add examples

examples/surround.lua

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+local vim_repeat = require 'u.repeat'
+local opkeymap = require 'u.opkeymap'
+local Pos = require 'u.pos'
+local Range = require 'u.range'
+local Buffer = require 'u.buffer'
+local CodeWriter = require 'u.codewriter'
+
+local M = {}
+
+local surrounds = {
+  [')'] = { left = '(', right = ')' },
+  ['('] = { left = '( ', right = ' )' },
+  [']'] = { left = '[', right = ']' },
+  ['['] = { left = '[ ', right = ' ]' },
+  ['}'] = { left = '{', right = '}' },
+  ['{'] = { left = '{ ', right = ' }' },
+  ['>'] = { left = '<', right = '>' },
+  ['<'] = { left = '< ', right = ' >' },
+  ["'"] = { left = "'", right = "'" },
+  ['"'] = { left = '"', right = '"' },
+  ['`'] = { left = '`', right = '`' },
+}
+
+---@return { left: string; right: string }|nil
+local function prompt_for_bounds()
+  local cn = vim.fn.getchar()
+  -- Check for non-printable characters:
+  if type(cn) ~= 'number' or cn < 32 or cn > 126 then return end
+  local c = vim.fn.nr2char(cn)
+
+  if c == '<' then
+    -- Surround with a tag:
+    vim.keymap.set('c', '>', '><CR>')
+    local tag = '<' .. vim.fn.input '<'
+    if tag == '<' then return end
+    vim.keymap.del('c', '>')
+    local endtag = '</' .. tag:sub(2):match '[^ >]*' .. '>'
+    -- selene: allow(global_usage)
+    return { left = tag, right = endtag }
+  else
+    -- Default surround:
+    return (surrounds)[c] or { left = c, right = c }
+  end
+end
+
+---@param range Range
+---@param bounds { left: string; right: string }
+local function do_surround(range, bounds)
+  local left = bounds.left
+  local right = bounds.right
+  if range.mode == 'V' then
+    -- If we are surrounding multiple lines, we don't care about
+    -- space-padding:
+    left = vim.trim(left)
+    right = vim.trim(right)
+  end
+
+  if range.mode == 'v' then
+    range:replace(left .. range:text() .. right)
+  elseif range.mode == 'V' then
+    local buf = Buffer.current()
+    local cw = CodeWriter.from_line(buf:line0(range.start.lnum):text(), buf.buf)
+
+    -- write the left bound at the current indent level:
+    cw:write(left)
+
+    local curr_ident_prefix = cw.indent_str:rep(cw.indent_level)
+    cw:indent(function(cw2)
+      for _, line in ipairs(range:lines()) do
+        -- trim the current indent prefix from the line:
+        if line:sub(1, #curr_ident_prefix) == curr_ident_prefix then
+          --
+          line = line:sub(#curr_ident_prefix + 1)
+        end
+
+        cw2:write(line)
+      end
+    end)
+
+    -- write the right bound at the current indent level:
+    cw:write(right)
+
+    range:replace(cw.lines)
+  end
+
+  range.start:save_to_pos '.'
+end
+
+function M.setup()
+  require('u.repeat').setup()
+
+  -- Visual
+  vim.keymap.set('v', 'S', function()
+    local c = vim.fn.getcharstr()
+    local range = Range.from_vtext()
+    local bounds = surrounds[c] or { left = c, right = c }
+    vim_repeat.run(function()
+      do_surround(range, bounds)
+      -- this is a visual mapping: end in normal mode:
+      vim.cmd { cmd = 'normal', args = { '' }, bang = true }
+    end)
+  end, { noremap = true, silent = true })
+
+  -- Change
+  vim.keymap.set('n', 'cs', function()
+    local from_cn = vim.fn.getchar()
+    -- Check for non-printable characters:
+    if from_cn < 32 or from_cn > 126 then return end
+    local from_c = vim.fn.nr2char(from_cn)
+    local from = surrounds[from_c] or { left = from_c, right = from_c }
+
+    local arange = Range.from_text_object('a' .. from_c, { user_defined = true })
+    if arange == nil then return nil end
+    local hl_info1 = Range.new(arange.start, arange.start, 'v'):highlight('IncSearch', { priority = 999 })
+    local hl_info2 = Range.new(arange.stop, arange.stop, 'v'):highlight('IncSearch', { priority = 999 })
+    local hl_clear = function()
+      hl_info1.clear()
+      hl_info2.clear()
+    end
+
+    local to = prompt_for_bounds()
+    hl_clear()
+    if to == nil then return end
+
+    vim_repeat.run(function()
+      if from_c == 't' then
+        -- For tags, we want to replace the inner text, not the tag:
+        local irange = Range.from_text_object('i' .. from_c, { user_defined = true })
