boolector 0.4.3

use crate::node::{Array, BV};
use crate::option::BtorOption;
use crate::option::*;
use crate::timeout::{self, TimeoutState};
use boolector_sys::*;
use std::borrow::Borrow;
use std::ffi::{CStr, CString};
use std::fmt;
use std::os::raw::{c_char, c_void};
use std::pin::Pin;

/// A `Btor` represents an instance of the Boolector solver.
/// Each `BV` and `Array` is created in a particular `Btor` instance.
pub struct Btor {
    btor: *mut boolector_sys::Btor,
    pub(crate) timeout_state: Pin<Box<timeout::TimeoutState>>, // needs to be `Pin`, because the Boolector callback will expect to continue to find the `TimeoutState` at the same location
}

// Two `Btor`s are equal if they have the same underlying Btor pointer.
// We disregard the `timeout_state` for this purpose.
impl PartialEq for Btor {
    fn eq(&self, other: &Self) -> bool {
        self.btor == other.btor
    }
}

impl Eq for Btor {}

impl fmt::Debug for Btor {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "<btor {:?}>", self.btor)
    }
}

/// According to
/// https://groups.google.com/forum/#!msg/boolector/itYGgJxU3mY/AC2O0898BAAJ,
/// the Boolector library is thread-safe, so we make `Btor` both `Send` and
/// `Sync`. (Note that `TimeoutState` is also careful to be both `Send` and
/// `Sync`.)
unsafe impl Send for Btor {}
unsafe impl Sync for Btor {}

impl Btor {
    /// Create a new `Btor` instance with no variables and no constraints.
    pub fn new() -> Self {
        Self {
            btor: unsafe { boolector_new() },
            timeout_state: Pin::new(Box::new(timeout::TimeoutState::new())),
        }
    }

    pub(crate) fn as_raw(&self) -> *mut boolector_sys::Btor {
        self.btor
    }

