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use std::fmt::Debug;
use std::marker::PhantomData;
use std::sync::Arc;
use anyhow::Result;
use crate::fst_properties::FstProperties;
use crate::fst_traits::iterators::StateIterator;
use crate::fst_traits::FstIterator;
use crate::semirings::Semiring;
use crate::trs::Trs;
use crate::{StateId, SymbolTable};
/// Trait defining necessary methods for a wFST to access start states and final states.
pub trait CoreFst<W: Semiring> {
/// Weight use in the wFST. This type must implement the Semiring trait.
type TRS: Trs<W>;
/// Returns the ID of the start state of the wFST if it exists else none.
///
/// # Example
///
/// ```
/// # use rustfst::fst_traits::{CoreFst, MutableFst};
/// # use rustfst::fst_impls::VectorFst;
/// # use rustfst::semirings::BooleanWeight;
/// // 1 - Create an FST
/// let mut fst = VectorFst::<BooleanWeight>::new();
/// let s = fst.add_state();
/// fst.set_start(s);
///
/// // 2 - Access the start state
/// let start_state = fst.start();
/// assert_eq!(start_state, Some(s));
/// ```
fn start(&self) -> Option<StateId>;
/// Retrieves the final weight of a state (if the state is a final one).
///
/// # Example
///
/// ```
/// # use rustfst::fst_traits::{CoreFst, MutableFst, ExpandedFst};
/// # use rustfst::fst_impls::VectorFst;
/// # use rustfst::semirings::{BooleanWeight, Semiring};
/// // 1 - Create an FST
/// let mut fst = VectorFst::<BooleanWeight>::new();
/// let s1 = fst.add_state();
/// let s2 = fst.add_state();
/// fst.set_final(s2, BooleanWeight::one());
///
/// // 2 - Access the final weight of each state
/// assert_eq!(fst.final_weight(s1).unwrap(), None);
/// assert_eq!(fst.final_weight(s2).unwrap(), Some(BooleanWeight::one()));
/// assert!(fst.final_weight(s2 + 1).is_err());
/// ```
fn final_weight(&self, state_id: StateId) -> Result<Option<W>>;
unsafe fn final_weight_unchecked(&self, state_id: StateId) -> Option<W>;
/// Number of trs leaving a specific state in the wFST.
///
/// # Example
///
/// ```
/// # use rustfst::fst_traits::{CoreFst, MutableFst, ExpandedFst};
/// # use rustfst::fst_impls::VectorFst;
/// # use rustfst::semirings::{BooleanWeight, Semiring};
/// # use rustfst::Tr;
/// let mut fst = VectorFst::<BooleanWeight>::new();
/// let s1 = fst.add_state();
/// let s2 = fst.add_state();
///
/// assert_eq!(fst.num_trs(s1).unwrap(), 0);
/// fst.add_tr(s1, Tr::new(3, 5, BooleanWeight::new(true), s2));
/// assert_eq!(fst.num_trs(s1).unwrap(), 1);
/// ```
fn num_trs(&self, s: StateId) -> Result<usize>;
unsafe fn num_trs_unchecked(&self, s: StateId) -> usize;
/// Returns whether or not the state with identifier passed as parameters is a final state.
///
/// # Example
///
/// ```
/// # use rustfst::fst_traits::{CoreFst, MutableFst, ExpandedFst};
/// # use rustfst::fst_impls::VectorFst;
/// # use rustfst::semirings::{BooleanWeight, Semiring};
/// // 1 - Create an FST
/// let mut fst = VectorFst::<BooleanWeight>::new();
/// let s1 = fst.add_state();
/// let s2 = fst.add_state();
/// fst.set_final(s2, BooleanWeight::one());
///
/// // 2 - Test if a state is final
/// assert_eq!(fst.is_final(s1).unwrap(), false);
/// assert_eq!(fst.is_final(s2).unwrap(), true);
/// assert!(fst.is_final(s2 + 1).is_err());
/// ```
#[inline]
fn is_final(&self, state_id: StateId) -> Result<bool> {
let w = self.final_weight(state_id)?;
Ok(w.is_some())
}
#[inline]
unsafe fn is_final_unchecked(&self, state_id: StateId) -> bool {
self.final_weight_unchecked(state_id).is_some()
}
/// Check whether a state is the start state or not.
#[inline]
fn is_start(&self, state_id: StateId) -> bool {
Some(state_id) == self.start()
}
fn get_trs(&self, state_id: StateId) -> Result<Self::TRS>;
unsafe fn get_trs_unchecked(&self, state_id: StateId) -> Self::TRS;
/// Retrieve the `FstProperties` stored in the Fst. As a result, all the properties returned
/// are verified by the Fst but some other properties might be true as well despite the flag
/// not being set.
fn properties(&self) -> FstProperties;
/// Apply a mask to the FstProperties returned.
fn properties_with_mask(&self, mask: FstProperties) -> FstProperties {
self.properties() & mask
}
/// Retrieve the `FstProperties` in the Fst and check that all the
/// properties in `props_known` are known (not the same as true). If not an error is returned.
///
/// A property is known if we known for sure if it is true of false.
fn properties_check(&self, props_known: FstProperties) -> Result<FstProperties> {
let props = self.properties();
if !props.knows(props_known) {
bail!(
"Properties are not known : {:?}. Properties of the Fst : {:?}",
props_known,
props
)
}
Ok(props)
}
/// Returns the number of trs with epsilon input labels leaving a state.
