Module:string utilities
Provides some utility functions for manipulating strings.
Functions
jhyukScript error: No such module "module documentation".
local module_name = "string_utilities"
local export = {}
local format_escapes = {
["op"] = "{",
["cl"] = "}",
}
function export.format_fun(str, fun)
return (str:gsub("{(\\?)((\\?)[^{}]*)}", function (p1, name, p2)
if #p1 + #p2 == 1 then
return format_escapes[name] or error(module_name .. ".format: unrecognized escape sequence '{\\" .. name .. "}'")
else
if fun(name) and type(fun(name)) ~= "string" then
error(module_name .. ".format: '" .. name .. "' is a " .. type(fun(name)) .. ", not a string")
end
return fun(name) or error(module_name .. ".format: '" .. name .. "' not found in table")
end
end))
end
--[==[This function, unlike {{code|lua|string.format}} and {{code|lua|mw.ustring.format}}, takes just two parameters—a format string and a table—and replaces all instances of {{code|lua|{param_name}}} in the format string with the table's entry for {{code|lua|param_name}}. The opening and closing brace characters can be escaped with <code>{\op}</code> and <code>{\cl}</code>, respectively. A table entry beginning with a slash can be escaped by doubling the initial slash.
====Examples====
* {{code|lua|2=string_utilities.format("{foo} fish, {bar} fish, {baz} fish, {quux} fish", {["foo"]="one", ["bar"]="two", ["baz"]="red", ["quux"]="blue"})}}
*: produces: {{code|lua|"one fish, two fish, red fish, blue fish"}}
* {{code|lua|2=string_utilities.format("The set {\\op}1, 2, 3{\\cl} contains {\\\\hello} elements.", {["\\hello"]="three"})}}
*: produces: {{code|lua|"The set {1, 2, 3} contains three elements."}}
*:* Note that the single and double backslashes should be entered as double and quadruple backslashes when quoted in a literal string.]==]
function export.format(str, tbl)
return export.format_fun(str, function (key) return tbl[key] end)
end
-- A helper function which takes a string, position and type ("byte" or "char"), and returns the equivalent position for the other type (e.g. iterate_utf8("字典", 2, "char") returns 4, because character 2 of "字典" begins with byte 4). `pos` can be positive or negative, and the function will iterate over the string forwards or backwards (respectively) until it reaches the input position. Checks byte-by-byte; skipping over trailing bytes, and then calculating the correct byte trail for any leading bytes (i.e. how many trailing bytes should follow); these trailing bytes are then checked together.
-- The optional parameters `init_from_type` and `init_to_type` can be used to start part-way through an iteration to improve performance, if multiple values need to be returned from the same string. For example, iterate_utf8("слова́рь", 11, "byte", 5, 3) will begin checking at byte 5/the start of character 3. Note: The function won't check if these values match each other (as the only way to do this would be to run the iteration from the beginning), so mismatched values will return incorrect results.
local function iterate_utf8(text, pos, from_type, init_from_type, init_to_type)
-- Position 0 is always valid and never changes.
if pos == 0 then
return pos
end
local to_type
if from_type == "char" then
to_type = "byte"
else
to_type = "char"
end
-- Positive positions iterate forwards; negative positions iterate backwards.
local iterate_val
if pos > 0 then
iterate_val = 1
else
iterate_val = -1
end
-- Adjust init_from_type and init_to_type to the iteration before, so that matches for the position given by them will work.
local trail, cp, min, b = 0
local c, leading_byte = {}
c[from_type] = init_from_type and init_from_type ~= 0 and init_from_type - iterate_val or 0
c[to_type] = init_to_type and init_to_type ~= 0 and init_to_type - iterate_val or 0
while true do
if pos > 0 then
b = text:byte(c.byte + 1)
else
b = text:byte(text:len() + c.byte)
end
-- Position byte doesn't exist, so iterate the return value and return it.
