored for the given preference and resourceUri when it exists,
+     * otherwise the given default value. If determinable the object will also contain the uri of the configuration
+     * resource in which the preference was stored.
+     */
     resolve<T>(preferenceName: string, defaultValue?: T, resourceUri?: string): PreferenceResolveResult<T>;
+    /**
+     * Returns the uri of the configuration resource for the given scope and optional resource uri.
+     * 
+     * @param scope the PreferenceScope to query for.
+     * @param resourceUri the optional uri of the resource-specific preference handling
+     * 
+     * @returns the uri of the configuration resource for the given scope and optional resource uri it it exists,
+     * `undefined` otherwise.
+     */
     getConfigUri(scope: PreferenceScope, resourceUri?: string): URI | undefined;
 }
 
+/**
+ * Return type of the {@link PreferenceService.inspect} call.
+ */
+export interface PreferenceInspection<T> {
+    /**
+     * The preference identifier.
+     */
+    preferenceName: string,
+    /**
+     * Value in default scope.
+     */
+    defaultValue: T | undefined,
+    /**
+     * Value in user scope.
+     */
+    globalValue: T | undefined,
+    /**
+     * Value in workspace scope.
+     */
+    workspaceValue: T | undefined,
+    /**
+     * Value in folder scope.
+     */
+    workspaceFolderValue: T | undefined
+}
+
 /**
  * We cannot load providers directly in the case if they depend on `PreferenceService` somehow.
- * It allows to load them lazilly after DI is configured.
+ * It allows to load them lazily after DI is configured.
  */
 export const PreferenceProviderProvider = Symbol('PreferenceProviderProvider');
 export type PreferenceProviderProvider = (scope: PreferenceScope, uri?: URI) => PreferenceProvider;
@@ -233,10 +362,7 @@ export class PreferenceServiceImpl implements PreferenceService {
         return this.resolve<T>(preferenceName, defaultValue, resourceUri).value;
     }
 
-    resolve<T>(preferenceName: string, defaultValue?: T, resourceUri?: string): {
-        configUri?: URI,
-        value?: T
-    } {
+    resolve<T>(preferenceName: string, defaultValue?: T, resourceUri?: string): PreferenceResolveResult<T> {
         const { value, configUri } = this.doResolve(preferenceName, defaultValue, resourceUri);
         if (value === undefined) {
             const overridden = this.overriddenPreferenceName(preferenceName);