Merged in eix-branch

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)