if not b then
return c[to_type] + iterate_val
elseif b < 0x80 then
-- 1-byte codepoint, 00-7F.
trail = 0
cp = b
min = 0
leading_byte = true
elseif b < 0xc0 then
-- A trailing byte.
leading_byte = false
elseif b < 0xc2 then
-- An overlong encoding for a 1-byte codepoint.
error("String " .. text .. " is not UTF-8.")
elseif b < 0xe0 then
-- 2-byte codepoint, C2-DF.
trail = 1
cp = b - 0xc0
min = 0x80
leading_byte = true
elseif b < 0xf0 then
-- 3-byte codepoint, E0-EF.
trail = 2
cp = b - 0xe0
min = 0x800
leading_byte = true
elseif b < 0xf4 then
-- 4-byte codepoint, F0-F3.
trail = 3
cp = b - 0xf0
min = 0x10000
leading_byte = true
elseif b == 0xf4 then
-- 4-byte codepoint, F4.
-- Make sure it doesn't decode to over U+10FFFF.
if text:byte(c.byte + 2) > 0x8f then
error("String " .. text .. " is not UTF-8.")
end
trail = 3
cp = 4
min = 0x100000
leading_byte = true
else
-- Codepoint over U+10FFFF, or invalid byte.
error("String " .. text .. " is not UTF-8.")
end
-- Check subsequent bytes for multibyte codepoints.
if leading_byte then
local from, to
if pos > 0 then
from, to = c.byte + 2, c.byte + 1 + trail
else
from, to = text:len() + c.byte + 1, text:len() + c.byte + trail
end
for trailing_byte = from, to do
b = text:byte(trailing_byte)
if not b or b < 0x80 or b > 0xbf then
error("String " .. text .. " is not UTF-8.")
end
cp = cp * 0x40 + b - 0x80
end
local next_byte = text:byte(to + 1)
if next_byte and next_byte >= 0x80 and next_byte <= 0xbf then
-- Too many trailing bytes.
error("String " .. text .. " is not UTF-8.")
elseif cp < min then
-- Overlong encoding.
error("String " .. text .. " is not UTF-8.")
end
end
c.byte = c.byte + iterate_val
if leading_byte then
c.char = c.char + iterate_val
end
if c[from_type] == pos then
return c[to_type]
end
end
end
--[==[Converts a character position to the equivalent byte position.]==]
function export.charsToBytes(text, pos)
return iterate_utf8(text, pos, "char")
end
--[==[Converts a byte position to the equivalent character position.]==]
function export.bytesToChars(text, pos)
local byte = text:byte(pos)
if byte and byte >= 0x80 and byte <= 0xbf then
error("Byte " .. pos .. " is not a leading byte.")
end
return iterate_utf8(text, pos, "byte")
end
-- A helper function which iterates through a pattern, and returns two values: a potentially modified version of the pattern, and a boolean indicating whether the returned pattern is simple (i.e. whether it can be used with the stock string library); if not, then the pattern is complex (i.e. it must be used with the ustring library, which is much more resource-intensive).
local function patternSimplifier(text, pattern, plain)
pattern = tostring(pattern)
-- If `plain` is set, then the pattern is treated as literal (so is always simple). Only used by find.
if plain then
return pattern, true
--If none of these are present, then the pattern has to be simple.
elseif not (
pattern:match("%[.-[\128-\255].-%]") or
pattern:match("[\128-\255][%*%+%?%-]") or
pattern:match("%%[abcdlpsuwxACDLPSUWXZ]") or
pattern:match("%[%^[^%]]+%]") or
pattern:match("%.[^%*%+%-]") or
pattern:match("%.$") or
pattern:match("%%b.?[\128-\255]") or
pattern:match("()", 1, true)
) then
return pattern, true
end
-- Otherwise, the pattern could go either way.
