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|
//! Variable metadata.
use partial_ref::{partial, PartialRef};
use rustc_hash::FxHashSet as HashSet;
use varisat_formula::Var;
use crate::{
context::{parts::*, Context},
processing::{process_step, CheckedProofStep, CheckedSamplingMode, CheckedUserVar},
CheckerError,
};
/// Data for each literal.
#[derive(Clone, Default)]
pub struct LitData {
pub clause_count: usize,
}
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum SamplingMode {
Sample,
Witness,
Hide,
}
/// Data for each variable.
#[derive(Clone)]
pub struct VarData {
pub user_var: Option<Var>,
pub sampling_mode: SamplingMode,
}
impl Default for VarData {
fn default() -> VarData {
VarData {
user_var: None,
sampling_mode: SamplingMode::Sample,
}
}
}
#[derive(Default)]
pub struct Variables {
/// Information about literals in the current formula.
pub lit_data: Vec<LitData>,
/// Information about variables in the current formula.
pub var_data: Vec<VarData>,
/// User var names in use.
///
/// This is used to check for colliding mappings which are not allowed.
used_user_vars: HashSet<Var>,
}
/// Check that var is a sampling user var and create new variables as necessary.
pub fn ensure_sampling_var(
mut ctx: partial!(Context, mut ClausesP, mut VariablesP, CheckerStateP),
var: Var,
) -> Result<(), CheckerError> {
ensure_var(ctx.borrow(), var);
let variables = ctx.part_mut(VariablesP);
if variables.var_data[var.index()].sampling_mode != SamplingMode::Sample {
return Err(CheckerError::check_failed(
ctx.part(CheckerStateP).step,
format!("variable {:?} is not a sampling variable", var),
));
}
Ok(())
}
/// Ensure that a variable is present.
pub fn ensure_var(mut ctx: partial!(Context, mut ClausesP, mut VariablesP), var: Var) {
let (variables, mut ctx) = ctx.split_part_mut(VariablesP);
if variables.var_data.len() <= var.index() {
variables
.var_data
.resize(var.index() + 1, VarData::default());
variables
.lit_data
.resize((var.index() + 1) * 2, LitData::default());
ctx.part_mut(ClausesP)
.unit_clauses
.resize(var.index() + 1, None);
}
}
/// Add a user/global var mapping.
pub fn add_user_mapping<'a>(
mut ctx: partial!(Context<'a>, mut ClausesP, mut ProcessingP<'a>, mut VariablesP, CheckerStateP),
global_var: Var,
user_var: Var,
) -> Result<(), CheckerError> {
ensure_var(ctx.borrow(), global_var);
let mut ctx_in = ctx;
let (variables, ctx) = ctx_in.split_part_mut(VariablesP);
// TODO will the first check cause problems when observing solver added variables?
// That check is required for the workaround in CheckerData's user from proof method
if user_var.index() >= variables.var_data.len() || variables.used_user_vars.contains(&user_var)
{
return Err(CheckerError::check_failed(
ctx.part(CheckerStateP).step,
format!("user name {:?} used for two different variables", user_var),
));
}
let var_data = &mut variables.var_data[global_var.index()];
// sampling_mode will be Witness for a newly observed internal variable and Sample for a a
// fresh variable
if var_data.sampling_mode == SamplingMode::Hide {
return Err(CheckerError::check_failed(
ctx.part(CheckerStateP).step,
format!(
"user name added to variable {:?} which is still hidden",
global_var
),
));
}
if var_data.user_var.is_some() {
return Err(CheckerError::check_failed(
ctx.part(CheckerStateP).step,
format!("change of user name for in use varible {:?}", global_var),
));
}
var_data.user_var = Some(user_var);
variables.used_user_vars.insert(user_var);
let sampling_mode = if var_data.sampling_mode == SamplingMode::Witness {
CheckedSamplingMode::Witness
} else {
CheckedSamplingMode::Sample
};
process_step(
ctx_in.borrow(),
&CheckedProofStep::UserVar {
var: global_var,
user_var: Some(CheckedUserVar {
user_var,
sampling_mode,
new_var: true,
}),
},
)?;
Ok(())
}
/// Remove a user/global var mapping.
pub fn remove_user_mapping<'a>(
mut ctx: partial!(Context<'a>, mut ClausesP, mut ProcessingP<'a>, mut VariablesP, CheckerStateP),
global_var: Var,
) -> Result<(), CheckerError> {
ensure_var(ctx.borrow(), global_var);
let variables = ctx.part_mut(VariablesP);
let var_data = &variables.var_data[global_var.index()];
// We process this step before removing the mapping, so the processor can still look up the
// mapping.
if var_data.user_var.is_some() {
process_step(
ctx.borrow(),
&CheckedProofStep::UserVar {
var: global_var,
user_var: None,
},
)?;
} else {
return Err(CheckerError::check_failed(
ctx.part(CheckerStateP).step,
format!("no user name to remove for variable {:?}", global_var),
));
}
let variables = ctx.part_mut(VariablesP);
let var_data = &mut variables.var_data[global_var.index()];
if let Some(user_var) = var_data.user_var {
variables.used_user_vars.remove(&user_var);
var_data.user_var = None;
var_data.sampling_mode = SamplingMode::Hide;
}
Ok(())
}
|
