Package pyxb :: Package utils :: Module utility
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Module utility

source code

Utility functions and classes.

Classes [hide private]
  _DeconflictSymbols_mixin
Mix-in used to deconflict public symbols in classes that may be inherited by generated binding classes.
  Graph
Represent a directed graph with arbitrary objects as nodes.
  UniqueIdentifier
Records a unique identifier, generally associated with a binding generation action.
  UTCOffsetTimeZone
A datetime.tzinfo subclass that helps deal with UTC conversions in an ISO8601 world.
  LocalTimeZone
A datetime.tzinfo subclass for the local time zone.
  PrivateTransient_mixin
Emulate the transient keyword from Java for private member variables.
  _LocationBase
Wrap a location.
  Location
  Locatable_mixin
Functions [hide private]
str
QuotedEscaped(s)
Convert a string into a literal value that can be used in Python source.
source code
 
_DefaultXMLIdentifierToPython(identifier)
Default implementation for _XMLIdentifierToPython
source code
unicode
_SetXMLIdentifierToPython(xml_identifier_to_python)
Configure a callable MakeIdentifier uses to pre-process an XM Lidentifier.
source code
 
_XMLIdentifierToPython(identifier)
Default implementation for _XMLIdentifierToPython
source code
str
MakeIdentifier(s, camel_case=False)
Convert a string into something suitable to be a Python identifier.
source code
str
DeconflictKeyword(s, aux_keywords=frozenset([]))
If the provided string s matches a Python language keyword, append an underscore to distinguish them.
source code
str
MakeUnique(s, in_use)
Return an identifier based on s that is not in the given set.
source code
str
PrepareIdentifier(s, in_use, aux_keywords=frozenset([]), private=False, protected=False)
Combine everything required to create a unique identifier.
source code
str
NormalizeWhitespace(text, preserve=False, replace=False, collapse=False)
Normalize the given string.
source code
 
SetLocationPrefixRewriteMap(prefix_map)
Set the map that is used to by NormalizeLocation to rewrite URI prefixes.
source code
 
NormalizeLocation(uri, parent_uri=None, prefix_map=None)
Normalize a URI against an optional parent_uri in the way that is done for schemaLocation attribute values.
source code
 
TextFromURI(uri, archive_directory=None)
Retrieve the contents of the uri as a text string.
source code
 
OpenOrCreate(file_name, tag=None, preserve_contents=False)
Return a file object used to write the given file.
source code
 
HashForText(text)
Calculate a cryptographic hash of the given string.
source code
str
_NewUUIDString()
Obtain a UUID using the best available method.
source code
 
GetMatchingFiles(path, pattern=None, default_path_wildcard=None, default_path=None, prefix_pattern=None, prefix_substituend=None)
Provide a list of absolute paths to files present in any of a set of directories and meeting certain criteria.
source code
Variables [hide private]
  _UnderscoreSubstitute_re = re.compile(r'[- \.]')
  _NonIdentifier_re = re.compile(r'[^a-zA-Z0-9_]')
  _PrefixUnderscore_re = re.compile(r'^_+')
  _PrefixDigit_re = re.compile(r'^\d+')
  _CamelCase_re = re.compile(r'_\w')
  _PythonKeywords = frozenset(['and', 'as', 'assert', 'break', '...
Python keywords.
  _PythonBuiltInConstants = frozenset(['Ellipsis', 'False', 'Non...
Other symbols that aren't keywords but that can't be used.
  _Keywords = frozenset(['Ellipsis', 'False', 'None', 'NotImplem...
The keywords reserved for Python, derived from _PythonKeywords and _PythonBuiltInConstants.
  __TabCRLF_re = re.compile(r'[\t\n\r]')
  __MultiSpace_re = re.compile(r' +')
  LocationPrefixRewriteMap_ = {}
  __HaveUUID = True
  __package__ = 'pyxb.utils'
Function Details [hide private]

QuotedEscaped(s)

source code 

Convert a string into a literal value that can be used in Python source.

This just calls repr. No point in getting all complex when the language already gives us what we need.

Returns: str

_DefaultXMLIdentifierToPython(identifier)

source code 

Default implementation for _XMLIdentifierToPython

For historical reasons, this converts the identifier from a str to unicode in the system default encoding. This should have no practical effect.

