Module:Escape/doc

Usage

This module is designed as an way to escape strings in a customized and efficient manner. It works by replacing characters that are preceded by your escape char (or phrase) There are two ways to call this module:

From another module:

<syntaxhighlight lang="lua" class="" style="background:none; border:none; color:inherit; padding: 0px 0px;" inline="1">local esc = require('Module:Escape')</syntaxhighlight>
esc:char(escape char (or sequence))
<syntaxhighlight lang="lua" class="" style="background:none; border:none; color:inherit; padding: 0px 0px;" inline="1">local to_escape = esc:text</syntaxhighlight>(string)
code that replaces or removes unescaped chars
<syntaxhighlight lang="lua" class="" style="background:none; border:none; color:inherit; padding: 0px 0px;" inline="1">local result = esc:undo(to_escape)</syntaxhighlight>

From a template:

{{#invoke:Escape|main|mode=function|char=escape char (or sequence)|text}}

In a template, the most useful function is <syntaxhighlight lang="text" class="" style="" inline="1">kill</syntaxhighlight>.

This module is primarily intended to be used by other modules. However all functions can be called in template space using |mode=the function you want to call followed by arguments.

All module functions (i.e. any func. other than <syntaxhighlight lang="text" class="" style="" inline="1">main()</syntaxhighlight>) should be called using a colon (:), e.g. <syntaxhighlight lang="lua" class="" style="" inline="1">esc:char('%')</syntaxhighlight> or <syntaxhighlight lang="lua" class="" style="" inline="1">esc:kill{'{{example|\\}}}', '}'} == '{{example|}'</syntaxhighlight>

escape:text() escape:text()	This function takes only one argument: A string. All characters in this string which are preceded by the sequence set by <syntaxhighlight lang="text" class="" style="" inline="1">escape:char()</syntaxhighlight> will be replaced with placeholders that can be converted back into that char by escape:undo()
escape:undo() escape:undo()	Takes two arguments: The string that may contain placeholders set by <syntaxhighlight lang="text" class="" style="" inline="1">escape:text()</syntaxhighlight> Optional, a char to be placed in front of any characters that have been de-escaped. (i.e. if you need to re-escape those string with a different char)
escape:kill() escape:kill()	This is basically equivalent to calling <syntaxhighlight lang="text" class="" style="" inline="1">string.gsub()</syntaxhighlight> on the string returned by <syntaxhighlight lang="text" class="" style="" inline="1">escape:text()</syntaxhighlight> and feeding that result into <syntaxhighlight lang="text" class="" style="" inline="1">escape:undo()</syntaxhighlight> in a single step. Takes three arguments: A string A sequence of characters to be removed from that string. (May use a <syntaxhighlight lang="text" class="" style="" inline="1">string.gsub()</syntaxhighlight> pattern) Optional, a char to be placed in front of any characters that have been de-escaped.
escape:char() escape:char()	This function's primary use is to initialize the patterns to scan a string for an escape/escaped sequence. It takes two arguments, the first being the escape character and the second being a table of arguments (optional). By default, this module will escape the <syntaxhighlight lang="text" class="" style="" inline="1">\</syntaxhighlight> char. To escape the <syntaxhighlight lang="text" class="" style="" inline="1">{</syntaxhighlight> char instead, you can do <syntaxhighlight lang="lua" class="" style="" inline="1">require('Module:Escape'):char('{')</syntaxhighlight> (or <syntaxhighlight lang="lua" class="" style="" inline="1">esc:char('{')</syntaxhighlight> (presuming you stored the table returned by this module in the local variable <syntaxhighlight lang="text" class="" style="" inline="1">esc</syntaxhighlight>). When called without the second argument, char() will return a table containing the functions. This allows, for example, <syntaxhighlight lang="lua" class="" style="" inline="1">escape:char('*'):kill('1*23', '%d')</syntaxhighlight> which would return '2'. For the most part, there is very little reason to set |mode= in template space since the patterns it stores are not shared with other invokations of this module. Templates should instead use the |char= if a new escape sequence is desired. Shortcut If provided a second argument that is a table containing a {key = value} pair, such that the key is <syntaxhighlight lang="text" class="" style="" inline="1">text</syntaxhighlight>, <syntaxhighlight lang="text" class="" style="" inline="1">undo</syntaxhighlight>, or <syntaxhighlight lang="text" class="" style="" inline="1">kill</syntaxhighlight> and the value is a table containing the arguments that would have been passed to those functions. For example, <syntaxhighlight lang="lua" class="" style="" inline="1">escape:char('\\', {text = 'string'})</syntaxhighlight> is equivalent to <syntaxhighlight lang="lua" class="" style="" inline="1">escape:char('\\'):text('string')</syntaxhighlight>. Note that if multiple key-value pairs are provided, only one may execute. <syntaxhighlight lang="text" class="" style="" inline="1">kill</syntaxhighlight> is ignored if either <syntaxhighlight lang="text" class="" style="" inline="1">text</syntaxhighlight> or <syntaxhighlight lang="text" class="" style="" inline="1">undo</syntaxhighlight> are present. <syntaxhighlight lang="text" class="" style="" inline="1">undo</syntaxhighlight> is ignored if <syntaxhighlight lang="text" class="" style="" inline="1">text</syntaxhighlight> is present.

