How to add error highlights for Importing Unknown Packages or Modules in Monaco Editor for newly registered Language Java?

Question

Currently we are integrating Java Language Server to Monaco Editor. There when I am trying to import unknown modules or packages it is not throwing warning or errors.. Tried using Tokenizer but didn't worked out.

When I am importing any unknown package or error I want error some thing red lines below the package name. Similar to how we will get for typescript. I want to know how to add these type to monaco editor for a new language that we are registering.

Answer 1

After you did the semantic validation send diagnostics back, which your extension can use to add such information. For example:

   /**
     * Convert diagnostic information for the given file to show in vscode.
     *
     * @param document The document for which this should happen.
     */
    private processDiagnostic = (document: TextDocument) => {
        const diagnostics = [];
        const entries = this.backend.getDiagnostics(document.fileName);
        for (const entry of entries) {
            const startRow = entry.range.start.row === 0 ? 0 : entry.range.start.row - 1;
            const endRow = entry.range.end.row === 0 ? 0 : entry.range.end.row - 1;
            const range = new Range(startRow, entry.range.start.column, endRow, entry.range.end.column);
            const diagnostic = new Diagnostic(range, entry.message, ExtensionHost.diagnosticTypeMap.get(entry.type));
            diagnostics.push(diagnostic);
        }
        this.diagnosticCollection.set(document.uri, diagnostics);
    };

(from my extension antlr4-vscode).

Answer 2

First, you need to provide some logic of detecting unknown imported packages.

Then, to underline errors, check corrrsponding page on Monaco editor playground or use this code:

     monaco.editor.setModelMarkers(window.editor.getModel(), 'owner', [
            {
                message: "import not found",
                severity: monaco.MarkerSeverity.Error,
                startLineNumber: 0,
                startColumn: 0,
                endLineNumber: 0,
                endColumn: 2,
            },
        ]);

(change startLineNumber and other range arguments according to highlighted code piece).