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init.lua
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init.lua
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local boolvalues = {
["1"] = "0";
["true"] = "false";
["on"] = "off";
["yes"] = "no";
["y"] = "n"
}
local eschars = {
"\"", "'", "\\"
}
local escregexchars = {
"(", ")", ".", "%", "+", "-", "*", "?", "[", "]", "^", "$"
}
local function includes(tbl, item)
for k, v in pairs(tbl) do
if v == item then
return true
end
end
return false
end
-- Splits string by supplied separator. If the `regex` parameter is set to true then the separator is considered as a regular expression
function string.split(self, sep, regex)
if sep == "" then
return self:totable()
end
local result = {}
local previdx = 1
while true do
local startidx, endidx = self:find(sep, previdx, not regex)
if not startidx then
table.insert(result, self:sub(previdx))
break
end
table.insert(result, self:sub(previdx, startidx - 1))
previdx = endidx + 1
end
return result
end
-- Trims string's characters from its endings. Trims whitespaces by default. The `chars` argument is a regex string containing which characters to trim
function string.trim(self, chars)
chars = chars or "%s"
return self:trimstart(chars):trimend(chars)
end
-- Trims string's characters from its left side. Trims whitespaces by default. The `chars` argument is a regex string containing which characters to trim
function string.trimstart(self, chars)
return self:gsub("^["..(chars or "%s").."]+", "")
end
-- Trims string's characters from its right side. Trims whitespaces by default. The `chars` argument is a regex string containing which characters to trim
function string.trimend(self, chars)
return self:gsub("["..(chars or "%s").."]+$", "")
end
-- Pads string at the start with specified string until specified length. " " pad string by default
function string.padstart(self, len, str)
str = str or " "
local selflen = self:len()
return (str:rep(math.ceil((len - selflen) / str:len()))..self):sub(-(selflen < len and len or selflen))
end
-- Pads string at the end with specified string until specified length. " " pad string by default
function string.padend(self, len, str)
str = str or " "
local selflen = self:len()
return (self..str:rep(math.ceil((len - selflen) / str:len()))):sub(1, selflen < len and len or selflen)
end
-- If the string starts with specified prefix then returns string itself, otherwise pads the string until it starts with the prefix
function string.ensurestart(self, prefix)
local prefixlen = prefix:len()
if prefixlen > self:len() then
return prefix:ensureend(self)
end
local left = self:sub(1, prefixlen)
local i = 1
while not prefix:endswith(left) and i <= prefixlen do
i = i + 1
left = left:sub(1, -2)
end
return prefix:sub(1, i - 1)..self
end
-- If the string ends with specified prefix then returns string itself, otherwise pads the string until it ends with the prefix
function string.ensureend(self, suffix)
local suffixlen = suffix:len()
if suffixlen > self:len() then
return suffix:ensurestart(self)
end
local right = self:sub(-suffixlen)
local i = suffixlen
while not suffix:startswith(right) and i >= 1 do
i = i - 1
right = right:sub(2)
end
return self..suffix:sub(i + 1)
end
-- Adds backslashes before ", ' and \ characters. Escape character can be specified ("\\" by default) as well as characters to escape ({"\"", "'", "\\"} by default)
function string.esc(self, eschar, eschartbl)
local result = ""
eschar = eschar or "\\"
eschartbl = eschartbl or eschars
for char in self:iter() do
result = includes(eschartbl, char) and result..eschar..char or result..char
end
return result
end
-- Strips backslashes from the string. Escape character can be specified ("\\" by default)
function string.unesc(self, eschar)
local result = ""
local i = 0
eschar = eschar or "\\"
while i <= #self do
local char = self:sub(i, i)
if char == eschar then
i = i + 1
result = result..self:sub(i, i)
else
result = result..char
end
i = i + 1
end
return result
end
-- Escapes regexp special characters so the can be used in regexp functions as is
function string.escregex(self)
return self:esc("%", escregexchars)
end
-- Unescapes regexp special characters
function string.unescregex(self)
return self:unesc("%")
end
--- Returns an iterator which can be used in for loops
function string.iter(self)
local i = 0
return function ()
i = i + 1
return i <= self:len() and self:sub(i, i) or nil
end
end
--- Truncates string to a specified length with optional suffix (usually "...", nil by default)
function string.truncate(self, len, suffix)
if suffix then
local newlen = len - suffix:len()
return 0 < newlen and newlen < self:len() and self:sub(1, newlen)..suffix or self:sub(1, len)
else
return self:sub(1, len)
end
end
-- Returns true if the string starts with specified string
function string.startswith(self, prefix)
return self:sub(0, prefix:len()) == prefix
end
-- Returns true if the string ends with specified string
function string.endswith(self, suffix)
return self:sub(self:len() - suffix:len() + 1) == suffix
end
-- Returns true if string's length is 0
function string.isempty(self)
return self:len() == 0
end
-- Returns true if string consists of whitespace characters
function string.isblank(self)
return self:match("^%s*$") ~= nil
end
-- Converts "1", "true", "on", "yes", "y" and their contraries into real boolean. Returns nil if casting cannot be done. Case-insensetive
function string.tobool(self)
local lowered = self:lower()
for truthy, falsy in pairs(boolvalues) do
if lowered == truthy then
return true
elseif lowered == falsy then
return false
end
end
return nil
end
-- Returns table containing all the chars in the string
function string.totable(self)
local result = {}
for ch in self:iter() do
table.insert(result, ch)
end
return result
end