-- Build up the new pattern in a table, then concatenate at the end. we do it this way, as occasionally entries get modified along the way.
local new_pattern = {}
local len, pos, b = pattern:len(), 0
local char, next_char
-- `escape` and `balanced` are counters, which ensure the effects of % or %b (respectively) are distributed over the following bytes.
-- `set` is a boolean that states whether the current byte is in a charset.
-- `capture` keeps track of how many layers of capture groups the position is in, while `captures` keeps a tally of how many groups have been detected (due to the string library limit of 32).
local escape, set, balanced, capture, captures = 0, false, 0, 0, 0
while pos < len do
pos = pos + 1
b = pattern:byte(pos)
if escape > 0 then escape = escape - 1 end
if balanced > 0 then balanced = balanced - 1 end
char = next_char or pattern:sub(pos, pos)
next_char = pattern:sub(pos + 1, pos + 1)
if escape == 0 then
if char == "%" then
-- Apply % escape.
if next_char == "." or next_char == "%" or next_char == "[" or next_char == "]" then
escape = 2
if balanced > 0 then balanced = balanced + 1 end
-- These charsets make the pattern complex.
elseif next_char:match("[acdlpsuwxACDLPSUWXZ]") then
return pattern, false
-- This is "%b".
elseif next_char == "b" then
balanced = 4
end
-- Enter or leave a charset.
elseif char == "[" then
set = true
elseif char == "]" then
set = false
elseif char == "(" then
capture = capture + 1
elseif char == ")" then
if capture > 0 and set == false and balanced == 0 then
captures = captures + 1
capture = capture - 1
end
end
end
-- Multibyte char.
if b > 0x7f then
-- If followed by "*", "+" or "-", then 2-byte chars can be converted into charsets. However, this is not possible with 3 or 4-byte chars, as the charset would be too permissive, because if the trailing bytes were in a different order then this could be a different valid character.
if next_char == "*" or next_char == "+" or next_char == "-" then
local prev_pos = pattern:byte(pos - 1)
if prev_pos > 0xc1 and prev_pos < 0xe0 then
new_pattern[#new_pattern] = "[" .. new_pattern[#new_pattern]
table.insert(new_pattern, char .. "]")
else
return pattern, false
end
-- If in a charset or used in "%b", then the pattern is complex.
-- If followed by "?", add "?" after each byte.
elseif next_char == "?" then
table.insert(new_pattern, char .. "?")
local check_pos, check_b, i = pos, pattern:byte(pos), #new_pattern
while check_b and check_b < 0xc0 do
check_pos = check_pos - 1
check_b = pattern:byte(check_pos)
i = i - 1
new_pattern[i] = new_pattern[i] .. "?"
end
pos = pos + 1
next_char = pattern:sub(pos + 1, pos + 1)
elseif set or balanced > 0 then
return pattern, false
else
table.insert(new_pattern, char)
end
elseif char == "." then
-- "*", "+", "-" are always okay after ".", as they don't care how many bytes a char has.
if set or next_char == "*" or next_char == "+" or next_char == "-" or escape > 0 then
table.insert(new_pattern, char)
-- If followed by "?", make sure "?" is after the leading byte of the UTF-8 char pattern, then skip forward one.
elseif next_char == "?" then
table.insert(new_pattern, "[%z\1-\127\194-\244]?[\128-\191]*")
pos = pos + 1
next_char = pattern:sub(pos + 1, pos + 1)
-- If used with "%b", pattern is complex.
elseif balanced > 0 then
return pattern, false
-- Otherwise, add the UTF-8 char pattern.
else
table.insert(new_pattern, "[%z\1-\127\194-\244][\128-\191]*")
end
-- Negative charsets are always complex, unless the text has no UTF-8 chars.
elseif char == "[" and next_char == "^" and escape == 0 and text:match("[\128-\255]") then
return pattern, false
-- "()" matches the position unless escaped or used with "%b", so always necessitates ustring (as we need it to match the char position, not the byte one).
