feat(telescope provider): (Smart) multiselect (#39)

Adds support for Telescope's multiselect mode and smart select mode.

lua/trouble/providers/telescope.lua

@@ -1,41 +1,73 @@
 local util = require("trouble.util")
+local action_state = require("telescope.actions.state")
+local actions = require("telescope.actions")
+
 local M = {}
 
 M.results = {}
 
+--- Turns a Telescope item into a Trouble item.
+local function item_to_result(item)
+  local row = (item.lnum or 1) - 1
+  local col = (item.col or 1) - 1
+
+  if not item.bufnr then
+    item.bufnr = vim.fn.bufnr(item.filename, true)
+  end
+
+  local pitem = {
+    row = row,
+    col = col,
+    message = item.text,
+    severity = 0,
+    range = {
+      start = { line = row, character = col },
+      ["end"] = { line = row, character = -1 },
+    },
+  }
+
+  return util.process_item(pitem, item.bufnr)
+end
+
+--- Shows all Telescope results in Trouble.
 function M.open_with_trouble(prompt_bufnr, _mode)
-  local action_state = require("telescope.actions.state")
-  local actions = require("telescope.actions")
   local picker = action_state.get_current_picker(prompt_bufnr)
   local manager = picker.manager
 
   M.results = {}
   for item in manager:iter() do
-    local row = (item.lnum or 1) - 1
-    local col = (item.col or 1) - 1
-
-    if not item.bufnr then
-      item.bufnr = vim.fn.bufnr(item.filename, true)
-    end
-
-    local pitem = {
-      row = row,
-      col = col,
-      message = item.text,
-      severity = 0,
-      range = {
-        start = { line = row, character = col },
-        ["end"] = { line = row, character = -1 },
-      },
-    }
-
-    table.insert(M.results, util.process_item(pitem, item.bufnr))
+
+    table.insert(M.results, item_to_result(item))
   end
 
   actions.close(prompt_bufnr)
   require("trouble").open("telescope")
 end
 
+--- Shows the selected Telescope results in Trouble.
+function M.open_selected_with_trouble(prompt_bufnr, _mode)
+  local picker = action_state.get_current_picker(prompt_bufnr)
+
+  M.results = {}
+  for _, item in ipairs(picker:get_multi_selection()) do
+    table.insert(M.results, item_to_result(item))
+  end
+
+  actions.close(prompt_bufnr)
+  require("trouble").open("telescope")
+end
+
+--- Shows the selected Telescope results in Trouble.
+--- If no results are currently selected, shows all of them.
+function M.smart_open_with_trouble(prompt_bufnr, _mode)
+  local picker = action_state.get_current_picker(prompt_bufnr)
+  if table.getn(picker:get_multi_selection()) > 0 then
+    M.open_selected_with_trouble(prompt_bufnr, _mode)
+  else
+    M.open_with_trouble(prompt_bufnr, _mode)
+  end
+end
+
 function M.telescope(_win, _buf, cb, _options)
   if #M.results == 0 then
     util.warn("No Telescope results found. Open Telescopen and send results to Trouble first. Refer to the documentation for more info.")