    /// Set an option to a particular value.
    #[allow(clippy::cognitive_complexity)]
    pub fn set_opt(&self, opt: BtorOption) {
        match opt {
            BtorOption::ModelGen(mg) => {
                let val = match mg {
                    ModelGen::Disabled => 0,
                    ModelGen::Asserted => 1,
                    ModelGen::All => 2,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_MODEL_GEN, val) }
            },
            BtorOption::Incremental(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_INCREMENTAL, if b { 1 } else { 0 })
            },
            BtorOption::IncrementalSMT1(ismt1) => {
                let val = match ismt1 {
                    IncrementalSMT1::Basic => BTOR_INCREMENTAL_SMT1_BASIC,
                    IncrementalSMT1::Continue => BTOR_INCREMENTAL_SMT1_CONTINUE,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_INCREMENTAL_SMT1, val) }
            },
            BtorOption::InputFileFormat(iff) => {
                let val = match iff {
                    InputFileFormat::Autodetect => BTOR_INPUT_FORMAT_NONE,
                    InputFileFormat::Btor => BTOR_INPUT_FORMAT_BTOR,
                    InputFileFormat::Btor2 => BTOR_INPUT_FORMAT_BTOR2,
                    InputFileFormat::SMTLIBv1 => BTOR_INPUT_FORMAT_SMT1,
                    InputFileFormat::SMTLIBv2 => BTOR_INPUT_FORMAT_SMT2,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_INPUT_FORMAT, val) }
            },
            BtorOption::OutputNumberFormat(nf) => {
                let val = match nf {
                    NumberFormat::Binary => BTOR_OUTPUT_BASE_BIN,
                    NumberFormat::Decimal => BTOR_OUTPUT_BASE_DEC,
                    NumberFormat::Hexadecimal => BTOR_OUTPUT_BASE_HEX,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_OUTPUT_NUMBER_FORMAT, val) }
            },
            BtorOption::OutputFileFormat(off) => {
                let val = match off {
                    OutputFileFormat::BTOR => BTOR_OUTPUT_FORMAT_BTOR,
                    OutputFileFormat::SMTLIBv2 => BTOR_OUTPUT_FORMAT_SMT2,
                    OutputFileFormat::AigerASCII => BTOR_OUTPUT_FORMAT_AIGER_ASCII,
                    OutputFileFormat::AigerBinary => BTOR_OUTPUT_FORMAT_AIGER_BINARY,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_OUTPUT_FORMAT, val) }
            },
            BtorOption::SolverTimeout(duration) => {
                self.timeout_state.set_timeout_duration(duration);
                match duration {
                    None => {
                        // remove any existing timeout
                        unsafe { boolector_set_term(self.as_raw(), None, std::ptr::null_mut()) }
                    },
                    Some(_) => {
                        let ptr_to_ts: Pin<&TimeoutState> = (&self.timeout_state).as_ref();
                        let raw_ptr_to_ts: *const TimeoutState =
                            Pin::into_inner(ptr_to_ts) as *const TimeoutState;
                        let void_ptr_to_ts: *mut c_void = raw_ptr_to_ts as *mut c_void;
                        unsafe {
                            boolector_set_term(
                                self.as_raw(),
                                Some(timeout::callback),
                                void_ptr_to_ts,
                            )
                        }
                    },
                }
            },
            BtorOption::SolverEngine(se) => {
                let val = match se {
                    SolverEngine::Fun => BTOR_ENGINE_FUN,
                    SolverEngine::SLS => BTOR_ENGINE_SLS,
                    SolverEngine::Prop => BTOR_ENGINE_PROP,
                    SolverEngine::AIGProp => BTOR_ENGINE_AIGPROP,
                    SolverEngine::Quant => BTOR_ENGINE_QUANT,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_ENGINE, val) }
            },
            BtorOption::SatEngine(se) => {
                let val = match se {
                    SatEngine::CaDiCaL => BTOR_SAT_ENGINE_CADICAL,
                    SatEngine::CMS => BTOR_SAT_ENGINE_CMS,
                    SatEngine::Lingeling => BTOR_SAT_ENGINE_LINGELING,
                    SatEngine::MiniSAT => BTOR_SAT_ENGINE_MINISAT,
                    SatEngine::PicoSAT => BTOR_SAT_ENGINE_PICOSAT,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_SAT_ENGINE, val) }
            },
            BtorOption::AutoCleanup(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_AUTO_CLEANUP, if b { 1 } else { 0 })
            },
            BtorOption::PrettyPrint(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PRETTY_PRINT, if b { 1 } else { 0 })
            },
            BtorOption::Seed(u) => unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_SEED, u) },
            BtorOption::RewriteLevel(rl) => {
                let val = match rl {
                    RewriteLevel::None => 0,
                    RewriteLevel::TermLevel => 1,
                    RewriteLevel::More => 2,
                    RewriteLevel::Full => 3,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_REWRITE_LEVEL, val) }
            },
            BtorOption::SkeletonPreproc(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SKELETON_PREPROC,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::Ackermann(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_ACKERMANN, if b { 1 } else { 0 })
            },
            BtorOption::BetaReduce(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_BETA_REDUCE, if b { 1 } else { 0 })
            },
            BtorOption::EliminateSlices(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_ELIMINATE_SLICES,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::VariableSubst(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_VAR_SUBST, if b { 1 } else { 0 })
            },
            BtorOption::UnconstrainedOpt(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_UCOPT, if b { 1 } else { 0 })
            },
            BtorOption::MergeLambdas(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_MERGE_LAMBDAS, if b { 1 } else { 0 })
            },
            BtorOption::ExtractLambdas(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_EXTRACT_LAMBDAS,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::Normalize(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_NORMALIZE, if b { 1 } else { 0 })
            },
            BtorOption::NormalizeAdd(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_NORMALIZE_ADD, if b { 1 } else { 0 })
            },
            BtorOption::FunPreProp(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_FUN_PREPROP, if b { 1 } else { 0 })
            },
            BtorOption::FunPreSLS(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_FUN_PRESLS, if b { 1 } else { 0 })
            },
            BtorOption::FunDualProp(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_FUN_DUAL_PROP, if b { 1 } else { 0 })
            },
            BtorOption::FunDualPropQsortOrder(dpqo) => {
                let val = match dpqo {
                    DualPropQsortOrder::Just => BTOR_DP_QSORT_JUST,
                    DualPropQsortOrder::Asc => BTOR_DP_QSORT_ASC,
                    DualPropQsortOrder::Desc => BTOR_DP_QSORT_DESC,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_FUN_DUAL_PROP_QSORT, val) }
            },
            BtorOption::FunJustification(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_FUN_JUST, if b { 1 } else { 0 })
            },
            BtorOption::FunJustificationHeuristic(jh) => {
                let val = match jh {
                    JustificationHeuristic::Left => BTOR_JUST_HEUR_BRANCH_LEFT,
                    JustificationHeuristic::MinApp => BTOR_JUST_HEUR_BRANCH_MIN_APP,
                    JustificationHeuristic::MinDepth => BTOR_JUST_HEUR_BRANCH_MIN_DEP,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_FUN_JUST_HEURISTIC, val) }
            },
            BtorOption::FunLazySynthesize(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_FUN_LAZY_SYNTHESIZE,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::FunEagerLemmas(el) => {
                let val = match el {
                    EagerLemmas::None => BTOR_FUN_EAGER_LEMMAS_NONE,
                    EagerLemmas::Conf => BTOR_FUN_EAGER_LEMMAS_CONF,
                    EagerLemmas::All => BTOR_FUN_EAGER_LEMMAS_ALL,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_FUN_EAGER_LEMMAS, val) }
            },
            BtorOption::SLSNumFlips(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_SLS_NFLIPS, u)
            },
            BtorOption::SLSMoveStrategy(sms) => {
                let val = match sms {
                    SLSMoveStrategy::BestMove => 0,
                    SLSMoveStrategy::RandomWalk => 1,
                    SLSMoveStrategy::FirstBestMove => 2,
                    SLSMoveStrategy::BestSameMove => 3,
                    SLSMoveStrategy::AlwaysProp => 4,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_SLS_STRATEGY, val) }
            },
            BtorOption::SLSJustification(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_SLS_JUST, if b { 1 } else { 0 })
            },
            BtorOption::SLSGroupWiseMoves(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_SLS_MOVE_GW, if b { 1 } else { 0 })
            },
            BtorOption::SLSRangeWiseMoves(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_MOVE_RANGE,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::SLSSegmentWiseMoves(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_MOVE_SEGMENT,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::SLSRandomWalkMoves(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_MOVE_RAND_WALK,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::SLSRandomWalkProbability(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_SLS_PROB_MOVE_RAND_WALK, u)
            },
            BtorOption::SLSRandomizeAll(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_MOVE_RAND_ALL,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::SLSRandomizeRange(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_MOVE_RAND_RANGE,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::SLSPropagationMoves(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_SLS_MOVE_PROP, if b { 1 } else { 0 })
            },
            BtorOption::SLSPropagationMovesNumProp(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_SLS_MOVE_PROP_N_PROP, u)
            },
            BtorOption::SLSPropagationMovesNumRegular(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_SLS_MOVE_PROP_N_SLS, u)
            },
            BtorOption::SLSForceRandomWalks(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_MOVE_PROP_FORCE_RW,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::SLSIncMoveTest(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_MOVE_INC_MOVE_TEST,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::SLSRestarts(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_USE_RESTARTS,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::SLSBanditScheme(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_SLS_USE_BANDIT,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::PropNumSteps(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_NPROPS, u)
            },
            BtorOption::PropRestarts(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_PROP_USE_RESTARTS,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::PropBanditScheme(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_PROP_USE_BANDIT,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::PropPathSelectionMode(pathsel) => {
                let val = match pathsel {
                    PropPathSelection::Controlling => BTOR_PROP_PATH_SEL_CONTROLLING,
                    PropPathSelection::Essential => BTOR_PROP_PATH_SEL_ESSENTIAL,
                    PropPathSelection::Random => BTOR_PROP_PATH_SEL_RANDOM,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PATH_SEL, val) }
            },
            BtorOption::PropInvValueProbability(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PROB_USE_INV_VALUE, u)
            },
            BtorOption::PropFlipConditionProbability(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PROB_FLIP_COND, u)
            },
            BtorOption::PropFlipConditionProbabilityConstant(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PROB_FLIP_COND_CONST, u)
            },
            BtorOption::PropFlipConditionNumPaths(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_FLIP_COND_CONST_NPATHSEL, u)
            },
            BtorOption::PropFlipConditionProbabilityConstantDelta(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_FLIP_COND_CONST_DELTA, u)
            },
            BtorOption::PropSliceKeepDCProbability(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PROB_SLICE_KEEP_DC, u)
            },
            BtorOption::PropConcatFlipProbability(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PROB_CONC_FLIP, u)
            },
            BtorOption::PropSliceFlipProbability(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PROB_SLICE_FLIP, u)
            },
            BtorOption::PropEqFlipProbability(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PROB_EQ_FLIP, u)
            },
            BtorOption::PropAndFlipProbability(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_PROP_PROB_AND_FLIP, u)
            },
            BtorOption::AIGPropUseRestarts(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_AIGPROP_USE_RESTARTS,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::AIGPropQuantSynthesis(pqs) => {
                let val = match pqs {
                    AIGPropQuantSynthesis::None => BTOR_QUANT_SYNTH_NONE,
                    AIGPropQuantSynthesis::EL => BTOR_QUANT_SYNTH_EL,
                    AIGPropQuantSynthesis::ELMC => BTOR_QUANT_SYNTH_ELMC,
                    AIGPropQuantSynthesis::ELELMC => BTOR_QUANT_SYNTH_EL_ELMC,
                    AIGPropQuantSynthesis::ELMR => BTOR_QUANT_SYNTH_ELMR,
                };
                unsafe { boolector_set_opt(self.as_raw(), BTOR_OPT_QUANT_SYNTH, val) }
            },
            BtorOption::AIGPropQuantDualSolver(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_QUANT_DUAL_SOLVER,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::AIGPropQuantSynthLimit(u) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_QUANT_SYNTH_LIMIT, u)
            },
            BtorOption::AIGPropSynthQI(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_QUANT_SYNTH_QI,
                    if b { 1 } else { 0 },
                )
            },
            BtorOption::AIGPropQuantDER(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_QUANT_DER, if b { 1 } else { 0 })
            },
            BtorOption::AIGPropQuantCER(b) => unsafe {
                boolector_set_opt(self.as_raw(), BTOR_OPT_QUANT_CER, if b { 1 } else { 0 })
            },
            BtorOption::AIGPropQuantMiniscope(b) => unsafe {
                boolector_set_opt(
                    self.as_raw(),
                    BTOR_OPT_QUANT_MINISCOPE,
                    if b { 1 } else { 0 },
                )
            },
        }
    }

    /// Solve the current input (defined by the constraints which have been added
    /// via [`BV::assert()`](struct.BV.html#method.assert) and
    /// [`BV::assume()`](struct.BV.html#method.assume)). All assertions and
    /// assumptions are implicitly combined via Boolean `and`.
    ///
    /// Calling this function multiple times requires incremental usage to be
    /// enabled via [`Btor::set_opt()`](struct.Btor.html#method.set_opt).
    /// If incremental usage is not enabled, this function may only be called
    /// once.
    ///
    /// ```
    /// # use boolector::{Btor, BV, SolverResult};
    /// # use boolector::option::{BtorOption, ModelGen};
    /// # use std::rc::Rc;
    /// let btor = Rc::new(Btor::new());
    /// btor.set_opt(BtorOption::Incremental(true));
    ///
    /// // An 8-bit unconstrained `BV` with the symbol "foo"
    /// let foo = BV::new(btor.clone(), 8, Some("foo"));
    ///
    /// // Assert that "foo" must be greater than `3`
    /// foo.ugt(&BV::from_u32(btor.clone(), 3, 8)).assert();
    ///
    /// // This state is satisfiable
    /// assert_eq!(btor.sat(), SolverResult::Sat);
    ///
    /// // Assert that "foo" must also be less than `2`
    /// foo.ult(&BV::from_u32(btor.clone(), 2, 8)).assert();
    ///
    /// // State is now unsatisfiable
    /// assert_eq!(btor.sat(), SolverResult::Unsat);
    ///
    /// // Repeat the first step above with the solver timeout set to something
    /// // extremely high (say, 200 sec) - should still be `Sat`
    /// # use std::time::Duration;
    /// let btor = Rc::new(Btor::new());
    /// btor.set_opt(BtorOption::Incremental(true));
    /// btor.set_opt(BtorOption::SolverTimeout(Some(Duration::from_secs(200))));
    /// let foo = BV::new(btor.clone(), 8, Some("foo"));
    /// foo.ugt(&BV::from_u32(btor.clone(), 3, 8)).assert();
    /// assert_eq!(btor.sat(), SolverResult::Sat);
    ///
    /// // But, if we make the second assertion and then set the solver timeout to
    /// // something extremely low (say, 2 ns), we'll get `SolverResult::Unknown`
    /// foo.ugt(&BV::from_u32(btor.clone(), 5, 8)).assert();
    /// btor.set_opt(BtorOption::SolverTimeout(Some(Duration::from_nanos(2))));
    /// assert_eq!(btor.sat(), SolverResult::Unknown);
    /// ```
    pub fn sat(&self) -> SolverResult {
        self.timeout_state.restart_timer();
        #[allow(non_upper_case_globals)]
        match unsafe { boolector_sat(self.as_raw()) } as u32 {
            BtorSolverResult_BTOR_RESULT_SAT => SolverResult::Sat,
            BtorSolverResult_BTOR_RESULT_UNSAT => SolverResult::Unsat,
            BtorSolverResult_BTOR_RESULT_UNKNOWN => SolverResult::Unknown,
            u => panic!("Unexpected return value from boolector_sat(): {}", u),
        }
    }

