qubit_argument/argument/constraint/length_constraint.rs
1// =============================================================================
2// Copyright (c) 2025 - 2026 Haixing Hu.
3//
4// SPDX-License-Identifier: Apache-2.0
5//
6// Licensed under the Apache License, Version 2.0.
7// =============================================================================
8//! Relationships used by string and collection length constraints.
9
10/// A numeric relationship required of a measured string or collection length.
11///
12/// [`LengthMetric`](super::LengthMetric) identifies the measurement unit in a
13/// structured validation error.
14///
15/// # Examples
16///
17/// ```
18/// use qubit_argument::LengthConstraint;
19///
20/// let constraint = LengthConstraint::InRange { min: 2, max: 5 };
21/// assert!(matches!(constraint, LengthConstraint::InRange { min: 2, max: 5 }));
22/// ```
23///
24/// ```compile_fail
25/// #![deny(unused_must_use)]
26/// use qubit_argument::LengthConstraint;
27///
28/// LengthConstraint::Exact(1);
29/// ```
30#[must_use]
31#[derive(Debug, Clone, PartialEq, Eq)]
32pub enum LengthConstraint {
33 /// Requires exactly the specified length.
34 Exact(usize),
35 /// Requires at least the specified length.
36 AtLeast(usize),
37 /// Requires at most the specified length.
38 AtMost(usize),
39 /// Requires a length between `min` and `max`, inclusive.
40 InRange {
41 /// The inclusive minimum length.
42 min: usize,
43 /// The inclusive maximum length.
44 max: usize,
45 },
46}