Hierarchies and Navigation

In this chapter you learn the tools that follow relationships: implementations, type definitions, declarations, call graphs and type hierarchies. They answer “what implements this”, “who calls this” and “what does this extend”.

Prerequisites

You know how to address code.

Jump tools

These three take a position (and the first two also accept symbol_name) and return a list of locations with uri, range and out_of_workspace. All accept context: "enclosing_symbol".

Tool	Answers	Typical use
`go_to_implementation`	Where is this trait method or interface member implemented?	Find implementors of a trait
`go_to_type_definition`	What type does this expression have, and where is it defined?	Jump from a variable to its type, not to its binding
`go_to_declaration`	Where is this symbol declared?	C and C++ headers, interface members; servers without the concept may return the definition

{ "file_path": "/work/app/src/store.rs", "symbol_name": "Storage::save" }

An empty result is valid. Lists are capped (truncated: true).

Call hierarchy

Call hierarchy is a two-step conversation. First ask for an item, then walk from it.

prepare_call_hierarchy takes a position or symbol_name and returns callable items.
get_incoming_calls returns the callers of an item. get_outgoing_calls returns the functions it calls.

{ "file_path": "/work/app/src/data.rs", "symbol_name": "initialize" }

Pass the item object to the next tool exactly as prepare_call_hierarchy returned it, unchanged: { "item": <the returned object> }. An item is only meaningful to the server that produced it, so all three tools are routed together.

Type hierarchy

The same pattern applies to inheritance and trait relationships:

prepare_type_hierarchy takes a position and returns type items.
get_supertypes returns the base classes and implemented interfaces of an item.
get_subtypes returns derived classes and implementors, one level at a time.

Feed an item back into either tool, including items they returned, to walk up or down the tree. Not every server supports type hierarchy: rust-analyzer and typescript-language-server do not advertise it, and the TypeScript 7 native server does not support it either. Ask get_tool_support first.

What’s Next

Finish the tool tour with Server Monitoring and Control.