Caveats

• When using a multi-character escape sequence, this module only marks it using the byte value of the first character. Thus, <syntaxhighlight lang="lua" class="" style="" inline="1">escape:undo()</syntaxhighlight> will unescape, for example, all characters escaped with <syntaxhighlight lang="text" class="" style="" inline="1">'e'</syntaxhighlight> and <syntaxhighlight lang="text" class="" style="" inline="1">'esc'</syntaxhighlight> if both were used. In practice however this shouldn't be a problem as multiple escape sequences are pretty rare unless you're transitioning between multiple code languages. (Multiple multi-char escape sequences beginning with the same character are simply bad practice anyhow.)
• Since byte values are stored as numbers, it is not recommended for you to use a number as an escape sequence (though it may work just fine).
• Placeholder byte values separated with return (<syntaxhighlight lang="text" class="" style="" inline="1">'\r'</syntaxhighlight>) characters--chosen because they are seldom used at all, and virtually never used unpaired with <syntaxhighlight lang="text" class="" style="" inline="1">'\n'</syntaxhighlight>; moreover, it is distinct from the markers generated by <nowiki>...</nowiki> or <syntaxhighlight lang="text" class="" style="" inline="1">mw.text.nowiki()</syntaxhighlight> (which use the delete char). To set a different separator char, include the key-value pair {safeChr = alternate character} in the table that you pass to escape:char().

Speed

The following are benchmarks...

when executing the following module function: <syntaxhighlight lang="lua">

function p.test_kill500(frame)
 local esc = require('Module:Escape')
 for k = 1, 500 do
  local v = esc:kill(p.test_string2(), 'test')
 end
 return os.clock(esc)
end

</syntaxhighlight> 0.05458

when repeating the following line 500 times in a template:

<syntaxhighlight lang="wikitext" class="" style="" inline="1">{{#invoke:Escape|main|mode=kill|{{#invoke:Escape/testcases|test_string2}}|test}}</syntaxhighlight>

0.767

All times in seconds. The module time x500 was calculated when you loaded this doc page (normally between 0.02 and 0.07). The template time x500 was recorded on Jan 15, 2015.

Examples

Module

Here's some sample output from the debug console below the module editor:

local escape = require('Module:Escape')
test = 'test, \\test, \\{,test\\\\ \\\\ \\\\\\\\'

test2 = escape:char('{'):text(test)
=test2

test, \test, \7b

044
7btest\\ \\ \\\\

test3 = escape:char('\\'):text(test2)
=test3

test, 5c

0116
5cest, 5c

055
5cb

044
7btest5c

092
5c 5c

092
5c 5c

092
5c5c

092
5c

test4 = escape:char('{', {undo = test3})
=test4

test, 5c

0116
5cest, 5c

055
5cb

044
7btest5c

092
5c 5c

092
5c 5c

092
5c5c

092
5c

test4 = escape:char('\\', {undo = test3})
=test4

test, test, 7b

044
7btest\ \ \\

test5 = escape:char('{', {undo = test4})
=test5 == test

true

=escape:undo(test3)--doesn't work because char is still set to '{' in current session

test, 5c

0116
5cest, 5c

055
5cb

044
7btest5c

092
5c 5c

092
5c 5c

092
5c5c

092
5c

=escape:undo(test4)

test, \test, \,test\\ \\ \\\\

=escape:char('\\'):undo(test3)

test, test, 7b

044
7btest\ \ \\

=escape:char('{', {undo = escape:char('\\'):undo(test3)})

test, test, {,test\ \ \\

=test == escape:char('{', {undo = escape:char('\\'):undo(test3)})

false

=test == escape:char('{', {undo = escape:char('\\'):undo(test3, '\\')})

true

local t = 'test { test {\\{ test, \\test, \\{,test\\ \\ \\ {\\'
=t

test { test {\{ test, \test, \{,test\ \ \ {\

local e = require('Module:Escape')
local t2 = escape:text(t)
local t3 = string.gsub(t2, '{', )
local t4 = escape:undo(t3)
=t4

test  test { test, test, {,test   \

local tk0 = escape:kill(t, '{')
=tk0 == t4

true