chameleon.core 1.0.2

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

1.0.2 (released 08/10/2009)

• Made translation-method overridable (this allows subclasses to provide their own method which may be prebound to some translation context).

1.0.1 (released 10/09/2009)

Bugfix:

• When detecting HTML content-type and encoding, don’t substitute out the meta-tag. [millie]

1.0.0 (released 6/07/2009)

• Disable file-cache by default.

• The read method is now able to recover from a character decoding error on initialization.

• Fixed file cache version check.

• Added support for repeat-variables ‘letter’, ‘Letter’, ‘roman’ and ‘Roman’. [wiggy, malthe]

• Improve performance of element repetition.

• Use remote scope if applicable. This fixes an issue where macros would not carry over from an XInclude. Tsutsumi Naoya contributed to this bugfix.

1.0b36 (released 13/06/2009)

• Fixed issue where global variable assignments would not get carried through to macros.

1.0b35 (released 05/06/2009)

• Fixed version number concatenation such that it includes the base template class.

1.0b34 (released 29/05/2009)

• Fixed issue with file cache where template byte-code would not get persisted on the file system.

• Fixed issue with file cache (it would get reset upon first use, defeating the purpose of it entirely).

• Fixed exception-handler in file cache.

• Local variable declarations (local or global) would be added to the dynamic variable scope (econtext) when a macro was used. This issue has been solved by making a copy of the scope when using macros; if globals are defined by the called macro, they will still be applied to the original scope.

1.0b33 (released 20/05/2009)

Changes:

• Template arguments are now always passed in through the dynamic variable scope (econtext). This change means that the compilation signature now only depends on variables that are known upon instantiation.

• Output is now always unicode, regardless of the encoding. This means that input will be converted to unicode as required, while the application must itself take care of the final conversion.

• Filled macro slots are now passed explicitly into the slots parameter, providing a formal API for rendering a macro. This mechanism was not open previously, relying on low-level machinery to function. As a technical aside, this change means that the provided slots are no longer part of the compilation signature, which could potentially reduce warm-up time.

Improvements:

• Added “strict” mode which currently acts as a flag to require filled macro slots to be defined in the macro that’s being used.

• Added test case for cancelation of attributes via a false value. [hannosch]

• Optimized “Assign” clause when used with single join statements. [hannosch]

• The required number of function calls needed for a rendering has been reduced.

• A default encoding can be defined on the template class; only if an explicit encoding is provided when instantiating a template will it be overriden.

• The file cache now relies on the standard module import routines to generate byte-code. When the file cache is enabled, a Python source-file is added next to the template file (with the ‘.py’ filename extension).

Bugfixes:

• Fixed issue where a repeat through blocks that should be omitted would generate unwanted whitespace. [malthe]

• Fixed issue where you could not use the variable name type since it would collide with the builtin method, which was used internally.

• Fixed incorrect variable name when reporting mismatched Python versions in the cache pickles. [davisagli]

• Fixed minor issues with the default symbol; it now defaults to None, if no default is available.

• Fixed an UnboundLocalError that occurred when attempting to load a truncated cache file. [shane]

• Buildout configuration no longer depends on lxml. [shane]

1.0b32 (released 24/04/2009)

• Dropped dependency on lxml. [malthe]

1.0b31 (released 22/04/2009)

• Correctly implement METAL 1.1 specification with regards to use-macro and extend-macro, the difference being whether slots are carried forward by default. To this effect, a key-error is now being raised if a slot is attempted to be carried forward without explicit redefinition. LP #364233. [malthe]

• Added validate-method to the parser class; it will be called for each parsed element, providing an option to raise language-level exceptions during parsing. [malthe]

• Add support for metal:extend-macro, even if it’s basically an alias for use-macro for now. [sidnei]

• Parse internal entities defined in <!DOCTYPE> and pass them around to output, working around a bug in lxml. [sidnei]

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.