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//! Solver Builder
use {
super::{Certificate, Solver, SolverEvent, SolverResult, State, StateIF},
crate::{
assign::{AssignIF, AssignStack, PropagateIF, VarManipulateIF},
cdb::{ClauseDB, ClauseDBIF},
types::*,
},
};
#[cfg(not(feature = "no_IO"))]
use std::{
fs::File,
io::{BufRead, BufReader},
path::Path,
};
/// API for SAT solver creation and modification.
pub trait SatSolverIF: Instantiate {
/// add an assignment to Solver.
///
/// # Errors
///
/// * `SolverError::Inconsistent` if it conflicts with existing assignments.
/// * `SolverError::InvalidLiteral` if it is out of range for var index.
///
/// # Example
///
/// ```
/// use crate::splr::*;
/// use crate::splr::assign::VarManipulateIF; // for s.asg.assign()
/// use std::path::Path;
///
/// let mut s = Solver::try_from(Path::new("cnfs/uf8.cnf")).expect("can't load");
/// assert!(s.add_assignment(1).is_ok());
/// assert_eq!(s.asg.assign(1), Some(true));
/// assert!(s.add_assignment(2).is_ok());
/// assert!(s.add_assignment(3).is_ok());
/// assert!(s.add_assignment(4).is_ok());
/// assert!(s.add_assignment(5).is_ok());
/// assert!(s.add_assignment(8).is_ok());
/// assert!(matches!(s.add_assignment(-1), Err(SolverError::RootLevelConflict(_))));
/// assert!(matches!(s.add_assignment(10), Err(SolverError::InvalidLiteral)));
/// assert!(matches!(s.add_assignment(0), Err(SolverError::InvalidLiteral)));
/// assert_eq!(s.solve(), Ok(Certificate::SAT(vec![1, 2, 3, 4, 5, -6, 7, 8])));
/// ```
fn add_assignment(&mut self, val: i32) -> Result<&mut Solver, SolverError>;
/// add a literal to Solver.
///
/// # Errors
///
/// * `SolverError::Inconsistent` if a given clause is unit and conflicts with existing assignments.
/// * `SolverError::InvalidLiteral` if a literal in it is out of range for var index.
///
/// # Example
///```
/// use crate::splr::*;
/// use std::path::Path;
///
/// let mut s = Solver::try_from(Path::new("cnfs/uf8.cnf")).expect("can't load");
/// assert!(s.add_clause(vec![1, -2]).is_ok());
/// assert!(s.add_clause(vec![2, -3]).is_ok());
/// assert!(s.add_clause(vec![3, 4]).is_ok());
/// assert!(s.add_clause(vec![-2, 4]).is_ok());
/// assert!(s.add_clause(vec![-4, 5]).is_ok());
/// assert!(s.add_clause(vec![-5, 6]).is_ok());
/// assert!(s.add_clause(vec![-7, 8]).is_ok());
/// assert!(matches!(s.add_clause(vec![10, 11]), Err(SolverError::InvalidLiteral)));
/// assert!(matches!(s.add_clause(vec![0, 8]), Err(SolverError::InvalidLiteral)));
/// assert_eq!(s.solve(), Ok(Certificate::UNSAT));
///```
fn add_clause<V>(&mut self, vec: V) -> Result<&mut Solver, SolverError>
where
V: AsRef<[i32]>;
/// add a var to solver and return the number of vars.
///
/// # Example
/// ```
/// use crate::splr::*;
/// use std::path::Path;
///
/// let mut s = Solver::try_from(Path::new("cnfs/uf8.cnf")).expect("can't load");
/// assert_eq!(s.asg.num_vars, 8);
/// assert!(matches!(s.add_assignment(9), Err(SolverError::InvalidLiteral)));
/// s.add_assignment(1).expect("panic");
/// s.add_assignment(2).expect("panic");
/// s.add_assignment(3).expect("panic");
/// s.add_assignment(4).expect("panic");
/// s.add_assignment(5).expect("panic");
/// s.add_assignment(8).expect("panic");
/// assert_eq!(s.add_var(), 9);
/// assert!(s.add_assignment(-9).is_ok());
/// assert_eq!(s.solve(), Ok(Certificate::SAT(vec![1, 2, 3, 4, 5, -6, 7, 8, -9])));
/// ```
fn add_var(&mut self) -> VarId;
#[cfg(not(feature = "no_IO"))]
/// make a solver and load a CNF into it.
///
/// # Errors
///
/// * `SolverError::IOError` if it failed to load a CNF file.
/// * `SolverError::Inconsistent` if the CNF is conflicting.
