Module _04_zval 

Zval

Refer to: https://www.phpinternalsbook.com/php7/zvals/basic_structure.html#the-zval-struct

A zval (short for “Zend value”) represents an arbitrary PHP value. As such it is likely the most important structure in all of PHP and you’ll be working with it a lot.

The phper::values::ZVal is the wrapper of php zval.

Actual type of ZVal

PHP is a dynamically typed language, zval can represent multiple types, but there is only one type at a time, you can use phper::values::ZVal::get_type_info to get the actual type.

Convert Rust type to ZVal

The phper::values::ZVal implements a lot of std::convert::From for the conversion.

Here is the mapping of relationships between Rust types and base PHP types.

Trait	Rust type	PHP type
From<()>	()	null
From<bool>	bool	bool
From<i64>	i64	long
From<f64>	f64	double
From<&str>	&str	string
From<&CStr>	&CStr	string
From<&[u8]>	&[u8]	string
From<Vec<u8>>	Vec<u8>	string
From<ZString>	phper::strings::ZString	string
From<ZArray>	phper::arrays::ZArray	array
From<ZObject>	phper::objects::ZObject	object

There are also composite types that implement From.

• From<Option<T>>: if Some(T), T will be converted to PHP type like From<T>, or None will be converted to null.

use phper::values::ZVal;

assert!(ZVal::from(()).get_type_info().is_null());
assert!(ZVal::from(100i64).get_type_info().is_long());

Convert ZVal to Rust type

Now you can use as_* or expect_* methods to convert ZVal to Rust types.

• The as_* returns Option<T>.

• The expect_* returns phper::Result<T>, if convert failed, phper::errors::ExpectTypeError will be returned, with the message: type error: must be of type {expect_type}, {actual_type} given").

use phper::echo;
use phper::values::ZVal;

fn say_hello(arguments: &mut [ZVal]) -> phper::Result<()> {
    // Get the first argument, expect the type `ZStr`, and convert to Rust utf-8
    // str.
    let name = arguments[0].expect_z_str()?.to_str()?;

    // Macro which runs PHP internal function `echo`.
    echo!("Hello, {}!\n", name);

    Ok(())
}

Value copy & reference counting copy

The phper::values::ZVal both implements std::clone::Clone and phper::alloc::RefClone.

• std::clone::Clone: represent value copy (Type ZObject is excluded because it is always passed by reference).

• phper::alloc::RefClone: represent reference counting copy (Type (), bool, i64, f64 is excluded because they are not reference counting types).

PHP internal cast

Refer to: https://www.phpinternalsbook.com/php7/zvals/casts_and_operations.html#casts

PHP is a weakly typed language, yet it supports type casting internally.

The zend engine provides convert_to_* functions to do the type cast, and ZVal wraps them directly.

Callable

The phper::values::ZVal can be called via phper::values::ZVal::call. Make sure that the actual type is callable (string, array or closure).

use phper::values::ZVal;
use phper::arrays::ZArray;

let mut arr = ZArray::new();
arr.insert("a", ZVal::from(1));
arr.insert("b", ZVal::from(2));
let ret = ZVal::from("json_encode").call(&mut [ZVal::from(arr)]).unwrap();
assert_eq!(ret.expect_z_str().unwrap().to_str(), Ok(r#"{"a":1,"b":2}"#));