MicroController/stdlib/string.lua
2019-03-05 19:50:21 +08:00

76 lines
2.8 KiB
Lua

--- String module
-- @module string
--- Returns a copy of the string with any leading or trailing whitespace from the string removed.
-- @param s the string to remove leading or trailing whitespace from
-- @return a copy of the string without leading or trailing whitespace
function string.trim(s)
return (s:gsub("^%s*(.-)%s*$", "%1"))
end
--- Tests if a string starts with a given substring
-- @param s the string to check for the start substring
-- @param start the substring to test for
-- @return true if the start substring was found in the string
function string.starts_with(s, start)
return string.find(s, start, 1, true) == 1
end
--- Tests if a string ends with a given substring
-- @param s the string to check for the end substring
-- @param ends the substring to test for
-- @return true if the end substring was found in the string
function string.ends_with(s, ends)
return #s >= #ends and string.find(s, ends, #s - #ends + 1, true) and true or false
end
--- Tests if a string contains a given substring
-- @param s the string to check for the substring
-- @param ends the substring to test for
-- @return true if the substring was found in the string
function string.contains(s, ends)
return s and string.find(s, ends) ~= nil
end
--- Tests whether a string is empty
-- @param s the string to test
function string.is_empty(s)
return s == nil or s == ''
end
--- Splits a string into a table
-- <p>
-- <b>Note:</b> Empty split substrings are not included in the resulting table.
-- For example, string.split('foo.bar...', '.', false) results in the table {'foo', 'bar'}
-- @param s the string to split
-- @param sep (optional) the separator to use. The period character, `.`, is the default separator.
-- @param pattern whether to interpret the separator as a lua pattern or plaintext for the string split
-- @return the table
function string.split(s, sep, pattern)
local sep, fields = sep or ".", {}
sep = sep ~= "" and sep or "."
sep = not pattern and string.gsub(sep, "([^%w])", "%%%1") or sep
local fields = {}
local start_idx, end_idx = string.find(s, sep)
local last_find = 1
local len = string.len(sep)
while start_idx do
local substr = string.sub(s, last_find, start_idx - 1)
if string.len(substr) > 0 then
table.insert(fields, string.sub(s, last_find, start_idx - 1))
end
last_find = end_idx + 1
start_idx, end_idx = string.find(s, sep, end_idx + 1)
end
local substr = string.sub(s, last_find)
if string.len(substr) > 0 then
table.insert(fields, string.sub(s, last_find))
end
return fields
end
function string.comma_value(n) -- credit http://richard.warburton.it
local left,num,right = string.match(n,'^([^%d]*%d)(%d*)(.-)$')
return left..(num:reverse():gsub('(%d%d%d)','%1,'):reverse())..right
end