refactor: move back the constant, add doc comments

miden-tx/src/tests/kernel_tests/test_prologue.rs

@@ -29,7 +29,7 @@ use miden_lib::{
 use miden_objects::{
     accounts::{
         AccountBuilder, AccountComponent, AccountProcedureInfo, AccountStorage, AccountType,
-        NUM_ELEMENTS_PER_STORAGE_SLOT,
+        StorageSlot,
     },
     testing::{
         account_component::BASIC_WALLET_CODE,
@@ -277,7 +277,7 @@ fn account_data_memory_assertions(process: &Process<MockHost>, inputs: &Transact
         .account()
         .storage()
         .as_elements()
-        .chunks(NUM_ELEMENTS_PER_STORAGE_SLOT / 2)
+        .chunks(StorageSlot::NUM_ELEMENTS_PER_STORAGE_SLOT / 2)
         .enumerate()
     {
         assert_eq!(

miden-tx/src/tests/kernel_tests/test_tx.rs

@@ -23,7 +23,7 @@ use miden_objects::{
             ACCOUNT_ID_FUNGIBLE_FAUCET_ON_CHAIN, ACCOUNT_ID_FUNGIBLE_FAUCET_ON_CHAIN_2,
         },
         Account, AccountBuilder, AccountComponent, AccountProcedureInfo, AccountStorage,
-        StorageSlot, NUM_ELEMENTS_PER_STORAGE_SLOT,
+        StorageSlot,
     },
     assets::NonFungibleAsset,
     crypto::merkle::{LeafIndex, MerklePath},
@@ -1119,7 +1119,7 @@ fn foreign_account_data_memory_assertions(foreign_account: &Account, process: &P
     for (i, elements) in foreign_account
         .storage()
         .as_elements()
-        .chunks(NUM_ELEMENTS_PER_STORAGE_SLOT / 2)
+        .chunks(StorageSlot::NUM_ELEMENTS_PER_STORAGE_SLOT / 2)
         .enumerate()
     {
         assert_eq!(

objects/src/accounts/mod.rs

@@ -33,10 +33,7 @@ mod seed;
 pub use seed::{get_account_seed, get_account_seed_single};
 
 mod storage;
-pub use storage::{
-    AccountStorage, AccountStorageHeader, StorageMap, StorageSlot, StorageSlotType,
-    NUM_ELEMENTS_PER_STORAGE_SLOT,
-};
+pub use storage::{AccountStorage, AccountStorageHeader, StorageMap, StorageSlot, StorageSlotType};
 
 mod header;
 pub use header::AccountHeader;

objects/src/accounts/storage/header.rs

@@ -6,36 +6,46 @@ use vm_core::{
 };
 use vm_processor::DeserializationError;
 
-use super::{
-    AccountStorage, Felt, StorageSlot, StorageSlotType, Word, NUM_ELEMENTS_PER_STORAGE_SLOT,
-};
+use super::{AccountStorage, Felt, StorageSlot, StorageSlotType, Word};
 use crate::AccountError;
 
 // ACCOUNT STORAGE HEADER
 // ================================================================================================
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+/// Storage slot header is a lighter version of the [StorageSlot] storing only the type and the
+/// top-level value for the slot, and being, in fact, just a thin wrapper around a tuple. 
+///
+/// That is, for complex storage slot (e.g., storage map), the header contains only the commitment
+/// to the underlying data.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct StorageSlotHeader(StorageSlotType, Word);
 
-impl From<&StorageSlot> for StorageSlotHeader {
-    fn from(value: &StorageSlot) -> Self {
-        Self(value.slot_type(), value.value())
-    }
-}
-
 impl StorageSlotHeader {
+    /// Returns a new instance of storage slot header from the provided storage slot type and value.
     pub fn new(value: &(StorageSlotType, Word)) -> Self {
-        Self(value.0.clone(), value.1)
+        Self(value.0, value.1)
     }
 
-    pub fn as_elements(&self) -> [Felt; NUM_ELEMENTS_PER_STORAGE_SLOT] {
-        let mut elements = [ZERO; NUM_ELEMENTS_PER_STORAGE_SLOT];
+    /// Returns this storage slot header as field elements.
+    ///
+    /// This is done by converting this storage slot into 8 field elements as follows:
+    /// ```text
+    /// [SLOT_VALUE, slot_type, 0, 0, 0]
+    /// ```
+    pub fn as_elements(&self) -> [Felt; StorageSlot::NUM_ELEMENTS_PER_STORAGE_SLOT] {
+        let mut elements = [ZERO; StorageSlot::NUM_ELEMENTS_PER_STORAGE_SLOT];
         elements[0..4].copy_from_slice(&self.1);
         elements[4..8].copy_from_slice(&self.0.as_word());
         elements
     }
 }
 
+impl From<&StorageSlot> for StorageSlotHeader {
+    fn from(value: &StorageSlot) -> Self {
+        Self(value.slot_type(), value.value())
+    }
+}
+
 /// Account storage header is a lighter version of the [AccountStorage] storing only the type and
 /// the top-level value for each storage slot.
 ///

objects/src/accounts/storage/mod.rs

@@ -15,12 +15,6 @@ pub use map::StorageMap;
 mod header;
 pub use header::{AccountStorageHeader, StorageSlotHeader};
 
-// CONSTANTS
-// ================================================================================================
-
-/// The number of field elements needed to represent a [StorageSlot] in kernel memory.
-pub const NUM_ELEMENTS_PER_STORAGE_SLOT: usize = 8;
-
 // ACCOUNT STORAGE
 // ================================================================================================
 

objects/src/accounts/storage/slot/mod.rs

@@ -20,6 +20,9 @@ pub enum StorageSlot {
 }
 
 impl StorageSlot {
+    /// The number of field elements needed to represent a [StorageSlot] in kernel memory.
+    pub const NUM_ELEMENTS_PER_STORAGE_SLOT: usize = 8;
+
     /// Returns true if this storage slot has a value equal the default of it's type
     pub fn is_default(&self) -> bool {
         match self {

objects/src/accounts/storage/slot/type.rs

@@ -10,7 +10,7 @@ use vm_processor::DeserializationError;
 // ================================================================================================
 
 /// An object that represents the type of a storage slot.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum StorageSlotType {
     /// Represents a slot that contains a value.
     Value,