elseif char == "(" and next_char == ")" and balanced == 0 and escape == 0 and text:match("[\128-\255]") then
return pattern, false
else
table.insert(new_pattern, char)
end
end
if captures > 32 then
return pattern, false
else
pattern = table.concat(new_pattern)
return pattern, true
end
end
--[==[A version of len which uses string.len, but returns the same result as mw.ustring.len.]==]
function export.len(text)
text = tostring(text)
local len_bytes = text:len()
if not text:match("[\128-\255]") then
return len_bytes
else
return iterate_utf8(text, len_bytes, "byte")
end
end
--[==[A version of sub which uses string.sub, but returns the same result as mw.ustring.sub.]==]
function export.sub(text, i_char, j_char)
text = tostring(text)
if not text:match("[\128-\255]") then
return text:sub(i_char, j_char)
end
local i_byte, j_byte
if j_char then
if i_char > 0 and j_char > 0 then
if j_char < i_char then return "" end
i_byte = iterate_utf8(text, i_char, "char")
j_byte = iterate_utf8(text, j_char + 1, "char", i_char, i_byte) - 1
elseif i_char < 0 and j_char < 0 then
if j_char < i_char then return "" end
j_byte = iterate_utf8(text, j_char + 1, "char") - 1
i_byte = iterate_utf8(text, i_char, "char", j_char, j_byte)
-- For some reason, mw.ustring.sub with i=0, j=0 returns the same result as for i=1, j=1, while string.sub always returns "". However, mw.ustring.sub does return "" with i=1, j=0. As such, we need to adjust j_char to 1 if i_char is either 0, or negative with a magnitude greater than the length of the string.
elseif j_char == 0 then
i_byte = iterate_utf8(text, i_char, "char")
if i_byte == 0 or -i_byte > text:len() then j_char = 1 end
j_byte = iterate_utf8(text, j_char + 1, "char") - 1
else
i_byte = iterate_utf8(text, i_char, "char")
j_byte = iterate_utf8(text, j_char + 1, "char") - 1
end
else
i_byte = iterate_utf8(text, i_char, "char")
end
return text:sub(i_byte, j_byte)
end
--[==[A version of lower which uses string.lower when possible, but otherwise uses mw.ustring.lower.]==]
function export.lower(text)
text = tostring(text)
if not text:match("[\128-\255]") then
return text:lower()
else
return mw.ustring.lower(text)
end
end
--[==[A version of upper which uses string.upper when possible, but otherwise uses mw.ustring.upper.]==]
function export.upper(text)
text = tostring(text)
if not text:match("[\128-\255]") then
return text:upper()
else
return mw.ustring.upper(text)
end
end
--[==[A version of find which uses string.find when possible, but otherwise uses mw.ustring.find.]==]
function export.find(text, pattern, init_char, plain)
text = tostring(text)
local simple
pattern, simple = patternSimplifier(text, pattern, plain)
-- If the pattern is simple but multibyte characters are present, then init_char needs to be converted into bytes for string.find to work properly, and the return values need to be converted back into chars.
if simple then
if not text:match("[\128-\255]") then
return text:find(pattern, init_char, plain)
else
local init_byte = init_char and iterate_utf8(text, init_char, "char")
local byte1, byte2, c1, c2, c3, c4, c5, c6, c7, c8, c9 = text:find(pattern, init_byte, plain)
-- If string.find returned nil, then return nil.
if not (byte1 and byte2) then
return nil
end
-- Get first return value. If we have a positive init_char, we can save resources by resuming at that point.
local char1, char2
if (not init_char) or init_char > 0 then
char1 = iterate_utf8(text, byte1, "byte", init_byte, init_char)
else
char1 = iterate_utf8(text, byte1, "byte")
end
-- If byte1 and byte2 are the same, don't bother running iterate_utf8 twice. Otherwise, resume iterate_utf8 from byte1 to find char2.