+        if arange == nil or irange == nil then return nil end
+
+        local lrange = Range.new(arange.start, irange.start:must_next(-1))
+        local rrange = Range.new(irange.stop:must_next(1), arange.stop)
+
+        rrange:replace(to.right)
+        lrange:replace(to.left)
+      else
+        -- replace `from.right` with `to.right`:
+        local last_line = arange:line0(-1).text() --[[@as string]]
+        local from_right_match = last_line:match(vim.pesc(from.right) .. '$')
+        if from_right_match then
+          local match_start = arange.stop:clone()
+          match_start.col = match_start.col - #from_right_match + 1
+          Range.new(match_start, arange.stop):replace(to.right)
+        end
+
+        -- replace `from.left` with `to.left`:
+        local first_line = arange:line0(0).text() --[[@as string]]
+        local from_left_match = first_line:match('^' .. vim.pesc(from.left))
+        if from_left_match then
+          local match_end = arange.start:clone()
+          match_end.col = match_end.col + #from_left_match - 1
+          Range.new(arange.start, match_end):replace(to.left)
+        end
+      end
+    end)
+  end, { noremap = true, silent = true })
+
+  -- Delete
+  vim.keymap.set('n', 'ds', function()
+    local txt_obj = vim.fn.getcharstr()
+    vim_repeat.run(function()
+      local buf = Buffer.current()
+      local irange = Range.from_text_object('i' .. txt_obj)
+      local arange = Range.from_text_object('a' .. txt_obj)
+      if arange == nil or irange == nil then return nil end
+      local starting_cursor_pos = arange.start:clone()
+
+      -- Now, replace `arange` with the content of `irange`.  If `arange` was multiple lines,
+      -- dedent the contents first, and operate in linewise mode
+      if arange.start.lnum ~= arange.stop.lnum then
+        -- Auto dedent:
+        vim.cmd.normal('<i' .. vim.trim(txt_obj))
+        -- Dedenting moves the cursor, so we need to set the cursor to a consistent starting spot:
+        arange.start:save_to_pos '.'
+        -- Dedenting also changed the inner text, so re-acquire it:
+        arange = Range.from_text_object('a' .. txt_obj)
+        irange = Range.from_text_object('i' .. txt_obj)
+        if arange == nil or irange == nil then return end -- should never be true
+        arange:replace(irange:lines())
+
+        local final_range = Range.new(
+          arange.start,
+          Pos.new(
+            arange.stop.buf,
+            irange.start.lnum + (arange.stop.lnum + arange.start.lnum),
+            arange.stop.col,
+            arange.stop.off
+          ),
+          irange.mode
+        )
+
+        -- delete last line, if it is empty:
+        local last = buf:line0(final_range.stop.lnum)
+        if last:text():match '^%s*$' then last:replace(nil) end
+
+        -- delete first line, if it is empty:
+        local first = buf:line0(final_range.start.lnum)
+        if first:text():match '^%s*$' then first:replace(nil) end
+      else
+        -- trim start:
+        irange = irange:trim_start():trim_stop()
+        arange:replace(irange:lines())
+      end
+
+      starting_cursor_pos:save_to_pos '.'
+    end)
+  end, { noremap = true, silent = true })
+
+  opkeymap('n', 'ys', function(range)
+    local hl_info = range:highlight('IncSearch', { priority = 999 })
+
+    ---@type { left: string; right: string }
+    local bounds
+    -- selene: allow(global_usage)
+    if _G.my_surround_bounds ~= nil then
+      -- This command was repeated with `.`, we don't need
+      -- to prompt for the bounds:
+      -- selene: allow(global_usage)
+      bounds = _G.my_surround_bounds
+    else
+      local prompted_bounds = prompt_for_bounds()
+      if prompted_bounds == nil then return hl_info.clear() end
+      bounds = prompted_bounds
+    end
+
+    hl_info.clear()
+    do_surround(range, bounds)
+    -- selene: allow(global_usage)
+    _G.my_surround_bounds = nil
+
+    -- return repeatable injection
+    return function()
+      -- on_repeat, we "stage" the bounds that we were originally called with:
+      -- selene: allow(global_usage)
+      _G.my_surround_bounds = bounds
+    end
+  end)
+end
+
+return M