Add initial fzf-lua support (fixes #3123)

lua/vimtex/fzf-lua/init.lua

@@ -0,0 +1,88 @@
+local M = {}
+
+-- the mapping of item types to ansi color codes
+-- Can be any of the keys in
+-- https://github.com/ibhagwan/fzf-lua/blob/caee13203d6143d691710c34f85ad6441fe3f535/lua/fzf-lua/utils.lua#L555C1-L574C1
+local color_map = {
+  content = "clear",
+  include = "blue",
+  label = "green",
+  todo = "red",
+}
+
+---Format the section/subsection/... numbers corresponding to an item into a string.
+---@param n table The TOC entry
+---@return string number
+local function format_number(n)
+  local num = {
+    n["chapter"] ~= 0 and n["chapter"] or nil,
+    n["section"] ~= 0 and n["section"] or nil,
+    n["subsection"] ~= 0 and n["subsection"] or nil,
+    n["subsubsection"] ~= 0 and n["subsubsection"] or nil,
+    n["subsubsubsection"] ~= 0 and n["subsubsubsection"] or nil,
+  }
+  if vim.tbl_isempty(num) then
+    return ""
+  end
+  num = vim.tbl_filter(function(t)
+    return t ~= nil
+  end, num)
+
+  -- for appendix items, we convert them into a letter 1 -> A, 2 -> B, etc.
+  if n.appendix ~= 0 then
+    local ind = table.sort(vim.tbl_keys(num))[1]
+    num[ind] = string.char(num[ind] + 64)
+  end
+
+  num = vim.tbl_map(function(t)
+    return string.format(t)
+  end, num)
+
+  return table.concat(num, ".")
+end
+
+
+---Runs Fzf-Lua for getting a list of TOC items. Upon selection, opens the file(s) at the correct lines.
+---@param layers string? the layers to filter. Can be a substring of `ctli` corresponding to
+---                     content, todos, labels, and includes.
+---@return nil
+M.run = function(layers)
+  if layers == nil then
+    layers = "ctli"
+  end
+
+  local fzf = require "fzf-lua"
+  local ansi = fzf.utils.ansi_codes
+
+  local entries = vim.fn["vimtex#parser#toc"]()
+  entries = vim.tbl_filter(function(t)
+    return string.find(layers, t.type:sub(1,1)) ~= nil
+  end, entries)
+
+  local fzf_entries = vim.tbl_map(function(v)
+    return string.format(
+      "%s:%d####%s####%s",
+      v.file,
+      v.line and v.line or 0,
+      ansi[color_map[v.type]](v.title),
+      format_number(v.number)
+    )
+  end, entries)
+
+  fzf.fzf_exec(fzf_entries, {
+    fzf_opts = {
+      ["--delimiter"] = "####",
+      ["--with-nth"] = "{2} {3}",
+    },
+    actions = {
+      ["default"] = function(selection, o)
+        local s = vim.tbl_map(function(t)
+          return vim.split(t, "####")[1]
+        end, selection)
+        fzf.actions.file_edit(s, o)
+      end,
+    },
+  })
+end
+
+return M