XSieve: XSLT+Scheme XSieve Extending XSLT with the roots of XSLT - - PowerPoint PPT Presentation

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XSieve: XSLT+Scheme XSieve Extending XSLT with the roots of XSLT - - PowerPoint PPT Presentation

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XSieve: XSLT+Scheme XSieve Extending XSLT with the roots of XSLT Oleg Parashchenko Saint-Petersburg State University, Russia olpa@ http://uucode.com/blog/ http://xmlhack.ru/ 1 XSieve: XSLT+Scheme XTech 2006 Top secret XSieve is a

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— 1 — XSieve: XSLT+Scheme

XTech 2006

XSieve: XSLT+Scheme

Oleg Parashchenko Saint-Petersburg State University, Russia

  • lpa@ http://uucode.com/blog/

http://xmlhack.ru/

Extending XSLT with the roots of XSLT

XSieve

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— 2 — XSieve: XSLT+Scheme

XTech 2006

XSieve is a by-side product.

Top secret

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XTech 2006

Outline

  • XSieve vs alternatives
  • SXML format and tools
  • XSieve language
  • XSieve in practice
  • Technical details
  • Conclusion and further work
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XTech 2006

My featured skill is:

  • XML data transformation
  • Word to XML
  • Quicksilver, Interleave to XML
  • Unstructured FrameMaker to XML
  • Etc
  • XML to HTML, PDF, etc

Background

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But XSLT fails. Data transformation should be supported by programming. XSLT is not a good programming language.

XSLT is the best

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“elemname[i]" vs

/** * Returns child element at given position. Position can be * negative. In this case nodes are counting from end. * Last node position is '-1'. * @param node parent node * @param name name of node, null if not important * @param pos position of node starting from zero, can be negative */ public static Element getChildElement (Element node, String name, int s) { // // Update position to be always positive. // boolean fromEnd = pos < 0; if (fromEnd) { pos = -(pos + 1); } // // Initialize // Node cur_node = fromEnd ? node.getLastChild(): node.getFirstChild(); int cur_pos = -1; // // Walk on children // for (; cur_node != null; cur_node = (fromEnd ? cur_node.getPreviousSibling() : cur_node.getNextSibling ())) { // // Check that current node is of type 'element' // if (cur_node.getNodeType() != Node.ELEMENT_NODE) { continue; } // // Get element, check its name and position // Element cur_elem = (Element)cur_node; if ((name != null) && (! name.equals (cur_elem.getTagName()))) { continue; } cur_pos++; if (cur_pos == pos) { return cur_elem; } } // // If node was found, it was returned from inside loop // return null; }

Another language?

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XTech 2006

“Isomorphism” to XPath and XSLT Greenspun's Tenth Rule of Programming: “Any sufficiently complicated C or Fortran program contains an ad hoc informally- specified bug-ridden slow implementation

  • f half of Common Lisp”

My addition: the same for data transformation and XSLT.

Good library?

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XTech 2006

XSLT plus a programming language

  • XSLT extensions?
  • New XML languages?
  • Old languages?

The need

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XTech 2006

DSSSL

Scheme dialect, but not Scheme. Genealogy: XSieve XSLT Scheme DSSSL

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XTech 2006

  • Scheme
  • SXPath, SXSLT and more
  • Effective design
  • A separate sandbox

SXML library

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XSLT A general-purpose programming language SXML Integration with XSLT

What XSieve fixes

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XTech 2006

“A gestalt entity is a physical, biological, psychological, or symbolic configuration

  • r pattern of elements, so unified as

a whole that its properties cannot be derived from a simple summation of its parts” — Wikipedia

Gestalt entity

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Outline

  • XSieve vs alternatives
  • SXML format and tools
  • XSieve language
  • XSieve in practice
  • Technical details
  • Conclusion and further work
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XTech 2006

“Show me your code and conceal your data structures, and I shall continue to be mystified. Show me your data structures, and I won't usually need your code; it'll be obvious” Eric Raymond (1997), paraphrase of Frederick Brooks (1975)

SXML format

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XTech 2006

SXML format

(elem “text”) <elem>text</elem> <elem>text<sube>subtext</sube></elem> (elem “text” (sube “subtext”))

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XTech 2006

<?pi db as-table?> (*PI* db “as-table”) <!--TODO--> (*COMMENT* “TODO”) (*TOP* (... ))

SXML format

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<elem a1=”val1” a2=”val2” /> (elem (@ (a1 “val1”) (a2 “val2”))

SXML format

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x = (elem “a” (b) “c”) <elem>a<b/>c</elem> (car x) == name() (cdr x) == @* | node() (map func (query x)) ~ xsl:apply-templates

Navigation by hand

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(elem1 elem2 @ attr) elem1/elem2/@attr (elem1 (elem2 condition) @ attr) elem1/elem2[condition]/@attr Custom Scheme steps, axes, predicates