    /// Push `n` context levels. `n` must be at least 1.
    pub fn push(&self, n: u32) {
        unsafe { boolector_push(self.as_raw(), n) }
    }

    /// Pop `n` context levels. `n` must be at least 1.
    pub fn pop(&self, n: u32) {
        unsafe { boolector_pop(self.as_raw(), n) }
    }

    /// Duplicate a `Btor` instance. This will copy all variables, assertions,
    /// etc into the new instance.
    ///
    /// Each `BV` or `Array` may only be used with the `Btor` it was originally
    /// created for. If you have a `BV` for one `Btor` and want to find the
    /// corresponding `BV` in another `Btor`, use
    /// [`Btor::get_matching_bv()`](struct.Btor.html#method.get_matching_bv) or
    /// [`Btor::get_bv_by_symbol()`](struct.Btor.html#method.get_bv_by_symbol).
    ///
    /// With [`SatEngine::Lingeling`](option/enum.SatEngine.html), this can be
    /// called at any time; but with `SatEngine::PicoSAT` or
    /// `SatEngine::MiniSAT`, this can only be called prior to the first
    /// `Btor::sat()` call.
    ///
    /// The Boolector API docs refer to this operation as "clone", but we use
    /// `duplicate()` to avoid confusion.
    ///
    /// # Example
    ///
    /// ```
    /// # use boolector::{Btor, BV, SolverResult};
    /// # use boolector::option::{BtorOption, ModelGen};
    /// # use std::rc::Rc;
    /// let btor = Rc::new(Btor::new());
    /// btor.set_opt(BtorOption::ModelGen(ModelGen::All));
    ///
    /// // `x` is an 8-bit `BV` less than `42`
    /// let x = BV::new(btor.clone(), 8, Some("x"));
    /// x.ult(&BV::from_u32(btor.clone(), 42, 8)).assert();
    ///
    /// // `y` is equal to `x + 7`
    /// let y = x.add(&BV::from_u32(btor.clone(), 7, 8));
    ///
    /// // We duplicate the `Btor` instance
    /// let btor_2 = Rc::new(btor.duplicate());
    ///
    /// // The duplicated instance has copied versions of
    /// // `x` and `y` which are distinct from the original
    /// // `x` and `y` but still have the corresponding
    /// // relationship (i.e., `y_2 = x_2 + 7`)
    /// let x_2 = Btor::get_matching_bv(btor_2.clone(), &x).unwrap();
    /// let y_2 = Btor::get_matching_bv(btor_2.clone(), &y).unwrap();
    ///
    /// // The instances are totally independent now. In the
    /// // original instance, we'll assert that `x > 3`, while
    /// // in the new instance, we'll assert that `x < 3`.
    /// // Note that we're careful to create constants with the
    /// // correct `Btor` instance.
    /// x.ugt(&BV::from_u32(btor.clone(), 3, 8)).assert();
    /// x_2.ult(&BV::from_u32(btor_2.clone(), 3, 8)).assert();
    ///
    /// // Each instance is satisfiable by itself
    /// assert_eq!(btor.sat(), SolverResult::Sat);
    /// assert_eq!(btor_2.sat(), SolverResult::Sat);
    ///
    /// // In the first instance, `y > 10`, while in the second,
    /// // `y < 10`
    /// let y_solution = y.get_a_solution().as_u64().unwrap();
    /// assert!(y_solution > 10);
    /// let y_2_solution = y_2.get_a_solution().as_u64().unwrap();
    /// assert!(y_2_solution < 10);
    /// ```
    pub fn duplicate(&self) -> Self {
        let duplicated = Self {
            btor: unsafe { boolector_clone(self.as_raw()) },
            timeout_state: Pin::new(Box::new(TimeoutState::with_timeout_duration(
                self.timeout_state.get_timeout_duration(),
            ))),
        };
        // we need to inform the callback about the new location of the `TimeoutState`
        let ptr_to_ts: Pin<&TimeoutState> = (&self.timeout_state).as_ref();
        let raw_ptr_to_ts: *const TimeoutState = Pin::into_inner(ptr_to_ts) as *const TimeoutState;
        let void_ptr_to_ts: *mut c_void = raw_ptr_to_ts as *mut c_void;
        unsafe { boolector_set_term(self.as_raw(), Some(timeout::callback), void_ptr_to_ts) }
        duplicated
    }

