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--- *mini.align* Align text interactively
--- MIT License Copyright (c) 2022 Evgeni Chasnovski
--- Rich and flexible customization of both alignment rules and user interaction.
--- Works with charwise, linewise, and blockwise selections in both Normal mode
--- (on textobject/motion; with dot-repeat) and Visual mode.
--- Features:
--- - Alignment is done in three main steps:
---     - <Split> lines into parts based on Lua pattern(s) or user-supplied rule.
---     - <Justify> parts for certain side(s) to be same width inside columns.
---     - <Merge> parts to be lines, with customizable delimiter(s).
---     Each main step can be preceded by other steps (pre-steps) to achieve
---     highly customizable outcome. See `steps` value in |MiniAlign.config|.
---     For more details, see |MiniAlign-glossary| and |MiniAlign-algorithm|.
--- - User can control alignment interactively by pressing customizable modifiers
---   (single keys representing how alignment steps and/or options should change).
---   Some of default modifiers:
---     - Press `s` to enter split Lua pattern.
---     - Press `j` to choose justification side from available ones ("left",
---       "center", "right", "none").
---     - Press `m` to enter merge delimiter.
---     - Press `f` to enter filter Lua expression to configure which parts
---       will be affected (like "align only first column").
---     - Press `i` to ignore some commonly unwanted split matches.
---     - Press `p` to pair neighboring parts so they be aligned together.
---     - Press `t` to trim whitespace from parts.
---     - Press `<BS>` (backspace) to delete some last pre-step.
---     For more details, see |MiniAlign-modifiers-builtin| and |MiniAlign-examples|.
--- - Alignment can be done with instant preview (result is updated after each
---   modifier) or without it (result is shown and accepted after non-default
---   split pattern is set).
--- - Every user interaction is accompanied with helper status message showing
---   relevant information about current alignment process.
--- # Setup ~
--- This module needs a setup with `require('mini.align').setup({})` (replace
--- `{}` with your `config` table). It will create global Lua table `MiniAlign`
--- which you can use for scripting or manually (with `:lua MiniAlign.*`).
--- See |MiniAlign.config| for available config settings.
--- You can override runtime config settings (like `config.modifiers`) locally
--- to buffer inside `vim.b.minialign_config` which should have same structure
--- as `MiniAlign.config`. See |mini.nvim-buffer-local-config| for more details.
--- To stop module from showing non-error feedback, set `config.silent = true`.
--- # Comparisons ~
--- - [junegunn/vim-easy-align](https://github.com/junegunn/vim-easy-align):
---     - 'mini.align' is mostly designed after 'junegunn/vim-easy-align', so
---       there are a lot of similarities.
---     - Both plugins allow users to change alignment options interactively by
---       pressing modifier keys (albeit completely different default ones).
---       'junegunn/vim-easy-align' has those modifiers fixed, while 'mini.align'
---       allows their full customization. See |MiniAlign.config| for examples.
---     - 'junegunn/vim-easy-align' is designed to treat delimiters differently
---       than other parts of strings. 'mini.align' doesn't distinguish split
---       parts from one another by design: splitting is allowed to be done
---       based on some other logic than by splitting on delimiters.
---     - 'junegunn/vim-easy-align' initially aligns by only first delimiter.
---       'mini.align' initially aligns by all delimiter.
---     - 'junegunn/vim-easy-align' implements special filtering by delimiter
---       row number. 'mini.align' has builtin filtering based on Lua code
---       supplied by user in modifier phase. See |MiniAlign.gen_step.filter()|
---       and 'f' builtin modifier.
---     - 'mini.align' treats any non-registered modifier as a plain delimiter
---       pattern, while 'junegunn/vim-easy-align' does not.
---     - 'mini.align' exports core Lua function used for aligning strings
---       (|MiniAlign.align_strings()|).
--- - [godlygeek/tabular](https://github.com/godlygeek/tabular):
---     - 'godlygeek/tabular' is mostly designed around single command which is
---       customized by printing its parameters. 'mini.align' implements
---       different concept of interactive alignment through pressing
---       customizable single character modifiers.
---     - 'godlygeek/tabular' can detect region upon which alignment can be
---       desirable. 'mini.align' does not by design: use Visual selection or
---       textobject/motion to explicitly define region to align.
--- # Disabling ~
--- To disable, set `vim.g.minialign_disable` (globally) or `vim.b.minialign_disable`
--- (for a buffer) to `true`. Considering high number of different scenarios
--- and customization intentions, writing exact rules for disabling module's
--- functionality is left to user. See |mini.nvim-disabling-recipes| for common
--- recipes.
