# Class `luci.util`

## Functions

append (src, ...) | Appends numerically indexed tables or single objects to a given table.
bigendian () | Test whether the current system is operating in big endian mode.
class (base) | Create a Class object (Python-style object model).
clone (object, deep) | Clones the given object and return it's copy.
cmatch (str, pattern) | Count the occurrences of given substring in given string.
combine (tbl1, tbl2, ...) | Combines two or more numerically indexed tables and single objects into one table.
contains (table, value) | Checks whether the given table contains the given value.
copcall (f, ...) | This is a coroutine-safe drop-in replacement for Lua's "pcall"-function
coxpcall (f, err, ...) | This is a coroutine-safe drop-in replacement for Lua's "xpcall"-function
dumptable (t, maxdepth) | Recursively dumps a table to stdout, useful for testing and debugging.
exec (command) | Execute given commandline and gather stdout.
execi (command) | Return a line-buffered iterator over the output of given command.
get_bytecode (val) | Return the current runtime bytecode of the given data.
imatch (val) | Return a matching iterator for the given value.
instanceof (object, class) | Test whether the given object is an instance of the given class.
keys (t) | Retrieve all keys of given associative table.
kspairs (t) | Return a key, value iterator for the given table.
libpath () | Returns the absolute path to LuCI base directory.
parse_units (ustr) | Parse certain units from the given string and return the canonical integer value or 0 if the unit is unknown.
pcdata (value) | Create valid XML PCDATA from given string.
perror (obj) | Write given object to stderr.
restore_data (str) | Restore data previously serialized with serialize_data().
serialize_data (val) | Recursively serialize given data to lua code, suitable for restoring with loadstring().
serialize_json (data, writer) | Convert data structure to JSON
shellquote (value) | Safely quote value for use in shell commands.
spairs (t, f) | Return a key, value iterator which returns the values sorted according to the provided callback function.
split (str, pat, max, regex) | Splits given string on a defined separator sequence and return a table containing the resulting substrings.
strip_bytecode (code) | Strips unnecessary lua bytecode from given string.
striptags (value) | Strip HTML tags from given string.
threadlocal () | Create a new or get an already existing thread local store associated with the current active coroutine.
trim (str) | Remove leading and trailing whitespace from given string value.
ubus (object, method, values) | Issue an ubus call.
update (t, updates) | Update values in given table with the values from the second given table.
urldecode (str, decode_plus) | Decode an URL-encoded string - optionally decoding the "+" sign to space.
urlencode (str) | URL-encode given string.
vspairs (t) | Return a key, value iterator for the given table.

## Functions

append (src, ...)
  Appends numerically indexed tables or single objects to a given table.

  ### Parameters

  - src: Target table
  - ...: Objects to insert

  ### Return value:

  Target table
bigendian ()
  Test whether the current system is operating in big endian mode.

  ### Return value:

  Boolean value indicating whether system is big endian
class (base)
  Create a Class object (Python-style object model). The class object can be instantiated by calling itself. Any class functions or shared parameters can be attached to this object. Attaching a table to the class object makes this table shared between all instances of this class. For object parameters use the __init__ function. Classes can inherit member functions and values from a base class. Class can be instantiated by calling them. All parameters will be passed to the __init__ function of this class - if such a function exists. The __init__ function must be used to set any object parameters that are not shared with other objects of this class. Any return values will be ignored.

  ### Parameters

  - base: The base class to inherit from (optional)

  ### Return value:

  A class object

  ### See also:

  - instanceof
  - clone
clone (object, deep)
  Clones the given object and return it's copy.

  ### Parameters

  - object: Table value to clone
  - deep: Boolean indicating whether to do recursive cloning

  ### Return value:

  Cloned table value
cmatch (str, pattern)
  Count the occurrences of given substring in given string.

  ### Parameters

  - str: String to search in
  - pattern: String containing pattern to find

  ### Return value:

  Number of found occurrences
combine (tbl1, tbl2, ...)
  Combines two or more numerically indexed tables and single objects into one table.

