Fork indexmap into ringmap, based on VecDeque

Author: cuviper

.github/workflows/ci.yml

@@ -1,8 +1,8 @@
 on:
   push:
-    branches: [ master ]
+    branches: [ main ]
   pull_request:
-    branches: [ master ]
+    branches: [ main ]
   merge_group:
 
 name: CI
@@ -17,16 +17,14 @@ jobs:
     strategy:
       matrix:
         include:
-          - rust: 1.63.0 # MSRV
+          - rust: 1.68.0 # MSRV
             features:
           - rust: stable
             features: arbitrary
           - rust: stable
             features: quickcheck
           - rust: stable
             features: rayon
-          - rust: stable
-            features: rustc-rayon
           - rust: stable
             features: serde
           - rust: stable
@@ -40,11 +38,6 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/cache@v4
-        if: matrix.rust == '1.63.0'
-        with:
-          path: ~/.cargo/registry/index
-          key: cargo-git-index
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -72,18 +65,13 @@ jobs:
     strategy:
       matrix:
         include:
-          - rust: 1.63.0
+          - rust: 1.68.0
             target: thumbv6m-none-eabi
           - rust: stable
             target: thumbv6m-none-eabi
 
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/cache@v4
-        if: matrix.rust == '1.63.0'
-        with:
-          path: ~/.cargo/registry/index
-          key: cargo-git-index
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -121,12 +109,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/cache@v4
-        with:
-          path: ~/.cargo/registry/index
-          key: cargo-git-index
       - uses: dtolnay/rust-toolchain@nightly
-      - uses: dtolnay/rust-toolchain@1.63.0 # MSRV
+      - uses: dtolnay/rust-toolchain@1.68.0 # MSRV
       - uses: taiki-e/install-action@v2
         with:
           tool: cargo-hack

Cargo.toml

@@ -1,14 +1,14 @@
 [package]
-name = "indexmap"
+name = "ringmap"
 edition = "2021"
-version = "2.7.1"
-documentation = "https://docs.rs/indexmap/"
-repository = "https://github.com/indexmap-rs/indexmap"
+version = "0.1.0"
+documentation = "https://docs.rs/ringmap/"
+repository = "https://github.com/indexmap-rs/ringmap"
 license = "Apache-2.0 OR MIT"
-description = "A hash table with consistent order and fast iteration."
+description = "A hash table with consistent deque-like order and fast iteration."
 keywords = ["hashmap", "no_std"]
 categories = ["data-structures", "no-std"]
-rust-version = "1.63"
+rust-version = "1.68"
 
 [lib]
 bench = false
@@ -22,10 +22,6 @@ serde = { version = "1.0", optional = true, default-features = false }
 borsh = { version = "1.2", optional = true, default-features = false }
 rayon = { version = "1.9", optional = true }
 
-# Internal feature, only used when building as part of rustc,
-# not part of the stable interface of this crate.
-rustc-rayon = { package = "rustc-rayon", version = "0.5", optional = true }
-
 [dependencies.hashbrown]
 version = "0.15.0"
 default-features = false
@@ -49,7 +45,7 @@ test_debug = []
 debug = true
 
 [package.metadata.release]
-allow-branch = ["master"]
+allow-branch = ["main"]
 sign-tag = true
 tag-name = "{{version}}"
 

README.md

@@ -1,59 +1,41 @@
-# indexmap
+# ringmap
 
-[![build status](https://github.com/indexmap-rs/indexmap/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/indexmap-rs/indexmap/actions)
-[![crates.io](https://img.shields.io/crates/v/indexmap.svg)](https://crates.io/crates/indexmap)
-[![docs](https://docs.rs/indexmap/badge.svg)](https://docs.rs/indexmap)
-[![rustc](https://img.shields.io/badge/rust-1.63%2B-orange.svg)](https://img.shields.io/badge/rust-1.63%2B-orange.svg)
+[![build status](https://github.com/indexmap-rs/ringmap/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/indexmap-rs/ringmap/actions)
+[![crates.io](https://img.shields.io/crates/v/ringmap.svg)](https://crates.io/crates/ringmap)
+[![docs](https://docs.rs/ringmap/badge.svg)](https://docs.rs/ringmap)
+[![rustc](https://img.shields.io/badge/rust-1.68%2B-orange.svg)](https://img.shields.io/badge/rust-1.68%2B-orange.svg)
 