---@tag MiniAlign
--- PARTS ~
--- 2d array of strings (array of arrays of strings).
--- See more in |MiniAlign.as_parts()|.
--- First-level array of parts (like `parts[1]`).
--- COLUMN ~
--- Array of strings, constructed from parts elements with the same
--- second-level index (like `{ parts[1][1],` `parts[2][1], ... }`).
--- A named callable. See |MiniAlign.new_step()|. When used in terms of alignment
--- steps, callable takes two arguments: some object (parts or string array)
--- and option table.
--- SPLIT ~
--- Process of taking array of strings and converting it into parts.
--- JUSTIFY ~
--- Process of taking parts and converting them to aligned parts (all elements
--- have same widths inside columns).
--- MERGE ~
--- Process of taking parts and converting it back to array of strings. Usually
--- by concatenating rows into strings.
--- REGION ~
--- Table representing region in a buffer. Fields <from> / <to> have inclusive
--- start / end positions (<to> might be `nil` to describe empty region).
--- Positions are also tables with <line> and <col> fields (both start at 1).
--- Either charwise ("char", `v`, |charwise|), linewise ("line", `V`, |linewise|)
--- or blockwise ("block", `<C-v>`, |blockwise-visual|)
---@tag MiniAlign-glossary
--- There are two main processes implemented in 'mini.align': strings alignment
--- and interactive region alignment. See |MiniAlign-glossary| for more information
--- about used terms.
--- # Strings alignment ~
--- Main implementation is in |MiniAlign.align_strings()|. Its input is array of
--- strings and output - array of aligned strings. The process consists from three
--- main steps (split, justify, merge) which can be preceded by any number of
--- preliminary steps (pre-split, pre-justify, pre-merge).
--- Algorithm:
--- - <Pre-split>. Take input array of strings and consecutively apply all
---   pre-split steps (`steps.pre_split`). Each one has `(strings, opts)` signature
---   and should modify array in place.
--- - <Split>. Take array of strings and convert it to parts with `steps.split()`.
---   It has `(strings, opts)` signature and should return parts.
--- - <Pre-justify>. Take parts and consecutively apply all pre-justify
---   steps (`steps.pre_justify`). Each one has `(parts, opts)` signature and
---   should modify parts in place.
--- - <Justify>. Take parts and apply `steps.justify()`. It has `(parts, opts)`
---   signature and should modify parts in place.
--- - <Pre-merge>. Take parts and consecutively apply all pre-merge
---   steps (`steps.pre_merge`). Each one has `(parts, opts)` signature and
---   should modify parts in place.
--- - <Merge>. Take parts and convert it to array of strings with `steps.merge()`.
---   It has `(parts, opts)` signature and should return array of strings.
--- - All table objects are initially copied so that modification in place doesn't
---   affect workflow.
--- - Default main steps are designed to be controlled via options. See
---   |MiniAlign.align_strings()| and default step entries in |MiniAlign.gen_step|.
--- - All steps are guaranteed to take same option table as second argument.
---   This allows steps to "talk" to each other, i.e. earlier steps can pass data
---   to later ones.
--- # Interactive region alignment ~
--- Interactive alignment is a main entry point for most users. It can be done
--- in two flavors:
--- - <Without-preview>. Initiated via mapping defined in `start` of
---   `MiniAlign.config.mappings`. Alignment is accepted once split pattern becomes
---   non-default.
--- - <With-preview>. Initiated via mapping defined in `start_with_preview` of
---   `MiniAlign.config.mappings`. Alignment result is shown after every modifier
---   and is accepted after `<CR>` (`Enter`) is hit. Note: each preview is done by
---   applying current alignment steps and options to the initial region lines,
---   not the ones currently displaying in preview.
--- Lifecycle (assuming default mappings):
--- - <Initiate-alignment>:
---     - In Normal mode type `ga` (or `gA` to show preview) followed by textobject
---       or motion defining region to be aligned.
---     - In Visual mode select region and type `ga` (or `gA` to show preview).
---   Strings contained in selected region will be used as input to
---   |MiniAlign.align_strings()|.
---   Beware of mode when selecting region: charwise (`v`), linewise (`V`), or
---   blockwise (`<C-v>`). They all behave differently.
--- - <Press-modifiers>. Press single keys one at a time:
---     - If pressed key is among table keys of `modifiers` table of
---       |MiniAlign.config|, its function value is executed. It usually modifies
---       some options(s) and/or affects some pre-step(s).