  ### Parameters

  - tbl1: Table value to combine
  - tbl2: Table value to combine
  - ...: More tables to combine

  ### Return value:

  Table value containing all values of given tables
contains (table, value)
  Checks whether the given table contains the given value.

  ### Parameters

  - table: Table value
  - value: Value to search within the given table

  ### Return value:

  Number indicating the first index at which the given value occurs within table or false.
copcall (f, ...)
  This is a coroutine-safe drop-in replacement for Lua's "pcall"-function

  ### Parameters

  - f: Lua function to be called protected
  - ...: Parameters passed to the function

  ### Return value:

  A boolean whether the function call succeeded and the returns values of the function or the error object
coxpcall (f, err, ...)
  This is a coroutine-safe drop-in replacement for Lua's "xpcall"-function

  ### Parameters

  - f: Lua function to be called protected
  - err: Custom error handler
  - ...: Parameters passed to the function

  ### Return value:

  A boolean whether the function call succeeded and the return values of either the function or the error handler
dumptable (t, maxdepth)
  Recursively dumps a table to stdout, useful for testing and debugging.

  ### Parameters

  - t: Table value to dump
  - maxdepth: Maximum depth

  ### Return value:

  Always nil
exec (command)
  Execute given commandline and gather stdout.

  ### Parameters

  - command: String containing command to execute

  ### Return value:

  String containing the command's stdout
execi (command)
  Return a line-buffered iterator over the output of given command.

  ### Parameters

  - command: String containing the command to execute

  ### Return value:

  Iterator
get_bytecode (val)
  Return the current runtime bytecode of the given data. The byte code will be stripped before it is returned.

  ### Parameters

  - val: Value to return as bytecode

  ### Return value:

  String value containing the bytecode of the given data
imatch (val)
  Return a matching iterator for the given value. The iterator will return one token per invocation, the tokens are separated by whitespace. If the input value is a table, it is transformed into a string first. A nil value will result in a valid iterator which aborts with the first invocation.

  ### Parameters

  - val: The value to scan (table, string or nil)

  ### Return value:

  Iterator which returns one token per call
instanceof (object, class)
  Test whether the given object is an instance of the given class.

  ### Parameters

  - object: Object instance
  - class: Class object to test against

  ### Return value:

  Boolean indicating whether the object is an instance

  ### See also:

  - class
  - clone
keys (t)
  Retrieve all keys of given associative table.

  ### Parameters

  - t: Table to extract keys from

  ### Return value:

  Sorted table containing the keys
kspairs (t)
  Return a key, value iterator for the given table. The table pairs are sorted by key.

  ### Parameters

  - t: The table to iterate

  ### Return value:

  Function value containing the corresponding iterator
libpath ()
  Returns the absolute path to LuCI base directory.

  ### Return value:

  String containing the directory path
parse_units (ustr)
  Parse certain units from the given string and return the canonical integer value or 0 if the unit is unknown. Upper- or lower case is irrelevant. Recognized units are: o "y" - one year (60*60*24*366) o "m" - one month (60*60*24*31) o "w" - one week (60*60*24*7) o "d" - one day (60*60*24) o "h" - one hour (60*60) o "min" - one minute (60) o "kb" - one kilobyte (1024) o "mb" - one megabyte (1024*1024) o "gb" - one gigabyte (1024*1024*1024) o "kib" - one si kilobyte (1000) o "mib" - one si megabyte (1000*1000) o "gib" - one si gigabyte (1000*1000*1000)

  ### Parameters

  - ustr: String containing a numerical value with trailing unit

  ### Return value:

  Number containing the canonical value
pcdata (value)
  Create valid XML PCDATA from given string.

  ### Parameters

  - value: String value containing the data to escape

  ### Return value:

  String value containing the escaped data
perror (obj)
  Write given object to stderr.

