.. -*-RST-*- ===================================== CL-DOCUTILS: Docutils for Common Lisp ===================================== :Author: Dr John A.R. Williams :Contact: J.A.R.Williams@jarw.org.uk :created: 22 September 2009 :status: Draft :version: 0.1 :copyright: © 2009 J.A.R. Williams :Abstract: |CDU| is a Common Lisp implementation of the Docutils text processing system for processing plaintext into presentational formats such as HTML and LaTeX. It is based upon the Python Docutils reference implementation but uses Common Lisp idioms making it easier to extend and more flexible. As with the reference implementation it includes a parser for the `reStructured text`_ plaintext markup syntax which is suitable for marking up documentation and for use as user markup for collaborative web sites. It is successfully used to support a higher education peer-review assessment and online tutorial system. .. meta:: :keywords: reStructuredText, Docutils, text, Common Lisp .. contents:: Table of Contents .. |CDU| replace:: CL-DOCUTILS .. _restructured text: http://docutils.sourceforge.net/docs/ref/rst/ .. _Python: http://www.python.org/ .. _FlexiStreams: http://weitz.de/flexi-streams/ Download and Installation ========================= |CDU| together with this documentation can be downloaded from <http://www.jarw.org.uk/lisp/cl-docutils.tar.gz>. The current version is 0.1.1. |CDU| comes with a system definition for `ASDF <http://www.cliki.net/asdf>`_ and is compiled and loaded in the usual way. It depends upon `CL-DATA-FORMAT-VALIDATION <http://www.jarw.org.uk/lisp/cl-data-format-validation.html>`_ and `<CL-PPCRE <http://weitz.de/cl-ppcre/>`_. A git repository is available at <http://www.jarw.org.uk/lisp/cl-docutils.git>. It has been developed and tested using SBCL but should be portable to any ANSI-compliant implementation of Common Lisp. |CDU| is made available under the terms of the GPL v3 license - see the file ``LICENSE.txt`` for details. Support ======= For questions, bug reports, feature requests, improvements, or patches relating to this implementation please email <J.A.R.Williams@jarw.org.uk>. See `reStructured text`_ for the wide range of documentation on the restructured text syntax and `Docutils <http://docutils.sourceforge.net/index.html>`_ for information on the reference implementation on which this is based. Convenience Functions For Users =============================== Although this is intended as a library for embedding in other applications the following functions in the DOCUTILS package are provided as examples suitable for direct use: - function **read-rst** `input => document` Read and parse restructured text from an input (a stream, string or pathname) and return the parsed document object. - function **write-html** `output document` Write the parsed document to output (a stream or pathname) in html format. - function **write-latex** `output document` Write the parsed document to output (a stream or pathname) in LaTeX format. API For Developers ================== This documentation is in early stages and those wishing to use the library are encouraged to read the documentation for the Python Docutils implementation to get a flavour and examine the code here to determine differences. The generic interface is largely defined and documented in the file ``publisher.lisp`` which is a good place to start. Queries to the author as mentioned under support are also welcome. --------- Data Flow --------- The following diagram shows the components and data flow:: -----READER---- / \ / \ SOURCE ---> PARSE ---> TRANSFORM ---> WRITER ---> OUTPUT ------ Source ------ Specialised methods of the API are already provided for `stream`, `pathname` and `string` source types. It is the responsibility of the source and output streams to handle external character encodings. - generic function **new-document** `source => document` Implementations of this should create a new document instance with the appropriate non-default document settings from source. The default method loads no settings and the method specialised on pathname source will load settings from `*standard-config-files*` and `cl-docutils.conf` in the pathname directory. - generic function **read-lines** `source => vector` Given a source, return a vector of the text lines from source for subsequent parsing. - generic function **settings** `source => hash-table` Return a hash table of processing settings to be associated with documents with this source. - function **register-settings-spec** `specifications => specifications` Register a list of setting specifications. Each entry corresponds to one setting and has the form `(name type default description)` where `name` is a keyword symbol used to look up that setting, `type` the data format validation type specification, `default` a default value to be used if unspecified and `description` a string description suitable for users. Specifications are normally given in text files in internet header style with the setting name, followed by a colon, followed by the textual representation of the value. Continuation lines are supported. ----- Parse ----- - generic function **read-document** `source reader => document` Read a document from `source` using `reader` and using the transforms associated with this reader return a fully parsed and transformed document. The following restructured text specific API is exported from package ``docutils.parser.rst``. - class **rst-reader** Class name of the standard restructured text parser. - macro **def-role** `((name textvar &rest argument-list) &body body)` Define a new interpreted role element handler for role with canonical name `name`. `textvar` is the name of the variable holding the textual argument to be referenced in `body` and `argument-list` is as follows:: lambda-list::= ({var | (var [[specializer] [default]])}* [{{&content {var [[specializer] [default]]}}] ) `body` is the list of forms which should return a `docutils:text` node instance to