[project/luci.git] / libs / core / luasrc / util.lua

--[[
LuCI - Utility library

Description:
Several common useful Lua functions

FileId:
$Id$

License:
Copyright 2008 Steven Barth <steven@midlink.org>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at 

        http://www.apache.org/licenses/LICENSE-2.0 

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

]]--

module("luci.util", package.seeall)


-- Lua simplified Python-style OO class support emulation
function class(base)
        local class = {}
        
        local create = function(class, ...)
                local inst = {}
                setmetatable(inst, {__index = class})
                
                if inst.__init__ then
                        local stat, err = copcall(inst.__init__, inst, ...)
                        if not stat then
                                error(err)
                        end
                end
                
                return inst
        end
        
        local classmeta = {__call = create}
        
        if base then
                classmeta.__index = base
        end
        
        setmetatable(class, classmeta)
        return class
end


-- Clones an object (deep on-demand)
function clone(object, deep)
        local copy = {}
        
        for k, v in pairs(object) do
                if deep and type(v) == "table" then
                        v = clone(v, deep)
                end
                copy[k] = v
        end
        
        setmetatable(copy, getmetatable(object))
        
        return copy
end


-- Combines two or more numerically indexed tables into one
function combine(...)
        local result = {}
        for i, a in ipairs(arg) do
                for j, v in ipairs(a) do
                        table.insert(result, v)
                end
        end
        return result
end


-- Checks whether a table has an object "value" in it
function contains(table, value)
        for k,v in pairs(table) do
                if value == v then
                        return true
                end
        end
        return false
end


-- Dumps and strips a Lua-Function
function dump(f)
        local d = string.dump(f)
        return d and strip_bytecode(d)
end


-- Dumps a table to stdout (useful for testing and debugging)
function dumptable(t, i)
        i = i or 0
        for k,v in pairs(t) do
                print(string.rep("\t", i) .. tostring(k), tostring(v))
                if type(v) == "table" then
                        dumptable(v, i+1)
                end
        end
end


-- Escapes all occurences of c in s
function escape(s, c)
        c = c or "\\"
        return s:gsub(c, "\\" .. c)
end


-- Populate obj in the scope of f as key 
function extfenv(f, key, obj)
        local scope = getfenv(f)
        scope[key] = obj
end


-- Checks whether an object is an instanceof class
function instanceof(object, class)
        local meta = getmetatable(object)
    while meta and meta.__index do 
        if meta.__index == class then
                return true
        end
        meta = getmetatable(meta.__index)
    end
    return false        
end


-- Creates valid XML PCDATA from a string
function pcdata(value)
        value = value:gsub("&", "&amp;")        
        value = value:gsub('"', "&quot;")
        value = value:gsub("'", "&apos;")
        value = value:gsub("<", "&lt;") 
        return value:gsub(">", "&gt;")
end


-- Returns an error message to stdout
function perror(obj)
        io.stderr:write(tostring(obj) .. "\n")
end


-- Resets the scope of f doing a shallow copy of its scope into a new table
function resfenv(f)
        setfenv(f, clone(getfenv(f)))
end 


-- Splits a string into an array
function split(str, pat, max, regex)
        pat = pat or "\n"
        max = max or #str
        
        local t = {}
        local c = 1
        
        if #str == 0 then
                return {""}
        end
        
        if #pat == 0 then
                return nil
        end
        
        if max == 0 then
                return str
        end
        
        repeat
                local s, e = str:find(pat, c, not regex)
                table.insert(t, str:sub(c, s and s - 1))
                max = max - 1
                c = e and e + 1 or #str + 1
        until not s or max < 0
        
        return t
end


-- Strips lua bytecode
-- Original version by Peter Cawley (http://lua-users.org/lists/lua-l/2008-02/msg01158.html)
function strip_bytecode(dump)
        local version, format, endian, int, size, ins, num, lnum = dump:byte(5, 12)
        local subint
        if endian == 1 then
                subint = function(dump, i, l)
                        local val = 0
                        for n = l, 1, -1 do
                                val = val * 256 + dump:byte(i + n - 1)
                        end
                        return val, i + l
                end
        else
                subint = function(dump, i, l)
                        local val = 0
                        for n = 1, l, 1 do
                                val = val * 256 + dump:byte(i + n - 1)
                        end
                        return val, i + l
                end
        end
    
