libs/core: Fixed luci.utils, Added missing in-line documentation
[project/luci.git] / libs / core / luasrc / util.lua
1 --[[
2 LuCI - Utility library
3
4 Description:
5 Several common useful Lua functions
6
7 FileId:
8 $Id$
9
10 License:
11 Copyright 2008 Steven Barth <steven@midlink.org>
12
13 Licensed under the Apache License, Version 2.0 (the "License");
14 you may not use this file except in compliance with the License.
15 You may obtain a copy of the License at
16
17 http://www.apache.org/licenses/LICENSE-2.0
18
19 Unless required by applicable law or agreed to in writing, software
20 distributed under the License is distributed on an "AS IS" BASIS,
21 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
22 See the License for the specific language governing permissions and
23 limitations under the License.
24
25 ]]--
26
27 -- LuCI utility functions.
28 module("luci.util", package.seeall)
29
30 --
31 -- Class helper routines
32 --
33
34 --- Creates a Class object (Python-style object model)
35 -- Creates a new class object which can be instantiated by calling itself.
36 -- Any class functions or shared parameters can be attached to this object.
37 -- Attaching a table to the class object makes this table shared between
38 -- all instances of this class. For object parameters use the __init__ function.
39 -- Classes can inherit member functions and values from a base class.
40 -- Class can be instantiated by calling them. All parameters will be passed
41 -- to the __init__ function of this class - if such a function exists.
42 -- The __init__ function must be used to set any object parameters that are not shared
43 -- with other objects of this class. Any return values will be ignored.
44 -- @param base The base class to inherit from (optional)
45 -- @return A class object
46 -- @see instanceof
47 -- @see clone
48 function class(base)
49 local class = {}
50
51 local create = function(class, ...)
52 local inst = {}
53 setmetatable(inst, {__index = class})
54
55 if inst.__init__ then
56 local stat, err = copcall(inst.__init__, inst, ...)
57 if not stat then
58 error(err)
59 end
60 end
61
62 return inst
63 end
64
65 local classmeta = {__call = create}
66
67 if base then
68 classmeta.__index = base
69 end
70
71 setmetatable(class, classmeta)
72 return class
73 end
74
75 --- Test whether the given object is an instance of the given class.
76 -- @param object Object instance
77 -- @param class Class object to test against
78 -- @return Boolean indicating wheather the object is an instance
79 -- @see class
80 -- @see clone
81 function instanceof(object, class)
82 local meta = getmetatable(object)
83 while meta and meta.__index do
84 if meta.__index == class then
85 return true
86 end
87 meta = getmetatable(meta.__index)
88 end
89 return false
90 end
91
92
93 --
94 -- Scope manipulation routines
95 --
96
97 --- Replace a function scope with a shallow copy of itself
98 -- This is useful if you want to get rid of several unwanted side effects
99 -- while changing the scope of a certain Lua function.
100 -- @param f Lua function
101 function resfenv(f)
102 setfenv(f, clone(getfenv(f)))
103 end
104
105 --- Store given object associated with given key in the scope of a function
106 -- @param f Lua function
107 -- @param key String value containg the key of the object to store
108 -- @param obj Object to store in the scope
109 -- @see updfenv
110 -- @see resfenv
111 -- @return Always nil
112 function extfenv(f, key, obj)
113 local scope = getfenv(f)
114 scope[key] = obj
115 end
116
117 --- Extend the scope of a function with the contents of a table
118 -- @param f Lua function
119 -- @param key String value containg the key of the object to store
120 -- @param obj Object to store in the scope
121 -- @see extfenv
122 -- @see resfenv
123 -- @return Always nil
124 function updfenv(f, extscope)
125 update(getfenv(f), extscope)
126 end
127
128 --- Create a new or get an already existing thread local store associated with
129 -- the current active coroutine. A thread local store is private a table object
130 -- whose values can't be accessed from outside of the running coroutine.
131 -- @return Table value representing the corresponding thread local store
132 function threadlocal()
133 local tbl = {}
134
135 local function get(self, key)
136 local c = coroutine.running()
137 local thread = coxpt[c] or c or 0
138 if not rawget(self, thread) then
139 return nil
140 end
141 return rawget(self, thread)[key]
142 end
143
144 local function set(self, key, value)
145 local c = coroutine.running()
146 local thread = coxpt[c] or c or 0
147 if not rawget(self, thread) then
148 rawset(self, thread, {})
149 end
150 rawget(self, thread)[key] = value
151 end
152
153 setmetatable(tbl, {__index = get, __newindex = set, __mode = "k"})
154
155 return tbl
156 end
157
158
159 --
160 -- Debugging routines
161 --
162
163 --- Write given object to stderr.
164 -- @param obj Value to write to stderr
165 -- @return Boolean indicating wheather the write operation was successful
166 function perror(obj)
167 return io.stderr:write(tostring(obj) .. "\n")
168 end
169
170 --- Recursively dumps a table to stdout, useful for testing and debugging.
171 -- @param t Table value to dump
172 -- @param i Number of tabs to prepend to each line
173 -- @return Always nil
174 function dumptable(t, i)
175 i = i or 0
176 for k,v in pairs(t) do
177 print(string.rep("\t", i) .. tostring(k), tostring(v))
178 if type(v) == "table" then
179 dumptable(v, i+1)
180 end
181 end
182 end
183
184
185 --
186 -- String and data manipulation routines
187 --
188
189 --- Escapes all occurences of the given character in given string.
190 -- @param s String value containing unescaped characters
191 -- @param c String value with character to escape (optional, defaults to "\")
192 -- @return String value with each occurence of character escaped with "\"
193 function escape(s, c)
194 c = c or "\\"
195 return s:gsub(c, "\\" .. c)
196 end
197
198 --- Create valid XML PCDATA from given string.
199 -- @param value String value containing the data to escape
200 -- @return String value containing the escaped data
201 function pcdata(value)
202 value = value:gsub("&", "&amp;")
203 value = value:gsub('"', "&quot;")
204 value = value:gsub("'", "&apos;")
205 value = value:gsub("<", "&lt;")
206 return value:gsub(">", "&gt;")
207 end
208
209 --- Splits given string on a defined seperator sequence and return a table
210 -- containing the resulting substrings. The optional max parameter specifies
211 -- the number of bytes to process, regardless of the actual length of the given
212 -- string. The optional last parameter, regex, sepcifies wheather the separator
213 -- sequence is interpreted as regular expression.
214 -- @param str String value containing the data to split up
215 -- @param pat String with separator pattern (optional, defaults to "\n")
216 -- @param max Num of bytes to process (optional, default is string length)
217 -- @param regexp Boolean indicating wheather to interprete the separator
218 -- pattern as regular expression (optional, default is false)
219 -- @return Table containing the resulting substrings
220 function split(str, pat, max, regex)
221 pat = pat or "\n"
222 max = max or #str
223
224 local t = {}
225 local c = 1
226
227 if #str == 0 then
228 return {""}
229 end
230
231 if #pat == 0 then
232 return nil
233 end
234
235 if max == 0 then
236 return str
237 end
238
239 repeat
240 local s, e = str:find(pat, c, not regex)
241 max = max - 1
242 if s and max < 0 then
243 table.insert(t, str:sub(c))
244 else
245 table.insert(t, str:sub(c, s and s - 1))
246 end
247 c = e and e + 1 or #str + 1
248 until not s or max < 0
249
250 return t
251 end
252
253 --- Remove leading and trailing whitespace from given string value.
254 -- @param str String value containing whitespace padded data
255 -- @return String value with leading and trailing space removed
256 function trim(str)
257 local s = str:gsub("^%s*(.-)%s*$", "%1")
258 return s
259 end
260
261 --- Parse certain units from the given string and return the canonical integer
262 -- value or 0 if the unit is unknown. Upper- or lowercase is irrelevant.
