qubit_codec/transcode/engine/
encode_context.rs

1// =============================================================================
2//    Copyright (c) 2026 Haixing Hu.
3//
4//    SPDX-License-Identifier: Apache-2.0
5//
6//    Licensed under the Apache License, Version 2.0.
7// =============================================================================
8//! Read-only policy context for one buffered encode attempt.
9
10/// Read-only context supplied to an encode policy hook.
11///
12/// The engine retains ownership of the mutable output slice. Hooks can inspect
13/// the current value and cursor/capacity metadata, then return an
14/// [`crate::engine::EncodeUnencodableAction`] without being able to mutate
15/// output behind the engine's progress accounting.
16///
17/// # Type Parameters
18///
19/// - `Value`: Logical input value type.
20#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
21pub struct EncodeContext<'a, Value> {
22    input_value: &'a Value,
23    input_index: usize,
24    output_index: usize,
25    available_output: usize,
26}
27
28impl<'a, Value> EncodeContext<'a, Value> {
29    /// Creates an encode policy context.
30    ///
31    /// # Parameters
32    ///
33    /// - `input_value`: Borrowed input value being encoded.
34    /// - `input_index`: Absolute input index of `input_value`.
35    /// - `output_index`: Absolute output index where writing begins.
36    /// - `available_output`: Output units writable from `output_index`.
37    ///
38    /// # Returns
39    ///
40    /// Returns a read-only encode context.
41    #[inline(always)]
42    #[must_use]
43    pub const fn new(
44        input_value: &'a Value,
45        input_index: usize,
46        output_index: usize,
47        available_output: usize,
48    ) -> Self {
49        Self {
50            input_value,
51            input_index,
52            output_index,
53            available_output,
54        }
55    }
56
57    /// Returns the input value being encoded.
58    #[inline(always)]
59    #[must_use]
60    pub const fn input_value(&self) -> &Value {
61        self.input_value
62    }
63
64    /// Returns the absolute input index of the current value.
65    #[inline(always)]
66    #[must_use]
67    pub const fn input_index(&self) -> usize {
68        self.input_index
69    }
70
71    /// Returns the absolute output index where writing begins.
72    #[inline(always)]
73    #[must_use]
74    pub const fn output_index(&self) -> usize {
75        self.output_index
76    }
77
78    /// Returns output capacity visible to this encode attempt.
79    #[inline(always)]
80    #[must_use]
81    pub const fn available_output(&self) -> usize {
82        self.available_output
83    }
84}
qubit_codec/transcode/engine/encode_context.rs

qubit_codec/transcode/engine/
encode_context.rs
