SCons/Node/Python.py

   1 # MIT License
   2 #
   3 # Copyright The SCons Foundation
   4 #
   5 # Permission is hereby granted, free of charge, to any person obtaining
   6 # a copy of this software and associated documentation files (the
   7 # "Software"), to deal in the Software without restriction, including
   8 # without limitation the rights to use, copy, modify, merge, publish,
   9 # distribute, sublicense, and/or sell copies of the Software, and to
  10 # permit persons to whom the Software is furnished to do so, subject to
  11 # the following conditions:
  12 #
  13 # The above copyright notice and this permission notice shall be included
  14 # in all copies or substantial portions of the Software.
  15 #
  16 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
  17 # KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
  18 # WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  19 # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  20 # LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  21 # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  22 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23
  24 """Python nodes."""
  25
  26 import SCons.Node
  27
  28 _memo_lookup_map = {}
  29
  30
  31 class ValueNodeInfo(SCons.Node.NodeInfoBase):
  32     __slots__ = ('csig',)
  33     current_version_id = 2
  34
  35     field_list = ['csig']
  36
  37     def str_to_node(self, s):
  38         return ValueWithMemo(s)
  39
  40
  41 class ValueBuildInfo(SCons.Node.BuildInfoBase):
  42     __slots__ = ()
  43     current_version_id = 2
  44
  45
  46 class Value(SCons.Node.Node):
  47     """A Node class for values represented by Python expressions.
  48
  49     Values are typically passed on the command line or generated
  50     by a script, but not from a file or some other source.
  51
  52     .. versionchanged:: 4.0
  53        the *name* parameter was added.
  54     """
  55
  56     NodeInfo = ValueNodeInfo
  57     BuildInfo = ValueBuildInfo
  58
  59     def __init__(self, value, built_value=None, name=None) -> None:
  60         super().__init__()
  61         self.value = value
  62         self.changed_since_last_build = 6
  63         self.store_info = 0
  64         if built_value is not None:
  65             self.built_value = built_value
  66
  67         # Set a name so it can be a child of a node and not break
  68         # its parent's implementation of Node.get_contents.
  69         if name:
  70             self.name = name
  71         else:
  72             self.name = str(value)
  73
  74     def str_for_display(self):
  75         return repr(self.value)
  76
  77     def __str__(self) -> str:
  78         return str(self.value)
  79
  80     def make_ready(self) -> None:
  81         self.get_csig()
  82
  83     def build(self, **kw) -> None:
  84         if not hasattr(self, 'built_value'):
  85             SCons.Node.Node.build(self, **kw)
  86
  87     is_up_to_date = SCons.Node.Node.children_are_up_to_date
  88
  89     def is_under(self, dir) -> bool:
  90         # Make Value nodes get built regardless of
  91         # what directory scons was run from. Value nodes
  92         # are outside the filesystem:
  93         return True
  94
  95     def write(self, built_value) -> None:
  96         """Set the value of the node."""
  97         self.built_value = built_value
  98
  99     def read(self):
 100         """Return the value. If necessary, the value is built."""
 101         self.build()
 102         if not hasattr(self, 'built_value'):
 103             self.built_value = self.value
 104         return self.built_value
 105
 106     def get_text_contents(self) -> str:
 107         """By the assumption that the node.built_value is a
 108         deterministic product of the sources, the contents of a Value
 109         are the concatenation of all the contents of its sources.  As
 110         the value need not be built when get_contents() is called, we
 111         cannot use the actual node.built_value."""
 112         ###TODO: something reasonable about universal newlines
 113         contents = str(self.value)
 114         for kid in self.children(None):
 115             # Get csig() value of child as this is more efficent
 116             contents = contents + kid.get_csig()
 117         return contents
 118
 119     def get_contents(self) -> bytes:
 120         """Get contents for signature calculations."""
 121         return self.get_text_contents().encode()
 122
 123     def get_csig(self, calc=None):
 124         """Because we're a Python value node and don't have a real
 125         timestamp, we get to ignore the calculator and just use the
 126         value contents.
 127
 128         Returns string. Ideally string of hex digits. (Not bytes)
 129         """
 130         try:
 131             return self.ninfo.csig
 132         except AttributeError:
 133             pass
 134
 135         contents = self.get_text_contents()
 136
 137         self.get_ninfo().csig = contents
 138         return contents
 139
 140
 141 def ValueWithMemo(value, built_value=None, name=None):
 142     """Memoized :class:`Value` node factory.
 143
 144     .. versionchanged:: 4.0
 145        the *name* parameter was added.
 146     """
 147     global _memo_lookup_map
 148
 149     # No current support for memoizing a value that needs to be built.
 150     if built_value:
 151         return Value(value, built_value, name=name)
 152
 153     try:
 154         memo_lookup_key = hash((value, name))
 155     except TypeError:
 156         # Non-primitive types will hit this codepath.
 157         return Value(value, name=name)
 158
 159     try:
 160         return _memo_lookup_map[memo_lookup_key]
 161     except KeyError:
 162         v = Value(value, built_value, name)
 163         _memo_lookup_map[memo_lookup_key] = v
 164         return v
 165
 166
 167 # Local Variables:
 168 # tab-width:4
 169 # indent-tabs-mode:nil
 170 # End:
 171 # vim: set expandtab tabstop=4 shiftwidth=4: