Event driven programming in PHP - Writing a PHP Extension (C++)





Download the source code for the PHP extension

Extending PHP - adding events

If we REALLY REALLY like this functionality, we can always write a PHP extension like demonstrated below - making it part of our PHP "distro".

Essentially this is a C++ representation of the php event class I wrote, but hooks into PHP 5 at source code level.

You will need the PHP 5 sources, and set the paths accordingly in order to compile the code, I wrote this using Visual C++.net 2005, sooo if you're compiling for Linux a little bit of work needs to be done.

I had a lot of fun writing this code, its the first PHP extension I've written, if anyone knows where to get some documentation on the subject, let me know. 

 
#include "stdafx.h"
#include <cstdlib>
 
zend_class_entry *event_entry;
zend_class_entry *callback_entry;
 
PHP_FUNCTION(Constructor)
{	
    zval *objvar = getThis();	
    zval *arr;
    MAKE_STD_ZVAL(arr);
    array_init(arr);
    add_property_zval(objvar, "list", arr);
}
 

I initially wanted to call this methods Count (since it returns the number of methods attached to a given event), but it seems to be some kind of internal method or something? Since it caused apache to crash every time I called it, so I renamed it to Subscriptions, which works fine. 

 
PHP_FUNCTION(_Subscriptions)
{
    zval **tmp;
    HashTable *prop = Z_OBJPROP_P(getThis());
 
    if (zend_hash_find(prop, "list", sizeof("list"), (void**)&tmp) == SUCCESS && Z_TYPE_PP(tmp) != IS_NULL) 
    {
        RETURN_LONG(zend_hash_num_elements(Z_ARRVAL_P(*tmp)));
    }
}
 

The method used for subscribing to an event, allows one (function name in global context) or two (current class instance, and method name) parameters to be passed to it. Which we add to an array of objects in our class. 

 
PHP_FUNCTION(_Subscribe)
{
    zval *list, **tmp, *callback, *object;
    zval *objvar = getThis();
    char *method;
    int method_len;
    HashTable *prop = Z_OBJPROP_P(getThis());
 
    if (zend_hash_find(prop, "list", sizeof("list"), (void**)&tmp) == SUCCESS && Z_TYPE_PP(tmp) != IS_NULL) 
    {
        list = *tmp;
    }
 
    if (ZEND_NUM_ARGS() == 1)
    {
        if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &method, &method_len) == FAILURE)
        {
            return;
        }
        else
        {
            add_next_index_string(list, method, 1);
        }
    }
    else if (ZEND_NUM_ARGS() == 2)
    {
        if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "zs", &object, &method, &method_len) == FAILURE)
        {
            return;
        }
        else
        {
            MAKE_STD_ZVAL(callback);
            object_init_ex(callback, callback_entry);
            add_property_zval(callback,"context", object);
            add_property_string(callback,"method", method, 1);
            add_next_index_zval(list, callback);	
        }
    }
    else
    {
        zend_error(E_WARNING, "Incorrect parameters added");
        return;			
    }
}
 

The unsubscribe method, just like the subscribe method we are allowed to pass one or two parameters (function name, or current class and method name) - removing the object from the array of subscribed events. 

 
PHP_FUNCTION(_Unsubscribe)
{
    zval **tmp, **attr, *object;
    char *method;
    int method_len;
    HashTable* prop = Z_OBJPROP_P(getThis());
    HashPosition pos;	
 
    if (ZEND_NUM_ARGS() == 1)
    {
        if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &method, &method_len) == FAILURE)
        {
            return;
        }
        else
        {
            MAKE_STD_ZVAL(object);			
            ZVAL_NULL(object);
        }
    }
    else if (ZEND_NUM_ARGS() == 2)
    {
        if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "zs", &object, &method, &method_len) == FAILURE)
        {
            return;
        }
    }
    else
    {
        zend_error(E_WARNING, "Incorrect parameters added");
        return;			
    }
 
    if (zend_hash_find(prop, "list", sizeof("list"), (void**)&tmp) == SUCCESS && Z_TYPE_PP(tmp) != IS_NULL) 
    {
        zend_hash_internal_pointer_reset_ex(Z_ARRVAL_P(*tmp), &pos);
        while (zend_hash_get_current_data_ex(Z_ARRVAL_P(*tmp), (void**)&attr, &pos) == SUCCESS)
        {
            zval *method2, *object2; 
            char *method2str;
 
