share/lua/common/quvi/util.lua

   1 -- libquvi-scripts
   2 -- Copyright (C) 2010-2012  Toni Gundogdu <legatvs@gmail.com>
   3 --
   4 -- This file is part of libquvi-scripts <http://quvi.sourceforge.net/>.
   5 --
   6 -- This library is free software; you can redistribute it and/or
   7 -- modify it under the terms of the GNU Lesser General Public
   8 -- License as published by the Free Software Foundation; either
   9 -- version 2.1 of the License, or (at your option) any later version.
  10 --
  11 -- This library is distributed in the hope that it will be useful,
  12 -- but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 -- Lesser General Public License for more details.
  15 --
  16 -- You should have received a copy of the GNU Lesser General Public
  17 -- License along with this library; if not, write to the Free Software
  18 -- Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 -- 02110-1301  USA
  20 --
  21
  22 local M = {}
  23
  24 --[[
  25 Check whether a string A ends with string B.
  26 Parameters:
  27   a .. String A
  28   b .. String B
  29 Returns:
  30   true if string A ends with string B.
  31 ]]--
  32 function M.ends(a, b) -- http://lua-users.org/wiki/StringRecipes
  33   return a:sub(-#b) == b
  34 end
  35
  36 --[[
  37 Compare quality properties of two media entities. Compares the height, then
  38 the width, followed by the bitrate property comparison (if it is set).
  39 Parameters:
  40   a .. Media entity A
  41   b .. Media entity B
  42 Returns:
  43   true if entity A is the higher quality, otherwise false.
  44 ]]--
  45 function M.is_higher_quality(a, b)
  46   if a.height > b.height then
  47     if a.width > b.width then
  48       if a['bitrate'] then -- Optional
  49         if a.bitrate > b.bitrate then return true end
  50       else
  51         return true
  52       end
  53     end
  54   end
  55   return false
  56 end
  57
  58 --[[
  59 Compare quality properties of two media entities. Compares the height, then
  60 the width, followed by the bitrate property comparison (if it is set).
  61 Parameters:
  62   a .. Media entity A
  63   b .. Media entity B
  64 Returns:
  65   true if entity A is the lower quality, otherwise false.
  66 ]]--
  67 function M.is_lower_quality(a, b)
  68   if a.height < b.height then
  69     if a.width < b.width then
  70       if a['bitrate'] then -- Optional
  71         if a.bitrate < b.bitrate then return true end
  72       else
  73         return true
  74       end
  75     end
  76   end
  77   return false
  78 end
  79
  80 --[[
  81 Choose a media entity best matching the "requested format" which is string
  82 set by an application using libquvi API.
  83 Parameters:
  84   qargs   .. Library args (containing .req_format)
  85   t       .. Table containing the media properties (incl. media stream URLs)
  86   cb_best .. Best format callback function
  87   cb_def  .. Default format callback function
  88   cb_to_s .. Format to string callback function
  89 Returns:
  90   Chosen media entity.
  91
  92 The req_format string may be an array of format strings (e.g.
  93 "foo,bar,baz").
  94
  95 A format string may be:
  96   - default .. Use whatever a media script determines the 'default'
  97   - croak   .. Fail if nothing matched
  98   - best    .. Whatever a media script determines to be the 'best'
  99
 100 By default, the function falls back to 'default' format if nothing
 101 matches. To override this, 'croak' may be used to trigger an error
 102 instead.
 103 ]]--
 104 function M.choose_format(qargs, t, cb_default, cb_best, cb_fmt_to_s)
 105   for f in M.tokenize(qargs.req_format, '[%w-_]+') do
 106     if     f == 'croak' then error('no match: requested format')
 107     elseif f == 'best'  then return cb_best(t)
 108     else
 109       for _,v in pairs(t) do -- Match to user format string.
 110         if f == cb_fmt_to_s(v) then return v end
 111       end
 112     end
 113   end
 114   return cb_default(t) -- Fall back to the 'default' format.
 115 end
 116
 117 --[[
 118 Try to match an array of patterns to a string.
 119 Parameters:
 120   t .. Array of patterns (if nil, simply return false)
 121   s .. A string
 122 Returns:
 123   true if a pattern matched, otherwise false.
 124 ]]--
 125 function M.match_any(t, s)
 126   if not s then return false end
 127   for _,p in pairs(t) do
 128     if s:match(p) then return true end
 129   end
 130   return false
 131 end
 132
 133 --[[
 134 Tokenize a string.
 135 Parameters:
 136   s .. String to tokenize
 137   p .. Pattern (e.g. "[%w-_]+")
 138 Returns:
 139   An array of tokens.
 140 ]]--
 141 function M.tokenize(s, p)
 142   return s:gmatch(p)
 143 end
 144
 145 --[[
 146 Convert a string to a timestamp.
 147 Parameters:
 148   s .. String to convert
 149 Returns:
 150   Converted string.
 151 ]]--
 152 function M.to_timestamp(s) -- Based on <http://is.gd/ee9ZTD>
 153   local p = "%a+, (%d+) (%a+) (%d+) (%d+):(%d+):(%d+)"
 154
 155   local d,m,y,hh,mm,ss = s:match(p)
 156   if not d then error('no match: date') end
 157
 158   local MON = {Jan=1, Feb=2, Mar=3, Apr=4, May=5, Jun=6, Jul=7, Aug=8,
 159                Sep=9, Oct=10, Nov=11, Dec=12}
 160
 161   local m = MON[m]
 162   local offset = os.time() - os.time(os.date("!*t"))
 163
 164   return os.time({day=d,month=m,year=y,
 165                   hour=hh,min=mm,sec=ss}) + offset
 166 end
 167
 168 --[[
 169 Decode a string.
 170 Parameters:
 171   s .. String to decode
 172 Returns:
 173   Decoded string.
 174 ]]--
 175 function M.decode(s) -- http://www.lua.org/pil/20.3.html
 176   r = {}
 177   for n,v in s:gmatch ("([^&=]+)=([^&=]+)") do
 178     n = M.unescape(n)
 179     r[n] = v
 180   end
 181   return r
 182 end
 183
 184 --[[
 185 Unescape a string.
 186 Parameters:
 187   s .. String to unescape
 188 Returns:
 189   Unescaped string
 190 ]]--
 191 function M.unescape(s) -- http://www.lua.org/pil/20.3.html
 192   s = s:gsub('+', ' ')
 193   return (s:gsub('%%(%x%x)',
 194             function(h)
 195               return string.char(tonumber(h, 16))
 196             end))
 197 end
 198
 199 --[[
 200 Unescape slashed string.
 201 Parameters:
 202   s .. String to unescape
 203 Returns:
 204   Unescaped string
 205 ]]--
 206 function M.slash_unescape(s)
 207   return (s:gsub('\\(.)', '%1'))
 208 end
 209
 210 return M
 211
 212 -- vim: set ts=2 sw=2 tw=72 expandtab: