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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
extern crate libc;
extern crate nserror;
extern crate nsstring;
extern crate xpcom;
mod bag;
use std::{
borrow::Cow,
convert::{TryFrom, TryInto},
};
use libc::c_double;
use nserror::{nsresult, NS_ERROR_CANNOT_CONVERT_DATA, NS_OK};
use nsstring::{nsACString, nsAString, nsCString, nsString};
use xpcom::{getter_addrefs, interfaces::nsIVariant, RefPtr};
pub use crate::bag::HashPropertyBag;
extern "C" {
fn NS_GetDataType(variant: *const nsIVariant) -> u16;
fn NS_NewStorageNullVariant(result: *mut *const nsIVariant);
fn NS_NewStorageBooleanVariant(value: bool, result: *mut *const nsIVariant);
fn NS_NewStorageIntegerVariant(value: i64, result: *mut *const nsIVariant);
fn NS_NewStorageFloatVariant(value: c_double, result: *mut *const nsIVariant);
fn NS_NewStorageTextVariant(value: *const nsAString, result: *mut *const nsIVariant);
fn NS_NewStorageUTF8TextVariant(value: *const nsACString, result: *mut *const nsIVariant);
}
// These are the relevant parts of the nsXPTTypeTag enum in xptinfo.h,
// which nsIVariant.idl reflects into the nsIDataType struct class and uses
// to constrain the values of nsIVariant::dataType.
#[repr(u16)]
#[derive(Debug, Copy, Clone, Eq, Hash, PartialEq)]
pub enum DataType {
Int32 = 2,
Int64 = 3,
Double = 9,
Bool = 10,
Void = 13,
CharStr = 15,
WCharStr = 16,
StringSizeIs = 20,
WStringSizeIs = 21,
Utf8String = 24,
CString = 25,
AString = 26,
EmptyArray = 254,
Empty = 255,
}
impl TryFrom<u16> for DataType {
type Error = nsresult;
/// Converts a raw type tag for an `nsIVariant` into a `DataType` variant.
/// Returns `NS_ERROR_CANNOT_CONVERT_DATA` if the type isn't one that we
/// support.
fn try_from(raw: u16) -> Result<Self, Self::Error> {
Ok(match raw {
2 => DataType::Int32,
3 => DataType::Int64,
9 => DataType::Double,
10 => DataType::Bool,
13 => DataType::Void,
15 => DataType::CharStr,
16 => DataType::WCharStr,
20 => DataType::StringSizeIs,
21 => DataType::WStringSizeIs,
24 => DataType::Utf8String,
25 => DataType::CString,
26 => DataType::AString,
254 => DataType::EmptyArray,
255 => DataType::Empty,
_ => Err(NS_ERROR_CANNOT_CONVERT_DATA)?,
})
}
}
/// Extension methods implemented on `nsIVariant` types, to make them easier
/// to work with.
pub trait NsIVariantExt {
/// Returns the raw type tag for this variant. Call
/// `DataType::try_from()` on this tag to turn it into a `DataType`.
fn get_data_type(&self) -> u16;
/// Tries to clone this variant, failing with `NS_ERROR_CANNOT_CONVERT_DATA`
/// if its type is unsupported.
fn try_clone(&self) -> Result<RefPtr<nsIVariant>, nsresult>;
}
impl NsIVariantExt for nsIVariant {
fn get_data_type(&self) -> u16 {
unsafe { NS_GetDataType(self) }
}
fn try_clone(&self) -> Result<RefPtr<nsIVariant>, nsresult> {
Ok(match self.get_data_type().try_into()? {
DataType::Bool => bool::from_variant(self)?.into_variant(),
DataType::Int32 => i32::from_variant(self)?.into_variant(),
DataType::Int64 => i64::from_variant(self)?.into_variant(),
DataType::Double => f64::from_variant(self)?.into_variant(),
DataType::AString | DataType::WCharStr | DataType::WStringSizeIs => {
nsString::from_variant(self)?.into_variant()
}
DataType::CString
| DataType::CharStr
| DataType::StringSizeIs
| DataType::Utf8String => nsCString::from_variant(self)?.into_variant(),
DataType::Void | DataType::EmptyArray | DataType::Empty => ().into_variant(),
})
}
}
pub trait VariantType {
fn type_name() -> Cow<'static, str>;
fn into_variant(self) -> RefPtr<nsIVariant>;
fn from_variant(variant: &nsIVariant) -> Result<Self, nsresult>
where
Self: Sized;
}
/// Implements traits to convert between variants and their types.