            if (Z_TYPE_P(*attr) == IS_OBJECT)
            {
                method2 = zend_read_property(callback_entry, *attr, "method", sizeof("method")-1, 1 TSRMLS_CC);
                object2 = zend_read_property(callback_entry, *attr, "context", sizeof("context")-1, 1 TSRMLS_CC);			
                method2str = Z_STRVAL_P(method2);
 
                if ((strcmp(method2str,method) == 0) && (object2->type == object->type))
                {
                    zend_hash_index_del(Z_ARRVAL_P(*tmp), pos->h);
                }
            }
            else
            {
                method2str = Z_STRVAL_P(*attr);
                if ((strcmp(method2str,method) == 0) && (ZVAL_IS_NULL(object)))
                {
                    zend_hash_index_del(Z_ARRVAL_P(*tmp), pos->h);
                }
            }
            zend_hash_move_forward_ex(Z_ARRVAL_P(*tmp), &pos);
        }
    }
}
 

Any number of events can be passed to the raise event, allowing the developer to pass values from the event to the subscribed object(s). 

 
PHP_FUNCTION(_Raise)
{
    zval *object, *method, **tmp, **attr, ***args;
    HashTable *prop;
    HashPosition pos;
    prop = Z_OBJPROP_P(getThis());
 
    args = (zval ***)emalloc(ZEND_NUM_ARGS() * sizeof(zval **));
    zend_get_parameters_array_ex(ZEND_NUM_ARGS(), args);
 
    if (zend_hash_find(prop, "list", sizeof("list"), (void**)&tmp) == SUCCESS && Z_TYPE_PP(tmp) != IS_NULL) 
    {
        zend_hash_internal_pointer_reset_ex(Z_ARRVAL_P(*tmp), &pos);
        while (zend_hash_get_current_data_ex(Z_ARRVAL_P(*tmp), (void**)&attr, &pos) == SUCCESS)
        {
            if (Z_TYPE_P(*attr) == IS_OBJECT)
            {
                method = zend_read_property(callback_entry, *attr, "method", sizeof("method")-1, 1 TSRMLS_CC);
                object = zend_read_property(callback_entry, *attr, "context", sizeof("context")-1, 1 TSRMLS_CC);
 
                if (call_user_function_ex(NULL, &object, method, &return_value, ZEND_NUM_ARGS(), args, 0, NULL TSRMLS_CC) == FAILURE)
                {
                    zend_error(E_WARNING, "%s does not exit", Z_STRVAL_P(method));
                }
            }
            else
            {				
                if (call_user_function_ex(CG(function_table), NULL, *attr, &return_value, ZEND_NUM_ARGS(), args, 0, NULL TSRMLS_CC) == FAILURE)
                {					
                    zend_error(E_WARNING, "%s does not exit", Z_STRVAL_P(method));				
                }
            }
            zend_hash_move_forward_ex(Z_ARRVAL_P(*tmp), &pos);
        }
    }
}
 

The following code defines the methods and properties we want to include in our PHP classes. Along with the entry points etc. 

 
static function_entry event_functions[] = {
    PHP_NAMED_FE(__construct, PHP_FN(Constructor), NULL)
    PHP_NAMED_FE(Subscriptions, PHP_FN(_Subscriptions), NULL)
    PHP_NAMED_FE(Raise, PHP_FN(_Raise), NULL)
    PHP_NAMED_FE(Subscribe, PHP_FN(_Subscribe), NULL)
    PHP_NAMED_FE(Unsubscribe, PHP_FN(_Unsubscribe), NULL)
 
};
 
PHP_MINIT_FUNCTION(event)
{
    zend_class_entry ce, ce2;
    INIT_CLASS_ENTRY(ce, "Event", event_functions);	
    event_entry = zend_register_internal_class(&ce TSRMLS_CC);
 
    INIT_CLASS_ENTRY(ce2, "Callback", NULL);	
    callback_entry = zend_register_internal_class(&ce2 TSRMLS_CC);
 
    return SUCCESS;
}	
 
PHP_MSHUTDOWN_FUNCTION(event)
{
    event_entry = NULL;
    callback_entry = NULL;
    return SUCCESS;
}
 
zend_module_entry event_module_entry = {
STANDARD_MODULE_HEADER_EX,
NULL,
NULL,
event_extname,
event_functions,
PHP_MINIT(event),
PHP_MSHUTDOWN(event),
NULL,
NULL,
NULL,
event_extver,
STANDARD_MODULE_PROPERTIES
};
 
ZEND_GET_MODULE(event)
 



Posted by - Christoff Truter
Created - 2008-07-28 12:48:09


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