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The generic API to OpenSP
The generic API to OpenSP
OpenSP provides a generic API in addition to its native API. The generic
interface is much simpler than the native interface. It is generic in
the sense that it could be easily implemented using parsers other than
OpenSP. It provides all ESIS information as well as some other
information about the instance that is commonly needed by
applications. However, it doesn't provide access to all information
available from OpenSP; in particular, it doesn't provide information about
the DTD. It is also slightly less efficient than the native
interface.
The interface uses two related abstract classes. An
SGMLApplication is an object that can handle a number of
different kinds of event which correspond to information in an SGML
document. An EventGenerator is an object that can
generate a sequence of events of the kinds handled by an
SGMLApplication. The
ParserEventGeneratorKit class makes an
EventGenerator that generates events using OpenSP.
Types
SGMLApplication has a number of local types that are used
in several contexts:
-
Char
-
This typedef is an unsigned integral type that represents a single bit
combination (character). It is
unsigned short if
SP_MULTI_BYTE is defined and unsigned char
otherwise.
-
CharString
-
This struct represents a string of
Char.
It has the following members:
-
const Char *ptr
-
A pointer to the
Chars of the string.
-
size_t len
-
The number of
Chars in the string.
-
Location
-
This struct holds information about a location in the entity structure
of a document. It is constucted using an
OpenEntityPtr
and a Position. The CharStrings in it will
remain valid as long as the OpenEntity that is pointed to
by the OpenEntityPtr that was used to construct it
remains valid.
It has the following members:
-
unsigned long lineNumber
-
The line number.
(unsigned long)-1 if invalid.
-
unsigned long columnNumber
-
The column number.
Note that tabs are not treated specially.
(unsigned long)-1 if invalid.
-
unsigned long byteOffset
-
The number of bytes in the storage object preceding the location.
(unsigned long)-1 if invalid.
-
unsigned long entityOffset
-
The number of bit combinations in the entity preceding the location.
(unsigned long)-1 if invalid.
-
CharString entityName
-
The name of the external entity containing the location.
An empty string if invalid.
-
CharString filename
-
The name of the file containing the location.
An empty string if invalid.
-
const void *other
-
Other implementation-dependent information about the location. In the
OpenSP implementation it will be a pointer to a StorageObjectSpec. 0 if
invalid.
When a location is in an internal entity, the location of the reference
to the entity will be used instead.
-
OpenEntity
-
This class represents a currently open entity. The only use for an
OpenEntity is, in conjunction with a
Position, to create a Location. An
OpenEntity is accessed using an
OpenEntityPtr.
-
OpenEntityPtr
-
This class is a reference-counted pointer to an
OpenEntity.
-
Position
-
This is an integral type that represents a position in an open entity.
The meaning of a
Position is completely determined by the
OpenEntity object with which it is associated. The only
use for an Position is, in conjunction with an
OpenEntity, to create a Location.
-
ExternalId
-
This struct represents an external identifier. It has the following
members:
-
bool haveSystemId
-
True iff the external identifier included an explicit system identifier.
-
CharString systemId
-
The system identifier included in the external identifier.
Valid only if
havePublicId is true.
-
bool havePublicId
-
True iff the external identifier included an explicit public identifier.
-
CharString publicId
-
The public identifier included in the external identifier.
Valid only if
havePublicId is true.
-
bool haveGeneratedSystemId
-
True iff a system identifier was generated for the external identifier.
-
-
CharString generatedSystemId
-
The system identifier generated for the external identifier.
Valid only if
haveGeneratedSystemId is true.
-
Notation
-
This struct represents a notation.
It has the following members:
-
CharString name
-
The name of the notation.
-
ExternalId externalId
-
The external identifier of the notation.
-
Entity
-
This struct represents an entity.
It has the following members.
-
CharString name
-
The name of the entity.
-
Entity::DataType dataType
-
The type of the data of the entity.
Entity::DataType is a local enum with the following possible
values:
-
Entity::sgml
-
-
Entity::cdata
-
-
Entity::sdata
-
-
Entity::ndata
-
-
Entity::subdoc
-
-
Entity::pi
-
-
Entity::DeclType declType
-
The type of the declaration of the entity.
Entity::DeclType is a local enum with the following possible
values:
-
Entity::general
-
The entity is a general entity.
-
Entity::parameter
-
The entity is a parameter entity.