if byte1 == byte2 then
char2 = char1
else
char2 = iterate_utf8(text, byte2, "byte", byte1, char1)
end
return unpack{char1, char2, c1, c2, c3, c4, c5, c6, c7, c8, c9}
end
else
return mw.ustring.find(text, pattern, init_char, plain)
end
end
--[==[A version of match which uses string.match when possible, but otherwise uses mw.ustring.match.]==]
function export.match(text, pattern, init)
text = tostring(text)
local simple
pattern, simple = patternSimplifier(text, pattern)
if simple then
if init and text:find("[\128-\255]") then
init = iterate_utf8(text, init, "char")
end
return text:match(pattern, init)
else
return mw.ustring.match(text, pattern, init)
end
end
--[==[A version of gmatch which uses string.gmatch when possible, but otherwise uses mw.ustring.gmatch.]==]
function export.gmatch(text, pattern)
text = tostring(text)
local simple
pattern, simple = patternSimplifier(text, pattern)
if simple then
return text:gmatch(pattern)
else
return mw.ustring.gmatch(text, pattern)
end
end
--[==[A version of gsub which uses string.gsub when possible, but otherwise uses mw.ustring.gsub.]==]
function export.gsub(text, pattern, repl, n)
text = tostring(text)
local simple
pattern, simple = patternSimplifier(text, pattern)
if simple then
return text:gsub(pattern, repl, n)
else
return mw.ustring.gsub(text, pattern, repl, n)
end
end
--[==[
-- Reimplementation of mw.ustring.split() that includes any capturing
-- groups in the splitting pattern. This works like Python's re.split()
-- function, except that it has Lua's behavior when the split pattern
-- is empty (i.e. advancing by one character at a time; Python returns the
-- whole remainder of the string).
]==]
function export.capturing_split(str, pattern)
local ret = {}
-- (.-) corresponds to (.*?) in Python or Perl; () captures the
-- current position after matching.
pattern = "(.-)" .. pattern .. "()"
local start = 1
while true do
-- Did we reach the end of the string?
if start > #str then
table.insert(ret, "")
return ret
end
-- match() returns all captures as multiple return values;
-- we need to insert into a table to get them all.
local captures = {export.match(str, pattern, start)}
-- If no match, add the remainder of the string.
if #captures == 0 then
table.insert(ret, export.sub(str, start))
return ret
end
local newstart = table.remove(captures)
-- Special case: If we don't advance by any characters, then advance
-- by one character; this avoids an infinite loop, and makes splitting
-- by an empty string work the way mw.ustring.split() does. If we
-- reach the end of the string this way, return immediately, so we
-- don't get a final empty string.
if newstart == start then
table.insert(ret, export.sub(str, start, start))
table.remove(captures, 1)
start = start + 1
if start > #str then
return ret
end
else
table.insert(ret, table.remove(captures, 1))
start = newstart
end
-- Insert any captures from the splitting pattern.
for _, x in ipairs(captures) do
table.insert(ret, x)
end
end
end
local function uclcfirst(text, dolower)
local function douclcfirst(text)
-- Actual function to re-case of the first letter.
local first_letter = export.sub(text, 1, 1)
first_letter = dolower and export.lower(first_letter) or export.upper(first_letter)
return first_letter .. export.sub(text, 2)
end
-- If there's a link at the beginning, re-case the first letter of the
-- link text. This pattern matches both piped and unpiped links.
