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authorRené 'Necoro' Neumann <necoro@necoro.net>2009-08-14 23:57:35 +0200
committerRené 'Necoro' Neumann <necoro@necoro.net>2009-08-14 23:57:35 +0200
commite4c2a57cdbb9082ce1cab7cbbfad122b16c56ff1 (patch)
treeb8b21b600c086aa9295af7317202476034930592 /portato/eix/py_parser.py
parentc916c961f34f47fdb25d5384370b0aed7e90ea49 (diff)
parent8d2b915b7705ba7d831d48ce9623ca8fe46f6f38 (diff)
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+# -*- coding: utf-8 -*-
+#
+# File: portato/eix/parser.py
+# This file is part of the Portato-Project, a graphical portage-frontend.
+#
+# Copyright (C) 2006-2009 René 'Necoro' Neumann
+# This is free software. You may redistribute copies of it under the terms of
+# the GNU General Public License version 2.
+# There is NO WARRANTY, to the extent permitted by law.
+#
+# Written by René 'Necoro' Neumann <necoro@necoro.net>
+
+"""
+The cache file supports different types of data.
+In this module (nearly) all of these types have a corresponding function.
+
+For the exact way all the functions work, have a look at the eix format description.
+"""
+
+from __future__ import absolute_import, with_statement
+__docformat__ = "restructuredtext"
+
+import os
+import struct
+from functools import partial
+
+from ..helper import debug
+from .exceptions import EndOfFileException
+
+#
+# Helper
+#
+
+def _get_bytes (file, length, expect_list = False):
+ """
+ Return a number of bytes.
+
+ :Parameters:
+
+ file : file
+ The file to read from.
+
+ length : int
+ The number of bytes to read.
+
+ expect_list : bool
+ In case ``length`` is 1, only a single byte is returned. If ``expect_list`` is true, then a list is also returned in this case.
+
+ :rtype: int or int[]
+ :raises EndOfFileException: if EOF is reached during execution
+ """
+
+ s = file.read(length)
+
+ if len(s) != length:
+ raise EndOfFileException, file.name
+
+ if length == 1 and not expect_list:
+ return ord(s) # is faster than unpack and we have a scalar
+ else:
+ return struct.unpack("%sB" % length, s)
+
+#
+# Base Types
+#
+
+def number (file, skip = False):
+ """
+ Returns a number.
+
+ :Parameters:
+
+ file : file
+ The file to read from.
+
+ skip : bool
+ Do not return the actual value, but just skip to the next datum.
+
+ :rtype: int
+ """
+
+ n = _get_bytes(file, 1)
+
+ if n < 0xFF:
+ value = n
+ else:
+ count = 0
+
+ while (n == 0xFF):
+ count += 1
+ n = _get_bytes(file, 1)
+
+ if n == 0:
+ n = 0xFF # 0xFF is encoded as 0xFF 0x00
+ count -= 1
+
+ value = n << (count*8)
+
+ if count > 0:
+
+ if skip:
+ file.seek(count, os.SEEK_CUR)
+ return
+
+ else:
+ rest = _get_bytes(file, count, expect_list = True)
+
+ for i, r in enumerate(rest):
+ value += r << ((count - i - 1)*8)
+
+ return value
+
+def vector (file, get_type, skip = False, nelems = None):
+ """
+ Returns a vector of elements.
+
+ :Parameters:
+
+ file : file
+ The file to read from.
+
+ get_type : function(file, bool)
+ The function determining type of the elements.
+
+ skip : bool
+ Do not return the actual value, but just skip to the next datum.
+
+ nelems : int
+ Normally the eix-Vector has the number of elements as the first argument.
+ If for some reason this is not the case, you can pass it in here.
+
+ :rtype: list
+ """
+
+ if nelems is None:
+ nelems = number(file)
+
+ if skip:
+ for i in range(nelems):
+ get_type(file, skip = True)
+ else:
+ return [get_type(file) for i in range(nelems)]
+
+def typed_vector(type, nelems = None):
+ """
+ Shortcut to create a function for a special type of vector.
+
+ :Parameters:
+
+ type : function(file, bool)
+ The function determining type of the elements.
+
+ nelems : int
+ Normally the eix-Vector has the number of elements as the first argument.
+ If for some reason this is not the case, you can pass it in here.
+ Do not return the actual value, but just skip to the next datum.
+
+ :rtype: function(file, bool)
+ :see: `vector`
+ """
+
+ if nelems is None:
+ return partial(vector, get_type = type)
+ else:
+ return partial(vector, get_type = type, nelems = nelems)
+
+def string (file, skip = False):
+ """
+ Returns a string.
+
+ :Parameters:
+
+ file : file
+ The file to read from.
+
+ skip : bool
+ Do not return the actual value, but just skip to the next datum.
+
+ :rtype: str
+ """
+ nelems = number(file)
+
+ if skip:
+ file.seek(nelems, os.SEEK_CUR)
+ return
+ else:
+ s = file.read(nelems)
+
+ if len(s) != nelems:
+ raise EndOfFileException, file.name
+
+ return s
+
+#
+# Complex Types
+#
+
+class LazyElement (object):
+ """
+ This class models a value in the cache, which is only read on access.
+
+ If not accessed directly, only the position inside the file is stored.
