zrx_graph/graph/iter/
groups.rs

1// Copyright (c) 2025-2026 Zensical and contributors
2
3// SPDX-License-Identifier: MIT
4// All contributions are certified under the DCO
5
6// Permission is hereby granted, free of charge, to any person obtaining a copy
7// of this software and associated documentation files (the "Software"), to
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9// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10// sell copies of the Software, and to permit persons to whom the Software is
11// furnished to do so, subject to the following conditions:
12
13// The above copyright notice and this permission notice shall be included in
14// all copies or substantial portions of the Software.
15
16// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18// FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
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20// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22// IN THE SOFTWARE.
23
24// ----------------------------------------------------------------------------
25
26//! Iterator over key-groups.
27
28use std::collections::btree_map::{self, BTreeMap};
29
30use crate::graph::Graph;
31
32// ----------------------------------------------------------------------------
33// Structs
34// ----------------------------------------------------------------------------
35
36/// Iterator over key-groups.
37pub struct Groups<K> {
38    /// Iterator over groups.
39    inner: btree_map::IntoIter<K, Vec<usize>>,
40}
41
42// ----------------------------------------------------------------------------
43// Implementations
44// ----------------------------------------------------------------------------
45
46impl<T, R> Graph<T, R> {
47    /// Creates an iterator over key-groups.
48    ///
49    /// # Examples
50    ///
51    /// ```
52    /// # use std::error::Error;
53    /// # fn main() -> Result<(), Box<dyn Error>> {
54    /// use zrx_graph::Graph;
55    ///
56    /// // Create graph builder and add nodes
57    /// let mut builder = Graph::builder();
58    /// let a = builder.add_node("a");
59    /// let b = builder.add_node("b");
60    /// let c = builder.add_node("c");
61    ///
62    /// // Create edges between nodes
63    /// builder.add_edge(a, b)?;
64    /// builder.add_edge(b, c)?;
65    ///
66    /// // Create graph from builder
67    /// let graph = builder.build();
68    ///
69    /// // Create iterator over key-groups
70    /// for (key, nodes) in graph.groups(|node| node.len()) {
71    ///     println!("{key}: {nodes:?}");
72    /// }
73    /// # Ok(())
74    /// # }
75    /// ```
76    #[must_use]
77    pub fn groups<'a, F, K>(&'a self, f: F) -> Groups<K>
78    where
79        F: Fn(&'a T) -> K,
80        K: Ord,
81    {
82        let mut groups: BTreeMap<K, Vec<usize>> = BTreeMap::new();
83        for node in self {
84            groups.entry(f(&self[node])).or_default().push(node);
85        }
86        Groups { inner: groups.into_iter() }
87    }
88}
89
90// ----------------------------------------------------------------------------
91// Trait implementations
92// ----------------------------------------------------------------------------
93
94impl<K> Iterator for Groups<K> {
95    type Item = (K, Vec<usize>);
96
97    /// Returns the next key-group.
98    fn next(&mut self) -> Option<Self::Item> {
99        self.inner.next()
100    }
101}
zrx_graph/graph/iter/groups.rs

zrx_graph/graph/iter/
groups.rs