        local strip_function
        strip_function = function(dump)
                local count, offset = subint(dump, 1, size)
                local stripped, dirty = string.rep("\0", size), offset + count
                offset = offset + count + int * 2 + 4
                offset = offset + int + subint(dump, offset, int) * ins
                count, offset = subint(dump, offset, int)
                for n = 1, count do
                        local t
                        t, offset = subint(dump, offset, 1)
                        if t == 1 then
                                offset = offset + 1
                        elseif t == 4 then
                                offset = offset + size + subint(dump, offset, size)
                        elseif t == 3 then
                                offset = offset + num
                        elseif t == 254 then
                                offset = offset + lnum
                        end
                end
                count, offset = subint(dump, offset, int)
                stripped = stripped .. dump:sub(dirty, offset - 1)
                for n = 1, count do
                        local proto, off = strip_function(dump:sub(offset, -1))
                        stripped, offset = stripped .. proto, offset + off - 1
                end
                offset = offset + subint(dump, offset, int) * int + int
                count, offset = subint(dump, offset, int)
                for n = 1, count do
                        offset = offset + subint(dump, offset, size) + size + int * 2
                end
                count, offset = subint(dump, offset, int)
                for n = 1, count do
                        offset = offset + subint(dump, offset, size) + size
                end
                stripped = stripped .. string.rep("\0", int * 3)
                return stripped, offset
        end
        
        return dump:sub(1,12) .. strip_function(dump:sub(13,-1))
end


-- Creates a new threadlocal store
function threadlocal()
        local tbl = {}
        
        local function get(self, key)
                local c = coroutine.running()
                local thread = coxpt[c] or c or 0
                if not rawget(self, thread) then
                        return nil
                end
                return rawget(self, thread)[key]
        end
                
        local function set(self, key, value)
                local c = coroutine.running()
                local thread = coxpt[c] or c or 0
                if not rawget(self, thread) then
                        rawset(self, thread, {})
                end
                rawget(self, thread)[key] = value
                
                -- Avoid memory leaks by removing abandoned stores
                for k, v in pairs(self) do
                        if type(k) == "thread" and coroutine.status(k) == "dead" then
                                rawset(self, k, nil)
                        end
                end
        end
        
        setmetatable(tbl, {__index = get, __newindex = set})
        
        return tbl
end


-- Removes whitespace from beginning and end of a string
function trim(str)
        local s = str:gsub("^%s*(.-)%s*$", "%1")
        return s
end


-- Updates given table with new values
function update(t, updates)
        for k, v in pairs(updates) do
                t[k] = v
        end     
end


-- Updates the scope of f with "extscope"
function updfenv(f, extscope)
        update(getfenv(f), extscope)
end


-- Parse units from a string and return integer value
function parse_units(ustr)

        local val = 0

        -- unit map
        local map = {
                -- date stuff
                y   = 60 * 60 * 24 * 366,
                m   = 60 * 60 * 24 * 31,
                w   = 60 * 60 * 24 * 7,
                d   = 60 * 60 * 24,
                h   = 60 * 60,
                min = 60,

                -- storage sizes
                kb  = 1024,
                mb  = 1024 * 1024,
                gb  = 1024 * 1024 * 1024,

                -- storage sizes (si)
                kib = 1000,
                mib = 1000 * 1000,
                gib = 1000 * 1000 * 1000
        }

        -- parse input string
        for spec in ustr:lower():gmatch("[0-9%.]+[a-zA-Z]*") do

                local num = spec:gsub("[^0-9%.]+$","")
                local spn = spec:gsub("^[0-9%.]+", "")

                if map[spn] or map[spn:sub(1,1)] then
                        val = val + num * ( map[spn] or map[spn:sub(1,1)] )
                else
                        val = val + num
                end
        end


        return val
end


-- Provide various sorting iterators
function _sortiter( t, f )
        local keys = { }

        for k, v in pairs(t) do
                table.insert( keys, k )
        end

        local _pos = 0
        local _len = table.getn( keys )

        table.sort( keys, f )

        return function()
                _pos = _pos + 1
                if _pos <= _len then
                        return keys[_pos], t[keys[_pos]]
                end
        end
end

-- Return key, value pairs sorted by provided callback function
function spairs(t,f)
        return _sortiter( t, f )                                        
end

-- Return key, value pairs sorted by keys
function kspairs(t)
        return _sortiter( t )
end

-- Return key, value pairs sorted by values
function vspairs(t)
        return _sortiter( t, function (a,b) return t[a] < t[b] end )
end


-- Coroutine safe xpcall and pcall versions modified for Luci
-- original version:
-- coxpcall 1.13 - Copyright 2005 - Kepler Project (www.keplerproject.org)
local performResume, handleReturnValue
local oldpcall, oldxpcall = pcall, xpcall
coxpt = {}

function handleReturnValue(err, co, status, ...)
    if not status then
        return false, err(debug.traceback(co, (...)), ...)
    end
    if coroutine.status(co) == 'suspended' then
        return performResume(err, co, coroutine.yield(...))
    else
        return true, ...
    end
end

function performResume(err, co, ...)
    return handleReturnValue(err, co, coroutine.resume(co, ...))
end    

function coxpcall(f, err, ...)
    local res, co = oldpcall(coroutine.create, f)
    if not res then
        local params = {...}
        local newf = function() return f(unpack(params)) end
        co = coroutine.create(newf)
    end
    local c = coroutine.running()
    coxpt[co] = coxpt[c] or c or 0
    return performResume(err, co, ...)
end

local function id(trace, ...)
  return ...
end

function copcall(f, ...)
    return coxpcall(f, id, ...)
end