feat: add ivy-style layout strategy (#771)

* feat: add new layout strategy

* [docgen] Update doc/telescope.txt
skip-checks: true

Co-authored-by: Github Actions <actions@github>

lua/telescope/themes.lua

@@ -2,10 +2,27 @@
 -- Currently certain designs need a number of parameters.
 --
 -- local opts = themes.get_dropdown { winblend = 3 }
---
+
+---@tag telescope.themes
+
+---@brief [[
+--- Themes are ways to combine several elements of styling together.
+---
+--- They are helpful for managing the several differnt UI aspects for telescope and provide
+--- a simple interface for users to get a particular "style" of picker.
+---@brief ]]
 
 local themes = {}
 
+--- Dropdown style theme.
+--- <pre>
+---
+--- Usage:
+---
+---     `local builtin = require('telescope.builtin')`
+---     `local themes = require('telescope.themes')`
+---     `builtin.find_files(themes.get_dropdown())`
+--- </pre>
 function themes.get_dropdown(opts)
   opts = opts or {}
 
@@ -21,14 +38,49 @@ function themes.get_dropdown(opts)
     width = 80,
     results_height = 15,
     borderchars = {
-      { '─', '│', '─', '│', '╭', '╮', '╯', '╰'},
+      { "─", "│", "─", "│", "╭", "╮", "╯", "╰"},
       prompt = {"─", "│", " ", "│", "╭", "╮", "│", "│"},
       results = {"─", "│", "─", "│", "├", "┤", "╯", "╰"},
-      preview = { '─', '│', '─', '│', '╭', '╮', '╯', '╰'},
+      preview = { "─", "│", "─", "│", "╭", "╮", "╯", "╰"},
     },
   }
 
   return vim.tbl_deep_extend("force", theme_opts, opts)
 end
 
+--- Ivy style theme.
+--- <pre>
+---
+--- Usage:
+---
+---     `local builtin = require('telescope.builtin')`
+---     `local themes = require('telescope.themes')`
+---     `builtin.find_files(themes.get_ivy())`
+--- </pre>
+function themes.get_ivy(opts)
+  opts = opts or {}
+
+  return vim.tbl_deep_extend("force", {
+    theme = "ivy",
+
+    sorting_strategy = "ascending",
+
+    preview_title = "",
+
+    layout_strategy = "bottom_pane",
+    layout_config = {
+      height = 25,
+    },
+
+    border = true,
+    borderchars = {
+      "z",
+      prompt = { "─", " ", " ", " ", "─", "─", " ", " " },
+      results = { " " },
+      -- results = { "a", "b", "c", "d", "e", "f", "g", "h" },
+      preview = { "─", "│", "─", "│", "╭", "╮", "╯", "╰"},
+    },
+  }, opts)
+end
+
 return themes