Parameters:
  • identifier - some XML identifier
Returns:
unicode(identifier)

_SetXMLIdentifierToPython(xml_identifier_to_python)

source code 

Configure a callable MakeIdentifier uses to pre-process an XM Lidentifier.

In Python3, identifiers can be full Unicode tokens, but in Python2, all identifiers must be ASCII characters. MakeIdentifier enforces this by removing all characters that are not valid within an identifier.

In some cases, an application generating bindings may be able to transliterate Unicode code points that are not valid Python identifier characters into something else. This callable can be assigned to perform that translation before the invalid characters are stripped.

It is not the responsibility of this callable to do anything other than replace whatever characters it wishes to. All transformations performed by MakeIdentifier will still be applied, to ensure the output is in fact a legal identifier.

Parameters:
  • xml_identifier_to_python - A callable that takes a string and returns a Unicode, possibly with non-identifier characters replaced by other characters. Pass None to reset to the default implementation, which is _DefaultXMLIdentifierToPython.
Returns: unicode

_XMLIdentifierToPython(identifier)

source code 

Default implementation for _XMLIdentifierToPython

For historical reasons, this converts the identifier from a str to unicode in the system default encoding. This should have no practical effect.

Parameters:
  • identifier - some XML identifier
Returns:
unicode(identifier)

MakeIdentifier(s, camel_case=False)

source code 

Convert a string into something suitable to be a Python identifier.

The string is processed by _XMLIdentifierToPython. Following this, dashes, spaces, and periods are replaced by underscores, and characters not permitted in Python identifiers are stripped. Furthermore, any leading underscores are removed. If the result begins with a digit, the character 'n' is prepended. If the result is the empty string, the string 'emptyString' is substituted.

No check is made for conflicts with keywords.

Parameters:
  • camel_case - If True, any underscore in the result string that is immediately followed by an alphanumeric is replaced by the capitalized version of that alphanumeric. Thus, 'one_or_two' becomes 'oneOrTwo'. If False (default), has no effect.
Returns: str

DeconflictKeyword(s, aux_keywords=frozenset([]))

source code 

If the provided string s matches a Python language keyword, append an underscore to distinguish them.

See also MakeUnique.

Parameters:
  • s - string to be deconflicted
  • aux_keywords - optional iterable of additional strings that should be treated as keywords.
Returns: str

MakeUnique(s, in_use)

source code 

Return an identifier based on s that is not in the given set.

The returned identifier is made unique by appending an underscore and, if necessary, a serial number.

The order is : x, x_, x_2, x_3, ...

Parameters:
  • in_use - The set of identifiers already in use in the relevant scope. in_use is updated to contain the returned identifier.
Returns: str

PrepareIdentifier(s, in_use, aux_keywords=frozenset([]), private=False, protected=False)

source code 

Combine everything required to create a unique identifier.

Leading and trailing underscores are stripped from all identifiers.

Parameters:
  • in_use - the set of already used identifiers. Upon return from this function, it is updated to include the returned identifier.
  • aux_keywords - an optional set of additional symbols that are illegal in the given context; use this to prevent conflicts with known method names.
  • private - if False (default), all leading underscores are stripped, guaranteeing the identifier will not be private. If True, the returned identifier has two leading underscores, making it a private variable within a Python class.
  • protected - as for private, but uses only one underscore.
Returns: str

Note: Only module-level identifiers should be treated as protected. The class-level _DeconflictSymbols_mixin infrastructure does not include protected symbols. All class and instance members beginning with a single underscore are reserved for the PyXB infrastructure.

NormalizeWhitespace(text, preserve=False, replace=False, collapse=False)

source code 

Normalize the given string.

Exactly one of the preserve, replace, and collapse keyword parameters must be assigned the value True by the caller.

  • preserve: the text is returned unchanged.
  • replace: all tabs, newlines, and carriage returns are replaced with ASCII spaces.
  • collapse: the replace normalization is done, then sequences of two or more spaces are replaced by a single space.

See the whiteSpace facet.

Returns: str

NormalizeLocation(uri, parent_uri=None, prefix_map=None)

source code 

Normalize a URI against an optional parent_uri in the way that is done for schemaLocation attribute values.

