X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2FDEVEL%2Fpxp%2Fpxp%2Fdoc%2FREADME.xml;fp=helm%2FDEVEL%2Fpxp%2Fpxp%2Fdoc%2FREADME.xml;h=34c7726ad192e01459f1301b57896222e0db5888;hb=c03d2c1fdab8d228cb88aaba5ca0f556318bebc5;hp=0000000000000000000000000000000000000000;hpb=758057e85325f94cd88583feb1fdf6b038e35055;p=helm.git diff --git a/helm/DEVEL/pxp/pxp/doc/README.xml b/helm/DEVEL/pxp/pxp/doc/README.xml new file mode 100644 index 000000000..34c7726ad --- /dev/null +++ b/helm/DEVEL/pxp/pxp/doc/README.xml @@ -0,0 +1,423 @@ + + + + + + +Gerd Stolpmann'> +--> + + +%common; + + +up'> + + +%config; + +]> + + + + Abstract +

+PXP is a validating parser for XML-1.0 which has been written +entirely in Objective Caml. +

+ +

PXP is the new name of the parser formerly known as "Markup". +PXP means "Polymorphic XML parser" and emphasizes its most useful +property: that the API is polymorphic and can be configured such that +different objects are used to store different types of elements.

+ + + + Download +

+You can download PXP as gzip'ed tarball. The parser needs the Netstring package (0.9.3). Note that PXP +requires O'Caml 3.00. +

+ + + + User's Manual +

+The manual is included in the distribution both as Postscript document and +bunch of HTML files. An online version can be found here. +

+ + + + Author, Credits, Copying +

+PXP has been written by &person.gps;; it contains contributions by +Claudio Sacerdoti Coen. You may copy it as you like, +you may use it even for commercial purposes as long as the license conditions +are respected, see the file LICENSE coming with the distribution. It allows +almost everything. +

+ +

Thanks also to Alain Frisch and Haruo Hosoya for discussions and bug +reports.

+ + + + Description +

+PXP is a validating XML parser for O'Caml. It strictly complies to the +XML-1.0 standard. +

+ +

The parser is simple to call, usually only one statement (function +call) is sufficient to parse an XML document and to represent it as object +tree.

+ +

+Once the document is parsed, it can be accessed using a class interface. +The interface allows arbitrary access including transformations. One of +the features of the document representation is its polymorphic nature; +it is simple to add custom methods to the document classes. Furthermore, +the parser can be configured such that different XML elements are represented +by objects created from different classes. This is a very powerful feature, +because it simplifies the structure of programs processing XML documents. +

+ +

+Note that the class interface does not comply to the DOM standard. It was not a +development goal to realize a standard API (industrial developers can this much +better than I); however, the API is powerful enough to be considered as +equivalent with DOM. More important, the interface is compatible with the +XML information model required by many XML-related standards. +

+ + + Detailed feature list + +
    +

  • The XML instance is validated against the DTD; any violation of +a validation constraint leads to the rejection of the instance. The validator +has been carefully implemented, and conforms strictly to the standard. If +needed, it is also possible to run the parser in a well-formedness mode.

    +
    • +

  • If possible, the validator applies a deterministic finite +automaton to validate the content models. This ensures that validation can +always be performed in linear time. However, in the case that the content +models are not deterministic, the parser uses a backtracking algorithm which +can be much slower. - It is also possible to reject non-deterministic content +models.

    +
    • +

  • In particular, the validator also checks the complicated rules +whether parentheses are properly nested with respect to entities, and whether +the standalone declaration is satisfied. On demand, it is checked whether the +IDREF attributes only refer to existing nodes.

    +
    • +

  • Entity references are automatically resolved while the XML text +is being scanned. It is not possible to recognize in the object tree where a +referenced entity begins or ends; the object tree only represents the logical structure.

    +
    • +

  • External entities are loaded using a configurable resolver +infrastructure. It is possible to connect the parser with an arbitrary XML source.

    +
    • +

  • The parser can read XML text encoded in a variety of character +sets. Independent of this, it is possible to choose the encoding of the +internal representation of the tree nodes; the parser automatically converts +the input text to this encoding. Currently, the parser supports UTF-8 and +ISO-8859-1 as internal encodings.

    +
    • +

  • The interface of the parser has been designed such that it is +best integrated into the language O'Caml. The first goal was simplicity of +usage which is achieved by many convenience methods and functions, and by +allowing the user to select which parts of the XML text are actually +represented in the tree. For example, it is possible to store processing +instructions as tree nodes, but the parser can also be configured such that +these instructions are put into hashtables. The information model is compatible +with the requirements of XML-related standards such as XPath.

