Module:Escape
 | This module is rated as ready for general use. It has reached a mature state, is considered relatively stable and bug-free, and may be used wherever appropriate. It can be mentioned on help pages and other Wikipedia resources as an option for new users. To minimise server load and avoid disruptive output, improvements should be developed through sandbox testing rather than repeated trial-and-error editing. |
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 | This Lua module is used on approximately 13,000 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
[edit]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:
local esc = require('Module:Escape')esc:char(escape char (or sequence))local to_escape = esc:text(string) code that replaces or removes unescaped charslocal result = esc:undo(to_escape)
From a template:
{{#invoke:Escape|main|mode=function|char=escape char (or sequence)|text}}
In a template, the most useful function is kill.
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 main()) should be called using a colon (:), e.g. esc:char('%') or esc:kill{'{{example|\\}}}', '}'} == '{{example|}'
| escape:text() | This function takes only one argument: A string. All characters in this string which are preceded by the sequence set by escape:char() 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 string.gsub() on the string returned by escape:text() and feeding that result into escape:undo() 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 \ char. To escape the { char instead, you can do require('Module:Escape'):char('{') (or esc:char('{') (presuming you stored the table returned by this module in the local variable esc).
When called without the second argument, char() will return a table containing the functions. This allows, for example, For the most part, there is very little reason to set Shortcut[edit]If provided a second argument that is a table containing a Note that if multiple key-value pairs are provided, only one may execute. |
Caveats
[edit]- When using a multi-character escape sequence, this module only marks it using the byte value of the first character. Thus,
escape:undo()will unescape, for example, all characters escaped with'e'and'esc'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 (
'\r') characters--chosen because they are seldom used at all, and virtually never used unpaired with'\n'; moreover, it is distinct from the markers generated by<nowiki>...</nowiki>ormw.text.nowiki()(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
[edit]The following are benchmarks...
when executing the following module function:
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
0.0655
when repeating the following line 500 times in a template:
{{#invoke:Escape|main|mode=kill|{{#invoke:Escape/testcases|test_string2}}|test}}
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
[edit]Template
[edit]Original:
[edit]test { test {\{ test, \test, \{,test\ \ \ {\
Using internal method to remove {:
[edit]{{#invoke:Escape|main|mode=kill|test { test {\{ test, \test, \{,test\ \ \ {\|{}}
{{#invoke:Escape|main|mode=undo|{{replace|{{#invoke:Escape|main|mode=text|test { test {\{ test, \test, \{,test\ \ \ {\}}|{|}}}}
No removal of { between escape/unescape (escape char not restored):
[edit]{{#invoke:Escape|main|mode=undo
|{{#invoke:Escape|main|mode=text|test { test {\{ test, \test, \{,test\ \ \ {\}}
}}
Restore to original after escape
[edit]{{#invoke:Escape|main|mode=undo
|{{#invoke:Escape|main|mode=text|test { test {\{ test, \test, \{,test\ \ \ {\}}
|\
}}
Remove the word test if not escaped and then place a different escape char in the place of the old escape char (for use by something else):
[edit]Note: The '%' char is a special in Lua, so use '%%' if that is the desired replacement. Otherwise, just a single char is fine (or a word).
{{#invoke:Escape|main|mode=kill
|test { test {\{ test, \test, \{,test\ \ \ {\
|test
|%%
}}
Module
[edit]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