chameleon.core 1.0b30

Attribute language template compiler

Overview
--------

Chameleon is a generic byte-code compiler for attribute template
languages; it supports macros, includes, interpolation and
internationalization.

The ``chameleon.core`` package implements a language parser API, the
byte-code compiler itself and abstract template classes. It should
only be used directly when implementing a language dialect.

Development
-----------

If you want to use the code directly from trunk (recommended only for
development and testing usage), provide ``chameleon.core==dev`` as your
dependency.

The code is maintained in a subversion repository::

svn://svn.repoze.org/svn/chameleon.core

Want to contribute? Join #repoze on Freenode IRC.

Changelog
=========

1.0b30 (released 17/04/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Added ``omit_default_prefix`` argument to template class; by default
this is enabled, such that attributes belonging to the same
namespace as the tag are printed without prefix. Certain legacy
applications require a prefix on all attributes however. [malthe]

1.0b29 (released 17/04/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed issue where a limit was put on the total length of XML
namespace declarations by ``lxml``. [malthe]

- Exclude "transient symbols", defined as those who evaluate the
``chameleon.core.config.TRANSIENT_SYMBOL``. [malthe]

1.0b28 (released 08/04/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Initialize macros-object immediately after parsing for
efficiency. [malthe]

- Attempt at sniffing the content_type and encoding from the source
file, like zope.pagetemplate.pagetemplatefile does. [sidnei]

1.0b27 (released 06/04/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed issue where nested variable definitions would not correctly
get restored, when doubly (or more) nested. [malthe]

- Use 'xmlcharrefreplace' sub-encoding when encoding output in
utils.attribute() [sidnei]

1.0b26 (released 01/04/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Worked around critical vulnerability in the built-in ``expat``
parser module that would cause a segmentation fault when parsing
certain unicode characters. [malthe]

- Add the internal symbol set to the first template scope; symbols in
this scope will never be passed when filling macro slots (this
supports a requirement in ZPT to keep a reference to the current
template instance, which should never be carried over). [malthe]

1.0b25 (released 31/03/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Use the 'xmlcharrefreplace' sub-encoding to ensure that non
unicode-compatible encodings are handled correctly. [malthe]

- Preserve HTML entities in output. See LP #350042. [malthe]

- Respect ordering of static attributes and apply also to dynamic
attributes. [malthe]

- Protect import of cache created with other Python-version. [malthe]

- Do not escape double quotes outside of attributes. LP
#348743. [malthe]

1.0b24 (released 23/03/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- When translating a section with unnamed blocks using a message id,
include contained elements as-is (without processing). [malthe]

- Catch type errors when loading template from cache. [malthe]

- Fixed issue where translating an element containing unnamed (missing
an i18n:name attribute) subelements would cause broken output. It's
now attempted to translate unnamed elements as-is (after processing,
as straight HTML), although ill-advised. LP #335937. [malthe]

- Fixed issue where concatenated output would sometimes fail due to
incorrect type checking. [malthe]

- Fixed bug where attributes from one of the default namespaces (those
defined by the engine and which do not require explicit definition
in the template). LP #340234. [malthe]

1.0b23 (released 13/03/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Added ``get`` method to repeat dictionary. [malthe]

- Avoid infinite loop when using nested macros. [sidnei, malthe]

- When computing generator in repeat dictionary, swallow only
type-errors. [malthe]

- When accessing the ``macros`` attribute, make sure compiler is reset
when ``auto_reload`` is true and the source file has been
modified. [malthe]

- Check attribute namespace against element namespace, instead of
checking prefix. [sidnei]

1.0b22 (released 09/03/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Do not reset a dynamic scope which is being passed in as a
parameter. [malthe]

- Fixed bug where code in exception handlers would not get correctly
transformed. [malthe]

1.0b21 (released 05/03/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Repeating over ``None`` is same as repeating over empty tuple. [malthe]

- Added support for dynamic defaults. [malthe]

- Parts may now prescribe which exceptions to allow (default is any). [malthe]

- Added support for 'default' to fallback to default static content. [malthe]

1.0b20 (released 27/02/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Revamped template exceptions formatting. Argument values are now
presented briefly, rather than fully. [malthe]

1.0b19 (released 22/02/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Added slight optimization to code transformer to avoid a second call
on the dynamic scope object. [malthe]

- Fixed bug where variable definition scope would not be
honored. [malthe]

1.0b18 (released 19/02/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Added support for cancelling an escape by offering a ``__html__``
method. [malthe]

- Fixed issue where namespace prefix would not be recognized if
defined below another namespace definition. [malthe]

- Simplifed escaping routine; we only care about the classic three
entities. [malthe]

- Escape default translation content. [malthe]

- Translation of ``None`` should return ``None``. [malthe]

- Omit the element that defines a slot, if it's filled. [malthe]