263 -- Recognized units are:
264 -- o "y" - one year (60*60*24*366)
265 -- o "m" - one month (60*60*24*31)
266 -- o "w" - one week (60*60*24*7)
267 -- o "d" - one day (60*60*24)
268 -- o "h" - one hour (60*60)
269 -- o "min" - one minute (60)
270 -- o "kb" - one kilobyte (1024)
271 -- o "mb" - one megabyte (1024*1024)
272 -- o "gb" - one gigabyte (1024*1024*1024)
273 -- o "kib" - one si kilobyte (1000)
274 -- o "mib" - one si megabyte (1000*1000)
275 -- o "gib" - one si gigabyte (1000*1000*1000)
276 -- @param ustr String containing a numerical value with trailing unit
277 -- @return Number containing the canonical value
278 function parse_units(ustr)
279
280 local val = 0
281
282 -- unit map
283 local map = {
284 -- date stuff
285 y = 60 * 60 * 24 * 366,
286 m = 60 * 60 * 24 * 31,
287 w = 60 * 60 * 24 * 7,
288 d = 60 * 60 * 24,
289 h = 60 * 60,
290 min = 60,
291
292 -- storage sizes
293 kb = 1024,
294 mb = 1024 * 1024,
295 gb = 1024 * 1024 * 1024,
296
297 -- storage sizes (si)
298 kib = 1000,
299 mib = 1000 * 1000,
300 gib = 1000 * 1000 * 1000
301 }
302
303 -- parse input string
304 for spec in ustr:lower():gmatch("[0-9%.]+[a-zA-Z]*") do
305
306 local num = spec:gsub("[^0-9%.]+$","")
307 local spn = spec:gsub("^[0-9%.]+", "")
308
309 if map[spn] or map[spn:sub(1,1)] then
310 val = val + num * ( map[spn] or map[spn:sub(1,1)] )
311 else
312 val = val + num
313 end
314 end
315
316
317 return val
318 end
319
320 --- Combines two or more numerically indexed tables into one.
321 -- @param tbl1 Table value to combine
322 -- @param tbl2 Table value to combine
323 -- @param tblN More values to combine
324 -- @return Table value containing all values of given tables
325 function combine(...)
326 local result = {}
327 for i, a in ipairs(arg) do
328 for j, v in ipairs(a) do
329 table.insert(result, v)
330 end
331 end
332 return result
333 end
334
335 --- Checks whether the given table contains the given value.
336 -- @param table Table value
337 -- @param value Value to search within the given table
338 -- @return Boolean indicating wheather the given value occurs within table
339 function contains(table, value)
340 for k, v in pairs(table) do
341 if value == v then
342 return k
343 end
344 end
345 return false
346 end
347
348 --- Update values in given table with the values from the second given table.
349 -- Both table are - in fact - merged together.
350 -- @param t Table which should be updated
351 -- @param updates Table containing the values to update
352 -- @return Always nil
353 function update(t, updates)
354 for k, v in pairs(updates) do
355 t[k] = v
356 end
357 end
358
359 --- Clones the given object and return it's copy.
360 -- @param object Table value to clone
361 -- @param deep Boolean indicating wheather to do recursive cloning
362 -- @return Cloned table value
363 function clone(object, deep)
364 local copy = {}
365
366 for k, v in pairs(object) do
367 if deep and type(v) == "table" then
368 v = clone(v, deep)
369 end
370 copy[k] = v
371 end
372
373 setmetatable(copy, getmetatable(object))
374
375 return copy
376 end
377
378
379 --
380 -- Byte code manipulation routines
381 --
382
383 --- Return the current runtime bytecode of the given function. The byte code
384 -- will be stripped before it is returned.
385 -- @param f Function value to return as bytecode
386 -- @return String value containing the bytecode of the given function
387 function get_bytecode(f)
388 local d = string.dump(f)
389 return d and strip_bytecode(d)
390 end
391
392 --- Strips unnescessary lua bytecode from given string. Information like line
393 -- numbers and debugging numbers will be discarded. Original version by
394 -- Peter Cawley (http://lua-users.org/lists/lua-l/2008-02/msg01158.html)
395 -- @param code String value containing the original lua byte code
396 -- @return String value containing the stripped lua byte code
397 function strip_bytecode(code)
398 local version, format, endian, int, size, ins, num, lnum = code:byte(5, 12)
399 local subint
400 if endian == 1 then
401 subint = function(code, i, l)
402 local val = 0
403 for n = l, 1, -1 do
404 val = val * 256 + code:byte(i + n - 1)
405 end
406 return val, i + l
407 end
408 else
409 subint = function(code, i, l)
410 local val = 0
411 for n = 1, l, 1 do
412 val = val * 256 + code:byte(i + n - 1)
413 end
414 return val, i + l
415 end
416 end
417
418 local strip_function
419 strip_function = function(code)
420 local count, offset = subint(code, 1, size)
421 local stripped, dirty = string.rep("\0", size), offset + count
422 offset = offset + count + int * 2 + 4