If no URI schema is present, this will normalize a file system path.

Optionally, the resulting absolute URI can subsequently be rewritten to replace specified prefix strings with alternative strings, e.g. to convert a remote URI to a local repository. This rewriting is done after the conversion to an absolute URI, but before normalizing file system URIs.

Parameters:
  • uri - The URI to normalize. If None, function returns None
  • parent_uri - The base URI against which normalization is done, if uri is a relative URI.
  • prefix_map - A map used to rewrite URI prefixes. If None, the value defaults to that stored by SetLocationPrefixRewriteMap.

TextFromURI(uri, archive_directory=None)

source code 

Retrieve the contents of the uri as a text string.

If the uri does not include a scheme (e.g., http:), it is assumed to be a file path on the local system.

OpenOrCreate(file_name, tag=None, preserve_contents=False)

source code 

Return a file object used to write the given file.

Use the tag keyword to preserve the contents of existing files that are not supposed to be overwritten.

To get a writable file but leaving any existing contents in place, set the preserve_contents keyword to True. Normally, existing file contents are erased.

The returned file pointer is positioned at the end of the file.

Parameters:
  • tag - If not None and the file already exists, absence of the given value in the first 4096 bytes of the file causes an IOError to be raised with errno set to EEXIST. I.e., only files with this value in the first 4KB will be returned for writing.
  • preserve_contents - This value controls whether existing contents of the file will be erased (False, default) or left in place (True).

HashForText(text)

source code 

Calculate a cryptographic hash of the given string.

For example, this is used to verify that a given module file contains bindings from a previous generation run for the same namespace. See OpenOrCreate. If the text is in Unicode, the hash is calculated on the UTF-8 encoding of the text.

Returns:
A str, generally a sequence of hexadecimal "digit"s.

_NewUUIDString()

source code 

Obtain a UUID using the best available method. On a version of python that does not incorporate the uuid class, this creates a string combining the current date and time (to the second) with a random number.

Returns: str

GetMatchingFiles(path, pattern=None, default_path_wildcard=None, default_path=None, prefix_pattern=None, prefix_substituend=None)

source code 

Provide a list of absolute paths to files present in any of a set of directories and meeting certain criteria.

This is used, for example, to locate namespace archive files within the archive path specified by the user. One could use:

 files = GetMatchingFiles('&bundles//:+',
                          pattern=re.compile('.*\.wxs$'),
                          default_path_wildcard='+',
                          default_path='/usr/local/pyxb/nsarchives',
                          prefix_pattern='&',
                          prefix_substituend='/opt/pyxb')

to obtain all files that can be recursively found within /opt/pyxb/bundles, or non-recursively within /usr/local/pyxb/nsarchives.

Parameters:
  • path - A colon separated list of directories in which the search should be performed. If a path entry ends with //, any directory beneath it is scanned as well, recursively.
  • pattern - Optional regular expression object used to determine whether a given directory entry should be returned. If left as None, all directory entries will be returned.
  • default_path_wildcard - An optional string which, if present as a single directory in the path, is replaced by the value of default-path.
  • default_path - A system-defined directory which can be restored to the path by placing the default_path_wildcard in the path.
  • prefix_pattern - An optional string which, if present at the start of a path element, is replaced by the value of prefix_substituend.
  • prefix_substituend - A system-defined string (path prefix) which can be combined with the user-provided path information to identify a file or subdirectory within an installation-specific area.

Variables Details [hide private]

_PythonKeywords

Python keywords. Note that types like int and float are not keywords.

Value:
frozenset(['and',
           'as',
           'assert',
           'break',
           'class',
           'continue',
           'def',
           'del',
...

_PythonBuiltInConstants

Other symbols that aren't keywords but that can't be used.

Value:
frozenset(['Ellipsis',
           'False',
           'None',
           'NotImplemented',
           'True',
           '__debug__'])

_Keywords

The keywords reserved for Python, derived from _PythonKeywords and _PythonBuiltInConstants.

Value:
frozenset(['Ellipsis',
           'False',
           'None',
           'NotImplemented',
           'True',
           '__debug__',
           'and',
           'as',
...