Package reference

Four packages. Three of them have no dependencies, and the fourth is the only one that costs you a WebSocket stack.

langserver01

JSON-RPC framing over Content-Length, request and notification handling, and a handler map keyed by method name. A language module registers the methods it answers and ignores the rest.

handlers := map[string]langserver.Handler{
	"textDocument/completion": completion,
	"textDocument/hover":      hover,
}

A handler receives the session and the raw params, and returns either a result or an *RPCError. Nothing in the dispatch layer inspects what a method means.

Sessions02

Open documents, their versions and their content are held per connection. A handler is given the text it is being asked about instead of reading from disk and hoping the two agree.

langserver/lsp03

Positions and ranges, including the arithmetic that makes them correct. See Positions, which is the part most worth reading before you write your own.

offset := lsp.OffsetFromPosition(src, lsp.Position{Line: 2, Character: 14})
pos    := lsp.PositionFromOffset(src, offset)

Bindings04

stdio is how editors launch a server. ws is how a browser reaches one. They are separate packages so that the dependency the second needs is not paid for by the first.

The boundary05

Nothing in the adapter is aware of a grammar, a type system or a symbol table. That is what lets it serve any language, and it is also why it cannot help you with any of them. The intelligence is yours to supply.