423 offset = offset + int + subint(code, offset, int) * ins
424 count, offset = subint(code, offset, int)
425 for n = 1, count do
426 local t
427 t, offset = subint(code, offset, 1)
428 if t == 1 then
429 offset = offset + 1
430 elseif t == 4 then
431 offset = offset + size + subint(code, offset, size)
432 elseif t == 3 then
433 offset = offset + num
434 elseif t == 254 or t == 9 then
435 offset = offset + lnum
436 end
437 end
438 count, offset = subint(code, offset, int)
439 stripped = stripped .. code:sub(dirty, offset - 1)
440 for n = 1, count do
441 local proto, off = strip_function(code:sub(offset, -1))
442 stripped, offset = stripped .. proto, offset + off - 1
443 end
444 offset = offset + subint(code, offset, int) * int + int
445 count, offset = subint(code, offset, int)
446 for n = 1, count do
447 offset = offset + subint(code, offset, size) + size + int * 2
448 end
449 count, offset = subint(code, offset, int)
450 for n = 1, count do
451 offset = offset + subint(code, offset, size) + size
452 end
453 stripped = stripped .. string.rep("\0", int * 3)
454 return stripped, offset
455 end
456
457 return code:sub(1,12) .. strip_function(code:sub(13,-1))
458 end
459
460
461 --
462 -- Sorting iterator functions
463 --
464
465 function _sortiter( t, f )
466 local keys = { }
467
468 for k, v in pairs(t) do
469 table.insert( keys, k )
470 end
471
472 local _pos = 0
473 local _len = table.getn( keys )
474
475 table.sort( keys, f )
476
477 return function()
478 _pos = _pos + 1
479 if _pos <= _len then
480 return keys[_pos], t[keys[_pos]]
481 end
482 end
483 end
484
485 --- Return a key, value iterator which returns the values sorted according to
486 -- the provided callback function.
487 -- @param t The table to iterate
488 -- @param f A callback function to decide the order of elements
489 -- @return Function value containing the corresponding iterator
490 function spairs(t,f)
491 return _sortiter( t, f )
492 end
493
494 --- Return a key, value iterator for the given table.
495 -- The table pairs are sorted by key.
496 -- @param t The table to iterate
497 -- @return Function value containing the corresponding iterator
498 function kspairs(t)
499 return _sortiter( t )
500 end
501
502 --- Return a key, value iterator for the given table.
503 -- The table pairs are sorted by value.
504 -- @param t The table to iterate
505 -- @return Function value containing the corresponding iterator
506 function vspairs(t)
507 return _sortiter( t, function (a,b) return t[a] < t[b] end )
508 end
509
510
511 --
512 -- Coroutine safe xpcall and pcall versions modified for Luci
513 -- original version:
514 -- coxpcall 1.13 - Copyright 2005 - Kepler Project (www.keplerproject.org)
515 --
516
517 local performResume, handleReturnValue
518 local oldpcall, oldxpcall = pcall, xpcall
519 coxpt = {}
520 setmetatable(coxpt, {__mode = "kv"})
521
522 -- Identity function for copcall
523 local function copcall_id(trace, ...)
524 return ...
525 end
526
527 --- This is a coroutine-safe drop-in replacement for Lua's "xpcall"-function
528 -- @param f Lua function to be called protected
529 -- @param err Custom error handler
530 -- @param ... parameters passed to the function
531 -- @return a boolean whether the function call succeeded and the return values of either the function or the error handler
532 function coxpcall(f, err, ...)
533 local res, co = oldpcall(coroutine.create, f)
534 if not res then
535 local params = {...}
536 local newf = function() return f(unpack(params)) end
537 co = coroutine.create(newf)
538 end
539 local c = coroutine.running()
540 coxpt[co] = coxpt[c] or c or 0
541
542 return performResume(err, co, ...)
543 end
544
545 --- This is a coroutine-safe drop-in replacement for Lua's "pcall"-function
546 -- @param f Lua function to be called protected
547 -- @param ... parameters passed to the function
548 -- @return a boolean whether the function call succeeded and the returns values of the function or the error object
549 function copcall(f, ...)
550 return coxpcall(f, copcall_id, ...)
551 end
552
553 -- Handle return value of protected call
554 function handleReturnValue(err, co, status, ...)
555 if not status then
556 return false, err(debug.traceback(co, (...)), ...)
557 end
558 if coroutine.status(co) == 'suspended' then
559 return performResume(err, co, coroutine.yield(...))
560 else
561 return true, ...
562 end
563 end
564
565 -- Resume execution of protected function call
566 function performResume(err, co, ...)
567 return handleReturnValue(err, co, coroutine.resume(co, ...))
568 end