---     - If pressed key is not among defined modifiers, it is treated as plain
---       split pattern.
---   This process can either end by itself (usually in case of no preview and
---   non-default split pattern being set) or you can choose to end it manually.
--- - <Accept-or-discard>. In case of active preview, accept current result by
---   pressing `<CR>`. Discard any result and return to initial regions with
---   either `<Esc>` or `<C-c>`.
--- See more in |MiniAlign-modifiers-builtin| and |MiniAlign-examples|.
--- - Visual blockwise selection works best with 'virtualedit' equal to "block"
---   or "all".
--- - Alignment with preview works best with 'showmode' disabled.
---@tag MiniAlign-algorithm
--- Overview of builtin modifiers
--- All examples assume interactive alignment with preview in linewise mode. With
--- default mappings, use `V` to select lines and `gA` to initiate alignment. It
--- might be helpful to copy lines into modifiable buffer and experiment yourself.
--- - Any pressed key which doesn't have defined modifier will be treated as
---   plain split pattern.
--- - All modifiers can be customized inside |MiniAlign.setup()|. See "Modifiers"
---   section of |MiniAlign.config|.
--- # Main option modifiers ~
--- <s> Enter split pattern (confirm prompt by pressing `<CR>`). Input is treated
---   as plain delimiter.
---   Before: >
---   a-b-c
---   aa-bb-cc
---   After typing `s-<CR>`: >
---   a -b -c
---   aa-bb-cc
--- <j> Choose justify side. Prompts user (with helper message) to type single
---   character identifier of side: `l`eft, `c`enter, `r`ight, `n`one.
---   Before: >
---   a_b_c
---   aa_bb_cc
---   After typing `_jr` (first make split by `_`): >
---    a_ b_ c
---   aa_bb_cc
--- <m> Enter merge delimiter (confirm prompt by pressing `<CR>`).
---   Before: >
---   a_b_c
---   aa_bb_cc
---   After typing `_m--<CR>` (first make split by `_`): >
---   a --_--b --_--c
---   aa--_--bb--_--cc
--- # Modifiers adding pre-steps ~
--- <f> Enter filter expression. See more details in |MiniAlign.gen_step.filter()|.
---   Before: >
---   a_b_c
---   aa_bb_cc
---   After typing `_fn==1<CR>` (first make split by `_`): >
---   a _b_c
---   aa_bb_cc
--- <i> Ignore some split matches. It modifies `split_exclude_patterns` option by
---   adding commonly wanted patterns. See more details in
---   |MiniAlign.gen_step.ignore_split()|.
---   Before: >
---   /* This_is_assumed_to_be_comment */
---   a"_"_b
---   aa_bb
---   After typing `_i` (first make split by `_`): >
---   /* This_is_assumed_to_be_comment */
---   a"_"_b
---   aa  _bb
--- <p> Pair neighboring parts.
---   Before: >
---   a_b_c
---   aaa_bbb_ccc
---   After typing `_p` (first make split by `_`): >
---   a_  b_  c
---   aaa_bbb_ccc
--- <t> Trim parts from whitespace on both sides (keeping indentation).
---   Before: >
---   a   _   b   _   c
---     aa _bb _cc
---   After typing `_t` (first make split by `_`): >
---   a   _b _c
---     aa_bb_cc
--- # Delete some last pre-step ~
--- <BS> Delete one of the pre-steps. If there is only one kind of pre-steps,
---   remove its latest added one. If not, prompt user to choose pre-step kind
---   by entering single character: `s`plit, `j`ustify, `m`erge.
---   Examples:
---   - `tp<BS>` results in only "trim" step to be left.
---   - `it<BS>` prompts to choose which step to delete (pre-split or
---     pre-justify in this case).
--- # Special configurations for common splits ~
--- <=> Use special pattern to align by a group of consecutive "=". It can be
---   preceded by any number of punctuation marks and followed by some sommon
---   punctuation characters. Trim whitespace and merge with single space.
---   Before: >
---   aa<=bb
---   aaa===bbb
---   aaaa   =   cccc
---   After typing `=`: >
---   a    =   b
---   aa   <=  bb
---   aaa  === bbb
---   aaaa =   cccc
--- <,> Besides splitting by "," character, trim whitespace, pair neighboring
---   parts and merge with single space.
---   Before: >
---   aa,bb
---   aaa    ,    bbb
---   After typing `,`: >
---   a,   b
---   aa,  bb
---   aaa, bbb
--- <|> Split by "|" character, trim whitespace, merge with single space.
