concordium_std

Trait HasStateEntry

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pub trait HasStateEntry
where
    Self: Read + Write<Err = Self::Error> + Seek<Err = Self::Error>,
{
    type StateEntryData;
    type StateEntryKey;
    type Error: Default;

    // Required methods
    fn move_to_start(&mut self);
    fn size(&self) -> Result<u32, Self::Error>;
    fn truncate(&mut self, new_size: u32) -> Result<(), Self::Error>;
    fn get_key(&self) -> &[u8] ⓘ;
    fn resize(&mut self, new_size: u32) -> Result<(), Self::Error>;

    // Provided method
    fn reserve(&mut self, len: u32) -> Result<(), Self::Error> { ... }
}
Expand description

A type that can serve as the contract state entry type.

§Deprecation notice

This trait is deprecated along with crate::test_infrastructure.

Use StateEntry instead unless you intend to use the deprecated test infrastructure.

See the crate documentation for more details.

Required Associated Types§

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type StateEntryData

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type StateEntryKey

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type Error: Default

Required Methods§

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fn move_to_start(&mut self)

Set the cursor to the beginning. Equivalent to .seek(SeekFrom::Start(0)) but can be implemented more efficiently.

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fn size(&self) -> Result<u32, Self::Error>

Get the current size of the entry. Returns an error if the entry does not exist.

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fn truncate(&mut self, new_size: u32) -> Result<(), Self::Error>

Truncate the entry to the given size. If the given size is more than the current size this operation does nothing. The new position is at most at the end of the stream. Returns an error if the entry does not exist.

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fn get_key(&self) -> &[u8] ⓘ

Get a reference to the entry’s key.

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fn resize(&mut self, new_size: u32) -> Result<(), Self::Error>

Resize the entry to the given size. Returns an error if the entry does not exist.

Provided Methods§

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fn reserve(&mut self, len: u32) -> Result<(), Self::Error>

Make sure that the memory size is at least that many bytes in size. Returns Ok iff this was successful. The new bytes are initialized as 0. Returns an error if the entry does not exist.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§