zrx-scheduler 0.0.2

// Copyright (c) 2025 Zensical and contributors

// SPDX-License-Identifier: MIT
// Third-party contributions licensed under DCO

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// ----------------------------------------------------------------------------

//! Source action.

use crate::scheduler::action::output::Outputs;
use crate::scheduler::action::{Action, Input, Result};

// ----------------------------------------------------------------------------
// Structs
// ----------------------------------------------------------------------------

/// Source action.
///
/// This action is solely intended as a marker, and is essential to represent
/// sources in a workflow, which is necessary to pass data to a workflow. Thus,
/// it will always panic, as it should never be executed, but merely serves as
/// a placeholder in the graph to represent a source.
pub struct Marker;

// ----------------------------------------------------------------------------
// Implementations
// ----------------------------------------------------------------------------

impl<I> Action<I> for Marker {
    /// Executes the action.
    fn execute(&mut self, _: Input<I>) -> Result<Outputs<I>> {
        // This action should never be executed, as it's solely a marker, so
        // if we ever reach this point, it denotes a bug in our implementation.
        panic!("invariant");
    }
}