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/*******************************************************************************
*
* Copyright (c) 2026 Haixing Hu.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0.
*
******************************************************************************/
//! Encode context for one buffered encode step.
/// Context for one encode attempt inside a buffered encoder engine.
///
/// The context carries the current input value and output cursor. It does not
/// contain the prepared [`crate::EncodePlan`]; the engine keeps planning
/// separate so callers and hooks can distinguish cursor state from policy state.
///
/// # Type Parameters
///
/// - `Value`: Logical input value type.
/// - `Unit`: Encoded output unit type.
#[derive(Debug)]
pub struct EncodeContext<'a, Value, Unit> {
/// Input value being encoded.
pub input_value: &'a Value,
/// Absolute input index of [`input_value`](Self::input_value).
pub input_index: usize,
/// Complete output unit slice visible to the encoder.
pub output: &'a mut [Unit],
/// Start position in [`output`](Self::output) where writing begins.
pub output_index: usize,
}
impl<Value, Unit> EncodeContext<'_, Value, Unit> {
/// Returns writable output units from the current output index.
///
/// # Returns
///
/// Returns output capacity visible to this encode step.
#[must_use]
#[inline(always)]
pub fn available_output(&self) -> usize {
self.output.len().saturating_sub(self.output_index)
}
}