function
Library: Xerces XML parser (OMXERCES)
Import : omxerces.xmd |
export external markup source function xml schemas value integer schema-validation-mode optional initial { auto-schema-validation } namespaces value integer namespace-processing-mode optional initial { namespace-validation } scan value string source data
Argument definitions
The xml
markup parser function uses the Xerces XML parser to generate a
stream of markup events (that is, a markup source
) that can be processed using do
markup-parse
.
The scan argument is to provide input to the parser. It can be any OmniMark source.
The xml
markup parser function invokes element and other OmniMark rules in the same manner as OmniMark's
built-in parsers. The information available in those rules differs from that provided by OmniMark's built-in
parsers in some respects, as described below.
The xml
markup parser function takes two optional arguments, schemas and namespaces, which control the W3C schema and XML namespace processing done by the xml
markup
parser function
omxerces.xmd defines named values for use with the schemas argument:
omxerces.xmd also defines named values for use with the namespaces argument:
The namespaces argument does not affect OmniMark namespace processing, which is done independently
of the namespace processing done by the xml
markup parser function. The easiest way of distinguishing
the two is to observe that the xml
markup parser function is responsible for namespace validation, and
OmniMark is responsible for making use of the namespace information.
import "omxerces.xmd" prefixed by xerces. process do markup-parse xerces.xml schemas xerces.no-schemas namespaces xerces.no-namespace-validation scan file #args[1] output "%c" done element #implied output "%c"
The following is a list of what information is available to an OmniMark program from the xml
markup
parser function. In particular, it describes both new things that the xml
markup parser function does
for OmniMark programs, and limitations as compared to using the built-in OmniMark markup parsers.
The xml
markup parser function processes and validates W3C Schemas; what is returned to the OmniMark
program is based on how the document is interpreted by any schema used. The most noticeable effect of using a
schema is in:
Schemas are read into an OmniMark program as external text entities. You can use the
external-text-entity #schema
rule to control how schemas are found and pre-processed by an
OmniMark program.
No information from a schema or from a DTD is available to the OmniMark program, even though it is used by the markup parser in interpreting the document.
Any whitespace not deemed to be significant (as defined by the XML specification) is
passed to the OmniMark program as the contents of an ignored marked section. The marked-section
ignore
rule can be used to capture ignorable white space. If there is no marked-section
ignore
rule, this whitespace is ignored.
Processing instructions in the input trigger processing-instruction
rules in the OmniMark
program, in the normal manner, with one exception: the XML declaration, which is encoded as a processing
instruction starting with <?xml
, is used by the markup parser and is not returned to the OmniMark program.
Errors and warnings from the xml
markup parser function trigger markup-error
rules in the
OmniMark program, in the same manner as for the built-in markup parsers.
The only difference is that there is just one numeric exception code for errors and one for warnings, so the numeric exception code cannot be used to distinguish between different kinds of errors.
The xml
markup parser function does not normally stop when it encounters what may be considered a
fatal error—it keeps on going. This is normally appropriate, because the xml
markup parser
function can recover from most errors. However, there are cases in which it cannot recover. In these cases
it is possible to have the same error reported multiple times.
To prevent run-away reporting of errors, the xml
markup parser function terminates if it encounters
5 fatal errors in a row, without other information intervening.
The following lists all the OmniMark markup parser rules that are of use with the xml
markup parser function