B::Hooks::OP::Annotation(3pm)

NAME

B::Hooks::OP::Annotation - annotate and delegate hooked OPs

SYNOPSIS

#include "hook_op_check.h"
#include "hook_op_annotation.h"

STATIC OPAnnotationGroup MYMODULE_ANNOTATIONS;

STATIC void mymodule_mydata_free(pTHX_ void *mydata) {
    // ...
}

STATIC OP * mymodule_check_entersub(pTHX_ OP *op, void *unused) {
    MyData * mydata;

    mydata = mymodule_get_mydata(); /* metadata to be associated with this OP */
    op_annotate(MYMODULE_ANNOTATIONS, op, mydata, mymodule_mydata_free);
    op->op_ppaddr = mymodule_entersub;

    return op;
}

STATIC OP * mymodule_entersub(pTHX) {
    OPAnnotation * annotation;
    MyData * mydata;
    OP *op = PL_op;

    annotation = op_annotation_get(MYMODULE_ANNOTATIONS, op);
    mydata = (MyData *)annotation->data;

    // ...

    if (ok) {
        return NORMAL;
    } else if (mymodule_stop_hooking(op)) { /* restore the previous op_ppaddr */
        op->op_ppaddr = annotation->op_ppaddr;
        op_annotation_delete(MYMODULE_ANNOTATIONS, op);
        return CALL_FPTR(op->op_ppaddr)(aTHX);
    } else {
        return CALL_FPTR(annotation->op_ppaddr)(aTHX); /* delegate to the previous op_ppaddr */
    }
}

MODULE = mymodule PACKAGE = mymodule

BOOT:
    MYMODULE_ANNOTATIONS = op_annotation_group_new();

void
END()
    CODE:
        op_annotation_group_free(aTHX_ MYMODULE_ANNOTATIONS);

void
setup()
    CODE:
        mymodule_hook_op_entersub_id = hook_op_check(
            OP_ENTERSUB,
            mymodule_check_entersub,
            NULL
        );

void
teardown()
    CODE:
        hook_op_check_remove(OP_ENTERSUB, mymodule_hook_op_entersub_id);

DESCRIPTION

This module provides a way for XS code that hijacks OP "op_ppaddr"
functions to delegate to (or restore) the previous functions, whether
assigned by perl or by another module. Typically this should be used in conjunction with B::Hooks::OP::Check.

"B::Hooks::OP::Annotation" makes its types and functions available to XS code by means of ExtUtils::Depends. Modules that wish to use these exports in their XS code should "use B::OP::Hooks::Annotation" in the Perl module that loads the XS, and include something like the following in their Makefile.PL:: use ExtUtils::MakeMaker;
use ExtUtils::Depends;; our %XS_PREREQUISITES = (
'B::Hooks::OP::Annotation' => '0.43',
'B::Hooks::OP::Check' => '0.15',; );; our %XS_DEPENDENCIES = ExtUtils::Depends->new(
'Your::XS::Module',
keys(%XS_PREREQUISITES)

)->get_makefile_vars();

WriteMakefile(

NAME => 'Your::XS::Module',
VERSION_FROM => 'lib/Your/XS/Module.pm',
PREREQ_PM => {
'B::Hooks::EndOfScope' => '0.07',
%XS_PREREQUISITES

},
($ExtUtils::MakeMaker::VERSION >= 6.46 ?

(META_MERGE => {
configure_requires => {
'ExtUtils::Depends' => '0.301',
%XS_PREREQUISITES

}})

: ()

),
%XS_DEPENDENCIES,
# ...

);
TYPES: OPAnnotation; This struct contains the metadata associated with a particular OP i.e. the data itself, a destructor for that data, and the "op_ppaddr"
function that was defined when the annotation was created by
"op_annotate" or "op_annotation_new".; o "op_ppaddr", the OP's previous "op_ppaddr" function (of type
"OPAnnotationPPAddr"); o "data", a "void *" to metadata that should be associated with the
OP; o "dtor", a function (of type "OPAnnotationDtor") used to free the
metadata; The fields are all read/write and can be modified after the annotation has been created.; OPAnnotationGroup; Annotations are stored in groups. Multiple groups can be created, and
each one manages all of the annotations associated with it.; Annotations can be removed from the group and freed by calling
"op_annotation_delete", and the group and all its members can be
destroyed by calling "op_annotation_group_free".; OPAnnotationPPAddr; This typedef corresponds to the type of perl's "op_ppaddr" functions
i.e.

typedef OP *(*OPAnnotationPPAddr)(pTHX);; OPAnnotationDtor; This is the typedef for the destructor used to free the metadata
associated with the OP.

typedef void (*OPAnnotationDtor)(pTHX_ void *data);
FUNCTIONS: op_annotation_new; This function creates and returns a new OP annotation.; It takes an "OPAnnotationGroup", an OP, a pointer to the metadata to be associated with the OP, and a destructor for that data. The data can be NULL and the destructor can be NULL if no cleanup is required.; If an annotation has already been assigned for the OP, then it is
replaced by the new annotation, and the old annotation is freed,
triggering the destruction of its data (if supplied) by its destructor (if supplied).

OPAnnotation * op_annotation_new(
OPAnnotationGroup group,
OP *op,
void *data,
OPAnnotationDtor dtor

);; op_annotate; This function is a void version of "op_annotation_new" for cases where the new annotation is not needed.

void op_annotate(
OPAnnotationGroup group,
OP *op,
void *data,
OPAnnotationDtor dtor

);; op_annotation_get; This retrieves the annotation associated with the supplied OP. If an
annotation has not been assigned for the OP, it raises a fatal
exception.

OPAnnotation * op_annotation_get(OPAnnotationGroup group, OP *op);; op_annotation_delete; This removes the specified annotation from the group and frees its
memory. If a destructor was supplied, it is called on the value in the "data" field (if supplied).

void op_annotation_delete(pTHX_ OPAnnotationGroup group, OP *op);; op_annotation_group_new; This function creates a new annotation group.

OPAnnotationGroup op_annotation_group_new(void);; op_annotation_group_free; This function destroys the annotations in an annotation group and frees the memory allocated for the group.

void op_annotation_group_free(pTHX_ OPAnnotationGroup group);

EXPORT

None by default.

VERSION

0.43

AUTHOR

chocolateboy <chocolate@cpan.org>

COPYRIGHT AND LICENSE

This module is free software.

You may distribute this code under the same terms as Perl itself.

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