string.lua

--- Function that splits a string into parts using a separator
-- @param str (string) - the string to be split, sep (string) - the separator to be used
-- @return a table containing the separated parts of the string
string.split = function(str, sep)
	local res = {}
	for v in str:gmatch("([^" .. sep .. "]+)") do
		res[#res + 1] = v
	end
	return res
end

--- Function that removes whitespace from the beginning and end of a string
-- @param str (string) - the string to be modified
-- @return the string without whitespace at the beginning and end
string.trim = function(str)
	return str:match("^()%s*$") and "" or str:match("^%s*(.*%S)")
end

--- Function that checks if a string starts with a specific substring
-- @param str (string) - the string to be checked, substr (string) - the substring to be searched for
-- @return true if the string starts with the substring, false otherwise
string.starts = function(str, substr)
	return string.sub(str, 1, #substr) == substr
end

--- Function that converts a string where each word starts with an uppercase letter
-- @param str (string) - the string to be modified
-- @return the string with each word starting with an uppercase letter
string.titleCase = function(str)
	return str:gsub("(%a)([%w_']*)", function(first, rest)
		return first:upper() .. rest:lower()
	end)
end

--- Function that converts a time interval into a human-readable format
-- @param diff (number) - the time interval in seconds
-- @return a string representing the time interval in a readable format
string.diff = function(diff)
	local format = {
		{ "day", diff / 60 / 60 / 24 },
		{ "hour", diff / 60 / 60 % 24 },
		{ "minute", diff / 60 % 60 },
		{ "second", diff % 60 },
	}

	local out = {}
	for k, t in ipairs(format) do
		local v = math.floor(t[2])
		if v > 0 then
			table.insert(out, (k < #format and (#out > 0 and ", " or "") or " and ") .. v .. " " .. t[1] .. (v ~= 1 and "s" or ""))
		end
	end
	local ret = table.concat(out)
	if ret:len() < 16 and ret:find("second") then
		local a, b = ret:find(" and ")
		ret = ret:sub(b + 1)
	end
	return ret
end

---- Function that removes whitespace from the beginning and end of a string
-- @param str (string) - the string to be modified
-- @return (string) the string without whitespace at the beginning and end
string.trimSpace = function(str)
	return str:gsub("^%s*(.-)%s*$", "%1")
end

---- Function that removes all whitespace characters from a string.
-- This includes spaces, tabs, and newline characters, both from the
-- beginning and end of the string, and from between words.
-- @param str (string) - The string to be modified.
-- @return (string) - The string with all whitespace characters removed.
string.removeAllSpaces = function(str)
	return str:gsub("%s+", "")
end

--- Function that splits a string into parts using a separator
-- @param str (string) - the string to be split, sep (string) - the separator to be used
-- @return a table containing the separated parts of the string
string.split = function(str, sep)
	local res = {}
	for v in str:gmatch("([^" .. sep .. "]+)") do
		res[#res + 1] = v
	end
	return res
end

--- Function that splits a string into parts using a separator, and trims whitespace from each part
-- @param str (string) - the string to be split, sep (string) - the separator to be used
-- @return a table containing the separated parts of the string with whitespace removed from each part
string.splitTrimmed = function(str, sep)
	local res = {}
	for v in str:gmatch("([^" .. sep .. "]+)") do
		res[#res + 1] = v:trim()
	end
	return res
end

-- Function that splits a string into parts using a separator
-- @param str (string) - the string to be split, sep (string) - the separator to be used
-- @return a table containing the separated parts of the string
function string.splitFirst(str, delimiter)
	local start, finish = string.find(str, delimiter)
	if start == nil then
		return str, nil
	end
	local firstPart = string.sub(str, 1, start - 1)
	local secondPart = string.sub(str, finish + 1)
	return firstPart:trim(), secondPart:trim()
end

--- Function that removes whitespace from the beginning and end of a string
-- @param str (string) - the string to be modified
-- @return the string without whitespace at the beginning and end
string.trim = function(str)
	return str:match("^%s*(.*%S)") or ""
end

--- Function to format a string with a table of arguments
-- @param str (string) - the string to be formatted, args (table) - the table of arguments to be used
-- @return the formatted string
-- Example: string.formatNamed("Hello ${name}!", {name = "World"}) -> "Hello World!"
string.formatNamed = function(str, args)
	return (str:gsub("($%b{})", function(w)
		return args[w:sub(3, -2)] or w
	end))
end

string.capitalize = function(str)
	return str:gsub("%f[%a].", string.upper)
end