macro_rules! variant {
($typ:ident, $constructor:ident, $getter:ident) => {
impl VariantType for $typ {
fn type_name() -> Cow<'static, str> {
stringify!($typ).into()
}
fn into_variant(self) -> RefPtr<nsIVariant> {
// getter_addrefs returns a Result<RefPtr<T>, nsresult>,
// but we know that our $constructor is infallible, so we can
// safely unwrap and return the RefPtr.
getter_addrefs(|p| {
unsafe { $constructor(self.into(), p) };
NS_OK
})
.unwrap()
}
fn from_variant(variant: &nsIVariant) -> Result<$typ, nsresult> {
let mut result = $typ::default();
let rv = unsafe { variant.$getter(&mut result) };
if rv.succeeded() {
Ok(result)
} else {
Err(rv)
}
}
}
};
(* $typ:ident, $constructor:ident, $getter:ident) => {
impl VariantType for $typ {
fn type_name() -> Cow<'static, str> {
stringify!($typ).into()
}
fn into_variant(self) -> RefPtr<nsIVariant> {
// getter_addrefs returns a Result<RefPtr<T>, nsresult>,
// but we know that our $constructor is infallible, so we can
// safely unwrap and return the RefPtr.
getter_addrefs(|p| {
unsafe { $constructor(&*self, p) };
NS_OK
})
.unwrap()
}
fn from_variant(variant: &nsIVariant) -> Result<$typ, nsresult> {
let mut result = $typ::new();
let rv = unsafe { variant.$getter(&mut *result) };
if rv.succeeded() {
Ok(result)
} else {
Err(rv)
}
}
}
};
}
// The unit type (()) is a reasonable equivalation of the null variant.
// The macro can't produce its implementations of VariantType, however,
// so we implement them concretely.
impl VariantType for () {
fn type_name() -> Cow<'static, str> {
"()".into()
}
fn into_variant(self) -> RefPtr<nsIVariant> {
// getter_addrefs returns a Result<RefPtr<T>, nsresult>,
// but we know that NS_NewStorageNullVariant is infallible, so we can
// safely unwrap and return the RefPtr.
getter_addrefs(|p| {
unsafe { NS_NewStorageNullVariant(p) };
NS_OK
})
.unwrap()
}
fn from_variant(_variant: &nsIVariant) -> Result<Self, nsresult> {
Ok(())
}
}
impl<T> VariantType for Option<T>
where
T: VariantType,
{
fn type_name() -> Cow<'static, str> {
format!("Option<{}>", T::type_name()).into()
}
fn into_variant(self) -> RefPtr<nsIVariant> {
match self {
Some(v) => v.into_variant(),
None => ().into_variant(),
}
}
fn from_variant(variant: &nsIVariant) -> Result<Self, nsresult> {
Ok(match variant.get_data_type().try_into() {
Ok(DataType::Void) | Ok(DataType::EmptyArray) | Ok(DataType::Empty) => None,
_ => Some(VariantType::from_variant(variant)?),
})
}
}
variant!(bool, NS_NewStorageBooleanVariant, GetAsBool);
variant!(i32, NS_NewStorageIntegerVariant, GetAsInt32);
variant!(i64, NS_NewStorageIntegerVariant, GetAsInt64);
variant!(f64, NS_NewStorageFloatVariant, GetAsDouble);
variant!(*nsString, NS_NewStorageTextVariant, GetAsAString);
variant!(*nsCString, NS_NewStorageUTF8TextVariant, GetAsAUTF8String);