1.0b17 (released 13/02/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Use ``tempfile.mkstemp`` to better garden temporary files. [malthe]

- Fixed issue where ``auto_reload`` would have no effect. [malthe]

- In debug-mode, source code is now written to disk, enabling us to
load (compile) it with ``imp.load_source`` instead of ``exec. This
allows pdb to step into the source code just like any other
file-based module. [malthe]

1.0b16 (released 12/02/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Parse templates only when needed, unless the environment variable
'CHAMELEON_EAGER' is set. [malthe]

- Correctly report back if the document is empty. [malthe]

- Fixed bug that prevented the parsing of XML fragments if they were
separated by comments. [malthe]

- Improved feedback on XML parsing errors. [malthe]

1.0b15 (released 29/01/2009)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed issue where attributes would be included for a foreign
namespace even though they were not part of that namespace. [malthe]

- Include (render) "foreign" namespace definitions in macros. [malthe]

- Support macro definitions on elements with METAL prefix. [malthe]

- Comments outside the root element get ignored (LP #317893). [sidnei]

- Set the template as __traceback_info__ in render_template, so that
for Zope 2/3 it shows up whenever an exception happens, making it
easier to diagnose what's the failing template in cases where many
templates and macros are being used to render a page. [sidnei]

- Verify that macros exist when accessed using the
dictionary-interface of the ``Macros`` object (LP #317572). [malthe]

- Restructured compilation step such that templates are always parsed
on source write, instead of 'just-in-time' before compilation. This
will enable us to query the parsed template separately from
compilation. [malthe]

- Added ``pass`` statement to guarantee valid block
structure (LP #312597). [malthe]

- Raise ``KeyError`` instead of ``ValueError`` when a macro cannot be
found. [malthe]

- Removed Zope security configuration. [malthe]

- Do not depend on component configuration. [malthe]

- Make tests pass under Python 2.4 [chrism]

1.0b14 (released 18/12/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Changed a try-except-finally construct into two nested try-except
clause to retain Python 2.4 compatibility. [cguardia]

1.0b13 (released 15/12/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed handling of static attributes on foreign elements. [malthe]

- Handle the case where the XML declaration does not have an
encoding. [malthe]

- Introduced new environment flag 'CHAMELEON_SOURCE' which determines
whether the source-code should be written to disk before
compilation. [malthe]

- Ignore comments that appear before a root element. [malthe]

- Issue a better error message if the expat parser has not been
properly initialized. [malthe]

- Merge adjacent strings in write-method. [malthe]

- Added version-control to file cache. This facilitates cache
invalidation on package upgrades. [malthe]

- Don't flush writes manually; instead, make sure all writes use the
`out` method and flush whenever `write` is used. This should prevent
consecutive writes (grouping them into one, instead). [malthe]

- Removed support for selectors bound to elements at compile-time. The
motivation for this functionality was to implement Genshi match
templates, however, incorrectly as it turns out. [malthe]

1.0b12 (released 03/12/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Support template fragments, e.g. documents with more than one
root element. [malthe]

- Added namespace prefix 'xml' to default namespace mapping. [malthe]

- Fixed root cause of issue with self-closing tags; an empty element
text is now correctly differentiated from a self-closed
tag (which does not have this attribute set). [malthe]

- Removed support for compilation without ``lxml``. [malthe]

- Use ``xml.parsers.expat`` to parse template document instead of
using ``lxml``. This gives much greater control over edge-cases and
allows us to lose many workarounds. [malthe]

- Do not use XPath-expressions during compilation if lxml is not
available. [malthe]

- Ensure argument uniqueness for macro functions over the combined set of
scope and keyword arguments. [hannosch]

- Protect all `itertools.chain` statements with an encapsulating set() to
ensure uniqueness. [hannosch]

1.0b11 (released 29/11/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Ensure that function arguments passed into macros are unique. [hannosch]

- Removed unused imports, thanks to PyFlakes. [hannosch]

- Removed warning about utf-8 as a recommend default encoding. There is no
apparent speed improvement anymore. [hannosch]

- Use ``sourcecodegen`` package to generate Python-code from AST; this
is done to avoid generating code using the ``compiler.pycodegen``
module, which has serious issues. Interestingly, this approach cuts
compilation time in half. [malthe]

- Bind code-generation utilities in closure as well. [malthe]

- Reworked global scope initialization; we now bind these using a
closure. [malthe]

- Reworked repeat-variable logic. An iterator would be realized at any
rate, so let's not try to be clever. [malthe]

- Made repeat-variable work with iterables which do not announce their
length before execution. [malthe]

- Added namespace attribute support. [malthe]

- Static attributes are now computed such that attributes are omitted
according to a `ns_omit` flag, and they are always prefixed
according to the element's `nsmap`. [malthe]

- Do not fix-up self-closing tags if an XML declaration is present
without a DOCTYPE. [malthe]

- Prefix tags which do not belong to the default namespace. [malthe]