    /// Given a `BV` originally created for any `Btor`, get the corresponding
    /// `BV` in the given `btor`. This only works if the `BV` was created before
    /// the relevant `Btor::duplicate()` was called; that is, it is intended to
    /// be used to find the copied version of a given `BV` in the new `Btor`.
    ///
    /// It's also fine to call this with a `BV` created for the given `Btor`
    /// itself, in which case you'll just get back `Some(bv.clone())`.
    ///
    /// For a code example, see
    /// [`Btor::duplicate()`](struct.Btor.html#method.duplicate).
    #[allow(clippy::if_same_then_else)]
    pub fn get_matching_bv<R: Borrow<Btor> + Clone>(btor: R, bv: &BV<R>) -> Option<BV<R>> {
        let node = unsafe { boolector_match_node(btor.borrow().as_raw(), bv.node) };
        if node.is_null() {
            None
        } else if unsafe { boolector_is_array(btor.borrow().as_raw(), node) } {
            None
        } else {
            Some(BV { btor, node })
        }
    }

    /// Given an `Array` originally created for any `Btor`, get the corresponding
    /// `Array` in the given `btor`. This only works if the `Array` was created
    /// before the relevant `Btor::duplicate()` was called; that is, it is
    /// intended to be used to find the copied version of a given `Array` in the
    /// new `Btor`.
    ///
    /// It's also fine to call this with an `Array` created for the given `Btor`
    /// itself, in which case you'll just get back `Some(array.clone())`.
    pub fn get_matching_array<R: Borrow<Btor> + Clone>(
        btor: R,
        array: &Array<R>,
    ) -> Option<Array<R>> {
        let node = unsafe { boolector_match_node(btor.borrow().as_raw(), array.node) };
        if node.is_null() {
            None
        } else if unsafe { boolector_is_array(btor.borrow().as_raw(), node) } {
            Some(Array { btor, node })
        } else {
            None
        }
    }

    /// Given a symbol, find the `BV` in the given `Btor` which has that symbol.
    ///
    /// Since `Btor::duplicate()` copies all `BV`s to the new `Btor` including
    /// their symbols, this can also be used to find the copied version of a
    /// given `BV` in the new `Btor`.
    #[allow(clippy::if_same_then_else)]
    pub fn get_bv_by_symbol<R: Borrow<Btor> + Clone>(btor: R, symbol: &str) -> Option<BV<R>> {
        let cstring = CString::new(symbol).unwrap();
        let symbol = cstring.as_ptr() as *const c_char;
        let node = unsafe { boolector_match_node_by_symbol(btor.borrow().as_raw(), symbol) };
        if node.is_null() {
            None
        } else if unsafe { boolector_is_array(btor.borrow().as_raw(), node) } {
            None
        } else {
            Some(BV { btor, node })
        }
    }

    /// Given a symbol, find the `Array` in the given `Btor` which has that
    /// symbol.
    ///
    /// Since `Btor::duplicate()` copies all `Array`s to the new `Btor` including
    /// their symbols, this can also be used to find the copied version of a
    /// given `Array` in the new `Btor`.
    pub fn get_array_by_symbol<R: Borrow<Btor> + Clone>(btor: R, symbol: &str) -> Option<Array<R>> {
        let cstring = CString::new(symbol).unwrap();
        let symbol = cstring.as_ptr() as *const c_char;
        let node = unsafe { boolector_match_node_by_symbol(btor.borrow().as_raw(), symbol) };
        if node.is_null() {
            None
        } else if unsafe { boolector_is_array(btor.borrow().as_raw(), node) } {
            Some(Array { btor, node })
        } else {
            None
        }
    }