/// * `SolverError::InvalidLiteral` if any literal used in the CNF is out of range for var index.
fn build(config: &Config) -> Result<Solver, SolverError>;
#[cfg(not(feature = "no_IO"))]
/// dump an UNSAT certification file
fn save_certification(&mut self);
#[cfg(not(feature = "no_IO"))]
/// dump the current status as a CNF
fn dump_cnf(&self, fname: &Path);
}
impl Instantiate for Solver {
/// ```
/// use crate::{splr::config::Config, splr::types::*};
/// use splr::solver::Solver;
/// let s = Solver::instantiate(&Config::default(), &CNFDescription::default());
///```
fn instantiate(config: &Config, cnf: &CNFDescription) -> Solver {
Solver {
asg: AssignStack::instantiate(config, cnf),
cdb: ClauseDB::instantiate(config, cnf),
state: State::instantiate(config, cnf),
}
}
}
/// Example
///```
/// use crate::splr::*;
///
/// let v: Vec<Vec<i32>> = vec![];
/// assert!(matches!(
/// Solver::try_from((Config::default(), v.as_ref())),
/// Ok(_)
/// ));
/// assert!(matches!(
/// Solver::try_from((Config::default(), vec![vec![0_i32]].as_ref())),
/// Err(Err(SolverError::InvalidLiteral))
/// ));
///```
impl<V> TryFrom<(Config, &[V])> for Solver
where
V: AsRef<[i32]>,
{
type Error = SolverResult;
fn try_from((config, vec): (Config, &[V])) -> Result<Self, Self::Error> {
let cnf = CNFDescription::from(vec);
match Solver::instantiate(&config, &cnf).inject_from_vec(vec) {
Err(SolverError::RootLevelConflict(_)) => Err(Ok(Certificate::UNSAT)),
Err(e) => Err(Err(e)),
Ok(s) => Ok(s),
}
}
}
#[cfg(not(feature = "no_IO"))]
impl TryFrom<&Path> for Solver {
type Error = SolverError;
/// return a new solver build for a CNF file.
///
/// # Example
/// ```
/// use crate::splr::solver::{SatSolverIF, Solver};
/// use std::path::Path;
///
/// let mut s = Solver::try_from(Path::new("cnfs/sample.cnf")).expect("fail to load");
///```
fn try_from(s: &Path) -> Result<Self, Self::Error> {
let config = Config::from(s);
Solver::build(&config)
}
}
impl SatSolverIF for Solver {
fn add_assignment(&mut self, val: i32) -> Result<&mut Solver, SolverError> {
let Solver { asg, cdb, .. } = self;
if val == 0 || asg.num_vars < val.unsigned_abs() as usize {
return Err(SolverError::InvalidLiteral);
}
let lit = Lit::from(val);
cdb.certificate_add_assertion(lit);
match asg.assigned(lit) {
None => asg.assign_at_root_level(cdb, lit).map(|_| self),
Some(true) => Ok(self),
Some(false) => Err(SolverError::RootLevelConflict((lit, asg.reason(lit.vi())))),
}
}
fn add_clause<V>(&mut self, vec: V) -> Result<&mut Solver, SolverError>
where
V: AsRef<[i32]>,
{
for i in vec.as_ref().iter() {
if *i == 0 || self.asg.num_vars < i.unsigned_abs() as usize {
return Err(SolverError::InvalidLiteral);
}
}
let mut clause = vec
.as_ref()
.iter()
.map(|i| Lit::from(*i))
.collect::<Vec<Lit>>();
if clause.is_empty() {
return Err(SolverError::EmptyClause);
}
if self.add_unchecked_clause(&mut clause) == RefClause::EmptyClause {
return Err(SolverError::EmptyClause);
}
Ok(self)
}
fn add_var(&mut self) -> VarId {
let Solver {
asg, cdb, state, ..
} = self;
asg.handle(SolverEvent::NewVar);
cdb.handle(SolverEvent::NewVar);
state.handle(SolverEvent::NewVar);
asg.num_vars as VarId
}
/// # Examples
///
/// ```
/// use splr::config::Config;
/// use splr::solver::{SatSolverIF, Solver};
///
/// let config = Config::from("cnfs/sample.cnf");
/// assert!(Solver::build(&config).is_ok());
///```
#[cfg(not(feature = "no_IO"))]
fn build(config: &Config) -> Result<Solver, SolverError> {
let CNFReader { cnf, reader } = CNFReader::try_from(Path::new(&config.cnf_file))?;
Solver::instantiate(config, &cnf).inject(reader)
}
#[cfg(not(feature = "no_IO"))]
/// dump an UNSAT certification file
fn save_certification(&mut self) {
self.cdb.certificate_save();
}
#[cfg(not(feature = "no_IO"))]
/// dump all active clauses and assertions as a CNF file.