-A pure-Rust hash table which preserves (in a limited sense) insertion order.
+A pure-Rust hash table which preserves (in a limited sense) insertion order,
+with efficient deque-like manipulation of both the front and back ends.
 
 This crate implements compact map and set data-structures,
 where the iteration order of the keys is independent from their hash or
-value. It preserves insertion order (except after removals), and it
+value. It preserves insertion order in most mutating operations, and it
 allows lookup of entries by either hash table key or numerical index.
 
-Note: this crate was originally released under the name `ordermap`,
-but it was renamed to `indexmap` to better reflect its features.
-The [`ordermap`](https://crates.io/crates/ordermap) crate now exists
-as a wrapper over `indexmap` with stronger ordering properties.
-
 # Background
 
-This was inspired by Python 3.6's new dict implementation (which remembers
-the insertion order and is fast to iterate, and is compact in memory).
-
-Some of those features were translated to Rust, and some were not. The result
-was indexmap, a hash table that has following properties:
+This crate was forked from [`indexmap`](https://crates.io/crates/indexmap),
+with the primary difference being a change from `Vec` to `VecDeque` for the
+primary item storage. As a result, it has many of the same properties, as
+well as a few new ones:
 
 - Order is **independent of hash function** and hash values of keys.
 - Fast to iterate.
 - Indexed in compact space.
-- Preserves insertion order **as long** as you don't call `.remove()`,
-  `.swap_remove()`, or other methods that explicitly change order.
-  The alternate `.shift_remove()` does preserve relative order.
+- Efficient pushing and popping from both the front and back.
+- Preserves insertion order **as long** as you don't call `.swap_remove_back()`
+  or other methods that explicitly change order.
+  - In `ringmap`, the regular `.remove()` **does** preserve insertion order,
+    equivalent to what `indexmap` calls `.shift_remove()`.
 - Uses hashbrown for the inner table, just like Rust's libstd `HashMap` does.
 
-## Performance
-
-`IndexMap` derives a couple of performance facts directly from how it is constructed,
-which is roughly:
-
-> A raw hash table of key-value indices, and a vector of key-value pairs.
-
-- Iteration is very fast since it is on the dense key-values.
-- Removal is fast since it moves memory areas only in the table,
-  and uses a single swap in the vector.
-- Lookup is fast-ish because the initial 7-bit hash lookup uses SIMD, and indices are
-  densely stored. Lookup also is slow-ish since the actual key-value pairs are stored
-  separately. (Visible when cpu caches size is limiting.)
-
-- In practice, `IndexMap` has been tested out as the hashmap in rustc in [PR45282] and
-  the performance was roughly on par across the whole workload.
-- If you want the properties of `IndexMap`, or its strongest performance points
-  fits your workload, it might be the best hash table implementation.
-
-[PR45282]: https://github.com/rust-lang/rust/pull/45282
+`ringmap` also follows [`ordermap`](https://crates.io/crates/ordermap) in using
+its entry order for `PartialEq` and `Eq`, whereas `indexmap` considers the same
+entries in *any* order to be equal for drop-in compatibility with `HashMap`
+semantics. Using the order is faster, and also allows `ringmap` to implement
+`PartialOrd`, `Ord`, and `Hash`.
 
 # Recent Changes
 
-See [RELEASES.md](https://github.com/indexmap-rs/indexmap/blob/master/RELEASES.md).
+See [RELEASES.md](https://github.com/indexmap-rs/ringmap/blob/main/RELEASES.md).