Initial population of solana-program-sdk

sdk/program/src/program_pack.rs

@@ -0,0 +1,57 @@
+//! State transition types
+
+use crate::program_error::ProgramError;
+
+/// Check if a program account state is initialized
+pub trait IsInitialized {
+    /// Is initialized
+    fn is_initialized(&self) -> bool;
+}
+
+/// Depends on Sized
+pub trait Sealed: Sized {}
+
+/// Safely and efficiently (de)serialize account state
+pub trait Pack: Sealed {
+    /// The length, in bytes, of the packed representation
+    const LEN: usize;
+    #[doc(hidden)]
+    fn pack_into_slice(&self, dst: &mut [u8]);
+    #[doc(hidden)]
+    fn unpack_from_slice(src: &[u8]) -> Result<Self, ProgramError>;
+
+    /// Get the packed length
+    fn get_packed_len() -> usize {
+        Self::LEN
+    }
+
+    /// Unpack from slice and check if initialized
+    fn unpack(input: &[u8]) -> Result<Self, ProgramError>
+    where
+        Self: IsInitialized,
+    {
+        let value = Self::unpack_unchecked(input)?;
+        if value.is_initialized() {
+            Ok(value)
+        } else {
+            Err(ProgramError::UninitializedAccount)
+        }
+    }
+
+    /// Unpack from slice without checking if initialized
+    fn unpack_unchecked(input: &[u8]) -> Result<Self, ProgramError> {
+        if input.len() != Self::LEN {
+            return Err(ProgramError::InvalidAccountData);
+        }
+        Ok(Self::unpack_from_slice(input)?)
+    }
+
+    /// Pack into slice
+    fn pack(src: Self, dst: &mut [u8]) -> Result<(), ProgramError> {
+        if dst.len() != Self::LEN {
+            return Err(ProgramError::InvalidAccountData);
+        }
+        src.pack_into_slice(dst);
+        Ok(())
+    }
+}