HSTRING wrapper

hstring.rs

use ::std::ptr;
use ::winapi::*;
use ::runtimeobject::*;

pub struct HString(HSTRING);

impl<'a> From<&'a str> for HString {
	fn from(s: &'a str) -> Self {
		let mut s16: Vec<_> = s.encode_utf16().collect();
		let len = s16.len();
		s16.push(0x0u16); // add null-terminator
		let mut hstr = HString(ptr::null_mut());
		let slice: &[u16] = &s16;
		let res = unsafe { WindowsCreateString(slice as *const _ as LPCWSTR, len as UINT32, &mut hstr.0) };
		assert!(res == S_OK);
		hstr
	}
}

impl HString {
	pub unsafe fn get(&self) -> HSTRING {
		self.0
	}
	
	pub unsafe fn wrap(hstr: HSTRING) -> HString {
		HString(hstr)
	}
	
	pub unsafe fn null() -> HString {
		HString(ptr::null_mut())
	}
	
	pub fn get_address(&mut self) -> &mut HSTRING {
		&mut self.0
	}
}

impl ToString for HString {
	fn to_string(&self) -> String {
		unsafe {
			let mut len = 0;
			let buf = WindowsGetStringRawBuffer(self.0, &mut len);
			let slice: &[u16] = ::std::slice::from_raw_parts(buf, len as usize);
			String::from_utf16_lossy(slice)
		}
	}
}

impl Drop for HString {
	fn drop(&mut self) {
		if !self.0.is_null() {
			unsafe { WindowsDeleteString(self.0) };
		}			
	}
}

#[test]
fn hstring_roundtrip() {
	let s = "12345";
	let hstr: HString = s.into();
	assert!(unsafe { WindowsGetStringLen(hstr.get()) } == 5);
	assert!(s == hstr.to_string());
}