fn dump_cnf(&self, fname: &Path) {
let Solver { asg, cdb, .. } = self;
cdb.dump_cnf(asg, fname)
}
}
impl Solver {
// renamed from clause_new
fn add_unchecked_clause(&mut self, lits: &mut Vec<Lit>) -> RefClause {
let Solver { asg, cdb, .. } = self;
if lits.is_empty() {
return RefClause::EmptyClause;
}
debug_assert!(asg.decision_level() == 0);
lits.sort();
let mut j = 0;
let mut l_: Option<Lit> = None; // last literal; [x, x.negate()] means tautology.
for i in 0..lits.len() {
let li = lits[i];
let sat = asg.assigned(li);
if sat == Some(true) || Some(!li) == l_ {
return RefClause::Dead;
} else if sat != Some(false) && Some(li) != l_ {
lits[j] = li;
j += 1;
l_ = Some(li);
}
}
lits.truncate(j);
match lits.len() {
0 => RefClause::EmptyClause, // for UNSAT
1 => {
let l0 = lits[0];
cdb.certificate_add_assertion(l0);
asg.assign_at_root_level(cdb, l0)
.map_or(RefClause::EmptyClause, |_| RefClause::UnitClause(l0))
}
_ => cdb.new_clause(lits, false),
}
}
#[cfg(not(feature = "no_IO"))]
fn inject(mut self, mut reader: BufReader<File>) -> Result<Solver, SolverError> {
self.state.progress_header();
self.state.progress(&self.asg, &self.cdb);
self.state.flush("Initialization phase: loading...");
let mut buf = String::new();
loop {
buf.clear();
let mut ends_zero = false;
match reader.read_line(&mut buf) {
Ok(0) => break,
Ok(_) if buf.starts_with('c') => continue,
Ok(_) => {
let iter = buf.split_whitespace();
let mut v: Vec<Lit> = Vec::new();
for s in iter {
match s.parse::<i32>() {
Ok(0) => {
ends_zero = true;
break;
}
Ok(val) => v.push(Lit::from(val)),
Err(_) => (),
}
}
if v.is_empty() {
if ends_zero {
return Err(SolverError::EmptyClause);
}
continue;
} else if self.add_unchecked_clause(&mut v) == RefClause::EmptyClause {
return Err(SolverError::EmptyClause);
}
}
Err(e) => panic!("{}", e),
}
}
debug_assert_eq!(self.asg.num_vars, self.state.target.num_of_variables);
// s.state[Stat::NumBin] = s.cdb.iter().skip(1).filter(|c| c.len() == 2).count();
Ok(self)
}
fn inject_from_vec<V>(mut self, v: &[V]) -> Result<Solver, SolverError>
where
V: AsRef<[i32]>,
{
self.state.progress_header();
self.state.progress(&self.asg, &self.cdb);
self.state.flush("injecting...");
for ints in v.iter() {
for i in ints.as_ref().iter() {
if *i == 0 || self.asg.num_vars < i.unsigned_abs() as usize {
return Err(SolverError::InvalidLiteral);
}
}
let mut lits = ints
.as_ref()
.iter()
.map(|i| Lit::from(*i))
.collect::<Vec<Lit>>();
if v.is_empty() {
return Err(SolverError::EmptyClause);
}
if self.add_unchecked_clause(&mut lits) == RefClause::EmptyClause {
return Err(SolverError::EmptyClause);
}
}
debug_assert_eq!(self.asg.num_vars, self.state.target.num_of_variables);
// s.state[Stat::NumBin] = s.cdb.iter().skip(1).filter(|c| c.len() == 2).count();
Ok(self)
}
}
#[cfg(test)]
mod tests {
// use super::*;
use crate::*;
use std::path::Path;
#[cfg(not(feature = "no_IO"))]
#[test]
fn test_add_var() {
let mut s = Solver::try_from(Path::new("cnfs/uf8.cnf")).expect("can't load");
assert_eq!(s.asg.num_vars, 8);
assert!(matches!(
s.add_assignment(9),
Err(SolverError::InvalidLiteral)
));
s.add_assignment(1).expect("panic");
s.add_assignment(2).expect("panic");
s.add_assignment(3).expect("panic");
s.add_assignment(4).expect("panic");
s.add_assignment(5).expect("panic");
s.add_assignment(8).expect("panic");
assert_eq!(s.add_var(), 9);
// assert!(s.add_assignment(-9).is_ok());
s.add_clause([-1, -8, -9]).expect("panic");
assert_eq!(
s.solve(),
Ok(Certificate::SAT(vec![1, 2, 3, 4, 5, -6, 7, 8, -9]))
);
}
}