---   Before: >
---   |a|b|
---   |aa|bb|
---   |aaa    |    bbb   |
---   After typing `|`: >
---   | a   | b   |
---   | aa  | bb  |
---   | aaa | bbb |
--- <Space> (Space bar) Squash consecutive whitespace into single space (except
---   possible indentation) and split by `%s+` pattern (keeps indentation).
---   Before: >
---   a b c
---     aa    bb   cc
---   After typing `<Space>`: >
---     a  b  c
---     aa bb cc
---@tag MiniAlign-modifiers-builtin
--- Copy lines in modifiable buffer, initiate alignment with preview (`gAip`)
--- and try typing suggested key sequences.
--- These are modified examples taken from 'junegunn/vim-easy-align'.
--- # Equal sign ~
--- Lines: >
---   # This=is=assumed=to be a comment
---   "a ="
---   a = 1
---   bbbb = 2
---   ccccccc = 3
---   ccccccccccccccc
---   ddd = 4
---   eeee === eee = eee = eee=f
---   fff = ggg += gg &&= gg
---   g != hhhhhhhh == 888
---   i   := 5
---   i     %= 5
---   i       *= 5
---   j     =~ 5
---   j   >= 5
---   aa      =>         123
---   aa <<= 123
---   aa        >>= 123
---   bbb               => 123
---   c     => 1233123
---   d   =>      123
---   dddddd &&= 123
---   dddddd ||= 123
---   dddddd /= 123
---   gg <=> ee
--- Key sequences:
--- - `=jc`
--- - `=jr`
--- - `=m!<CR>`
--- - `=i` (execute `:lua vim.o.commentstring = '# %s'` for full experience)
--- - `=<BS>`
--- - `=<BS>p`
--- - `=fn==1<CR>`
--- - `=<BS>fn==1<CR>t`
--- - `=frow>7<CR>`
---@tag MiniAlign-examples
---@alias __align_with_preview boolean|nil Whether to align with live preview.
-- Module definition ==========================================================
local MiniAlign = {}
local H = {}
--- Module setup
---@param config table|nil Module config table. See |MiniAlign.config|.
---@usage >lua
---   require('mini.align').setup() -- use default config
---   -- OR
---   require('mini.align').setup({}) -- replace {} with your config table
MiniAlign.setup = function(config)
  -- Export module
  _G.MiniAlign = MiniAlign
  -- Setup config
  config = H.setup_config(config)
  -- Apply config
  H.apply_config(config)
--- Defaults ~
---@eval return MiniDoc.afterlines_to_code(MiniDoc.current.eval_section)
---@text # Modifiers ~
--- `MiniAlign.config.modifiers` is used to define interactive user experience
--- of managing alignment process. It is a table with single character keys and
--- modifier function values.
--- Each modifier function:
--- - Is called when corresponding modifier key is pressed.
--- - Has signature `(steps, opts)` and should modify any of its input in place.
--- Examples:
--- - Modifier function used for default 'i' modifier: >lua
---   function(steps, _)
---     table.insert(steps.pre_split, MiniAlign.gen_step.ignore_split())
--- - Tweak 't' modifier to use highest indentation instead of keeping it: >lua
---   require('mini.align').setup({
---     modifiers = {
---       t = function(steps, _)
---         local trim_high = MiniAlign.gen_step.trim('both', 'high')
---         table.insert(steps.pre_justify, trim_high)
---       end
--- - Tweak `j` modifier to cycle through available "justify_side" option
---   values (like in 'junegunn/vim-easy-align'): >lua
---   require('mini.align').setup({
---     modifiers = {
---       j = function(_, opts)
---         local next_option = ({
---           left = 'center', center = 'right', right = 'none', none = 'left',
---         })[opts.justify_side]
---         opts.justify_side = next_option or 'left'
---       end,
--- # Options ~
--- `MiniAlign.config.options` defines default values of options used to control
--- behavior of steps.
--- Examples:
--- - Set `justify_side = 'center'` to center align at initialization.
--- For more details about options see |MiniAlign.align_strings()| and entries of
--- |MiniAlign.gen_step| for default main steps.
--- # Steps ~
--- `MiniAlign.config.steps` defines default steps to be applied during
--- alignment process.
