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-- Text processing functions.
local M = {}
local alphabet = '0123456789ABCDEF'
local atoi = {} ---@type table<string, integer>
local itoa = {} ---@type table<integer, string>
do
for i = 1, #alphabet do
local char = alphabet:sub(i, i)
itoa[i - 1] = char
atoi[char] = i - 1
atoi[char:lower()] = i - 1
end
end
--- Hex encode a string.
---
--- @param str string String to encode
--- @return string : Hex encoded string
function M.hexencode(str)
local enc = {} ---@type string[]
for i = 1, #str do
local byte = str:byte(i)
enc[2 * i - 1] = itoa[math.floor(byte / 16)]
enc[2 * i] = itoa[byte % 16]
end
return table.concat(enc)
end
--- Hex decode a string.
---
--- @param enc string String to decode
--- @return string? : Decoded string
--- @return string? : Error message, if any
function M.hexdecode(enc)
if #enc % 2 ~= 0 then
return nil, 'string must have an even number of hex characters'
end
local str = {} ---@type string[]
for i = 1, #enc, 2 do
local u = atoi[enc:sub(i, i)]
local l = atoi[enc:sub(i + 1, i + 1)]
if not u or not l then
return nil, 'string must contain only hex characters'
end
str[(i + 1) / 2] = string.char(u * 16 + l)
end
return table.concat(str), nil
end
--- Sets the indent (i.e. the common leading whitespace) of non-empty lines in `text` to `size`
--- spaces/tabs.
---
--- Indent is calculated by number of consecutive indent chars.
--- - The first indented, non-empty line decides the indent char (space/tab):
--- - `SPC SPC TAB …` = two-space indent.
--- - `TAB SPC …` = one-tab indent.
--- - Set `opts.expandtab` to treat tabs as spaces.
---
--- To "dedent" (remove the common indent), pass `size=0`:
--- ```lua
--- vim.print(vim.text.indent(0, ' a\n b\n'))
--- ```
---
--- To adjust relative-to an existing indent, call indent() twice:
--- ```lua
--- local indented, old_indent = vim.text.indent(0, ' a\n b\n')
--- indented = vim.text.indent(old_indent + 2, indented)
--- vim.print(indented)
--- ```
---
--- To ignore the final, blank line when calculating the indent, use gsub() before calling indent():
--- ```lua
--- local text = ' a\n b\n '
--- vim.print(vim.text.indent(0, (text:gsub('\n[\t ]+\n?$', '\n'))))
--- ```
---
--- @param size integer Number of spaces.
--- @param text string Text to indent.
--- @param opts? { expandtab?: number }
--- @return string # Indented text.
--- @return integer # Indent size _before_ modification.
function M.indent(size, text, opts)
vim.validate('size', size, 'number')
vim.validate('text', text, 'string')
vim.validate('opts', opts, 'table', true)
-- TODO(justinmk): `opts.prefix`, `predicate` like python https://docs.python.org/3/library/textwrap.html
opts = opts or {}
local tabspaces = opts.expandtab and (' '):rep(opts.expandtab) or nil
--- Minimum common indent shared by all lines.
local old_indent --[[@type number?]]
local prefix = tabspaces and ' ' or nil -- Indent char (space or tab).
--- Check all non-empty lines, capturing leading whitespace (if any).
--- @diagnostic disable-next-line: no-unknown
for line_ws, extra in text:gmatch('([\t ]*)([^\n]+)') do
line_ws = tabspaces and line_ws:gsub('[\t]', tabspaces) or line_ws
-- XXX: blank line will miss the last whitespace char in `line_ws`, so we need to check `extra`.
line_ws = line_ws .. (extra:match('^%s+$') or '')
if 0 == #line_ws then
-- Optimization: If any non-empty line has indent=0, there is no common indent.
old_indent = 0
break
end
prefix = prefix and prefix or line_ws:sub(1, 1)
local _, end_ = line_ws:find('^[' .. prefix .. ']+')
old_indent = math.min(old_indent or math.huge, end_ or 0)
end
-- Default to 0 if all lines are empty.
old_indent = old_indent or 0
prefix = prefix and prefix or ' '
if old_indent == size then
-- Optimization: if the indent is the same, return the text unchanged.
return text, old_indent
end
local new_indent = prefix:rep(size)
--- Replaces indentation of a line.
--- @param line string
local function replace_line(line)
-- Match the existing indent exactly; avoid over-matching any following whitespace.
local pat = prefix:rep(old_indent)
-- Expand tabs before replacing indentation.
line = not tabspaces and line
or line:gsub('^[\t ]+', function(s)
return s:gsub('\t', tabspaces)
end)
-- Text following the indent.
local line_text = line:match('^' .. pat .. '(.*)') or line
return new_indent .. line_text
end
return (text:gsub('[^\n]+', replace_line)), old_indent
end
return M
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