quantrs2-sim 0.1.3

Quantum circuit simulators for the QuantRS2 framework
Documentation
//! Metal-based GPU acceleration for macOS
//!
//! This module provides GPU acceleration using Apple's Metal API
//! for quantum circuit simulation on macOS devices.
//!
//! TODO: Implement using Metal Performance Shaders (MPS) and Metal Compute Shaders
//!
//! Key components to implement:
//! - State vector allocation using Metal buffers
//! - Quantum gate kernels using Metal shaders
//! - Memory management for unified memory architecture
//! - Optimizations for Apple Silicon (M1/M2/M3)

use crate::error::{Result, SimulatorError};
use quantrs2_circuit::prelude::Circuit;
use quantrs2_core::prelude::QubitId;
use std::sync::Arc;

/// Metal-based GPU simulator for macOS
pub struct MetalGpuSimulator {
    /// Number of qubits
    num_qubits: usize,
    /// Metal device handle (placeholder)
    _device: Arc<()>,
}

impl MetalGpuSimulator {
    /// Create a new Metal GPU simulator
    pub fn new(num_qubits: usize) -> Result<Self> {
        // TODO: Initialize Metal device
        // TODO: Check for Metal support
        // TODO: Create command queue

        Err(SimulatorError::GpuError(
            "Metal GPU support not yet implemented. Please use CPU simulation on macOS for now."
                .to_string(),
        ))
    }

    /// Simulate a quantum circuit
    pub fn simulate<const N: usize>(&mut self, _circuit: &Circuit<N>) -> Result<()> {
        Err(SimulatorError::GpuError(
            "Metal GPU simulation not yet implemented".to_string(),
        ))
    }

    /// Get available Metal devices
    pub const fn available_devices() -> Vec<String> {
        // TODO: Query Metal devices
        // - Apple Silicon GPU
        // - Intel integrated GPU
        // - AMD Radeon GPU
        vec![]
    }

    /// Check if Metal is available on this system
    pub const fn is_available() -> bool {
        // TODO: Check for Metal framework availability
        false
    }
}

/// Metal GPU backend interface (placeholder for future implementation)
pub trait MetalBackend {
    /// Allocate state vector on GPU
    fn allocate_state_vector(&self, size: usize) -> Result<()>;

    /// Apply quantum gate
    fn apply_gate(&self, gate: &str, qubits: &[QubitId]) -> Result<()>;

    /// Transfer data between CPU and GPU
    fn sync(&self) -> Result<()>;
}