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/pickers/layout_strategies.lua

@@ -61,38 +61,7 @@
 local config = require('telescope.config')
 local resolve = require("telescope.config.resolve")
 
-local function get_initial_window_options(picker)
-  local popup_border = resolve.win_option(picker.window.border)
-  local popup_borderchars = resolve.win_option(picker.window.borderchars)
-
-  local preview = {
-    title = picker.preview_title,
-    border = popup_border.preview,
-    borderchars = popup_borderchars.preview,
-    enter = false,
-    highlight = false
-  }
-
-  local results = {
-    title = picker.results_title,
-    border = popup_border.results,
-    borderchars = popup_borderchars.results,
-    enter = false,
-  }
-
-  local prompt = {
-    title = picker.prompt_title,
-    border = popup_border.prompt,
-    borderchars = popup_borderchars.prompt,
-    enter = true
-  }
-
-  return {
-    preview = preview,
-    results = results,
-    prompt = prompt,
-  }
-end
+local p_window = require('telescope.pickers.window')
 
 
 -- Check if there are any borders. Right now it's a little raw as
@@ -139,7 +108,7 @@ layout_strategies.horizontal = function(self, max_columns, max_lines)
     scroll_speed = "The speed when scrolling through the previewer",
   })
 
-  local initial_options = get_initial_window_options(self)
+  local initial_options = p_window.get_initial_window_options(self)
   local preview = initial_options.preview
   local results = initial_options.results
   local prompt = initial_options.prompt
@@ -237,7 +206,7 @@ end
 ---    +--------------+
 --- </pre>
 layout_strategies.center = function(self, columns, lines)
-  local initial_options = get_initial_window_options(self)
+  local initial_options = p_window.get_initial_window_options(self)
   local preview = initial_options.preview
   local results = initial_options.results
   local prompt = initial_options.prompt
@@ -307,7 +276,7 @@ layout_strategies.vertical = function(self, max_columns, max_lines)
     scroll_speed = "The speed when scrolling through the previewer",
   })
 
-  local initial_options = get_initial_window_options(self)
+  local initial_options = p_window.get_initial_window_options(self)
   local preview = initial_options.preview
   local results = initial_options.results
   local prompt = initial_options.prompt
@@ -447,4 +416,67 @@ layout_strategies.current_buffer = function(self, _, _)
   }
 end
 
+layout_strategies.bottom_pane = function(self, max_columns, max_lines)
+  local layout_config = validate_layout_config(self.layout_config or {}, {
+    height = "The height of the layout",
+  })
+
+  local initial_options = p_window.get_initial_window_options(self)
+  local results = initial_options.results
+  local prompt = initial_options.prompt
+  local preview = initial_options.preview
+
+  local result_height = layout_config.height or 25
+
+  local prompt_width = max_columns
+  local col = 0
+
+  local has_border = not not self.window.border
+  if has_border then
+    col = 1
+    prompt_width = prompt_width - 2
+  end
+
+  local result_width
+  if self.previewer then
+    result_width = math.floor(prompt_width / 2)
+
+    local base_col = result_width + 1
+    if has_border then
+      preview = vim.tbl_deep_extend("force", {
+        col = base_col + 2,
+        line = max_lines - result_height + 1,
+        width = prompt_width - result_width - 2,
+        height = result_height - 1,
+      }, preview)
+    else
+      preview = vim.tbl_deep_extend("force", {
+        col = base_col,
+        line = max_lines - result_height,
+        width = prompt_width - result_width,
+        height = result_height,
+      }, preview)
+    end
+  else
+    preview = nil
+    result_width = prompt_width
+  end
+
+  return {
+    preview = preview,
+    prompt = vim.tbl_deep_extend("force", prompt, {
+      line = max_lines - result_height - 1,
+      col = col,
+      height = 1,
+      width = prompt_width,
+    }),
+    results = vim.tbl_deep_extend("force", results, {
+      line = max_lines - result_height,
+      col = col,
+      height = result_height,
+      width = result_width,
+    }),
+  }
+end
+
 return layout_strategies

lua/telescope/pickers/window.lua

@@ -1,10 +1,10 @@
-local p_layouts = require('telescope.pickers.layout_strategies')
+local resolve = require("telescope.config.resolve")
 
 local p_window = {}
 
 function p_window.get_window_options(picker, max_columns, max_lines)
   local layout_strategy = picker.layout_strategy
-  local getter = p_layouts[layout_strategy]
+  local getter = require('telescope.pickers.layout_strategies')[layout_strategy]
 
   if not getter then
     error("Not a valid layout strategy: " .. layout_strategy)
@@ -13,5 +13,38 @@ function p_window.get_window_options(picker, max_columns, max_lines)
   return getter(picker, max_columns, max_lines)
 end
 
+function p_window.get_initial_window_options(picker)
+  local popup_border = resolve.win_option(picker.window.border)
+  local popup_borderchars = resolve.win_option(picker.window.borderchars)
+
+  local preview = {
+    title = picker.preview_title,
+    border = popup_border.preview,
+    borderchars = popup_borderchars.preview,
+    enter = false,
+    highlight = false
+  }
+
+  local results = {
+    title = picker.results_title,
+    border = popup_border.results,
+    borderchars = popup_borderchars.results,
+    enter = false,
+  }
+
+  local prompt = {
+    title = picker.prompt_title,
+    border = popup_border.prompt,
+    borderchars = popup_borderchars.prompt,
+    enter = true
+  }
+
+  return {
+    preview = preview,
+    results = results,
+    prompt = prompt,
+  }
+end
+
 
 return p_window

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