ABI-compatible and fixed-capacity vectors

.vscode/settings.json

@@ -100,8 +100,12 @@
     "[rust]": {
         "editor.defaultFormatter": "rust-lang.rust-analyzer",
         "editor.formatOnSave": true,
+        "editor.rulers": [
+            150
+        ]
     },
     "rust-analyzer.cargo.cfgs": [
         "!miri"
     ],
+    "rust-analyzer.check.command": "clippy"
 }

Cargo.toml

@@ -2,9 +2,15 @@
 resolver = "2"
 # Split to default members without tests and examples.
 # Used when executing cargo from project root.
-default-members = ["src/log"]
+default-members = [
+    "src/containers",
+    "src/log"
+]
 # Include tests and examples as a member for IDE support and Bazel builds.
-members = ["src/log"]
+members = [
+    "src/containers",
+    "src/log"
+]
 
 
 [workspace.package]

rustfmt.toml

@@ -2,5 +2,7 @@
 # check configuration fields here: https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=
 
 
-tab_spaces = 4
+match_block_trailing_comma = true
 max_width = 150
+tab_spaces = 4
+use_field_init_shorthand = true

src/containers/BUILD

@@ -0,0 +1,30 @@
+# *******************************************************************************
+# Copyright (c) 2025 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License Version 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# SPDX-License-Identifier: Apache-2.0
+# *******************************************************************************
+
+load("@rules_rust//rust:defs.bzl", "rust_library", "rust_test")
+
+rust_library(
+    name = "containers",
+    srcs = glob(["**/*.rs"]),
+    edition = "2024",
+    visibility = ["//visibility:public"],
+)
+
+rust_test(
+    name = "tests",
+    crate = "containers",
+    tags = [
+        "unit_tests",
+        "ut",
+    ],
+)

src/containers/Cargo.toml

@@ -0,0 +1,23 @@
+# *******************************************************************************
+# Copyright (c) 2025 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License Version 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# SPDX-License-Identifier: Apache-2.0
+# *******************************************************************************
+
+[package]
+name = "containers"
+description = "Fixed-capacity and inline-storage containers"
+version = "0.1.0"
+authors = ["Contributors to the Eclipse Foundation"]
+edition = "2024"
+license-file = "../../LICENSE.md"
+
+[lib]
+path = "lib.rs"

src/containers/fixed_capacity/mod.rs

@@ -0,0 +1,16 @@
+// *******************************************************************************
+// Copyright (c) 2025 Contributors to the Eclipse Foundation
+//
+// See the NOTICE file(s) distributed with this work for additional
+// information regarding copyright ownership.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Apache License Version 2.0 which is available at
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// SPDX-License-Identifier: Apache-2.0
+// *******************************************************************************
+
+mod vec;
+
+pub use self::vec::FixedCapacityVec;

src/containers/fixed_capacity/vec.rs

@@ -0,0 +1,136 @@
+// *******************************************************************************
+// Copyright (c) 2025 Contributors to the Eclipse Foundation
+//
+// See the NOTICE file(s) distributed with this work for additional
+// information regarding copyright ownership.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Apache License Version 2.0 which is available at
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// SPDX-License-Identifier: Apache-2.0
+// *******************************************************************************
+
+use core::fmt;
+use core::ops;
+
+use crate::generic::vec::GenericVec;
+use crate::storage::Heap;
+
+/// A fixed-capacity vector.
+///
+/// The vector can hold between 0 and `CAPACITY` elements, and behaves similarly to Rust's `Vec`,
+/// except that it allocates memory immediately on construction, and can't shrink or grow.
+pub struct FixedCapacityVec<T> {
+    inner: GenericVec<T, Heap<T>>,
+}
+
+impl<T> FixedCapacityVec<T> {
+    /// Creates an empty vector and allocates memory for up to `capacity` elements, where `capacity <= u32::MAX`.
+    ///
+    /// # Panics
+    ///
+    /// - Panics if `capacity > u32::MAX`.
+    /// - Panics if the memory allocation fails.
+    #[must_use]
+    pub fn new(capacity: usize) -> Self {
+        assert!(capacity <= u32::MAX as usize, "FixedCapacityVec can hold at most u32::MAX elements");
+        Self {
+            inner: GenericVec::new(capacity as u32),
+        }
+    }
+}
+
+impl<T> Drop for FixedCapacityVec<T> {
+    fn drop(&mut self) {
+        self.inner.clear();
+    }
+}
+
+impl<T> ops::Deref for FixedCapacityVec<T> {
+    type Target = GenericVec<T, Heap<T>>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+impl<T> ops::DerefMut for FixedCapacityVec<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.inner
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for FixedCapacityVec<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(self.as_slice(), f)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn push_and_pop() {
+        fn run_test(n: usize) {
+            let mut vector = FixedCapacityVec::<i64>::new(n);
+            let mut control = vec![];
+
+            let result = vector.pop();
+            assert_eq!(result, None);
+
+            for i in 0..n {
+                let value = i as i64 * 123 + 456;
+                let result = vector.push(value);
+                assert_eq!(*result.unwrap(), value);
+                control.push(value);
+                assert_eq!(vector.as_slice(), control.as_slice());
+            }
+
+            let result = vector.push(123456);
+            assert!(result.is_err());
+
+            for _ in 0..n {
+                let expected = control.pop().unwrap();
+                let actual = vector.pop();
+                assert_eq!(actual, Some(expected));
+            }
+
+            let result = vector.pop();
+            assert_eq!(result, None);
+        }
+
+        for i in 0..6 {
+            run_test(i);
+        }
+    }
+
+    #[test]
+    fn is_full_and_is_empty() {
+        fn run_test(n: usize) {
+            let mut vector = FixedCapacityVec::<i64>::new(n);
+            assert!(vector.is_empty());
+
+            for i in 0..n {
+                assert!(!vector.is_full());
+                vector.push(i as i64 * 123 + 456).unwrap();
+                assert!(!vector.is_empty());
+            }
+
+            assert!(vector.is_full());
+
+            for _ in 0..n {
+                assert!(!vector.is_empty());
+                vector.pop();
+                assert!(!vector.is_full());
+            }
+
+            assert!(vector.is_empty());
+        }
+
+        for i in 0..6 {
+            run_test(i);
+        }
+    }
+}

src/containers/generic/mod.rs

@@ -0,0 +1,14 @@
+// *******************************************************************************
+// Copyright (c) 2025 Contributors to the Eclipse Foundation
+//
+// See the NOTICE file(s) distributed with this work for additional
+// information regarding copyright ownership.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Apache License Version 2.0 which is available at
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// SPDX-License-Identifier: Apache-2.0
+// *******************************************************************************
+
+pub(crate) mod vec;