/ 
B-Hooks-OP-Annotation-0.10
River stage two • 3 direct dependents • 67 total dependents
/ B::Hooks::OP::Annotation

NAME

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

SYNOPSIS

#include "hook_op_check.h"
#include "hook_op_ppaddr.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) {
    OPAnnotation * annotation;
    MyData * mydata;

    mydata = mymodule_get_mydata(); /* metadata to be associated with this op */
    annotation = op_annotation_new(mymodule_annotations, op->op_ppaddr, mydata, mymodule_mydata_free);
    hook_op_ppaddr(op, mymodule_entersub, annotation);
}

STATIC OP * mymodule_entersub(pTHX_ OP *op, void *user_data) {
    OPAnnotation * annotation;
    MyData * mydata;
    
    mydata = (MyData *)annotation->data;

    // ...

    if (ok) {
        return NORMAL;
    } else if (mymodule_stop_hooking(op)) { /* restore the previous op_ppaddr */
        op->op_ppaddr = annotation->ppaddr;
        op_annotation_free(annotation);
        return CALL_FPTR(op->op_ppaddr)(aTHX);
    } else {
        return CALL_FPTR(annotation->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(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 and B::Hooks::OP::PPAddr.

This module makes its types and functions available to XS code by utilising 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:

my $XS_DEPENDENCIES = eval {
    require ExtUtils::Depends;
    my %hash = ExtUtils::Depends->new(
        'Your::XS::Module' => 'B::Hooks::OP::Annotation', # &c. e.g. B::Hooks::OP::Check and/or B::Hooks::OP::PPAddr
    )->get_makefile_vars();
    \%hash
} || {};

WriteMakefile(
    NAME => 'Your::XS::Module',
    # ...
    PREREQ_PM => {
        # ...
        'B::Hooks::OP::Annotation' => 0,
        'ExtUtils::Depends'        => 0,
        # ...
    },
    # ...
    %$XS_DEPENDENCIES,
);

TYPES

OPAnnotation

This struct contains three members:

  • ppaddr, the op_ppaddr function (of type "OPAnnotationPPAddr") that is being replaced

  • data, a void * containing metadata that should be associated with the current OP

  • dtor, a function type "OPAnnotationDtor" used to free the data

OPAnnotationGroup

Annotations are stored in groups. Multiple groups can be created, and each one manages all the annotations associated with it.

Annotations can be removed from the group and freed by calling "op_annotation_free", and the group and all its annotations 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 meadata associated with the OP.

typedef void (*OPAnnotationDtor)(pTHX_ void *data);

FUNCTIONS

op_annotation_group_new

This function creates a new annotation group. Annotation groups manage a collection of annotations and allow them to be freed with "op_annotation_group_free".

OPAnnotationGroup op_annotation_group_new();

op_annotation_new

This function creates a new annotation. It takes an "OPAnnotationGroup", the previous op_ppaddr function, a pointer to the metadata to be associated with the OP, and a destructor for that data. The data can be NULL and the constructor can be NULL if no cleanup is needed.

OPAnnotation * op_annotation_new(OPAnnotationGroup group, OPAnnotationPPAddr ppaddr, void *data, OPAnnotationDtor dtor);

op_annotation_free

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.

void op_annotation_free(OPAnnotation *annotation);

op_annotation_group_free

This function frees the memory allocated for the annotation group and its contents.

void op_annotation_group_free(OPAnnotationGroup group);

EXPORT

None by default.

VERSION

0.10

SEE ALSO

AUTHOR

chocolateboy <chocolate@cpan.org>

COPYRIGHT AND LICENSE

Copyright (c) 2009 chocolateboy

This module is free software.

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