Clarify semantics with better name and documentation.

Author: toinehartman

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/BaseWorkspaceService.java

@@ -84,7 +84,7 @@ public void initialize(ClientCapabilities clientCap, @Nullable List<WorkspaceFol
             this.workspaceFolders.addAll(currentWorkspaceFolders);
         }
 
-        var workspaceCapabilities = Nullables.initAndGet(capabilities, ServerCapabilities::getWorkspace, ServerCapabilities::setWorkspace, WorkspaceServerCapabilities::new);
+        var workspaceCapabilities = Nullables.ensureNonNullAndGet(capabilities, ServerCapabilities::getWorkspace, ServerCapabilities::setWorkspace, WorkspaceServerCapabilities::new);
         if (Nullables.has(clientCap.getWorkspace(), WorkspaceClientCapabilities::getWorkspaceFolders)) {
             var folderOptions = new WorkspaceFoldersOptions();
             folderOptions.setSupported(true);

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/FileOperationCapability.java

@@ -103,8 +103,8 @@ private static FileOperationFilter extensionFilter(String ext) {
     }
 
     private static FileOperationsServerCapabilities fileOperationCapabilities(ServerCapabilities caps) {
-        var workspace = Nullables.initAndGet(caps, ServerCapabilities::getWorkspace, ServerCapabilities::setWorkspace, WorkspaceServerCapabilities::new);
-        return Nullables.initAndGet(workspace, WorkspaceServerCapabilities::getFileOperations, WorkspaceServerCapabilities::setFileOperations, FileOperationsServerCapabilities::new);
+        var workspace = Nullables.ensureNonNullAndGet(caps, ServerCapabilities::getWorkspace, ServerCapabilities::setWorkspace, WorkspaceServerCapabilities::new);
+        return Nullables.ensureNonNullAndGet(workspace, WorkspaceServerCapabilities::getFileOperations, WorkspaceServerCapabilities::setFileOperations, FileOperationsServerCapabilities::new);
     }
 
     /**

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/rascal/RascalWorkspaceService.java

@@ -57,8 +57,8 @@ public void initialize(ClientCapabilities clientCap, @Nullable List<WorkspaceFol
             ServerCapabilities capabilities) {
         super.initialize(clientCap, currentWorkspaceFolders, capabilities);
 
-        var workspaceCap = Nullables.initAndGet(capabilities, ServerCapabilities::getWorkspace, ServerCapabilities::setWorkspace, WorkspaceServerCapabilities::new);
-        var fileOperationCapabilities = Nullables.initAndGet(workspaceCap, WorkspaceServerCapabilities::getFileOperations, WorkspaceServerCapabilities::setFileOperations, FileOperationsServerCapabilities::new);
+        var workspaceCap = Nullables.ensureNonNullAndGet(capabilities, ServerCapabilities::getWorkspace, ServerCapabilities::setWorkspace, WorkspaceServerCapabilities::new);
+        var fileOperationCapabilities = Nullables.ensureNonNullAndGet(workspaceCap, WorkspaceServerCapabilities::getFileOperations, WorkspaceServerCapabilities::setFileOperations, FileOperationsServerCapabilities::new);
 
         var rascalFile = new FileOperationPattern("**/*.rsc");
         rascalFile.setMatches(FileOperationPatternKind.File);

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/util/Nullables.java

@@ -102,7 +102,7 @@ public static <A, B> boolean has(@Nullable A a, Function<A, @Nullable B> getFunc
     }
 
     /**
-     * Get a value from an object. If it was not set yet (i.e. `null`), initialize it before returning.
+     * Get a value from an object. If it was not set yet (i.e. `null`), initialize and set it before returning.
      * @param <C> The type of the containing object.
      * @param <T> The type of the value to get.
      * @param container The containing object.
@@ -111,11 +111,12 @@ public static <A, B> boolean has(@Nullable A a, Function<A, @Nullable B> getFunc
      * @param initializer The value initializer (e.g. a constructor). Only called if the value is not initialized yet.
      * @return The gotten value, or the initialized value if was not initialized yet.
      */
-    public static <C, T> T initAndGet(C container, Function<C, @Nullable T> getter, BiConsumer<C, T> setter, Supplier<T> initializer) {
+    public static <C, T> T ensureNonNullAndGet(C container, Function<C, @Nullable T> getter, BiConsumer<C, T> setter, Supplier<T> initializer) {
         var t = getter.apply(container);
         if (t == null) {
             t = initializer.get();
             setter.accept(container, t);
+            assert getter.apply(container) != null : "Setter should set same value as getter gets";
         }
         return t;
     }