-
Entity::doctype
-
The entity was declared in a doctype declaration.
-
Entity::linktype
-
The entity was declared in a linktype declaration.
-
bool isInternal
-
True iff the entity is internal rather than external.
-
CharString text
-
The replacement text of the entity.
Valid only if
isInternal is true.
-
ExternalId externalId
-
The external identifier of the entity.
Valid only if
isInternal is false.
-
const Attribute *attributes
-
Pointer to the data attributes of the entity.
Valid only if
isInternal is false.
-
size_t nAttributes
-
The number of data attributes of the entity.
Valid only if
isInternal is false.
-
Notation notation
-
The entity's notation.
An empty string if the entity has no notation.
Valid only if
isInternal is false.
-
Attribute
-
This struct represents an attribute. More precisely it represents the
assignment of an attribute value to an attribute name.
It has the following members:
-
CharString name
-
The attribute name.
-
Attribute::Type type
-
An enumeration describing the type of the attribute.
Attribute::Type is a local type with the following possible
values:
Attribute::invalid
-
The attribute is invalid.
Attribute::implied
-
The attribute is an impliable attribute for which
no value was specified.
Attribute::cdata
-
The attribute is a CDATA attribute.
Attribute::tokenized
-
The attribute is a tokenized attribute.
-
Attribute::Defaulted defaulted
-
An enumeration specifying whether the entity was defaulted, and, if
so, how.
This is non-ESIS information.
Attribute::Defaulted is a local enum with the following
possible values:
-
Attribute::specified
-
The value was explicitly specified.
-
Attribute::definition
-
The value was defaulted from the attribute definition.
-
Attribute::current
-
The value was defaulted using the CURRENT value of the attribute.
-
size_t nCdataChunks
-
The number of
Attribute::CdataChunks comprising the value
of the attribute. Valid only if type is
cdata.
-
const Attribute::CdataChunk *cdataChunks
-
The
Attribute::CdataChunks comprising the value of this attribute.
Valid only if type is cdata.
Attribute::CdataChunk is a local struct with the
following members:
-
bool isSdata
-
True iff this chunk is the replacement text of an internal SDATA entity.
-
CharString data
-
The data of this chunk.
-
CharString entityName
-
The name of the internal SDATA entity that this chunk is the
replacement text of. Valid only if
isSdata is true.
This is non-ESIS information.
-
CharString tokens
-
Valid only if
type is Attribute::tokenized.
-
bool isId
-
True iff the declared value is ID.
This is non-ESIS information.
-
size_t nEntities
-
The number of entities associated with this attribute.
This will be zero unless the declared value is ENTITY or ENTITIES.
-
const Entity *entities
-
The entities associated with this attribute.
-
Notation notation
-
The notation associated with this attribute.
If the declared value of the attribute is not NOTATION,
then the name member will be an empty string.
Events
For each event xyzEvent handled by
SGMLApplication, there is a virtual function of
SGMLApplication named xyz to
handle the event, and a local struct of SGMLApplication
named XyzEvent.
Pointers within an event xyzEvent are valid
only during the call to xyz. None of the
structs in events have copy constructors or assignment operators
defined. It is up to the event handling function to make a copy of
any data that it needs to preserve after the function returns.
Except as otherwise stated,
the information in events is ESIS information.
All position information is non-ESIS information.
There are the following types of event:
-
AppinfoEvent
-
Generated for the APPINFO section of the SGML declaration.
The event has the following members:
Position pos
-
The position of APPINFO parameter of the SGML declaration.
bool none
-
True iff APPINFO NONE was specified.
CharString string
-
The interpreted value of the minimum literal specified
in the appinfo parameter of the SGML declaration.
Valid only if
none is false.
-
PiEvent
-
Generated for a processing instruction.
The event has the following members:
-
Position pos
-
The position of the processing instruction.
-
CharString data
-
The system data of the processing instuction.
-
CharString entityName
-
If the processing instruction was the result of the
reference to a PI entity, the name of the entity.
If not, an empty string.
This is non-ESIS information.
-
StartElementEvent
-
Generated for the start of an element.
The event has the following members:
-
Position pos
-
The position of the start of the element.
-
CharString gi
-
The generic identifier of the element.
-
Element::ContentType contentType
-
The type of the element's content.
This is non-ESIS information.
