php-src / README.PARAMETER_PARSING_API

New parameter parsing functions
===============================

It should be easier to parse input parameters to an extension function.
Hence, borrowing from Python's example, there are now a set of functions
that given the string of type specifiers, can parse the input parameters
and store the results in the user specified variables. This avoids most
of the IS_* checks and convert_to_* conversions. The functions also
check for the appropriate number of parameters, and try to output
meaningful error messages.


Prototypes
----------
/* Implemented. */
int zend_parse_parameters(int num_args TSRMLS_DC, char *type_spec, ...);
int zend_parse_parameters_ex(int flags, int num_args TSRMLS_DC, char *type_spec, ...);

The zend_parse_parameters() function takes the number of parameters
passed to the extension function, the type specifier string, and the
list of pointers to variables to store the results in. The _ex() version
also takes 'flags' argument -- current only ZEND_PARSE_PARAMS_QUIET can
be used as 'flags' to specify that the function should operate quietly
and not output any error messages.

Both functions return SUCCESS or FAILURE depending on the result.

The auto-conversions are performed as necessary. Arrays, objects, and
resources cannot be auto-converted.


Type specifiers
---------------
 a	- array
 b	- boolean, stored in zend_bool
 d	- double
 f	- function or array containing php method call info (returned as 
	  zend_fcall_info* and zend_fcall_info_cache*)
 h	- array (returned as HashTable*)
 l	- long
 o	- object (of any type)
 O	- object (of specific type, specified by class entry)
 r	- resource (stored in zval)
 s	- string (with possible null bytes) and its length
 z	- the actual zval

 The following characters also have a meaning in the specifier string:
	| - indicates that the remaining parameters are optional, they
	    should be initialized to default values by the extension since they
	    will not be touched by the parsing function if they are not
	    passed to it.
	/ - use SEPARATE_ZVAL_IF_NOT_REF() on the parameter it follows
	! - the parameter it follows can be of specified type or NULL (only applies
		to 's', 'a', 'o', 'O', 'r', 'h', 'C', 'z', and 'Z'). If NULL is passed,
	 	the results pointer is set to NULL as well.

Examples
--------
/* Gets a long, a string and its length, and a zval */
long l;
char *s;
int s_len;
zval *param;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "lsz",
						  &l, &s, &s_len, &param) == FAILURE) {
	return;
}


/* Gets an object of class specified by my_ce, and an optional double. */
zval *obj;
double d = 0.5;
zend_class_entry *my_ce;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "O|d",
						  &obj, my_ce, &d) == FAILURE) {
	return;
}


/* Gets an object or null, and an array.
   If null is passed for object, obj will be set to NULL. */
zval *obj;
zval *arr;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "o!a",
						  &obj, &arr) == FAILURE) {
	return;
}


/* Gets a separated array which can also be null. */
zval *arr;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "a/!",
						  &arr) == FAILURE) {
	return;
}


/* Get only the first three parameters (useful for varargs functions). */
zval *z;
zend_bool b;
zval *r;
if (zend_parse_parameters(3 TSRMLS_CC, "zbr!",
						  &z, &b, &r) == FAILURE) {
	return;
}


/* Get either a set of 3 longs or a string. */
long l1, l2, l3;
char *s;
/* 
 * The function expects a pointer to a integer in this case, not a long
 * or any other type.  If you specify a type which is larger
 * than a 'int', the upper bits might not be initialized
 * properly, leading to random crashes on platforms like
 * Tru64 or Linux/Alpha.
 */
int length;

if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC,
							 "lll", &l1, &l2, &l3) == SUCCESS) {
	/* manipulate longs */
} else if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC,
									"s", &s, &length) == SUCCESS) {
	/* manipulate string */
} else {
	/* output error */

	return;
}
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