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Diffstat (limited to 'portato/eix/py_parser.py')
| -rw-r--r-- | portato/eix/py_parser.py | 416 |
1 files changed, 416 insertions, 0 deletions
diff --git a/portato/eix/py_parser.py b/portato/eix/py_parser.py new file mode 100644 index 0000000..cc42553 --- /dev/null +++ b/portato/eix/py_parser.py @@ -0,0 +1,416 @@ +# -*- 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) |