Element::ContentType is an enum with the following
possible values:
-
Element::empty
-
The element has empty content, either because it was
declared as EMPTY or because there was a #CONREF attribute.
-
Element::cdata
-
The element has CDATA content.
-
Element::rcdata
-
The element has RCDATA content.
-
Element::mixed
-
The element has mixed content.
-
Element::element
-
The element has element content.
-
bool included
-
True iff the element was an included subelement
(rather than a proper subelement).
This is non-ESIS information.
-
size_t nAttributes
-
The number of attributes of this element.
-
const Attribute *attributes
-
A pointer to the attributes for this element.
-
EndElementEvent
-
Generated for the end of an elemenet.
The event has the following members:
-
Position pos
-
The position of the end of the element.
-
CharString gi
-
The generic identifier of the element.
-
DataEvent
-
Generated for character data.
Separate data events may be generated for consecutive data characters.
Applications should make no assumptions about how character data is split
into
DataEvents.
The event has the following members:
-
Position pos
-
The position of the first character of the data.
-
CharString data
-
The data.
-
SdataEvent
-
Generated for a reference to an internal sdata entity in content.
The event has the following members:
-
Position pos
-
The position of the entity reference.
-
CharString text
-
The replacement text of the entity.
-
CharString entityName
-
The entity name.
This is non-ESIS information.
-
ExternalDataEntityRefEvent
-
Generated for a reference to an external data entity.
The event has the following members:
-
Position pos
-
The position of the entity reference.
-
Entity entity
-
The referenced entity.
-
SubdocEntityRefEvent
-
Generated for a reference to a subdoc entity.
The event has the following members:
-
Position pos
-
The position of the entity reference.
-
Entity entity
-
The referenced entity.
-
StartDtdEvent
-
Generated at the start of a document type declaration.
This is non-ESIS information.
The event has the following members:
-
Position pos
-
The position of the start of the document type declaration.
-
CharString name
-
The document type name.
-
bool haveExternalId
-
The external identifier for the entity declared in the document type
declaration.
-
ExternalId externalId
-
Valid iff haveExternalId is true.
-
EndDtdEvent
-
Generated at the end of a document type declaration.
This is non-ESIS information.
The event has the following members:
-
Position pos
-
The position of the end of the DTD.
-
CharString name
-
-
EndPrologEvent
-
Generated at the end of the prolog.
The event has the following members:
-
Position pos
-
The position of the start of the instance.
-
GeneralEntityEvent
-
Generated for each general entity in the name space of the governing
doctype, but only if the
ParserEventGeneratorKit::outputGeneralEntities option is
enabled. This is non-ESIS information. The event has the following
members:
-
Entity entity
-
The entity.
No event will be generated for the declaration of the
#default entity; instead an event will be generated when
an entity reference uses the #default entity if that is
the first time on which an entity with that name is used. This means
that GeneralEntityEvent can occur after the end of the
prolog.
-
CommentDeclEvent
-
Generated for each comment declaration in the instance, but only if
ParserEventGeneratorKit::outputCommentDecls option is
enabled. This is non-ESIS information. The event has the following
members:
-
Position pos
-
The position of the start of the comment declaration.
-
size_t nComments
-
The number of comments in the comment declaration.
-
const CharString *comments
-
The content of each comment in the declaration.
This excludes the com delimiters.
-
const CharString *seps
-
The separator following each comment in the declaration.
-
MarkedSectionStartEvent
-
Generated for the start of a marked section in the instance,
but only if the
ParserEventGeneratorKit::outputMarkedSections
option is enabled.
This is non-ESIS information.
The event has the following members:
-
Position pos
-
The position of the start of the marked section declaration.
-
MarkedSectionStartEvent::Status status
-
The effective status of the marked section.
MarkedSectionStartEvent::Status is a local enum with the
following possible values:
MarkedSectionStartEvent::include
MarkedSectionStartEvent::rcdata
MarkedSectionStartEvent::cdata
MarkedSectionStartEvent::ignore
-
size_t nParams
-
The number of top-level parameters in the status keyword specification.
-
const MarkedSectionStartEvent::Param *params
-
The top-level parameters in the status keyword specification.
