feat: set defaults for each picker in telescope setup (#883)

This allows easier picker configuration for example:

```lua
require("telescope").setup {
  pickers = {
    buffers = {
      show_all_buffers = true,
      sort_lastused = true,
      theme = "dropdown",
      previewer = false,
      mappings = {
        i = {
          ["<c-q>"] = "smart_send_to_qflist",
        }
      }
    }
  }
}
```

This configuration will be applied when running `:Telescope buffers`

.luacheckrc

@@ -19,6 +19,7 @@ globals = {
   "TelescopeCachedTails",
   "TelescopeCachedNgrams",
   "_TelescopeConfigurationValues",
+  "_TelescopeConfigurationPickers",
   "__TelescopeKeymapStore",
 }
 

README.md

@@ -235,6 +235,45 @@ EOF
 | `file_ignore_patterns` | Pattern to be ignored `{ "scratch/.*", "%.env" }`      | dict                       |
 | `shorten_path`         | Whether to shorten paths or not.                      | boolean                    |
 
+### Customize Default Builtin behavior
+
+You can customize each default builtin behavior by adding the prefered options
+into the table that is passed into `require("telescope").setup()`.
+
+Example:
+
+```lua
+require("telescope").setup {
+  defaults = {
+    -- Your defaults config goes in here
+  },
+  pickers = {
+    -- Your special builtin config goes in here
+    buffers = {
+      sort_lastused = true,
+      theme = "dropdown",
+      previewer = false,
+      mappings = {
+        i = {
+          ["<c-d>"] = require("telescope.actions").delete_buffer,
+          -- or right hand side can also be a the name of the action as string
+          ["<c-d>"] = "delete_buffer",
+        },
+        n = {
+          ["<c-d>"] = require("telescope.actions").delete_buffer,
+        }
+      }
+    },
+    find_files = {
+      theme = "dropdown"
+    }
+  },
+  extensions = {
+    -- your extension config goes in here
+  }
+}
+```
+
 ## Mappings
 
 Mappings are fully customizable.

doc/telescope.txt

@@ -389,7 +389,35 @@ options you want to use. Here's an example with the live_grep picker:
 :lua require('telescope.builtin').live_grep({
   prompt_title = 'find string in open buffers...',
   grep_open_files = true
- })
+})
+-- or with dropdown theme
+:lua require('telescope.builtin').find_files(require('telescope.themes').get_dropdown{
+  previewer = false
+})
+
+You can also pass default configurations to builtin pickers. These options will
+also be added if the picker is executed with `Telescope find_files`.
+
+require("telescope").setup {
+  pickers = {
+    buffers = {
+      show_all_buffers = true,
+      sort_lastused = true,
+      theme = "dropdown",
+      previewer = false,
+      mappings = {
+        i = {
+          ["<c-d>"] = require("telescope.actions").delete_buffer,
+          -- or right hand side can also be a the name of the action as string
+          ["<c-d>"] = "delete_buffer",
+        },
+        n = {
+          ["<c-d>"] = require("telescope.actions").delete_buffer,
+        }
+      }
+    }
+  }
+}
 
 This will use the default configuration options. Other configuration options
 are still in flux at the moment

lua/telescope/builtin/init.lua

@@ -17,6 +17,36 @@
 ---   prompt_title = 'find string in open buffers...',
 ---   grep_open_files = true
 --- })
+--- -- or with dropdown theme
+--- :lua require('telescope.builtin').find_files(require('telescope.themes').get_dropdown{
+---   previewer = false
+--- })
+--- </pre>
+---
+--- You can also pass default configurations to builtin pickers. These options will also be added if
+--- the picker is executed with `Telescope find_files`.
+---
+--- <pre>
+--- require("telescope").setup {
+---   pickers = {
+---     buffers = {
+---       show_all_buffers = true,
+---       sort_lastused = true,
+---       theme = "dropdown",
+---       previewer = false,
+---       mappings = {
+---         i = {
+---           ["<c-d>"] = require("telescope.actions").delete_buffer,
+---           -- or right hand side can also be a the name of the action as string
+---           ["<c-d>"] = "delete_buffer",
+---         },
+---         n = {
+---           ["<c-d>"] = require("telescope.actions").delete_buffer,
+---         }
+---       }
+---     }
+---   }
+--- }
 --- </pre>
 ---
 --- This will use the default configuration options. Other configuration options are still in flux at the moment
@@ -325,4 +355,46 @@ builtin.lsp_document_diagnostics = require('telescope.builtin.lsp').diagnostics
 ---@field hide_filename boolean: if true, hides the name of the file in the current picker (default is false)
 builtin.lsp_workspace_diagnostics = require('telescope.builtin.lsp').workspace_diagnostics
 
