Update map iterator to be index based (#1061)

### What

Sdk part of stellar/rs-soroban-env#992

### Why

[TODO: Why this change is being made. Include any context required to
understand the why.]

### Known limitations

[TODO or N/A]

Cargo.toml

@@ -40,17 +40,17 @@ soroban-token-sdk = { version = "0.9.2", path = "soroban-token-sdk" }
 [workspace.dependencies.soroban-env-common]
 version = "0.0.17"
 git = "https://github.com/stellar/rs-soroban-env"
-rev = "d92944576e2301c9866215efcdc4bbd24a5f3981"
+rev = "c2e1c21cf8d44db23a159090e3cbaab741860295"
 
 [workspace.dependencies.soroban-env-guest]
 version = "0.0.17"
 git = "https://github.com/stellar/rs-soroban-env"
-rev = "d92944576e2301c9866215efcdc4bbd24a5f3981"
+rev = "c2e1c21cf8d44db23a159090e3cbaab741860295"
 
 [workspace.dependencies.soroban-env-host]
 version = "0.0.17"
 git = "https://github.com/stellar/rs-soroban-env"
-rev = "d92944576e2301c9866215efcdc4bbd24a5f3981"
+rev = "c2e1c21cf8d44db23a159090e3cbaab741860295"
 
 [workspace.dependencies.stellar-strkey]
 version = "0.0.7"
@@ -60,7 +60,7 @@ rev = "e6ba45c60c16de28c7522586b80ed0150157df73"
 [workspace.dependencies.stellar-xdr]
 version = "0.0.17"
 git = "https://github.com/stellar/rs-stellar-xdr"
-rev = "4876e5eb20016caebbd13bcf6401626dc6073b8e"
+rev = "2d2526f515a476b1e3df70233a4cf9232287977e"
 default-features = false
 
 #[patch."https://github.com/stellar/rs-soroban-env"]

soroban-sdk/src/map.rs

@@ -508,18 +508,15 @@ where
 #[derive(Clone)]
 pub struct MapTryIter<K, V> {
     map: Map<K, V>,
+    pos: u32,
     len: u32,
-    min_key: Val,
-    max_key: Val,
 }
 
 impl<K, V> MapTryIter<K, V> {
     fn new(map: Map<K, V>) -> Self {
-        let env = map.env();
         Self {
+            pos: 0,
             len: map.len(),
-            min_key: env.map_min_key(map.to_object()).unwrap_infallible(),
-            max_key: env.map_max_key(map.to_object()).unwrap_infallible(),
             map,
         }
     }
@@ -534,15 +531,16 @@ where
 
     fn next(&mut self) -> Option<Self::Item> {
         let env = self.map.env();
-        if self.len == 0 {
+        if self.pos == self.len {
             return None;
         }
-        let key = self.min_key;
-        self.min_key = env
-            .map_next_key(self.map.to_object(), key)
+        let key = env
+            .map_key_by_pos(self.map.to_object(), self.pos.into())
             .unwrap_infallible();
-        self.len -= 1;
-        let value = env.map_get(self.map.to_object(), key).unwrap_infallible();
+        let value = env
+            .map_val_by_pos(self.map.to_object(), self.pos.into())
+            .unwrap_infallible();
+        self.pos += 1;
         Some(Ok((
             match K::try_from_val(env, &key) {
                 Ok(k) => k,
@@ -556,7 +554,7 @@ where
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let len = self.len as usize;
+        let len = (self.len - self.pos) as usize;
         (len, Some(len))
     }
 
@@ -570,15 +568,16 @@ where
 {
     fn next_back(&mut self) -> Option<Self::Item> {
         let env = self.map.env();
-        if self.len == 0 {
+        if self.pos == self.len {
             return None;
         }
-        let key = self.max_key;
-        self.max_key = env
-            .map_prev_key(self.map.to_object(), key)
-            .unwrap_infallible();
         self.len -= 1;
-        let value = env.map_get(self.map.to_object(), key).unwrap_infallible();
+        let key = env
+            .map_key_by_pos(self.map.to_object(), self.len.into())
+            .unwrap_infallible();
+        let value = env
+            .map_val_by_pos(self.map.to_object(), self.len.into())
+            .unwrap_infallible();
         Some(Ok((
             match K::try_from_val(env, &key) {
                 Ok(k) => k,
@@ -607,7 +606,7 @@ where
     V: IntoVal<Env, Val> + TryFromVal<Env, Val>,
 {
     fn len(&self) -> usize {
-        self.len as usize
+        (self.len - self.pos) as usize
     }
 }
 

soroban-sdk/src/vec.rs

@@ -365,7 +365,7 @@ where
     /// Create an empty Vec.
     #[inline(always)]
     pub fn new(env: &Env) -> Vec<T> {
-        unsafe { Self::unchecked_new(env.clone(), env.vec_new(().into()).unwrap_infallible()) }
+        unsafe { Self::unchecked_new(env.clone(), env.vec_new().unwrap_infallible()) }
     }
 
     /// Create a Vec from the array of items.