added a new DynamicFinder (which can be used with rust_analyzer) (#705)

* started tree finder

* made tree more ergonmic

* deleted unneeded comments

* added stack root and node

* added preprocessing

* using staticfinder instead of separate finder, custom entry maker

* added selections and remember

* removed unused stuff

* fixed warnings

* fixed remember and selections pop

* started branch

* added go function

* changed up test

* removed root parameter from go function

* changed back to not do_close

* removed node and leaf classes

* removed stack class instead for table.insert and table.remove

* fixed warning

* started branch

* added better preprocessor and tree class

* started some tests

* finished making tests pass

* cleaned up

* fixed make entry and updated example

* started

* added some stuff

* deleted uneeded stuff

* added cancelable

* changed workspace requester

* use better cancellation mechanism

* removed accidental stuff

* removed useless print

* delete more useless stuff

* rename to dynamic

* added request cancellation

* CHECK IF NIL

* removed unused

* added trash global variable

lua/telescope/builtin/lsp.lua

@@ -4,6 +4,9 @@ local finders = require('telescope.finders')
 local make_entry = require('telescope.make_entry')
 local pickers = require('telescope.pickers')
 local utils = require('telescope.utils')
+local a = require('plenary.async_lib')
+local async, await = a.async, a.await
+local channel = a.util.channel
 
 local conf = require('telescope.config').values
 
@@ -218,6 +221,36 @@ lsp.workspace_symbols = function(opts)
   }):find()
 end
 
+local function get_workspace_symbols_requester(bufnr)
+  local cancel = function() end
+
+  return async(function(prompt)
+    local tx, rx = channel.oneshot()
+    cancel()
+    _, cancel = vim.lsp.buf_request(bufnr, "workspace/symbol", {query = prompt}, tx)
+
+    local err, _, results_lsp = await(rx())
+    assert(not err, err)
+
+    local locations = vim.lsp.util.symbols_to_items(results_lsp or {}, bufnr) or {}
+    return locations
+  end)
+end
+
+lsp.dynamic_workspace_symbols = function(opts)
+  local curr_bufnr = vim.api.nvim_get_current_buf()
+
+  pickers.new(opts, {
+    prompt_title = 'LSP Dynamic Workspace Symbols',
+    finder    = finders.new_dynamic {
+      entry_maker = opts.entry_maker or make_entry.gen_from_lsp_symbols(opts),
+      fn = get_workspace_symbols_requester(curr_bufnr),
+    },
+    previewer = conf.qflist_previewer(opts),
+    sorter = conf.generic_sorter()
+  }):find()
+end
+
 lsp.diagnostics = function(opts)
   local locations = utils.diagnostics_to_tbl(opts)