+local apply_config = function(mod)
+  local pickers_conf = require('telescope.config').pickers
+  for k, v in pairs(mod) do
+    local pconf = vim.deepcopy(pickers_conf[k] or {})
+    if pconf.theme then
+      local theme = pconf.theme
+      pconf.theme = nil
+      pconf = require("telescope.themes")["get_" .. theme](pconf)
+    end
+    if pconf.mappings then
+      local mappings = pconf.mappings
+      pconf.mappings = nil
+      pconf.attach_mappings = function(_, map)
+        for mode, tbl in pairs(mappings) do
+          for key, action in pairs(tbl) do
+            map(mode, key, action)
+          end
+        end
+        return true
+      end
+    end
+    mod[k] = function(opts)
+      opts = opts or {}
+      if pconf.attach_mappings and opts.attach_mappings then
+        local attach_mappings = pconf.attach_mappings
+        pconf.attach_mappings = nil
+        local opts_attach = opts.attach_mappings
+        opts.attach_mappings = function(prompt_bufnr, map)
+          attach_mappings(prompt_bufnr, map)
+          return opts_attach(prompt_bufnr, map)
+        end
+      end
+
+      v(vim.tbl_extend("force", pconf, opts))
+    end
+  end
+
+  return mod
+end
+
+-- We can't do this in one statement because tree-sitter-lua docgen gets confused if we do
+builtin = apply_config(builtin)
 return builtin

lua/telescope/config.lua

@@ -1,5 +1,6 @@
 -- Keep the values around between reloads
 _TelescopeConfigurationValues = _TelescopeConfigurationValues or {}
+_TelescopeConfigurationPickers = _TelescopeConfigurationPickers or {}
 
 local function first_non_null(...)
   local n = select('#', ...)
@@ -45,6 +46,15 @@ local config = {}
 
 config.values = _TelescopeConfigurationValues
 config.descriptions = {}
+config.pickers = _TelescopeConfigurationPickers
+
+function config.set_pickers(pickers)
+  pickers = pickers or {}
+
+  for k, v in pairs(pickers) do
+    config.pickers[k] = v
+  end
+end
 
 function config.set_defaults(defaults)
   defaults = defaults or {}

lua/telescope/init.lua

@@ -37,6 +37,7 @@ function telescope.setup(opts)
   end
 
   require('telescope.config').set_defaults(opts.defaults)
+  require('telescope.config').set_pickers(opts.pickers)
   _extensions.set_config(opts.extensions)
 end
 

lua/telescope/mappings.lua

@@ -111,16 +111,26 @@ local telescope_map = function(prompt_bufnr, mode, key_bind, key_func, opts)
   if opts.silent == nil then opts.silent = true end
 
   if type(key_func) == "string" then
+    key_func = actions[key_func]
+  elseif type(key_func) == "table" then
+    if key_func.type == "command" then
       a.nvim_buf_set_keymap(
         prompt_bufnr,
         mode,
         key_bind,
-      key_func,
+        key_func[1],
         opts or {
           silent = true
         }
       )
-  else
+      return
+    elseif key_func.type == "action_key" then
+      key_func = actions[key_func[1]]
+    elseif key_func.type == "action" then
+      key_func = key_func[1]
+    end
+  end
+
   local key_id = assign_function(prompt_bufnr, key_func)
   local prefix
 
@@ -155,7 +165,6 @@ local telescope_map = function(prompt_bufnr, mode, key_bind, key_func, opts)
     map_string,
     opts
   )
-  end
 end
 
 mappings.apply_keymap = function(prompt_bufnr, attach_mappings, buffer_keymap)