tnc(n) tnc(n)

NAME
       tnc  -  tnc is an expat parser object extension, that validates the XML
       stream against the document DTD while parsing.

SYNOPSIS
       package require tdom
       package require tnc

       set parser [expat]

       tnc $parser enable


DESCRIPTION
       tnc adds the C handler set "tnc" to a tcl expat parser obj.  This  han-
       dler  set is a simple DTD validator. If the validator detects a valida-
       tion error, it sets the interp result, signals error and stops parsing.
       There  isn't  any  validation  error recovering. As a consequence, only
       valid documents are completely parsed.

       This handler set has only three methods:

       ttnncc parserObj eennaabbllee


              Adds the tnc C handler set to a Tcl expat parser object.

       ttnncc parserObj rreemmoovvee


              Removes the tnc validatore from the parser parserObj  and  frees
              all information, stored by it.

       ttnncc parserObj ggeettVVaalliiddaatteeCCmmdd ??vvaalliiddaatteeCCmmddNNaammee??


              Returns  a  new  created validation command, if one is avaliable
              from the parser command, otherwise it signals error. The name of
              the  validation command is the validateCmdName, if this optional
              argument was given, or a random choosen name. A validation  com-
              mand  is  avaliable  in a parser command, if the parser with tnc
              enabled was previously used, to parse an  XML  document  with  a
              valid  doctype  declaration, a valid external subset, if one was
              given by the doctype declaration, and a valid  internal  subset.
              The further document doesn't need to be valid, to make the vali-
              dation command avaliable. The validation command  can  only  get
              received  one  time from the parser command. The created valida-
              tion command has this syntax:



                     vvaalliiddaattiioonnCCmmdd method ?args?

              The valid methods are:

              vvaalliiddaatteeDDooccuummeenntt domDocument ?varName?
                     Checks, if the given domDocument is valid against the DTD
                     information   represented   by  the  validation  command.
                     Returns 1, if the document ist valid, 0 otherwise. If the
                     varName  argument is given, then the variable it names is
                     set to the detected reason for the validation error or to
                     the empty string in case of a valid document.

              vvaalliiddaatteeTTrreeee elementNode ?varName?
                     Checks, if the given subtree with domNode as root element
                     is a posible valid subtree of a  document  conforming  to
                     the  DTD  information  represented by teh validation com-
                     mand. IDREF could not checked, while  validating  only  a
                     subtree, but it is checked, that every known ID attribute
                     in the subtree is unique. Returns 1, if  the  subtree  is
                     OK,  0  otherwise. If the varName argument is given, then
                     the variable it names is set to the detected  reason  for
                     the  validation error or to the empty string in case of a
                     valid subtree.

              vvaalliiddaatteeAAttttrriibbuutteess elementNode ?varName?
                     Checks, if there is an element declaration for  the  name
                     of  the elementNode in the DTD represented by the valida-
                     tion command and, if yes, if the attributes of  the  ele-
                     mentNode are conform to the ATTLIST declarations for that
                     element in the DTD. Returns  1,  if  the  attributes  and
                     there  value  types  are  OK, 0 otherwise. If the varName
                     argument is given, then the variable it names is  set  to
                     the  detected  reason  for the validation error or to the
                     empty string in case the element  has  all  its  required
                     attributes,  only  declared  attributes and the values of
                     the attributes matches there type.

              ddeelleettee Deletes the validation command and frees the memory  used
                     by it. Returns the empty string.

BUGS
       The  validation  error reports could be much more informative and user-
       friendly.

       The validator doesn't detect ambiguous content models (see XML recomen-
       dation  Section  3.2.1  and  Appendix  E).  Most  Java  validators also
       doesn't, but handle such content models right anyhow. Tnc does not;  if
       your  DTD  has such ambiguous content models, tnc can not used to vali-
       date documents against such (not completely XML spec compliant) DTDs.

       It isn't possible to validate XML documents  with  standalone="yes"  in
       the XML Declaration

       Violations  of  the  validity  constraints  Proper Group/PE Nesting and
       Proper Conditional Section/PE Nesting are not detected. They could only
       happen inside a invalid DTD, not in the content of a document.

KKEEYYWWOORRDDSS
       Validation, DTD



Tcl                                                                     tnc(n)