NAME
EntryHandler -- Add an entry handler to the iffhandle context.
SYNOPSIS
error = EntryHandler (iff, type, id, position, hook, object)
d0 a0 d0 d1 d2 a1 a2
LONG error;
struct iffhandle *iff;
LONG type, id, position;
struct hook *hook;
APTR object;
FUNCTION
Installs an entry handler vector for a specific type of chunk into
the context for the given iffhandle struct. type and id are the
longword identifiers for the chunk to handle. The hook is a client-
supplied standard 2.0 hook structure, properly initialized. position
tells where to put the handler in the context. The handler will be
called whenever the parser enters a chunk of the given type, so the
IFF stream will be positioned to read the first data byte in the
chunk. The handler will execute in the same context as whoever
called parseiff(). the handler will be called (through the hook)
with the following arguments:
A0: the hook pointer you passed.
A2: the 'object' pointer you passed.
A1: pointer to a LONG containing the value
IFFCMD_ENTRY.
The error code your call-back routine returns will affect the parser
in three different ways:
Return value Result
------------ ------
0: Normal success; parseiff() will continue
through the file.
IFF_RETURN2CLIENT: parseiff() will stop and return the value 0.
(StopChunk() is internally implemented using
this return value.)
Any other value: parseiff() will stop and return the value
you supplied. This is how errors should be
returned.
INPUTS
iff - pointer to iffhandle struct.
type - type code for chunk to handle (ex. "ILBM").
id - ID code for chunk to handle (ex. "CMAP").
position- Local context item position. One of the IFFSLI_#? codes.
hook - pointer to hook structure.
object - a client-defined pointer which is passed in A2 during call-
back.
RESULT
error - 0 if successful or an IFFERR_#? error code if not
successful.
EXAMPLE
NOTES
BUGS
Returning the values IFFERR_EOF or IFFERR_EOC from the call-back
routine *may* confuse the parser.
There is no way to explicitly remove a handler once installed.
However, by installing a do-nothing handler using IFFSLI_TOP,
previous handlers will be overridden until the context expires.
SEE ALSO
exithandler(), storelocalitem(), storeitemincontext(),
utility/hooks.h