Add stake flags struct (#32521)

Co-authored-by: HaoranYi <haoran.yi@solana.com>

sdk/program/src/stake/mod.rs

@@ -4,6 +4,7 @@
 
 pub mod config;
 pub mod instruction;
+pub mod stake_flags;
 pub mod state;
 pub mod tools;
 

sdk/program/src/stake/stake_flags.rs

@@ -0,0 +1,97 @@
+use borsh::{BorshDeserialize, BorshSchema, BorshSerialize};
+
+/// Additional flags for stake state.
+#[allow(dead_code)]
+#[derive(
+    Serialize,
+    Deserialize,
+    AbiExample,
+    BorshDeserialize,
+    BorshSchema,
+    BorshSerialize,
+    Copy,
+    PartialEq,
+    Eq,
+    Clone,
+    PartialOrd,
+    Ord,
+    Hash,
+    Debug,
+)]
+pub struct StakeFlags {
+    bits: u8,
+}
+
+/// Currently, only bit 1 is used. The other 7 bits are reserved for future usage.
+#[allow(dead_code)]
+impl StakeFlags {
+    ///  Stake must be fully activated before deactivation is allowed (bit 1).
+    pub const MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED: Self =
+        Self { bits: 0b0000_0001 };
+
+    pub const fn empty() -> Self {
+        Self { bits: 0 }
+    }
+
+    pub const fn contains(&self, other: Self) -> bool {
+        (self.bits & other.bits) == other.bits
+    }
+
+    pub fn remove(&mut self, other: Self) {
+        self.bits &= !other.bits;
+    }
+
+    pub fn set(&mut self, other: Self) {
+        self.bits |= other.bits;
+    }
+
+    pub const fn union(self, other: Self) -> Self {
+        Self {
+            bits: self.bits | other.bits,
+        }
+    }
+}
+
+#[allow(dead_code)]
+impl Default for StakeFlags {
+    fn default() -> Self {
+        StakeFlags::empty()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_stake_flags() {
+        let mut f = StakeFlags::empty();
+        assert!(!f.contains(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED));
+
+        f.set(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED);
+        assert!(f.contains(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED));
+
+        f.remove(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED);
+        assert!(!f.contains(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED));
+
+        let f1 = StakeFlags::empty();
+        let f2 = StakeFlags::empty();
+        let f3 = f1.union(f2);
+        assert!(!f3.contains(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED));
+
+        let f1 = StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED;
+        let f2 = StakeFlags::empty();
+        let f3 = f1.union(f2);
+        assert!(f3.contains(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED));
+
+        let f1 = StakeFlags::empty();
+        let f2 = StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED;
+        let f3 = f1.union(f2);
+        assert!(f3.contains(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED));
+
+        let f1 = StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED;
+        let f2 = StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED;
+        let f3 = f1.union(f2);
+        assert!(f3.contains(StakeFlags::MUST_FULLY_ACTIVATE_BEFORE_DEACTIVATION_IS_PERMITTED));
+    }
+}