-- If the link is not piped, the second capture (linktext) will be empty.
local link, linktext, remainder = export.match(text, "^%[%[([^|%]]+)%|?(.-)%]%](.*)$")
if link then
return "[[" .. link .. "|" .. douclcfirst(linktext ~= "" and linktext or link) .. "]]" .. remainder
end
return douclcfirst(text)
end
function export.ucfirst(text)
return uclcfirst(text, false)
end
function export.lcfirst(text)
return uclcfirst(text, true)
end
-- Almost identical to mw.text.nowiki, but with minor changes to be identical to the PHP equivalent: ";" always escapes, and colons in certain protocols only escape after regex \b. Also about 2-3 times as fast.
function export.nowiki(text)
return (text
:gsub("[\"&'<=>%[%]{|};]", {
["\""] = """, ["&"] = "&", ["'"] = "'",
["<"] = "<", ["="] = "=", [">"] = ">",
["["] = "[", ["]"] = "]", ["{"] = "{",
["|"] = "|", ["}"] = "}", [";"] = ";"
})
:gsub("%f[^%z\r\n][#*: \n\r\t]", {
["#"] = "#", ["*"] = "*", [":"] = ":",
[" "] = " ", ["\n"] = " ", ["\r"] = " ",
["\t"] = "	"
})
:gsub("(%f[^%z\r\n])%-(%-%-%-)", "%1-%2")
:gsub("__", "__")
:gsub("://", "://")
:gsub("([IP]?[MRS][BFI][CDN])([\t\n\f\r ])", function(m1, m2)
if m1 == "ISBN" or m1 == "RFC" or m1 == "PMID" then
return m1 .. m2:gsub(".", {
["\t"] = "	", ["\n"] = " ", ["\f"] = "",
["\r"] = " ", [" "] = " "
})
end
end)
:gsub("[%w_]+:", {
["bitcoin:"] = "bitcoin:", ["geo:"] = "geo:", ["magnet:"] = "magnet:",
["mailto:"] = "mailto:", ["matrix:"] = "matrix:", ["news:"] = "news:",
["sip:"] = "sip:", ["sips:"] = "sips:", ["sms:"] = "sms:",
["tel:"] = "tel:", ["urn:"] = "urn:", ["xmpp:"] = "xmpp:"
}))
end
function export.capitalize(text)
if type(text) == "table" then
-- allow calling from a template
text = text.args[1]
end
-- Capitalize multi-word that is separated by spaces
-- by uppercasing the first letter of each part.
-- I assume nobody will input all CAP text.
w2 = {}
for w in export.gmatch(text, "%S+") do
table.insert(w2, uclcfirst(w, false))
end
return table.concat(w2, " ")
end
function export.pluralize(text)
if type(text) == "table" then
-- allow calling from a template
text = text.args[1]
end
-- Pluralize a word in a smart fashion, according to normal English rules.
-- 1. If word ends in consonant + -y, replace the -y with -ies.
-- 2. If the word ends in -s, -x, -z, -sh, -ch, add -es.
-- 3. Otherwise, add -s.
-- This handles links correctly:
-- 1. If a piped link, change the second part appropriately.
-- 2. If a non-piped link and rule #1 above applies, convert to a piped link
-- with the second part containing the plural.
-- 3. If a non-piped link and rules #2 or #3 above apply, add the plural
-- outside the link.
local function word_ends_in_consonant_plus_y(text)
-- FIXME, a subrule of rule #1 above says the -ies ending doesn't
-- apply to proper nouns, hence "the Gettys", "the public Ivys".
-- We should maybe consider applying this rule here; but it may not
-- be important as this function is almost always called on common nouns
-- (e.g. parts of speech, place types).
return text:find("[^aeiouAEIOU ]y$")
end
local function word_takes_es_plural(text)
return text:find("[sxz]$") or text:find("[cs]h$")
end
local function do_pluralize(text)
if word_ends_in_consonant_plus_y(text) then
-- avoid returning multiple values
local hack_single_retval = text:gsub("y$", "ies")
return hack_single_retval
elseif word_takes_es_plural(text) then
return text .. "es"
else
return text .. "s"
end
end
-- Check for a link. This pattern matches both piped and unpiped links.