    /// Add all current assumptions as assertions
    pub fn fixate_assumptions(&self) {
        unsafe { boolector_fixate_assumptions(self.as_raw()) }
    }

    /// Remove all added assumptions
    pub fn reset_assumptions(&self) {
        unsafe { boolector_reset_assumptions(self.as_raw()) }
    }

    /// Reset all statistics other than time statistics
    pub fn reset_stats(&self) {
        unsafe { boolector_reset_stats(self.as_raw()) }
    }

    /// Reset time statistics
    pub fn reset_time(&self) {
        unsafe { boolector_reset_time(self.as_raw()) }
    }

    /// Get a `String` describing the current constraints
    pub fn print_constraints(&self) -> String {
        unsafe {
            let tmpfile: *mut libc::FILE = libc::tmpfile();
            if tmpfile.is_null() {
                panic!("Failed to create a temp file");
            }
            // Write the data to `tmpfile`
            boolector_dump_smt2(self.as_raw(), tmpfile);
            // Seek to the end of `tmpfile`
            assert_eq!(libc::fseek(tmpfile, 0, libc::SEEK_END), 0);
            // Get the length of `tmpfile`
            let length = libc::ftell(tmpfile);
            if length < 0 {
                panic!("ftell() returned a negative value");
            }
            // Seek back to the beginning of `tmpfile`
            assert_eq!(libc::fseek(tmpfile, 0, libc::SEEK_SET), 0);
            let mut buffer = Vec::with_capacity(length as usize);
            libc::fread(
                buffer.as_mut_ptr() as *mut c_void,
                1,
                length as usize,
                tmpfile,
            );
            libc::fclose(tmpfile);
            buffer.set_len(length as usize);
            String::from_utf8_unchecked(buffer)
        }
    }

    /// Get a `String` describing the current model, including a set of
    /// satisfying assignments for all variables
    pub fn print_model(&self) -> String {
        unsafe {
            let tmpfile: *mut libc::FILE = libc::tmpfile();
            if tmpfile.is_null() {
                panic!("Failed to create a temp file");
            }
            // Write the data to `tmpfile`
            let format_cstring = CString::new("btor").unwrap();
            boolector_print_model(
                self.as_raw(),
                format_cstring.as_ptr() as *mut c_char,
                tmpfile,
            );
            // Seek to the end of `tmpfile`
            assert_eq!(libc::fseek(tmpfile, 0, libc::SEEK_END), 0);
            // Get the length of `tmpfile`
            let length = libc::ftell(tmpfile);
            if length < 0 {
                panic!("ftell() returned a negative value");
            }
            // Seek back to the beginning of `tmpfile`
            assert_eq!(libc::fseek(tmpfile, 0, libc::SEEK_SET), 0);
            let mut buffer = Vec::with_capacity(length as usize);
            libc::fread(
                buffer.as_mut_ptr() as *mut c_void,
                1,
                length as usize,
                tmpfile,
            );
            libc::fclose(tmpfile);
            buffer.set_len(length as usize);
            String::from_utf8_unchecked(buffer)
        }
    }

    /// Get Boolector's version string
    pub fn get_version(&self) -> String {
        let cstr = unsafe { CStr::from_ptr(boolector_version(self.as_raw())) };
        cstr.to_str().unwrap().to_owned()
    }

    /// Get Boolector's copyright notice
    pub fn get_copyright(&self) -> String {
        let cstr = unsafe { CStr::from_ptr(boolector_copyright(self.as_raw())) };
        cstr.to_str().unwrap().to_owned()
    }
}

impl Default for Btor {
    fn default() -> Self {
        Self::new()
    }
}

impl Drop for Btor {
    fn drop(&mut self) {
        unsafe {
            boolector_release_all(self.as_raw());
            assert_eq!(boolector_get_refs(self.as_raw()) as i32, 0);
            boolector_delete(self.as_raw());
        }
    }
}

#[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub enum SolverResult {
    Sat,
    Unsat,
    Unknown,
}