    +
    • +

  • In particular, the node tree can optionally contain or leave out +processing instructions and comments. It is also possible to generate a "super +root" object which is the parent of the root element. The attributes of +elements are normally not stored as nodes, but it is possible to get them +wrapped into nodes.

    +
    • +

  • There is also an interface for DTDs; you can parse and access +sequences of declarations. The declarations are fully represented as recursive +O'Caml values. +

    +
    • +
+ + + + + Code examples +

+This distribution contains several examples:

+
    +

  • +validate: simply parses a +document and prints all error messages +

    • + +

  • +readme: Defines a DTD for simple "README"-like documents, and offers +conversion to HTML and text filesThis particular document is an +example of this DTD!. +

    • + +

  • +xmlforms: This is already a +sophisticated application that uses XML as style sheet language and data +storage format. It shows how a Tk user interface can be configured by an +XML style, and how data records can be stored using XML. +

    • +
+ + + + Restrictions and missing features +

+The following restrictions apply that are not violations of the standard: +

+
    +

  • +The attributes "xml:space", and "xml:lang" are not supported specially. + (The application can do this.)

    • + +

  • +The built-in support for SYSTEM and PUBLIC identifiers is limited to + local file access. There is no support for catalogs. The parser offers + a hook to add missing features.

    • + +

  • +It is currently not possible to check for interoperatibility with SGML. +

    • +
+ +

The following features are also missing:

+
    +

  • There is no special support for namespaces. (Perhaps in the next release?)

    +
    • +

  • There is no support for XPATH or XSLT.

    +
    • +
+

However, I hope that these features will be implemented soon, either by +myself or by contributors (who are invited to do so).

+ + + + Recent Changes +
    +
  • +

    Changed in 1.0:

    +

    Support for document order.

    +
    • +
  • +

    Changed in 0.99.8:

    +

    Several fixes of bugs reported by Haruo Hosoya and Alain +Frisch.

    +

    The class type "node" has been extended: you can go directly to +the next and previous nodes in the list; you can refer to nodes by +position.

    +

    There are now some iterators for nodes: find, find_all, +find_element, find_all_elements, map_tree, iter_tree.

    +

    Experimental support for viewing attributes as nodes; I hope that +helps Alain writing his XPath evaluator.

    +

    The user's manual has been revised and is almost up to date.

    +
    • +
  • +

    Changed in 0.99.7:

    +

    There are now additional node types T_super_root, T_pinstr and +T_comment, and the parser is able to create the corresponding nodes.

    +

    The functions for character set conversion have been moved to +the Netstring package; they are not specific for XML.

    +
    • +
  • +

    Changed in 0.99.6:

    +

    Implemented a check on deterministic content models. Added +an alternate validator basing on a DFA. - This means that now all mandatory +features for an XML-1.0 parser are implemented! The parser is now substantially +complete.

    +
    • +
  • +

    Changed in 0.99.5:

    +

    The handling of ID and IDREF attributes has changed. The +index of nodes containing an ID attribute is now separated from the document. +Optionally the parser now checks whether the IDREF attributes refer to +existing elements.

    +

    The element nodes can optionally store the location in the +source XML code.

    +

    The method 'write' writes the XML tree in every supported +encoding. (Successor of 'write_compact_as_latin1'.)

    +

    Several smaller changes and fixes.

    +
    • +
  • +

    Changed in 0.99.4:

    +

    The module Pxp_reader has been modernized. The resolver classes +are simpler to use. There is now support for URLs.

    +

    The interface of Pxp_yacc has been improved: The type 'source' +is now simpler. The type 'domspec' has gone; the new 'spec' is opaque and +performs better. There are some new parsing modes.

    +

    Many smaller changes.

    +
    • +
  • +

    Changed in 0.99.3:

    +

    The markup_* modules have been renamed to pxp_*. There is a new +compatibility API that tries to be compatible with markup-0.2.10.

    +

    The type "encoding" is now a polymorphic variant.

    +
    • +
  • +

    Changed in 0.99.2:

    +

    Added checks for the constraints about the standalone +declaration.

    +

    Added regression tests about attribute normalization, +attribute checks, standalone checks.

    +

    Fixed some minor errors of the attribute normalization +function.

    +

    The bytecode/native archives are now separated in +a general part, in a ISO-8859-1-relevant part, and a UTF-8-relevant +part. The parser can again be compiled with ocamlopt.

    +
    • +
  • +

    Changed in 0.99.1:

    +

    In general, this release is an early pre-release of the +next stable version 1.00. I do not recommend to use it for serious +work; it is still very experimental!

    +

    The core of the parser has been rewritten using a self-written +parser generator.

    +

    The lexer has been restructured, and can now handle UTF-8 +encoded files.

    +

    Numerous other changes.

    +
    • + + +
+ + + +