--- Examples:
--- - Align by default only first pair of columns: >lua
---   local align = require('mini.align')
---   align.setup({
---     steps = {
---       pre_justify = { align.gen_step.filter('n == 1') }
MiniAlign.config = {
  -- Module mappings. Use `''` (empty string) to disable one.
  mappings = {
    start = 'ga',
    start_with_preview = 'gA',
  -- Modifiers changing alignment steps and/or options
  modifiers = {
    -- Main option modifiers
    --minidoc_replace_start ['s'] = --<function: enter split pattern>,
    ['s'] = function(_, opts)
      local input = H.user_input('Enter split Lua pattern')
      if input == nil then return end
      opts.split_pattern = input
    --minidoc_replace_end
    --minidoc_replace_start ['j'] = --<function: choose justify side>,
    ['j'] = function(_, opts)
      -- stylua: ignore
      H.echo({
        { 'Select justify: ', 'ModeMsg' }, { 'l', 'Question' }, { 'eft, ' },
        { 'c', 'Question' }, { 'enter, ' }, { 'r', 'Question' }, { 'ight, ' },
        { 'n', 'Question' }, { 'one' }
      local ok, char = pcall(vim.fn.getcharstr)
      if not ok or char == '\27' then return end
      local direction = ({ l = 'left', c = 'center', r = 'right', n = 'none' })[char]
      if direction == nil then return end
      opts.justify_side = direction
    --minidoc_replace_end
    --minidoc_replace_start ['m'] = --<function: enter merge delimiter>,
    ['m'] = function(_, opts)
      local input = H.user_input('Enter merge delimiter')
      if input == nil then return end
      opts.merge_delimiter = input
    --minidoc_replace_end
    -- Modifiers adding pre-steps
    --minidoc_replace_start ['f'] = --<function: filter parts by entering Lua expression>,
    ['f'] = function(steps, _)
      local input = H.user_input('Enter filter expression')
      local step = MiniAlign.gen_step.filter(input)
      if step == nil then return end
      table.insert(steps.pre_justify, step)
    --minidoc_replace_end
    --minidoc_replace_start ['i'] = --<function: ignore some split matches>,
    ['i'] = function(steps, _) table.insert(steps.pre_split, MiniAlign.gen_step.ignore_split()) end,
    --minidoc_replace_end
    --minidoc_replace_start ['p'] = --<function: pair parts>,
    ['p'] = function(steps, _) table.insert(steps.pre_justify, MiniAlign.gen_step.pair()) end,
    --minidoc_replace_end
    --minidoc_replace_start ['t'] = --<function: trim parts>,
    ['t'] = function(steps, _) table.insert(steps.pre_justify, MiniAlign.gen_step.trim()) end,
    --minidoc_replace_end
    -- Delete some last pre-step
    --minidoc_replace_start ['<BS>'] = --<function: delete some last pre-step>,
    [vim.api.nvim_replace_termcodes('<BS>', true, true, true)] = function(steps, _)
      local has_pre = {}
      for _, pre in ipairs({ 'pre_split', 'pre_justify', 'pre_merge' }) do
        if #steps[pre] > 0 then table.insert(has_pre, pre) end
      if #has_pre == 0 then return end
      if #has_pre == 1 then
        local pre = steps[has_pre[1]]
        table.remove(pre, #pre)
        return
      --stylua: ignore
      H.echo({
        { 'Select pre-step to remove: ', 'ModeMsg' }, { 's', 'Question' }, { 'plit, ' },
        { 'j', 'Question' }, { 'ustify, ' }, { 'm', 'Question' }, { 'erge' },
      local ok, char = pcall(vim.fn.getcharstr)
      if not ok or char == '\27' then return end
      if char == 's' then table.remove(steps.pre_split, #steps.pre_split) end
      if char == 'j' then table.remove(steps.pre_justify, #steps.pre_justify) end
      if char == 'm' then table.remove(steps.pre_merge, #steps.pre_merge) end
    --minidoc_replace_end
    -- Special configurations for common splits
    --minidoc_replace_start ['='] = --<function: enhanced setup for '='>,
    ['='] = function(steps, opts)
      opts.split_pattern = '%p*=+[<>~]*'
      table.insert(steps.pre_justify, MiniAlign.gen_step.trim())
      opts.merge_delimiter = ' '
    --minidoc_replace_end
    --minidoc_replace_start [','] = --<function: enhanced setup for ','>,
    [','] = function(steps, opts)
      opts.split_pattern = ','
      table.insert(steps.pre_justify, MiniAlign.gen_step.trim())
      table.insert(steps.pre_justify, MiniAlign.gen_step.pair())
      opts.merge_delimiter = ' '
    --minidoc_replace_end
    --minidoc_replace_start ['|'] = --<function: enhanced setup for '|'>,
    ['|'] = function(steps, opts)
      opts.split_pattern = '|'
      table.insert(steps.pre_justify, MiniAlign.gen_step.trim())
      opts.merge_delimiter = ' '
    --minidoc_replace_end
    --minidoc_replace_start [' '] = --<function: enhanced setup for ' '>,
    [' '] = function(steps, opts)
      table.insert(
        steps.pre_split,
        MiniAlign.new_step('squash', function(strings)
          -- Replace all space sequences with single space (except indent)
          for i, s in ipairs(strings) do
            strings[i] = s:gsub('()(%s+)', function(n, space) return n == 1 and space or ' ' end)
          end
        end)
      -- Don't use `' '` to respect indent
      opts.split_pattern = '%s+'
    --minidoc_replace_end
  -- Default options controlling alignment process
  options = {
    split_pattern = '',
    justify_side = 'left',
    merge_delimiter = '',
  -- Default steps performing alignment (if `nil`, default is used)
  steps = {
    pre_split = {},
    split = nil,
    pre_justify = {},
    justify = nil,
    pre_merge = {},
    merge = nil,
  -- Whether to disable showing non-error feedback
  -- This also affects (purely informational) helper messages shown after
  -- idle time if user input is required.
