Module:Escape
 | This module is rated as ready for general use. It has reached a mature form and is thought to be relatively bug-free and ready for use wherever appropriate. It is ready to mention on help pages and other Wikipedia resources as an option for new users to learn. To reduce server load and bad output, it should be improved by sandbox testing rather than repeated trial-and-error editing. |
 | This Lua module is used on approximately 12,000 pages and changes may be widely noticed. Test changes in the module's /sandbox or /testcases subpages, or in your own module sandbox. Consider discussing changes on the talk page before implementing them. |
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() | 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() | Takes two arguments:
|
| 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:
|
| 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 ShortcutIf provided a second argument that is a table containing a 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> 0.0665
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
Template
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
local escape = {
char = function(self, chr, args)
args = args or {}
local safe = args.safeChr or string.char(13)
chr = tostring(chr or '\\')
self[1] = ('%s0%%s%s'):format(
('%x%s%s'):format(chr:byte(), safe, safe),
('%s%x'):format(safe, chr:byte())
)
if not self[self[1]] then
self[self[1]] = {
char = chr,
text = ('%s(.)'):format(chr),
undo = self[1]:format'(%d+)'
}
end
return args.text and self:text(args.text)
or args.undo and self:undo(args.undo, chr)
or args.kill and self:kill(args.kill)
or self
end,
exec = function(self, text, mode, newEscape)
local target = self[self[1] or self:char() and self[1]]
for v in text:gfind(target[mode]) do
text = text:gsub(
mode == 'text' and
('%s%s'):format(target.char, v:gsub('%W', '%%%1'))
or self[1]:format(v),
mode == 'text' and
self[1]:format(v:byte())
or (newEscape or '') .. v:char()
)
end
return text
end,
text = function(self, text)
return self:exec(type(text) == 'table' and text[1] or text, 'text')
end,
undo = function(self, text, newEscape)
if type(text) == 'table' then
text, newEscape = unpack(text)
end
return self:exec(text, 'undo', newEscape)
end,
kill = function(self, text, chars, newEscape)
if type(text) == 'table' then
text, chars, newEscape = unpack(text)
end
return self:undo(self:text(text):gsub(chars or '', ''), newEscape)
end
}
function escape.main(frame)
local args, family = {}, {frame:getParent(), frame}
for f = 1, 2 do
for k, v in pairs(family[f] and family[f].args or {}) do
args[k] = args[k] or v:match('^%s*(.-)%s*$')
end
end
if args.mode == 'char' then
return escape:char(args.char or args[2], args)
end
return escape[args.mode](escape:char(args.char), args)
end
return escape