+ """
+ __slots__ = ("file", "get_type", "_value", "pos")
+
+ def __init__ (self, get_type, file):
+ """
+ :Parameters:
+
+ get_type : function(file, bool)
+ The function determining type of the elements.
+
+ file : file
+ The file to read from.
+ """
+
+ self.file = file
+ self.get_type = get_type
+ self._value = None
+
+ self.pos = file.tell()
+ get_type(file, skip=True) # skip it for the moment
+
+ @property
+ def value (self):
+ """
+ The value of the element.
+ """
+
+ if self._value is None:
+ old_pos = self.file.tell()
+ self.file.seek(self.pos, os.SEEK_SET)
+ self._value = self.get_type(self.file, skip = False)
+ self.file.seek(old_pos, os.SEEK_SET)
+
+ return self._value
+
+ def __call__ (self):
+ """
+ Convenience function. Also returns the value.
+ """
+ return self.value
+
+class overlay (object):
+ """
+ Represents an overlay object.
+
+ :IVariables:
+
+ path : `LazyElement` <string>
+ The path to the overlay
+
+ label : `LazyElement` <string>
+ The label/name of the overlay
+ """
+ __slots__ = ("path", "label")
+
+ def __init__ (self, file, skip = False):
+ """
+ :Parameters:
+
+ file : file
+ The file to read from.
+
+ skip : bool
+ Do not return the actual value, but just skip to the next datum.
+ """
+
+ self.path = LazyElement(string, file)
+ self.label = LazyElement(string, file)
+
+class header (object):
+ """
+ Represents the header of the cache.
+
+ :IVariables:
+
+ version : `LazyElement` <int>
+ The version of the cache file.
+
+ ncats : `LazyElement` <int>
+ The number of categories.
+
+ overlays : `LazyElement` <`overlay` []>
+ The list of overlays.
+
+ provide : `LazyElement` <string[]>
+ A list of "PROVIDE" values.
+
+ licenses : `LazyElement` <string[]>
+ The list of licenses.
+
+ keywords : `LazyElement` <string[]>
+ The list of keywords.
+
+ useflags : `LazyElement` <string[]>
+ The list of useflags.
+
+ slots : `LazyElement` <string[]>
+ The list of slots different from "0".
+
+ sets : `LazyElement` <string[]>
+ The names of world sets are the names (without leading @) of the world sets stored in /var/lib/portage/world_sets.
+ If SAVE_WORLD=false, the list is empty.
+ """
+ __slots__ = ("version", "ncats", "overlays", "provide",
+ "licenses", "keywords", "useflags", "slots", "sets")
+
+ def __init__ (self, file, skip = False):
+ """
+ :Parameters:
+
+ file : file
+ The file to read from.
+
+ skip : bool
+ Do not return the actual value, but just skip to the next datum.
+ """
+ def LE (t):
+ return LazyElement(t, file)
+
+ self.version = LE(number)
+ self.ncats = LE(number)
+ self.overlays = LE(typed_vector(overlay))
+ self.provide = LE(typed_vector(string))
+ self.licenses = LE(typed_vector(string))
+ self.keywords = LE(typed_vector(string))
+ self.useflags = LE(typed_vector(string))
+ self.slots = LE(typed_vector(string))
+ self.sets = LE(typed_vector(string))
+
+class package (object):
+ """
+ The representation of one package.
+
+ Currently, version information is not parsed and stored.
+ So you can gain general infos only.
+
+ :IVariables:
+
+ name : `LazyElement` <string>
+ The name of the package.
+
+ description : `LazyElement` <string>
+ Description of the package.
+
+ homepage : `LazyElement` <string>
+ The homepage of the package.
+
+ provide : `LazyElement` <int[]>
+ The indices of `header.provide` representing the PROVIDE value of the package.
+
+ license : `LazyElement` <int>
+ The index of `header.licenses` representing the license of the package.
+
+ useflags : `LazyElement` <int[]>
+ The indices of `header.useflags` representing the IUSE value of the package.
+ """
+
+ __slots__ = ("_offset", "name", "description", "provide",
+ "homepage", "license", "useflags")
+
+ def __init__ (self, file, skip = False):
+ """
+ :Parameters:
+
+ file : file
+ The file to read from.
+
+ skip : bool
+ Do not return the actual value, but just skip to the next datum.
+ """
+ def LE (t):
+ return LazyElement(t, file)
+
+ self._offset = number(file)
+
+ after_offset = file.tell()
+
+ self.name = LE(string)
+ self.description = LE(string)
+ self.provide = LE(typed_vector(number))
+ self.homepage = LE(string)
+ self.license = LE(number)
+ self.useflags = LE(typed_vector(number))
+
+ # self.versions = LE(typed_vector(version))
+ # for the moment just skip the versions
+ file.seek(self._offset - (file.tell() - after_offset), os.SEEK_CUR)
+
+class category (object):
+ """
+ Represents a whole category.
+
+ :IVariables:
+
+ name : `LazyElement` <string>
+ The category name.
+
+ packages : `LazyElement` <`package` []>
+ All the packages of the category.
+ """
+ __slots__ = ("name", "packages")
+
+ def __init__ (self, file, skip = False):
+ """
+ :Parameters:
+
+ file : file
+ The file to read from.
+
+ skip : bool
+ Do not return the actual value, but just skip to the next datum.
+ """
+ self.name = LazyElement(string, file)
+ self.packages = LazyElement(typed_vector(package), file)