  silent = false,
--minidoc_afterlines_end
-- Module functionality =======================================================
--- Align strings
--- For details about alignment process see |MiniAlign-algorithm|.
---@param strings table Array of strings.
---@param opts table|nil Options. Its copy will be passed to steps as second
---   argument. Extended with `MiniAlign.config.options`.
---   This is a place to control default main steps:
---   - `opts.split_pattern` - Lua pattern(s) used to make split parts.
---   - `opts.split_exclude_patterns` - which split matches should be ignored.
---   - `opts.justify_side` - which direction(s) alignment should be done.
---   - `opts.justify_offsets` - offsets tweaking width of first column
---   - `opts.merge_delimiter` - which delimiter(s) to use when merging.
---   For more information see |MiniAlign.gen_step| entry for corresponding
---   default step.
---@param steps table|nil Steps. Extended with `MiniAlign.config.steps`.
---   Possible `nil` values are replaced with corresponding default steps:
---   - `split` - |MiniAlign.gen_step.default_split()|.
---   - `justify` - |MiniAlign.gen_step.default_justify()|.
---   - `merge` - |MiniAlign.gen_step.default_merge()|.
MiniAlign.align_strings = function(strings, opts, steps)
  -- Validate arguments
  if not H.is_array_of(strings, H.is_string) then
    H.error('First argument of `MiniAlign.align_strings()` should be array of strings.')
  opts = H.normalize_opts(opts)
  steps = H.normalize_steps(steps, 'steps')
  -- Make a copy so that modification in place doesn't affect input
  strings = vim.deepcopy(strings)
  -- Pre split
  for _, step in ipairs(steps.pre_split) do
    H.apply_step(step, strings, opts, 'pre_split')
  local parts = H.apply_step(steps.split, strings, opts, 'split')
  if not H.is_parts(parts) then
    if H.can_be_parts(parts) then
      parts = MiniAlign.as_parts(parts)
      H.error('Output of `split` step should be convertible to parts. See `:h MiniAlign.as_parts()`.')
  -- Pre justify
  for _, step in ipairs(steps.pre_justify) do
    H.apply_step(step, parts, opts, 'pre_justify')
  -- Justify
  H.apply_step(steps.justify, parts, opts, 'justify')
  -- Pre merge
  for _, step in ipairs(steps.pre_merge) do
    H.apply_step(step, parts, opts, 'pre_merge')
  local new_strings = H.apply_step(steps.merge, parts, opts, 'merge')
  if not H.is_array_of(new_strings, H.is_string) then H.error('Output of `merge` step should be array of strings.') end
  return new_strings
--- Align current region with user-supplied steps
--- Mostly designed to be used inside mappings.
--- Will use |MiniAlign.align_strings()| and set the following options in `opts`:
--- - `justify_offsets` - array of offsets used to achieve actual alignment of
---   a region. It is non-trivial (not array of zeros) only for charwise
---   selection: offset of first string is computed as width of prefix to the
---   left of region start.
--- - `region` - current affected region (see |MiniAlign-glossary|). Can be
---   used to create more advanced steps.
--- - `mode` - mode of selection (see |MiniAlign-glossary|).
---@param mode string Selection mode. One of "char", "line", "block".
MiniAlign.align_user = function(mode)
  local modifiers = H.get_config().modifiers
  local with_preview = H.cache.with_preview
  local opts = H.cache.opts or H.normalize_opts()
  local steps = H.cache.steps or H.normalize_steps()
  local steps_are_from_cache = H.cache.steps ~= nil
  H.cache.region = nil
  -- Track if lines were actually changed to properly undo during preview
  local lines_were_changed = false
  -- Make initial process
  lines_were_changed = H.process_current_region(lines_were_changed, mode, opts, steps)
  -- Make early return:
  -- - If cache is present (enables dot-repeat).
  -- - If `split` is not default with no preview (no more information needed).
  if steps_are_from_cache or (not with_preview and opts.split_pattern ~= '') then return end
  -- Ask user to input modifier id until no more is needed
  local n_iter = 0
  while true do
    -- Get modifier from user
    local id = H.user_modifier(with_preview, H.make_status_msg_chunks(opts, steps))
    n_iter = n_iter + 1
    -- Stop in case user supplied inappropriate modifier id (abort)
    -- Also stop in case of too many iterations (guard from infinite cycle)
    if id == nil or n_iter > 1000 then
      if lines_were_changed then H.undo() end
      if n_iter > 1000 then H.echo({ { 'Too many modifiers typed.', 'WarningMsg' } }, true) end
      break
    -- Stop preview after `<CR>` (confirmation)
    if with_preview and id == '\r' then break end
    -- Apply modifier
    local mod = modifiers[id]
    if mod == nil then
      -- Use supplied identifier as split pattern
      opts.split_pattern = vim.pesc(id)
      -- Modifier should change input `steps` table in place
      local ok, out = pcall(mod, steps, opts)
      if not ok then
        -- Force message to appear for 500ms because it might be overridden by
        -- helper status message
        local msg = string.format('Modifier %s should be properly callable. Reason: %s', vim.inspect(id), out)
        H.echo({ { msg, 'WarningMsg' } }, true)
        vim.cmd('redraw')
        vim.loop.sleep(500)
    -- Normalize steps and options while validating their correctness
    opts = H.normalize_opts(opts)
    steps = H.normalize_steps(steps, opts)
    -- Process region while tracking if lines were set at least once
    local lines_now_changed = H.process_current_region(lines_were_changed, mode, opts, steps)
    lines_were_changed = lines_were_changed or lines_now_changed
    -- Stop in "no preview" mode right after `split` is defined
    if not with_preview and opts.split_pattern ~= '' then break end
  -- Remove helper status message (if shown)
  H.unecho()
--- Convert 2d array of strings to parts
--- This function verifies if input is a proper 2d array of strings and adds
--- methods to its copy.
---@class parts
---@field apply function Takes callable `f` and applies it to every part.
---   Callable should have signature `(s, data)`: `s` is a string part,
---   `data` - table with its data (<row> has row number, <col> has column number).
---   Returns new 2d array.
---@field apply_inplace function Takes callable `f` and applies it to every part.
---   Should have same signature as in `apply` method. Outputs (should all be
---   strings) are assigned in place to a corresponding parts element. Returns
---   parts itself to enable method chaining.
---@field get_dims function Return dimensions of parts array: a table with
---   <row> and <col> keys having number of rows and number of columns (maximum
---   number of elements across all rows).
---@field group function Concatenate neighboring strings based on supplied
---   boolean mask and direction (one of "left", default, or "right"). Has
---   signature `(mask, direction)` and modifies parts in place. Returns parts
---   itself to enable method chaining.
---   Example:
---   - Parts: `{ { "a", "b", "c" }, { "d", "e" }, { "f" } }`
---   - Mask: `{ { false, false, true }, { true, false }, { false } }`
---   - Result for direction "left":  `{ { "abc" },    { "d", "e" }, { "f" } }`
---   - Result for direction "right": `{ { "ab","c" }, { "de" },     { "f" } }`
---@field pair function Concatenate neighboring element pairs. Takes
---   `direction` as input (one of "left", default, or "right") and applies
---   `group()` for an alternating mask.
---   Example:
---   - Parts: `{ { "a", "b", "c" }, { "d", "e" }, { "f" } }`
---   - Result for direction "left":  `{ { "ab", "c" }, { "de" }, { "f" } }`
---   - Result for direction "right": `{ { "a", "bc" }, { "de" }, { "f" } }`
---@field slice_col function Return column with input index `j`. Note: it might
---   not be an array if rows have unequal number of columns.
