quantrs2_circuit/verifier/

model_checker.rs

//! Model checker for temporal properties

use super::config::VerifierConfig;
use super::types::*;
use crate::builder::Circuit;
use crate::scirs2_integration::SciRS2CircuitAnalyzer;
use quantrs2_core::error::QuantRS2Result;
use serde::{Deserialize, Serialize};
use std::collections::{HashMap, HashSet};
use std::time::Duration;

/// Model checker for temporal properties
pub struct ModelChecker<const N: usize> {
    /// Temporal properties to check
    properties: Vec<TemporalProperty>,
    /// Model checking results
    results: HashMap<String, ModelCheckResult>,
    /// State space representation
    state_space: StateSpace<N>,
    /// `SciRS2` analyzer
    analyzer: SciRS2CircuitAnalyzer,
}

/// State space representation
pub struct StateSpace<const N: usize> {
    /// States in the space
    pub states: HashMap<usize, QuantumState>,
    /// Transitions between states
    pub transitions: HashMap<(usize, usize), StateTransition>,
    /// Initial states
    pub initial_states: HashSet<usize>,
    /// Final states
    pub final_states: HashSet<usize>,
}

/// Temporal logic properties
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum TemporalProperty {
    /// Always property (globally)
    Always { property: String },
    /// Eventually property (finally)
    Eventually { property: String },
    /// Next property
    Next { property: String },
    /// Until property
    Until {
        property1: String,
        property2: String,
    },
    /// Liveness property
    Liveness { property: String },
    /// Safety property
    Safety { property: String },
    /// CTL formula
    Ctl { formula: String },
    /// LTL formula
    Ltl { formula: String },
}

/// Model checking result
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ModelCheckResult {
    /// Property name
    pub property_name: String,
    /// Model checking outcome
    pub result: VerificationOutcome,
    /// Witness trace if property holds
    pub witness_trace: Option<ExecutionTrace>,
    /// Counterexample trace if property violated
    pub counterexample_trace: Option<ExecutionTrace>,
    /// Model checking time
    pub check_time: Duration,
    /// State space statistics
    pub state_space_stats: StateSpaceStatistics,
}

impl<const N: usize> ModelChecker<N> {
    /// Create new model checker
    #[must_use]
    pub fn new() -> Self {
        Self {
            properties: Vec::new(),
            results: HashMap::new(),
            state_space: StateSpace {
                states: HashMap::new(),
                transitions: HashMap::new(),
                initial_states: HashSet::new(),
                final_states: HashSet::new(),
            },
            analyzer: SciRS2CircuitAnalyzer::new(),
        }
    }

    /// Check all properties
    pub fn check_all_properties(
        &self,
        circuit: &Circuit<N>,
        _config: &VerifierConfig,
    ) -> QuantRS2Result<Vec<ModelCheckResult>> {
        // Run lightweight syntactic checks against the registered temporal
        // properties. Without enumerating the full state space we cannot
        // give a definitive answer, so any non-trivial property reports
        // `Unknown`; structural properties — non-empty circuit / qubit
        // bound — are answered concretely.
        let total = circuit.num_gates();
        let mut results = Vec::new();
        let stats = StateSpaceStatistics {
            total_states: total,
            total_transitions: total.saturating_sub(1),
            max_path_length: total,
            avg_path_length: if total == 0 { 0.0 } else { total as f64 },
            diameter: total,
            memory_usage: std::mem::size_of::<Self>(),
        };
        for property in &self.properties {
            let (name, outcome) = match property {
                TemporalProperty::Always { property } => (
                    property.clone(),
                    if total > 0 {
                        VerificationOutcome::Unknown
                    } else {
                        VerificationOutcome::Satisfied
                    },
                ),
                TemporalProperty::Eventually { property }
                | TemporalProperty::Next { property }
                | TemporalProperty::Liveness { property }
                | TemporalProperty::Safety { property } => {
                    (property.clone(), VerificationOutcome::Unknown)
                }
                TemporalProperty::Until {
                    property1,
                    property2,
                } => (
                    format!("{property1} U {property2}"),
                    VerificationOutcome::Unknown,
                ),
                TemporalProperty::Ctl { formula } | TemporalProperty::Ltl { formula } => {
                    (formula.clone(), VerificationOutcome::Unknown)
                }
            };
            results.push(ModelCheckResult {
                property_name: name,
                result: outcome,
                witness_trace: None,
                counterexample_trace: None,
                check_time: Duration::from_micros(0),
                state_space_stats: stats.clone(),
            });
        }
        Ok(results)
    }
}

impl<const N: usize> Default for ModelChecker<N> {
    fn default() -> Self {
        Self::new()
    }
}

/// Correctness checker
pub struct CorrectnessChecker<const N: usize> {
    /// Correctness criteria
    criteria: Vec<CorrectnessCriterion<N>>,
    /// Checking results
    results: HashMap<String, CorrectnessResult>,
    /// Reference implementations
    references: HashMap<String, Circuit<N>>,
    /// `SciRS2` analyzer
    analyzer: SciRS2CircuitAnalyzer,
}

/// Correctness criteria
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum CorrectnessCriterion<const N: usize> {
    /// Functional correctness
    Functional {
        test_cases: Vec<TestCase>,
        tolerance: f64,
    },
    /// Performance correctness
    Performance {
        max_execution_time: Duration,
        max_memory_usage: usize,
    },
    /// Robustness to noise
    Robustness {
        noise_models: Vec<ErrorModel>,
        tolerance: f64,
    },
    /// Resource efficiency
    ResourceEfficiency {
        max_gates: usize,
        max_depth: usize,
        max_qubits: usize,
    },
    /// Scalability
    Scalability {
        problem_sizes: Vec<usize>,
        expected_complexity: ComplexityClass,
    },
}

/// Correctness checking result
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CorrectnessResult {
    /// Criterion name
    pub criterion_name: String,
    /// Correctness status
    pub status: VerificationOutcome,
    /// Test results
    pub test_results: Vec<VerifierTestResult>,
    /// Overall score
    pub score: f64,
    /// Checking time
    pub check_time: Duration,
}

/// Individual test result
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct VerifierTestResult {
    /// Test case description
    pub test_description: String,
    /// Test outcome
    pub outcome: TestOutcome,
    /// Measured error
    pub error: f64,
    /// Test execution time
    pub execution_time: Duration,
}

impl<const N: usize> CorrectnessChecker<N> {
    /// Create new correctness checker
    #[must_use]
    pub fn new() -> Self {
        Self {
            criteria: Vec::new(),
            results: HashMap::new(),
            references: HashMap::new(),
            analyzer: SciRS2CircuitAnalyzer::new(),
        }
    }
}

impl<const N: usize> Default for CorrectnessChecker<N> {
    fn default() -> Self {
        Self::new()
    }
}