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

3 files changed, 70 insertions, 1 deletions

diff --git a/lua/telescope/builtin/init.lua b/lua/telescope/builtin/init.lua
index 2b3c1ca..b9cc99f 100644
--- a/lua/telescope/builtin/init.lua
+++ b/lua/telescope/builtin/init.lua
@@ -40,6 +40,7 @@ builtin.git_branches = require('telescope.builtin.git').branches
 builtin.git_status = require('telescope.builtin.git').status
 
 builtin.builtin = require('telescope.builtin.internal').builtin
+
 builtin.planets = require('telescope.builtin.internal').planets
 builtin.symbols = require('telescope.builtin.internal').symbols
 builtin.commands = require('telescope.builtin.internal').commands
@@ -70,5 +71,6 @@ builtin.lsp_document_diagnostics = require('telescope.builtin.lsp').diagnostics
 builtin.lsp_workspace_diagnostics = require('telescope.builtin.lsp').workspace_diagnostics
 builtin.lsp_range_code_actions = require('telescope.builtin.lsp').range_code_actions
 builtin.lsp_workspace_symbols = require('telescope.builtin.lsp').workspace_symbols
+builtin.lsp_dynamic_workspace_symbols = require('telescope.builtin.lsp').dynamic_workspace_symbols
 
 return builtin
diff --git a/lua/telescope/builtin/lsp.lua b/lua/telescope/builtin/lsp.lua
index 741eb36..b2ab981 100644
--- a/lua/telescope/builtin/lsp.lua
+++ b/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)
 
diff --git a/lua/telescope/finders.lua b/lua/telescope/finders.lua
index d2acd05..62c05a1 100644
--- a/lua/telescope/finders.lua
+++ b/lua/telescope/finders.lua
@@ -2,6 +2,8 @@ local Job = require('plenary.job')
 
 local make_entry = require('telescope.make_entry')
 local log = require('telescope.log')
+local a = require('plenary.async_lib')
+local await = a.await
 
 local async_static_finder = require('telescope.finders.async_static_finder')
 local async_oneshot_finder = require('telescope.finders.async_oneshot_finder')
@@ -20,7 +22,6 @@ local _callable_obj = function()
   return obj
 end
 
-
 --[[ =============================================================
 
     JobFinder
@@ -108,6 +109,35 @@ function JobFinder:_find(prompt, process_result, process_complete)
   self.job:start()
 end
 
+local DynamicFinder = _callable_obj()
+
+function DynamicFinder:new(opts)
+  opts = opts or {}
+
+  assert(not opts.results, "`results` should be used with finder.new_table")
+  assert(not opts.static, "`static` should be used with finder.new_oneshot_job")
+
+  local obj = setmetatable({
+    curr_buf = opts.curr_buf,
+    fn = opts.fn,
+    entry_maker = opts.entry_maker or make_entry.from_string,
+  }, self)
+
+  return obj
+end
+
+function DynamicFinder:_find(prompt, process_result, process_complete)
+  a.scope(function()
+    local results = await(self.fn(prompt))
+
+    for _, result in ipairs(results) do
+      if process_result(self.entry_maker(result)) then return end
+    end
+
+    process_complete()
+  end)
+end
+
 --- Return a new Finder
 --
 -- Use at your own risk.
@@ -185,4 +215,8 @@ finders.new_table = function(t)
   return async_static_finder(t)
 end
 
+finders.new_dynamic = function(t)
+  return DynamicFinder:new(t)
+end
+
 return finders