///
/// # Example :
/// ```
/// # use rustfst::fst_traits::{MutableFst, Fst, CoreFst};
/// # use rustfst::fst_impls::VectorFst;
/// # use rustfst::semirings::{Semiring, IntegerWeight};
/// # use rustfst::EPS_LABEL;
/// # use rustfst::Tr;
/// let mut fst = VectorFst::<IntegerWeight>::new();
/// let s0 = fst.add_state();
/// let s1 = fst.add_state();
///
/// fst.add_tr(s0, Tr::new(EPS_LABEL, 18, IntegerWeight::one(), s1));
/// fst.add_tr(s0, Tr::new(76, EPS_LABEL, IntegerWeight::one(), s1));
/// fst.add_tr(s0, Tr::new(EPS_LABEL, 18, IntegerWeight::one(), s1));
/// fst.add_tr(s0, Tr::new(45, 18, IntegerWeight::one(), s0));
/// fst.add_tr(s1, Tr::new(76, 18, IntegerWeight::one(), s1));
///
/// assert_eq!(fst.num_input_epsilons(s0).unwrap(), 2);
/// assert_eq!(fst.num_input_epsilons(s1).unwrap(), 0);
/// ```
fn num_input_epsilons(&self, state: StateId) -> Result<usize>;
/// Returns the number of trs with epsilon output labels leaving a state.
///
/// # Example :
/// ```
/// # use rustfst::fst_traits::{MutableFst, Fst, CoreFst};
/// # use rustfst::fst_impls::VectorFst;
/// # use rustfst::semirings::{Semiring, IntegerWeight};
/// # use rustfst::EPS_LABEL;
/// # use rustfst::Tr;
/// let mut fst = VectorFst::<IntegerWeight>::new();
/// let s0 = fst.add_state();
/// let s1 = fst.add_state();
///
/// fst.add_tr(s0, Tr::new(EPS_LABEL, 18, IntegerWeight::one(), s1));
/// fst.add_tr(s0, Tr::new(76, EPS_LABEL, IntegerWeight::one(), s1));
/// fst.add_tr(s0, Tr::new(EPS_LABEL, 18, IntegerWeight::one(), s1));
/// fst.add_tr(s0, Tr::new(45, 18, IntegerWeight::one(), s0));
/// fst.add_tr(s1, Tr::new(76, 18, IntegerWeight::one(), s1));
///
/// assert_eq!(fst.num_output_epsilons(s0).unwrap(), 1);
/// assert_eq!(fst.num_output_epsilons(s1).unwrap(), 0);
/// ```
fn num_output_epsilons(&self, state: StateId) -> Result<usize>;
}
/// Trait defining the minimum interface necessary for a wFST.
pub trait Fst<W: Semiring>:
CoreFst<W> + for<'b> StateIterator<'b> + Debug + for<'c> FstIterator<'c, W>
{
/// Retrieves the input `SymbolTable` associated to the Fst.
/// If no SymbolTable has been previously attached then `None` is returned.
fn input_symbols(&self) -> Option<&Arc<SymbolTable>>;
/// Retrieves the output `SymbolTable` associated to the Fst.
/// If no SymbolTable has been previously attached then `None` is returned.
fn output_symbols(&self) -> Option<&Arc<SymbolTable>>;
/// Attaches an output `SymbolTable` to the Fst.
/// The `SymbolTable` is not duplicated with the use of Arc.
fn set_input_symbols(&mut self, symt: Arc<SymbolTable>);
/// Attaches an output `SymbolTable` to the Fst.
/// The `SymbolTable` is not duplicated with the use of Arc.
fn set_output_symbols(&mut self, symt: Arc<SymbolTable>);
/// Removes the input symbol table from the Fst and retrieves it.
fn take_input_symbols(&mut self) -> Option<Arc<SymbolTable>>;
/// Removes the output symbol table from the Fst and retrieves it.
fn take_output_symbols(&mut self) -> Option<Arc<SymbolTable>>;
fn set_symts_from_fst<W2: Semiring, OF: Fst<W2>>(&mut self, other_fst: &OF) {
if let Some(symt) = other_fst.input_symbols() {
self.set_input_symbols(Arc::clone(symt));
} else {
self.take_input_symbols();
}
if let Some(symt) = other_fst.output_symbols() {
self.set_output_symbols(Arc::clone(symt));
} else {
self.take_output_symbols();
}
}
fn final_states_iter(&self) -> FinalStatesIterator<W, Self>
where
Self: std::marker::Sized,
{
FinalStatesIterator {
fst: self,
state_iter: self.states_iter(),
w: PhantomData,
}
}
}
pub struct FinalStatesIterator<'a, W, F>
where
W: Semiring,
F: Fst<W>,
{
fst: &'a F,
state_iter: <F as StateIterator<'a>>::Iter,
w: PhantomData<W>,
}
impl<'a, W, F> Iterator for FinalStatesIterator<'a, W, F>
where
W: Semiring,
F: Fst<W>,
{
type Item = StateId;
fn next(&mut self) -> Option<Self::Item> {
loop {
if let Some(s) = self.state_iter.next() {
if unsafe { self.fst.is_final_unchecked(s) } {
return Some(s);
}
} else {
return None;
}
}
}
}