SXPath

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  • Local scoping of re-writing “templates”
  • First-class stylesheets
  • Traversal strategies
  • Ability to re-traverse the original or

transformed trees

SXSLT

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Outline

  • XSieve vs alternatives
  • SXML format and tools
  • XSieve language
  • XSieve in practice
  • Technical details
  • Conclusion and further work
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XTech 2006

<xsl:stylesheet xmlns:xsl = "http://www.w3.org/1999/XSL/Transform" xmlns:s = "http://xsieve.sourceforge.net" extension-element-prefixes="s" version = "1.0"> <xsl:template match="/"> <s:scheme> (display (x:current))(newline) </s:scheme> </xsl:template> </xsl:stylesheet>

XSieve example

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XTech 2006

<xsl:template match="/"> <s:scheme> '(article (@ (id "hw")) (title "Hello") (para "Hello, " (object "World") "!")) </s:scheme> </xsl:template> <article id="hw"> <title>Hello</title> <para>Hello, <object>World</object>!</para> </article>

XSieve example

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(x:eval xpath [basenode]) (x:apply-templates ['mode 'mode-name] ['with-param 'param1 value1 ...] ['with-param 'paramN valueN] nodeset)

More XSieve

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<items> <item price="20" qty="2"/> ... <item price="50" qty="0"/> </items> (apply + (map (lambda (node) (* (x:eval "number(@qty)" node) (x:eval "number(@price)" node))) (x:eval "//item")))

Multiple sum

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Outline

  • XSieve vs alternatives
  • SXML format and tools
  • XSieve language
  • XSieve in practice
  • Technical details
  • Conclusion and further work
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(Re)grouping

<h2>Device</h2> <p>In this section...</p> <h3>Overview</h3> ... <h3>Maintenance</h3> <p>1. ...</p> <p>2. ...</p> ...

Device Overview Maintenance

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OpenOffice hinting

<text:p text:style-name="P9">Some text</text:p> <text:p text:style-name="P9" fo:font-weight="bold" ><style-hint:name>P9</style-hint:name ><style-hint:name>Standard</style-hint:name >Some text</text:p>

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Syntax highlighting

<programlisting role="xml"> &lt;para>Hello, <emphasis>&amp;who;</emphasis >!&lt;/para> <co id="who-entity"/> </programlisting> Default: <para>Hello, &who;!</para> (1) Highlighted: <para>Hello, &who;!</para> XSieve: <para>Hello, &who;!</para> (1) http://tohtml.com/dbsy/

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Outline

  • XSieve vs alternatives
  • SXML format and tools
  • XSieve language
  • XSieve in practice
  • Technical details
  • Conclusion and further work
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The executable

  • Standard XSLT extension
  • Scheme as the language
  • xsltproc plus Guile
  • xsltproc plugin
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The main problems were

  • Uncertainty with results
  • S-expressions and XML are

different, incompatible creatures

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Other problems were

  • XML ⇔ SXML: namespaces
  • Garbage collection and memory management
  • apply-templates from “s:scheme”
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Correctness

DocBook stylesheets <xsl:apply-templates select=”xpath”/> <s:scheme> (x:apply-templates (x:eval “xpath”)) </s:scheme>

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Performance

It depends.

  • Auto-generated: slow
  • OpenOffice hinting: very fast
  • Lazy instantiation: very slow
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More implementations?

Java, .NET: problems are easier. XSieve: alternative or partner for EXSLT.

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Outline

  • XSieve vs alternatives
  • SXML format and tools
  • XSieve language
  • XSieve in practice
  • Technical details
  • Development behind XSieve
  • Conclusion and further work
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Generative XPath

  • Compilers
  • Text processors
  • Etc
  • Hard for C
  • XML virtual machine as Scheme plus SXML
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Testing XPath

Test suite vs test-by-practice (x:apply-templates (x:eval “xpath”))

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Main development

  • http://xmlhack.ru/protva/xquery/
  • Testing XML VM in C:
  • GNU find with XPath
  • libxml/libxslt
  • Testing generative XPath

by-side: XSieve

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Outline

  • XSieve vs alternatives
  • SXML format and tools
  • XSieve language
  • XSieve in practice
  • Technical details
  • Conclusion and further work
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XTech 2006

Future work

  • XSieve is frozen
  • DocBook XSieve/TeXML stylesheets
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New language

  • What does it look like?
  • Scheme and SXML in XSLT
  • What does it fix?
  • XML to programming language
  • SXML integration
  • Will I use it?
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XTech 2006

Thank you!

Oleg Parashchenko Saint-Petersburg State University, Russia

  • lpa@ http://uucode.com/blog/

http://xmlhack.ru/

Extending XSLT with the roots of XSLT

XSieve