Param is a local struct with the following members:
-
MarkedSectionStartEvent::Param::Type type
-
The type of top-level parameter:
MarkedSectionStartEvent::Param::Type is a local enum with the
following possible values:
-
MarkedSectionStartEvent::Param::temp
-
MarkedSectionStartEvent::Param::include
-
MarkedSectionStartEvent::Param::rcdata
-
MarkedSectionStartEvent::Param::cdata
-
MarkedSectionStartEvent::Param::ignore
-
The parameter is the corresponding keyword.
-
MarkedSectionStartEvent::Param::entityRef
-
The parameter is an entity reference.
-
CharString entityName
-
Valid when
type is
MarkedSectionStartEvent::Param::entityRef.
-
MarkedSectionEndEvent
-
Generated for the end of a marked section in the instance, but only if
the
ParserEventGeneratorKit::outputMarkedSections option is
enabled. This is non-ESIS information. The event has the following
members:
-
Position pos
-
The position of the end of the marked section declaration.
-
MarkedSectionEndEvent::Status status
-
The effective status of the marked section.
MarkedSectionEndEvent::Status is a local enum with the
following possible values:
MarkedSectionEndEvent::include
MarkedSectionEndEvent::rcdata
MarkedSectionEndEvent::cdata
MarkedSectionEndEvent::ignore
-
IgnoredCharsEvent
-
Generated for a sequence of characters in an ignored marked section in
the instance, but only if the
ParserEventGeneratorKit::outputMarkedSections option is
enabled. This is non-ESIS information. The event has the following
members:
-
Position pos
-
The position of the first of the ignored characters.
-
CharString data
-
The ignored characters.
-
ErrorEvent
-
Generated for each error detected by the parser,
and also for any other cases where the parser produces a message.
This is non-ESIS information.
It has the following members:
-
Position pos
-
The position at which the error was detected.
-
ErrorEvent::Type type
-
The type of error.
ErrorEvent::Type is a local enum with the following possible
values:
-
ErrorEvent::quantity
-
Exceeding a quantity limit.
-
ErrorEvent::idref
-
An IDREF to a non-existent ID.
-
ErrorEvent::capacity
-
Exceeding a capacity limit.
-
ErrorEvent::otherError
-
Any other kind of error.
-
ErrorEvent::warning
-
A warning. Not actually an error.
-
ErrorEvent::info
-
An informational message. Not actually an error.
-
CharString message
-
The message produced by the parser.
If messages are not disabled, this will be the same as the message
printed to standard error.
SGMLApplication also has a virtual function
void openEntityChange(const OpenEntityPtr &);
which is similar to an event. An application that wishes to makes use
of position information must maintain a variable of type
OpenEntityPtr representing the current open entity, and
must provide an implementation of the openEntityChange
function that updates this variable. It can then use the value of
this variable in conjunction with a Position to obtain a
Location; this can be relatively slow. Unlike events, an
OpenEntityPtr has copy constructors and assignment
operators defined.
EventGenerator
The EventGenerator interface provides the following
functions:
-
unsigned run(SGMLApplication &app)
-
Generate the sequence of events, calling the corresponding member of
app for each event. Returns the number of
errors. This must not be called more than once for any
EventGeneratorobject.
-
EventGenerator *makeSubdocEventGenerator(const SGMLApplication::Char *s, size_t n)
-
Makes a new
EventGenerator for a subdocument of the
current document. s and n together specify the
system identifier of the subdocument entity. These should usually be
obtained from the generatedSystemId member of the
externalId member of the Entity object for
the subdocument entity. This function can only be called after
run has been called; the call to run need
not have returned, but the SGMLApplication
must have been passed events from the prolog or instance (ie the SGML
declaration must have been parsed).
-
void inhibitMessages(bool b)
-
If b is true, disables error and warning messages,
otherwise enables them. Initially errors and warnings are enabled.
This function may be called at any time, including while
run() is executing.
-
void halt()
-
Halt the generation of events by
run().
This can be at any point during the execution of run().
It is safe to call this function from a different thread from that which
called run().
ParserEventGeneratorKit
The ParserEventGeneratorKit class is used to create an
EventGenerator that generate events using OpenSP. It
provides the following members:
-
EventGenerator *makeEventGenerator(int nFiles, char *const *files)
-
This returns a new
EventGenerator that will generate events
for the SGML document whose document entity is contained in the
files.
The returned EventGenerator should be deleted when it
is no longer needed.
makeEventGenerator may be called more than once.