-- If the link is not piped, the second capture (linktext) will be empty.
local beginning, link, linktext = export.match(text, "^(.*)%[%[([^|%]]+)%|?(.-)%]%]$")
if link then
if linktext ~= "" then
return beginning .. "[[" .. link .. "|" .. do_pluralize(linktext) .. "]]"
end
if word_ends_in_consonant_plus_y(link) then
return beginning .. "[[" .. link .. "|" .. link:gsub("y$", "ies") .. "]]"
end
return beginning .. "[[" .. link .. "]]" .. (word_takes_es_plural(link) and "es" or "s")
end
return do_pluralize(text)
end
function export.singularize(text)
if type(text) == "table" then
-- allow calling from a template
text = text.args[1]
end
-- Singularize a word in a smart fashion, according to normal English rules.
-- Works analogously to pluralize().
-- NOTE: This doesn't always work as well as pluralize(). Beware. It will
-- mishandle cases like "passes" -> "passe", "eyries" -> "eyry".
-- 1. If word ends in -ies, replace -ies with -y.
-- 2. If the word ends in -xes, -shes, -ches, remove -es. [Does not affect
-- -ses, cf. "houses", "impasses".]
-- 3. Otherwise, remove -s.
-- This handles links correctly:
-- 1. If a piped link, change the second part appropriately. Collapse the
-- link to a simple link if both parts end up the same.
-- 2. If a non-piped link, singularize the link.
-- 3. A link like "[[parish]]es" will be handled correctly because the
-- code that checks for -shes etc. allows ] characters between the
-- 'sh' etc. and final -es.
local function do_singularize(text)
local sing = text:match("^(.-)ies$")
if sing then
return sing .. "y"
end
-- Handle cases like "[[parish]]es"
local sing = text:match("^(.-[sc]h%]*)es$")
if sing then
return sing
end
-- Handle cases like "[[box]]es"
local sing = text:match("^(.-x%]*)es$")
if sing then
return sing
end
local sing = text:match("^(.-)s$")
if sing then
return sing
end
return text
end
local function collapse_link(link, linktext)
if link == linktext then
return "[[" .. link .. "]]"
else
return "[[" .. link .. "|" .. linktext .. "]]"
end
end
-- Check for a link. This pattern matches both piped and unpiped links.
-- If the link is not piped, the second capture (linktext) will be empty.
local beginning, link, linktext = export.match(text, "^(.*)%[%[([^|%]]+)%|?(.-)%]%]$")
if link then
if linktext ~= "" then
return beginning .. collapse_link(link, do_singularize(linktext))
end
return beginning .. "[[" .. do_singularize(link) .. "]]"
end
return do_singularize(text)
end
function export.add_indefinite_article(text, uppercase)
local is_vowel = false
-- If there's a link at the beginning, examine the first letter of the
-- link text. This pattern matches both piped and unpiped links.
-- If the link is not piped, the second capture (linktext) will be empty.
local link, linktext, remainder = export.match(text, "^%[%[([^|%]]+)%|?(.-)%]%](.*)$")
if link then
is_vowel = export.find(linktext ~= "" and linktext or link, "^[AEIOUaeiou]")
else
is_vowel = export.find(text, "^[AEIOUaeiou]")
end
return (is_vowel and (uppercase and "An " or "an ") or (uppercase and "A " or "a ")) .. text
end
-- Convert risky characters to HTML entities, which minimizes interference once returned (e.g. for "sms:a", "<!-- -->" etc.).
function export.escape_risky_characters(text)
if text:match("\"'") then
for _, pattern in ipairs(require("Module:languages/data/patterns")) do
text = text:gsub(pattern, function(m1) return mw.text.encode(m1, "\"'") end)
end
end
-- Spacing characters in isolation generally need to be escaped in order to be properly processed by the MediaWiki software.
if not mw.ustring.match(text, "%S") then
return mw.text.encode(text, "%s")
else
return mw.text.encode(text, "!#%%&*+/:;<=>?@[\\%]_{|}")
end
end
return export