gear_common/storage/primitives/
iterable.rs

1// Copyright (C) Gear Technologies Inc.
2// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
3
4//! Module for map's iterator primitives.
5//!
6//! Map's iterators primitives declares the ability
7//! to iter through defined generic `Item` over the map
8//! with specified (associated) types of iterators
9//! for drain or just iter elements.
10//!
11//! `DrainIter` used for element's removal
12//! on each iteration, while `Iter` used for
13//! just checking them.
14
15use super::TransposeCallback;
16use core::marker::PhantomData;
17
18/// Represents iterable logic for double key maps
19/// (Key1 -> Key2 -> Value).
20///
21/// Returns the iterators over specified (associated)
22/// type of the first key's items.
23pub trait IterableByKeyMap<Item> {
24    /// Map's first key type.
25    type Key;
26    /// Removal iterator type.
27    type DrainIter: Iterator<Item = Item>;
28    /// Getting iterator type.
29    type Iter: Iterator<Item = Item>;
30
31    /// Creates the removal iterator over double map Items.
32    fn drain_key(key: Self::Key) -> Self::DrainIter;
33    /// Creates the getting iterator over double map Items.
34    fn iter_key(key: Self::Key) -> Self::Iter;
35}
36
37/// Represents iterable logic for single key maps
38/// (Key -> Value).
39pub trait IterableMap<Item> {
40    /// Removal iterator type.
41    type DrainIter: Iterator<Item = Item>;
42    /// Getting iterator type.
43    type Iter: Iterator<Item = Item>;
44
45    /// Creates the removal iterator over map Items.
46    fn drain() -> Self::DrainIter;
47    /// Creates the getting iterator over map Items.
48    fn iter() -> Self::Iter;
49}
50
51/// Represents iterable over second keys logic for double key maps
52/// (Key1 -> Key2 -> Value).
53///
54/// Returns the iterators over specified (associated)
55/// type of the second map keys by given first key.
56pub trait KeyIterableByKeyMap {
57    /// Map's first key type.
58    type Key1;
59    /// Map's second key type.
60    type Key2;
61    /// Removal iterator type.
62    type DrainIter: Iterator<Item = Self::Key2>;
63    /// Getting iterator type.
64    type Iter: Iterator<Item = Self::Key2>;
65
66    /// Creates the removal iterator over double map Items.
67    fn drain_prefix_keys(key: Self::Key1) -> Self::DrainIter;
68    /// Creates the getting iterator over double map Items.
69    fn iter_prefix_keys(key: Self::Key1) -> Self::Iter;
70}
71
72/// Transpose callback for getting first element of tuple.
73pub struct GetFirstPos;
74
75// `TransposeCallback` implementation for tuple with two elements.
76impl<K, V> TransposeCallback<(K, V), K> for GetFirstPos {
77    fn call(arg: (K, V)) -> K {
78        arg.0
79    }
80}
81
82// `TransposeCallback` implementation for tuple with three elements.
83impl<K1, K2, V> TransposeCallback<(K1, K2, V), K1> for GetFirstPos {
84    fn call(arg: (K1, K2, V)) -> K1 {
85        arg.0
86    }
87}
88
89/// Transpose callback for getting second element of tuple.
90pub struct GetSecondPos;
91
92// `TransposeCallback` implementation for tuple with two elements.
93impl<K, V> TransposeCallback<(K, V), V> for GetSecondPos {
94    fn call(arg: (K, V)) -> V {
95        arg.1
96    }
97}
98
99// `TransposeCallback` implementation for tuple with three elements.
100impl<K1, K2, V> TransposeCallback<(K1, K2, V), K2> for GetSecondPos {
101    fn call(arg: (K1, K2, V)) -> K2 {
102        arg.1
103    }
104}
105
106/// Transpose callback for getting third element of tuple.
107pub struct GetThirdPos;
108
109// `TransposeCallback` implementation for tuple with three elements.
110impl<K1, K2, V> TransposeCallback<(K1, K2, V), V> for GetThirdPos {
111    fn call(arg: (K1, K2, V)) -> V {
112        arg.2
113    }
114}
115
116/// Represents wrapper for any iterator with ability
117/// to transpose `.next()` result.
118pub struct IteratorWrap<I, Item = <I as Iterator>::Item, TC = ()>(I, PhantomData<(Item, TC)>)
119where
120    I: Iterator,
121    TC: TransposeCallback<I::Item, Item>;
122
123// Implementation of `From` for any iterator.
124impl<I, Item, TC> From<I> for IteratorWrap<I, Item, TC>
125where
126    I: Iterator,
127    TC: TransposeCallback<I::Item, Item>,
128{
129    fn from(iterator: I) -> Self {
130        Self(iterator, PhantomData)
131    }
132}
133
134// Implementation of `Iterator` itself for the wrapper
135// based on inner iterator and transpose callback.
136impl<I, Item, TC> Iterator for IteratorWrap<I, Item, TC>
137where
138    I: Iterator,
139    TC: TransposeCallback<I::Item, Item>,
140{
141    type Item = Item;
142
143    fn next(&mut self) -> Option<Self::Item> {
144        self.0.next().map(TC::call)
145    }
146}
gear_common/storage/primitives/iterable.rs

gear_common/storage/primitives/
iterable.rs