-
void setOption(ParserEventGeneratorKit::Option opt)
-
This can be called any time before
makeEventGenerator() is called.
ParserEventGeneratorKit::Option is a local enum with the following possible
values:
-
ParserEventGeneratorKit::showOpenEntities
-
This corresponds to the
-e option of nsgmls.
-
ParserEventGeneratorKit::showOpenElements
-
This corresponds to the
-g option of nsgmls.
-
ParserEventGeneratorKit::outputCommentDecls
-
This will cause
CommentDeclEvents to be generated.
-
ParserEventGeneratorKit::outputMarkedSections
-
This will cause
MarkedSectionStartEvents,
MarkedSectionStartEvents
and IgnoredCharsEvents
to be generated.
-
ParserEventGeneratorKit::outputGeneralEntities
-
This will cause
GeneralEntityEvents to be generated.
-
ParserEventGeneratorKit::showErrorNumbers
-
This corresponds to the
-n option of nsgmls.
-
void setOption(ParserEventGeneratorKit::OptionWithArg opt, const char *arg)
-
This can be called any time before
makeEventGenerator() is called.
ParserEventGeneratorKit::OptionWithArg is a local enum with the following possible
values:
-
ParserEventGeneratorKit::addCatalog
-
This corresponds to the
-m option of nsgmls.
-
ParserEventGeneratorKit::includeParam
-
This corresponds to the
-i option of nsgmls.
-
ParserEventGeneratorKit::enableWarning
-
This corresponds to the
-w option of nsgmls.
-
ParserEventGeneratorKit::addSearchDir
-
This corresponds to the
-D option of nsgmls.
Using the interface
Creating an application with this interface involves the following steps:
-
Derive a class from
SGMLApplication,
called, say, MyApplication.
-
For each kind of event
FooEvent that the application
needs information from, define a member of MyApplication
void MyApplication::foo(const FooEvent &).
-
Declare an object of type
ParserEventGeneratorKit.
-
Optionally set options for the
ParserEventGeneratorKit using
ParserEventGeneratorKit::setOption.
-
Create an
EventGenerator using
ParserEventGeneratorKit::makeEventGenerator.
-
Create an instance of
MyApplication
(usually on the stack).
-
Call
EventGenerator::run passing it a reference to
the instance of MyApplication.
-
Delete the
EventGenerator.
The application must include the ParserEventGeneratorKit.h
file (which in turn includes EventGenerator.h and
SGMLApplication.h), which is in the generic
directory. If your compiler does not support the standard C++
bool type, you must ensure that bool is
defined as a typedef for int, before including this. One
way to do this is to include config.h and then
Boolean.h from the lib subdirectory of the OpenSP
distribution.
On Unix, the application must be linked with the
lib/libsp.a library.
Example
Here's a simple example of an application that uses this interface.
The application prints an outline of the element structure of a
document, using indentation to represent nesting.
// The next two lines are only to ensure bool gets defined appropriately.
#include "config.h"
#include "Boolean.h"
#include "ParserEventGeneratorKit.h"
#include <iostream.h>
ostream &operator<<(ostream &os, SGMLApplication::CharString s)
{
for (size_t i = 0; i < s.len; i++)
os << char(s.ptr[i]);
return os;
}
class OutlineApplication : public SGMLApplication {
public:
OutlineApplication() : depth_(0) { }
void startElement(const StartElementEvent &event) {
for (unsigned i = 0; i < depth_; i++)
cout << " ";
cout << event.gi << '\n';
depth_++;
}
void endElement(const EndElementEvent &) { depth_--; }
private:
unsigned depth_;
};
int main(int argc, char **argv)
{
ParserEventGeneratorKit parserKit;
// Use all the arguments after argv[0] as filenames.
EventGenerator *egp = parserKit.makeEventGenerator(argc - 1, argv + 1);
OutlineApplication app;
unsigned nErrors = egp->run(app);
delete egp;
return nErrors > 0;
}
This example will only work for the non-multibyte version of OpenSP;
for the multibyte version you will need to use the standard C++ library's
facilities for wide character output, or roll your own equivalents
(like the OutputCharStream used by OpenSP applications).
There's a bigger example in the osgmlnorm directory in the OpenSP
distribution.
This uses the SGMLApplication interface, but it doesn't
use the ParserEventGeneratorKit interface.
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