Add prefix

.circleci/config.yml

@@ -590,6 +590,12 @@ jobs:
       - run:
           name: Run unit tests
           command: cargo test --locked
+      - run:
+          name: Build library for native target (with iterator)
+          command: cargo build --locked --features iterator
+      - run:
+          name: Run unit tests (with iterator)
+          command: cargo test --locked --features iterator
       - save_cache:
           paths:
             - /usr/local/cargo/registry

packages/storage-plus/Cargo.toml

@@ -10,6 +10,8 @@ homepage = "https://cosmwasm.com"
 documentation = "https://docs.cosmwasm.com"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[features]
+iterator = ["cosmwasm-std/iterator"]
 
 [dependencies]
 cosmwasm-std = { version = "0.11.0-alpha3" }

packages/storage-plus/src/lib.rs

@@ -2,10 +2,13 @@ mod length_prefixed;
 mod map;
 mod namespace_helpers;
 mod path;
+mod prefix;
 mod type_helpers;
 
 pub use map::Map;
 pub use path::Path;
+#[cfg(feature = "iterator")]
+pub use prefix::Prefix;
 
 #[cfg(test)]
 mod test {

packages/storage-plus/src/map.rs

@@ -4,6 +4,8 @@ use std::marker::PhantomData;
 
 use crate::path::Path;
 
+// TODO: where to add PREFIX_PK???? Only in an Indexed Map?
+
 pub struct Map<'a, K, T> {
     namespaces: &'a [&'a [u8]],
     // see https://doc.rust-lang.org/std/marker/struct.PhantomData.html#unused-type-parameters for why this is needed
@@ -30,6 +32,8 @@ where
         let (namespaces, key) = k.namespaced(self.namespaces);
         Path::new(namespaces, key)
     }
+
+    // TODO: how to do range queries on the prefix...
 }
 
 pub trait PrimaryKey<'a> {
@@ -54,6 +58,15 @@ impl<'a> PrimaryKey<'a> for (&'a [u8], &'a [u8]) {
     }
 }
 
+impl<'a> PrimaryKey<'a> for (&'a [u8], &'a [u8], &'a [u8]) {
+    fn namespaced(&self, namespaces: &'a [&'a [u8]]) -> (Vec<&'a [u8]>, Vec<u8>) {
+        let mut spaces = namespaces.to_vec();
+        spaces.extend_from_slice(&[self.0, self.1]);
+        // move the first parts into the namespace, last as key
+        (spaces, self.2.to_vec())
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

packages/storage-plus/src/path.rs

@@ -6,8 +6,7 @@ use crate::length_prefixed::namespaces_with_key;
 use crate::type_helpers::{may_deserialize, must_deserialize};
 use cosmwasm_std::{to_vec, StdResult, Storage};
 
-// TODO: where to add PREFIX_PK????
-
+// TODO: build the final storage key (build_storage_key()) in the constructor, so cheap when we reuse
 pub struct Path<'a, T>
 where
     T: Serialize + DeserializeOwned,

packages/storage-plus/src/prefix.rs

@@ -0,0 +1,51 @@
+#![cfg(feature = "iterator")]
+
+use serde::de::DeserializeOwned;
+use serde::Serialize;
+use std::marker::PhantomData;
+
+use crate::length_prefixed::namespaces_with_key;
+use crate::namespace_helpers::range_with_prefix;
+use crate::type_helpers::deserialize_kv;
+use cosmwasm_std::{Order, StdResult, Storage, KV};
+
+pub struct Prefix<'a, T>
+where
+    T: Serialize + DeserializeOwned,
+{
+    // these are not prefixed
+    namespaces: Vec<&'a [u8]>,
+    // see https://doc.rust-lang.org/std/marker/struct.PhantomData.html#unused-type-parameters for why this is needed
+    data: PhantomData<T>,
+}
+
+impl<'a, T> Prefix<'a, T>
+where
+    T: Serialize + DeserializeOwned,
+{
+    pub fn new(namespaces: Vec<&'a [u8]>) -> Self {
+        Prefix {
+            namespaces,
+            data: PhantomData,
+        }
+    }
+
+    // TODO: parse out composite key prefix???
+    pub fn range<'c, S: Storage>(
+        &'c self,
+        store: &'c S,
+        start: Option<&[u8]>,
+        end: Option<&[u8]>,
+        order: Order,
+    ) -> Box<dyn Iterator<Item = StdResult<KV<T>>> + 'c> {
+        let namespace = self.build_storage_prefix();
+        let mapped =
+            range_with_prefix(store, &namespace, start, end, order).map(deserialize_kv::<T>);
+        Box::new(mapped)
+    }
+
+    /// This provides the raw storage prefix that we use for ranges
+    pub(crate) fn build_storage_prefix(&self) -> Vec<u8> {
+        namespaces_with_key(&self.namespaces, b"")
+    }
+}