27 lines
949 B
Rust
27 lines
949 B
Rust
use objc2::encode::{Encode, Encoding, RefEncode};
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use objc2::runtime::AnyObject;
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#[repr(transparent)]
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struct NSString {
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// `NSString` has the same layout / works the same as `AnyObject`.
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_priv: AnyObject,
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}
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// We don't know the size of NSString, so we can only hold pointers to it.
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//
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// SAFETY: The string is `repr(transparent)` over `AnyObject`.
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unsafe impl RefEncode for NSString {
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const ENCODING_REF: Encoding = Encoding::Object;
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}
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fn main() {
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// The `RefEncode` implementation provide an `Encode` implementation for
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// pointers to the object.
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assert_eq!(<*const NSString>::ENCODING, Encoding::Object);
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assert_eq!(<*mut NSString>::ENCODING, Encoding::Object);
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assert_eq!(<&NSString>::ENCODING, Encoding::Object);
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assert_eq!(<&mut NSString>::ENCODING, Encoding::Object);
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assert_eq!(<Option<&NSString>>::ENCODING, Encoding::Object);
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assert_eq!(<Option<&mut NSString>>::ENCODING, Encoding::Object);
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}
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