  ### Parameters

  - obj: Value to write to stderr

  ### Return value:

  Boolean indicating whether the write operation was successful
restore_data (str)
  Restore data previously serialized with serialize_data().

  ### Parameters

  - str: String containing the data to restore

  ### Return value:

  Value containing the restored data structure

  ### See also:

  - serialize_data
  - get_bytecode
serialize_data (val)
  Recursively serialize given data to lua code, suitable for restoring with loadstring().

  ### Parameters

  - val: Value containing the data to serialize

  ### Return value:

  String value containing the serialized code

  ### See also:

  - restore_data
  - get_bytecode
serialize_json (data, writer)
  Convert data structure to JSON

  ### Parameters

  - data: The data to serialize
  - writer: A function to write a chunk of JSON data (optional)

  ### Return value:

  String containing the JSON if called without write callback
shellquote (value)
  Safely quote value for use in shell commands.

  ### Parameters

  - value: String containing the value to quote

  ### Return value:

  Single-quote enclosed string with embedded quotes escaped
spairs (t, f)
  Return a key, value iterator which returns the values sorted according to the provided callback function.

  ### Parameters

  - t: The table to iterate
  - f: A callback function to decide the order of elements

  ### Return value:

  Function value containing the corresponding iterator
split (str, pat, max, regex)
  Splits given string on a defined separator sequence and return a table containing the resulting substrings. The optional max parameter specifies the number of bytes to process, regardless of the actual length of the given string. The optional last parameter, regex, specifies whether the separator sequence is nterpreted as regular expression.

  ### Parameters

  - str: String value containing the data to split up
  - pat: String with separator pattern (optional, defaults to "\n")
  - max: Maximum times to split (optional)
  - regex: Boolean indicating whether to interpret the separator pattern as regular expression (optional, default is false)

  ### Return value:

  Table containing the resulting substrings
strip_bytecode (code)
  Strips unnecessary lua bytecode from given string. Information like line numbers and debugging numbers will be discarded. Original version by Peter Cawley (http://lua-users.org/lists/lua-l/2008-02/msg01158.html)

  ### Parameters

  - code: String value containing the original lua byte code

  ### Return value:

  String value containing the stripped lua byte code
striptags (value)
  Strip HTML tags from given string.

  ### Parameters

  - value: String containing the HTML text

  ### Return value:

  String with HTML tags stripped of
threadlocal ()
  Create a new or get an already existing thread local store associated with the current active coroutine. A thread local store is private a table object whose values can't be accessed from outside of the running coroutine.

  ### Return value:

  Table value representing the corresponding thread local store
trim (str)
  Remove leading and trailing whitespace from given string value.

  ### Parameters

  - str: String value containing whitespace padded data

  ### Return value:

  String value with leading and trailing space removed
ubus (object, method, values)
  Issue an ubus call.

  ### Parameters

  - object: String containing the ubus object to call
  - method: String containing the ubus method to call
  - values: Table containing the values to pass

  ### Return value:

  Table containin the ubus result
update (t, updates)
  Update values in given table with the values from the second given table. Both table are - in fact - merged together.

  ### Parameters

  - t: Table which should be updated
  - updates: Table containing the values to update

  ### Return value:

  Always nil
urldecode (str, decode_plus)
  Decode an URL-encoded string - optionally decoding the "+" sign to space.

  ### Parameters

  - str: Input string in x-www-urlencoded format
  - decode_plus: Decode "+" signs to spaces if true (optional)

  ### Return value:

  The decoded string

  ### See also:

  - urlencode
urlencode (str)
  URL-encode given string.

  ### Parameters

  - str: String to encode

  ### Return value:

  String containing the encoded data

  ### See also:

  - urldecode
vspairs (t)
  Return a key, value iterator for the given table. The table pairs are sorted by value.

  ### Parameters

  - t: The table to iterate

  ### Return value:

  Function value containing the corresponding iterator