Module:Unindent

Unindent
Description	Resets the indentation level of mulitline strings.
Author(s)	8nml
Code source	Unindent
Status	Release
Using code by	@kikito (GitHub)
License	MIT

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Unindent resets the indentation level of mulitline strings. It is useful for multiline strings inside functions and large tables. This module serves as a utility function for string parsing, Testharness test suites, I18n datastores.

Lua supports multiline strings in the format [[\n...\n]]. In general, Lua does not outdent indented multiline strings out of the box. Though Lua supports variable indentation in multiline strings, custom logic is necessary to reset the string's indentation. This module adopts a flexible approach based on string scanning.

Unlike Penlight's pl.text.dedent behaviour where every line has the indentation of the first line removed, the line prefixed with the least non-tab whitespace is reset to zero indentation. Thus, the opening line of the string may retain some indentation if there are lines of less indentation terminating the string.

Documentation

Package function

unindent(str) (function): Unindent resets the indentation level of mulitline strings.; Parameter: str Multiline string indented consistently. (string); Returns: Unindented string. (string)

The above documentation is transcluded from Module:Unindent/doc.
Editors can experiment in this module's sandbox and testcases pages.
Subpages of this module.

-- <nowiki>
--- Unindent resets the indentation level of mulitline strings.
--  It is useful for multiline strings inside functions and large tables.
--  This module serves as a utility function for string parsing, [[Global
--  Lua Modules/Testharness|Testharness]] test suites, [[Global Lua
--  Modules/I18n|I18n]] datastores.
--  
--  Lua supports multiline strings in the format `[[\n...\n]]`. In general,
--  Lua does not outdent indented multiline strings out of the box. Though
--  Lua supports variable indentation in multiline strings, custom logic is
--  necessary to reset the string's indentation. This module adopts a
--  flexible approach based on string scanning.
--  
--  Unlike Penlight's `pl.text.dedent` behaviour where every line has the
--  indentation of the first line removed, the line prefixed with the least
--  non-tab whitespace is reset to zero indentation. Thus, the opening line
--  of the string may retain some indentation *if* there are lines of less
--  indentation terminating the string.
--  
--  @script             unindent
--  @license            MIT
--  @release            stable
--  @author             [[wikia:c:User:8nml|8nml]]
--  @attribution        [https://github.com/kikito @kikito] ([https://github.com/kikito/inspect.lua/blob/master/spec/unindent.lua GitHub])
--  @param              {string} str Multiline string indented consistently.
--  @return             {string} Unindented string.
return function(str)
    str = str:gsub(' +$', ''):gsub('^ +', '') -- remove spaces at start and end
    local level = math.huge
    local minPrefix = ''
    local len
    for prefix in str:gmatch('\n( +)') do
        len = #prefix
        if len < level then
            level = len
            minPrefix = prefix
        end
    end
    return (str:gsub('\n' .. minPrefix, '\n'):gsub('\n$', ''))
end