---@field slice_row function Return row with input index `i`.
---@field trim function Trim elements whitespace. Has signature `(direction, indent)`
---   and modifies parts in place. Returns parts itself to enable method chaining.
---   - Possible values of `direction`: "both" (default), "left", "right",
---   "none". Defines from which side whitespaces should be removed.
---   - Possible values of `indent`: "keep" (default), "low", "high", "remove".
---   Defines what to do with possible indent (left whitespace of first string
---   in a row). Value "keep" keeps it; "low" makes all indent equal to the
---   lowest across rows; "high" - highest across rows; "remove" - removes indent.
---@usage >lua
---   parts = MiniAlign.as_parts({ { 'a', 'b' }, { 'c' } })
---   print(vim.inspect(parts.get_dims())) -- Should be { row = 2, col = 2 }
---   parts.apply_inplace(function(s, data)
---     return ' ' .. data.row .. s .. data.col .. ' '
---   print(vim.inspect(parts)) -- Should be { { ' 1a1 ', ' 1b2 ' }, { ' 2c1 ' } }
---   parts.trim('both', 'remove').pair()
---   print(vim.inspect(parts)) -- Should be { { '1a11b2' }, { '2c1' } }
MiniAlign.as_parts = function(arr2d)
  local ok, msg = H.can_be_parts(arr2d)
  if not ok then H.error('Input of `as_parts()` ' .. msg) end
  local parts = vim.deepcopy(arr2d)
  local methods = {}
  methods.apply = function(f)
    local res = {}
    for i, row in ipairs(parts) do
      res[i] = {}
      for j, s in ipairs(row) do
        res[i][j] = f(s, { row = i, col = j })
    return res
  methods.apply_inplace = function(f)
    for i, row in ipairs(parts) do
      for j, s in ipairs(row) do
        local new_val = f(s, { row = i, col = j })
        if type(new_val) ~= 'string' then H.error('Input of `apply_inplace()` method should always return string.') end
        parts[i][j] = new_val
    return parts
  methods.get_dims = function()
    local n_cols = 0
    for _, row in ipairs(parts) do
      n_cols = math.max(n_cols, #row)
    return { row = #parts, col = n_cols }
  -- Group cells into single string based on boolean mask.
  -- Can be used for filtering separators and sticking separator to its part.
  methods.group = function(mask, direction)
    direction = direction or 'left'
    for i, row in ipairs(parts) do
      local group_tables = H.group_by_mask(row, mask[i], direction)
      parts[i] = vim.tbl_map(table.concat, group_tables)
    return parts
  methods.pair = function(direction)
    direction = direction or 'left'
    local mask = {}
    for i, row in ipairs(parts) do
      mask[i] = {}
      for j, _ in ipairs(row) do
        -- Count from corresponding end
        local num = direction == 'left' and j or (#row - j + 1)
        mask[i][j] = num % 2 == 0
    parts.group(mask, direction)
    return parts
  -- NOTE: output might not be an array (some rows can not have input column)
  -- Use `vim.tbl_keys()` and `vim.tbl_values()`
  methods.slice_col = function(j)
    return vim.tbl_map(function(row) return row[j] end, parts)
  methods.slice_row = function(i) return parts[i] or {} end
  methods.trim = function(direction, indent)
    direction = direction or 'both'
    indent = indent or 'keep'
    -- Verify arguments
    local trim_fun = H.trim_functions[direction]
    if not vim.is_callable(trim_fun) then
      local allowed = vim.tbl_map(vim.inspect, vim.tbl_keys(H.trim_functions))
      table.sort(allowed)
      H.error('`direction` should be one of ' .. table.concat(allowed, ', ') .. '.')
    local indent_fun = H.indent_functions[indent]
    if not vim.is_callable(indent_fun) then
      local allowed = vim.tbl_map(vim.inspect, vim.tbl_keys(H.indent_functions))
      table.sort(allowed)
      H.error('`indent` should be one of ' .. table.concat(allowed, ', ') .. '.')
    -- Compute indentation to restore later
    local row_indent = vim.tbl_map(function(row) return row[1]:match('^(%s*)') end, parts)
    row_indent = indent_fun(row_indent)
    -- Trim
    parts.apply_inplace(trim_fun)
    -- Restore indentation if it was removed
    if vim.tbl_contains({ 'both', 'left' }, direction) then
      for i, row in ipairs(parts) do
        row[1] = string.format('%s%s', row_indent[i], row[1])
    return parts
  return setmetatable(parts, { class = 'parts', __index = methods })

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