[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Formulas in XML values
A simple XSLT implementation is to use the LR-parsing framework of FXSL (func-LRparse.xsl) and produce a function, which acts as a simple arithmetic interpreter. In fact, this has already been done and used as the first and simplest application of this framework: http://fxsl.cvs.sourceforge.net/viewvc/fxsl/fxsl-xslt2/Tests/TestFunc-lrParse.xsl?revision=1.3&view=markup and this interpreter, including the lexer and the regex token definitions is just 220 lines of code. -- Cheers, Dimitre Novatchev --------------------------------------- Truly great madness cannot be achieved without significant intelligence. --------------------------------------- To invent, you need a good imagination and a pile of junk ------------------------------------- Never fight an inanimate object ------------------------------------- You've achieved success in your field when you don't know whether what you're doing is work or play On Thu, Jun 25, 2009 at 10:35 AM, COUTHURES Alain<alain.couthures@agencexml.com> wrote: > Formulas in XML values are a persistent concern for me for some days and > xml-dev appears to be the best place to discuss this... > > From mathematical point of view, 35+7 and 42 are equals but human beings can > interpret them differently. When a value has to be put in a field by an > user, sometimes it's, in fact, the result of a basic computation and, when > someone else has to verify the field value, the initial formula might help > to understand. Excel users do that every day ! > > XML is a text notation so it's not disturbing to write 35+7 where 42 can be. > But, schema languages should evaluate values before testing if they are > valid or not. XPath should, at least, do the same or, better, be able to say > that 15+6 multiplied by 2 is (15+6)*2. Students calculators can do that > already, don't they ? > > There are interesting possibilities with such a notation improvement : > numbers such as 1/3, pi, sqrt(2) would be written as what they are and not > just in a limited amount of digits. Of course, a bunch of mathematical > functions and constants should be named... > > I will probably implement some basic approach for this in my XForms > implementation (XSLTForms : http://www.agencexml.com/xsltforms) because I > already need it for setting values in XBRL documents. > > XSLTForms has its own XPath implementation and XML Schema validation, both > written in Javascript, and some eval() calls at the right place might be all > what is needed. Formulas will then be submitted and stored as ordinary > values would be. If needed, I will design an XSLT stylesheet to resolve > formulas into values (XSLTForms already has an XPath 1.0 expression parser > written in XSLT 1.0 ...). > > Thank you for your remarks and suggestions. > > Best regards, > > Alain Couthures > <agenceXML> > http://www.agencexml.com > Bordeaux, France > Twitter account: AlainCouthures > > _______________________________________________________________________ > > XML-DEV is a publicly archived, unmoderated list hosted by OASIS > to support XML implementation and development. To minimize > spam in the archives, you must subscribe before posting. > > [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ > Or unsubscribe: xml-dev-unsubscribe@lists.xml.org > subscribe: xml-dev-subscribe@lists.xml.org > List archive: http://lists.xml.org/archives/xml-dev/ > List Guidelines: http://www.oasis-open.org/maillists/guidelines.php > >
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