1.0b10 (released 24/11/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Do not apply namespace attribute 'xmlns' to root element if not
set. [malthe]

- Fixed tuple unpacking in repeat loops. [malthe]

- Use a custom simple BufferIO class for the lxml.etree parser instead of
standard StringIO. [hannosch]

- This was the wrong fix, however; what needed to be changed is that
the class of the marker isntance must be available at
module-scope. [malthe]

- Changed generation.marker back to a normal object instance. Otherwise we get
PicklingError: Can't pickle <class 'chameleon.core.generation.marker'>:
it's not the same object as chameleon.core.generation.marker. [hannosch]

- Changed two isinstance checks to check for basestring instead of str or
unicode. [hannosch]

1.0b9 (released 19/11/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Added ``label`` property to expressions; this allows providing a
human-readable label for values that are going to
evaluated. [malthe]

- Normalize METAL slot names to ensure they're valid Python variable
names. Non-valid characters are converted to underscore. [malthe]

- Renamed dynamic scope variable to `econtext` in order to reduce
compatibility issues with ZPT. [malthe]

- Fixed issue where multiple defines would cause integrity
issues. [malthe]

- Avoid self-closing tags that are not allowed in transitional
HTML. [malthe]

- Use custom serialization method to serialize static default
translation blocks; we can't rely on `lxml` for sane
output. [malthe]

- Make `default` symbol available to dynamic attribute
evaluations. [malthe]

- Visit evaluation before assignment in order to support assignments
that rely on the same name in the dynamic variable scope. [malthe]

- Conditions may now be inverted; this facilitates the bug-fix of an
issue where omit conditions were multi-part. [malthe]

- Make sure that arguments passed into the `render`-method are
introduced in every nested scope. [malthe]

- Added translation language to main scope and make sure redefining it
inside a closure does not cause issues with nested scope
locals. [malthe]

1.0b8 (released 16/11/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Only pretend to delete variables; this improves performance and
guarantees that we don't attempt to delete a variables which is used
in a nested scope (closure). It works, because the code generation
transform silently drops the delete-statements, but removes them
from its internal scope dictionary. [malthe]

- Remove variables from scope dictionary upon block exit. [malthe]

- Split out compile-function such that we can always write the source
code to disk in debug-mode. [malthe]

- Correctly transfer scope to callback-function that will fill macro
slot contents. Previously, we would precompute fill-slots, but this
was wrong since it's expected to inherit the scope of the macro
currently in use. [malthe]

- Made error handler compatible with Python 2.4 [malthe]

- Maintain symbol mappings for joined expressions. [malthe]

1.0b7 (released 15/11/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed interpolation edge where a right curly brace not part of an
interpolation expression would cancel a succeeding
interpolation. [malthe]

- Pass `target_language` when using macros. [malthe]

1.0b6 (released 13/11/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

- When validating inserted content (in debug-mode), make sure we wrap
content as a proper HTML document, including HTML entity
definitions. [malthe]

- If an element does not belong to a known namespace, assume it's the
default namespace. This change is relevant after the introduction of
fallback elements. [malthe]

- XML declarations should be printed with or without a doctype
element, and only if the template includes it. [malthe]

1.0b5 (released 12/11/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Encode code annotations if encoding is required. [malthe]

- Added filename to XML syntax error exception message. [malthe]

- Fixed bug where a template would be wrapped with namespace
definitions even if an XML header is present. [malthe]

- Added support for fallback element. [malthe]

- Enabled error handler for macro renderer. [malthe]

- Added error handler which adds debugging information to the
exception object's string output (in debug-mode only). [malthe]

1.0b4 (released 28/10/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed translation issues (see recently added tests). [malthe]

- Refactored string coercion. [malthe]

1.0b3 (released 13/10/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed issue with parsing expression containing curly
braces. [malthe]

- Added support for unscoped variable assignment. [malthe]

1.0b2 (released 11/10/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Added support for translating dynamic body text (used in
interpolation expressions). [malthe]

- Added support for macros prebound to keyword arguments. [malthe]

1.0b1 (released 2/10/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed bugs related to temporary variables with loops and
conditions. [malthe]

- Set default value for `auto-reload` based on the CHAMELEON_DEBUG
environment variable check. [malthe]

1.0a4 (released 9/29/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~

- Added method to generate unscoped temporary variables. [malthe]

- Make lxml a hard dependency for now until the lxml-less logic is stable.
[wichert]

1.0a3 (released 9/26/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~

- TemplateLoader now checks a default_parser class attribute if no
parser is specified. [wichert]

1.0a2 (released 9/26/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~

- Added support for dynamic skip condition. [malthe]

- Fixed bug where an AttributeError would be raised when using the
file cache. [malthe]

1.0a1 (released 9/24/2008)
~~~~~~~~~~~~~~~~~~~~~~~~~~

- First release.