feat(lsp): initial support for dynamic capabilities (#23681)

- `client.dynamic_capabilities` is an object that tracks client register/unregister
- `client.supports_method` will additionally check if a dynamic capability supports the method, taking document filters into account. But only if the client enabled `dynamicRegistration` for the capability
- updated the default client capabilities to include dynamicRegistration for:
    - formatting
    - rangeFormatting
    - hover
    - codeAction
    - hover
    - rename

runtime/lua/vim/lsp/_dynamic.lua

@@ -0,0 +1,109 @@
+local wf = require('vim.lsp._watchfiles')
+
+--- @class lsp.DynamicCapabilities
+--- @field capabilities table<string, lsp.Registration[]>
+--- @field client_id number
+local M = {}
+
+--- @param client_id number
+function M.new(client_id)
+  return setmetatable({
+    capabilities = {},
+    client_id = client_id,
+  }, { __index = M })
+end
+
+function M:supports_registration(method)
+  local client = vim.lsp.get_client_by_id(self.client_id)
+  if not client then
+    return false
+  end
+  local capability = vim.tbl_get(client.config.capabilities, unpack(vim.split(method, '/')))
+  return type(capability) == 'table' and capability.dynamicRegistration
+end
+
+--- @param registrations lsp.Registration[]
+--- @private
+function M:register(registrations)
+  -- remove duplicates
+  self:unregister(registrations)
+  for _, reg in ipairs(registrations) do
+    local method = reg.method
+    if not self.capabilities[method] then
+      self.capabilities[method] = {}
+    end
+    table.insert(self.capabilities[method], reg)
+  end
+end
+
+--- @param unregisterations lsp.Unregistration[]
+--- @private
+function M:unregister(unregisterations)
+  for _, unreg in ipairs(unregisterations) do
+    local method = unreg.method
+    if not self.capabilities[method] then
+      return
+    end
+    local id = unreg.id
+    for i, reg in ipairs(self.capabilities[method]) do
+      if reg.id == id then
+        table.remove(self.capabilities[method], i)
+        break
+      end
+    end
+  end
+end
+
+--- @param method string
+--- @param opts? {bufnr?: number}
+--- @return lsp.Registration? (table|nil) the registration if found
+--- @private
+function M:get(method, opts)
+  opts = opts or {}
+  opts.bufnr = opts.bufnr or vim.api.nvim_get_current_buf()
+  for _, reg in ipairs(self.capabilities[method] or {}) do
+    if not reg.registerOptions then
+      return reg
+    end
+    local documentSelector = reg.registerOptions.documentSelector
+    if not documentSelector then
+      return reg
+    end
+    if M.match(opts.bufnr, documentSelector) then
+      return reg
+    end
+  end
+end
+
+--- @param method string
+--- @param opts? {bufnr?: number}
+--- @private
+function M:supports(method, opts)
+  return self:get(method, opts) ~= nil
+end
+
+--- @param bufnr number
+--- @param documentSelector lsp.DocumentSelector
+--- @private
+function M.match(bufnr, documentSelector)
+  local ft = vim.bo[bufnr].filetype
+  local uri = vim.uri_from_bufnr(bufnr)
+  local fname = vim.uri_to_fname(uri)
+  for _, filter in ipairs(documentSelector) do
+    local matches = true
+    if filter.language and ft ~= filter.language then
+      matches = false
+    end
+    if matches and filter.scheme and not vim.startswith(uri, filter.scheme .. ':') then
+      matches = false
+    end
+    if matches and filter.pattern and not wf._match(filter.pattern, fname) then
+      matches = false
+    end
+    if matches then
+      return true
+    end
+  end
+end
+
+return M