be substituted into the document - macro **def-directive** `((name parent &rest argument-list) &body body)` Define a new directive element handler with name `name`. Similar to ``def-role`` except the `body` is responsible for adding nodes to the `parent` node. --------- Transform --------- - generic function **transforms** `reader => list` Return a list of transform specifications (class names) to be applied by this reader after parsing. - generic function **transform** `transform` Evaluate the given transform instance on its node. - generic function **do-transforms** `transforms document => document` Apply a list of transformation to the document in priority order. ------ Writer ------ - class **writer** Base class for all writer instances. - generic function **visit-node** `writer node` Process the node updating `writer` parts accordingly. Visiting a document node will clear all document parts first. - generic function **write-document** `writer document destination` Use `writer` to visit the `document` and write all parts in order to `destination` - generic function **write-part** `writer part destination` Write a given named document part from a `writer` to `destination`. - generic function **settings** `writer` => settings Return an alist of settings associated with this specific writer instance which will override the document settings during `writer` processing. - macro **with-part** `((part-name) &body)` => result Specify dynamically the document part to be written to using `part-append` and `part-prepend`. - function **part-append** `&rest values` function **part-prepend** `&rest values` These function append or prepend their arguments to the currently set part of the current writer. - class **docutils.writer.html:html-writer** The base class for writing a document out in html format. The provided file ``docutils.css`` provides an example style sheet for the generated documents. - class **docutils.writer.latex:latex-writer** The base class for writing a document out in latex format. The provided file ``docutils.tex`` should be placed in the latex search path as it is required by the produced latex documents. --------- Variables --------- - variable **`*unknown-reference-resolvers*`** List of functions to try to resolve unknown references during the transformation process. This can usefully be set to, for example, check against a database of pages in a live online system and return the relevant reference into the document. - variable **`*standard-config-files*`** List of pathnames to files to be parsed in order for document configuration settings. Defaults include ``/etc/cl-docutils.conf`` and ``~/.cl-docutils.conf``. A pathname source will also check for ``cl-docutils.conf`` file in the same directory. - variable **`*default-reader-package*`** Value to bind `*package*` to when reading lisp forms from the document. - variable **`*evaluator*`** Name of function to use to evaluate lisp forms in evaluateable nodes/ - variable **`*evaluation-error-hook*`** Function to be called if there are errors when calling `*evaluator*` Differences from Reference Implementation ========================================= Character Sets This Common Lisp implementation uses standard Lisp string handling and the CL-PPCRE regular expression library. Character set translation on input and output is orthogonal to this processing and can be formed using the appropriate specialised stream libraries such as FlexiStreams_. Nested Inline Elements This implementation supports nested inline elements (where they make sense) whereas the reference implementation did not. Error Messages Error messages is handled differently in this implementation with the result that they may not be located in exactly the same position relative the cause as in the Python implementation. Python Enhancement Proposals Parsing of Python Enhancement Proposals (PEPs) is not supported as these have significance only for the Python community, however PEP references are supported as to enable the use of the stand-alone test documents provided with the reference Python implementation. Customisation ============= A fundamental requirement and important feature of restructured text is that it can easily be customised and extended for use in embedded applications (particularly web applications) without changing the core language. Restructured text was explicitly designed with this in mind, however the Common Lisp implementation is quite different, and more powerful in this regard than the reference Python implementation. Directives The major feature for language extension at the block level is by the use of the named directive explicit markup. New directives can be defined using the ``def-directive`` macro. Roles Roles provide a means of implementing new inline elements. They are defined using the ``def-role`` macro. Transformations Transformations are associated with the parser element. If you wish new transformations to be run, use a subclass of the parser which return the appropriate list of transformations. ------------------- Additional Elements ------------------- - role **math** This role allows the embedding of mathematical expressions using LaTeX syntax. An implict syntax, delimiting the argument with '$$' is also provided. - directive **equation** This directive allows the embedding of equations in LaTeX format. - role **eval** A role allowing the embedding of inline evaluateable expressions in Lisp syntax - directive **evaluation** A directive allowing embedding of expressions to be evaluated - Currently only Lisp expressions are supported. Acknowledgements ================ The many contributers to the original Docutils project on which this based and the many examples of code made available by Common Lisp community which have inspired and taught me. Particular mention should go to Edi Weitz for making available the CL-PPCRE used here and the Flex-Streams library which can be used to deal with external character coding issue.