variant.py

   1 #Copyright (c) 2009 Vincent Povirk
   2 #
   3 #Permission is hereby granted, free of charge, to any person
   4 #obtaining a copy of this software and associated documentation
   5 #files (the "Software"), to deal in the Software without
   6 #restriction, including without limitation the rights to use,
   7 #copy, modify, merge, publish, distribute, sublicense, and/or sell
   8 #copies of the Software, and to permit persons to whom the
   9 #Software is furnished to do so, subject to the following
  10 #conditions:
  11 #
  12 #The above copyright notice and this permission notice shall be
  13 #included in all copies or substantial portions of the Software.
  14 #
  15 #THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16 #EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  17 #OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18 #NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  19 #HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  20 #WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21 #FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  22 #OTHER DEALINGS IN THE SOFTWARE.
  23
  24 # variant and related types
  25
  26 from ctypes import Structure, c_void_p, windll, POINTER, HRESULT, byref
  27 from windef import USHORT, WORD
  28 from winliteutils import get_symbols
  29
  30 VARTYPE = USHORT
  31
  32 VT_EMPTY = 0
  33 VT_NULL = 1
  34 VT_I2 = 2
  35 VT_I4 = 3
  36 VT_R4 = 4
  37 VT_R8 = 5
  38 VT_CY = 6
  39 VT_DATE = 7
  40 VT_BSTR = 8
  41 VT_DISPATCH = 9
  42 VT_ERROR = 10
  43 VT_BOOL = 11
  44 VT_VARIANT = 12
  45 VT_UNKNOWN = 13
  46 VT_DECIMAL = 14
  47 VT_I1 = 16
  48 VT_UI1 = 17
  49 VT_UI2 = 18
  50 VT_UI4 = 19
  51 VT_I8 = 20
  52 VT_UI8 = 21
  53 VT_INT = 22
  54 VT_UINT = 23
  55 VT_VOID = 24
  56 VT_HRESULT = 25
  57 VT_PTR = 26
  58 VT_SAFEARRAY = 27
  59 VT_CARRAY = 28
  60 VT_USERDEFINED = 29
  61 VT_LPSTR = 30
  62 VT_LPWSTR = 31
  63 VT_RECORD = 36
  64 VT_INT_PTR = 37
  65 VT_UINT_PTR = 38
  66 VT_FILETIME = 64
  67 VT_BLOB = 65
  68 VT_STREAM = 66
  69 VT_STORAGE = 67
  70 VT_STREAMED_OBJECT = 68
  71 VT_STORED_OBJECT = 69
  72 VT_BLOB_OBJECT = 70
  73 VT_CF = 71
  74 VT_CLSID = 72
  75 VT_VERSIONED_STREAM = 73
  76 VT_BSTR_BLOB = 0x0fff
  77 VT_VECTOR = 0x1000
  78 VT_ARRAY = 0x2000
  79 VT_BYREF = 0x4000
  80 VT_RESERVED = 0x8000
  81 VT_ILLEGAL = 0xffff
  82 VT_ILLEGALMASKED = 0x0fff
  83 VT_TYPEMASK = 0x0fff
  84
  85 _oleaut32 = windll.oleaut32
  86 get_symbols(globals(), _oleaut32, ['VariantClear', 'VariantInit'])
  87
  88 class _VARIANT_VAL(Structure):
  89     _fields_ = [('p1', c_void_p),
  90                 ('p2', c_void_p),
  91                 ]
  92
  93 class VARIANT(Structure):
  94     _fields_ = [('vt', VARTYPE),
  95                 ('wReserved1', WORD),
  96                 ('wReserved2', WORD),
  97                 ('wReserved3', WORD),
  98                 ('_value', _VARIANT_VAL),
  99                 ]
 100
 101     def __init__(self):
 102         VariantInit(byref(self))
 103
 104     def _set_value(self, value):
 105         try:
 106             setter = value.__setvariant__
 107         except AttributeError:
 108             try:
 109                 setter = _variant_setters[type(value)]
 110             except KeyError:
 111                 raise TypeError("variable of type %s cannot be converted to variant" % str(type(value)))
 112             else:
 113                 setter[0](self, value, *setter[1:])
 114         else:
 115             setter(self)
 116
 117     def _get_value(self):
 118         try:
 119             getter = _variant_getters[self.vt]
 120         except KeyError:
 121             raise TypeError("getting variant type %s not supported" % self.vt)
 122         else:
 123             return getter[0](self, *getter[1:])
 124
 125     value = property(_get_value, _set_value)
 126
 127     def __del__(self):
 128         VariantClear(byref(self))
 129
 130 VARIANTARG = VARIANT
 131 LPVARIANTARG = LPVARIANT = POINTER(VARIANT)
 132
 133 VariantClear.argtypes = [LPVARIANTARG]
 134 VariantClear.restype = HRESULT
 135
 136 VariantInit.argtypes = [LPVARIANTARG]
 137 VariantInit.restype = None
 138
 139 def _get_empty(variant):
 140     return None
 141
 142 def _set_empty(variant, value):
 143     VariantClear(byref(var))
 144
 145 class _SQL_NULL(object):
 146     def __setvariant__(self, var):
 147         VariantClear(byref(var))
 148         var.vt = VT_NULL
 149
 150 sql_null = _SQL_NULL()
 151
 152 def _get_null(variant):
 153     return sql_null
 154
 155 _variant_getters = {
 156     VT_EMPTY: (_get_empty,),
 157     VT_NULL: (_get_null,),
 158     }
 159
 160 _variant_setters = {
 161     type(None): (_set_empty,),
 162     }
 163