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Custom LSP Features

Swap individual LSP providers without rewriting the whole language server layer.

Common extension points

  • completion
  • hover
  • rename
  • references
  • semantic tokens
  • formatter

Strategy

Start from the default services, then swap one provider at a time. The rest of the language server stack stays stable while you iterate on a single feature.

Typical wiring:

auto services = pegium::makeDefaultServices(
    sharedServices, "my-language");

services->parser = std::make_unique<const my::parser::MyParser>(*services);
services->lsp.hoverProvider = std::make_unique<lsp::MyHoverProvider>(*services);

For completion, subclass pegium::DefaultCompletionProvider and override its narrow hooks rather than rewriting the whole provider. The completion provider reference lists the available extension points.

When to write a custom provider

  • the language has unusual scoping or symbol lookup rules
  • completion items depend on semantic state the default provider cannot see
  • hover content needs custom documentation rendering
  • rename or definition behavior depends on domain-specific semantics

Practical advice

Replace the most visible or most language-specific feature first:

  1. formatter
  2. hover
  3. completion
  4. navigation features such as definition or rename