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// Author: Daniel van Niekerk <dvn.demitasse@gmail.com> // // Copyright 2016 The Department of Arts and Culture of the Government // of South Africa // // See the "LICENCE" file for information on usage and redistribution // of this file. //////////////////////////////////////////////////////////////////////////////// //! This crate implements Weighted Finite-State Transducers (WFSTs) as //! described in: //! //! Mehryar Mohri, Fernando Pereira, and Michael Riley. "The design //! principles of a weighted finite-state transducer library," In: //! *Theoretical Computer Science* vol. 231 issue 1 (2000): pp. 17-32. //! //! This is a re-implementation in Rust, containing ported fragments //! from the following existing projects (see appropriate licences and //! attribution in the source repository): //! //! * OpenFst (http://www.openfst.org) //! * CMU Sphinx (http://cmusphinx.sourceforge.net/) extern crate rustc_serialize; use std::fmt::Debug; //////////////////////////////////////////////////////////////////////////////// ////////// SEMIRING MODULE PROVIDES WEIGHT TYPES //////////////////////////////////////////////////////////////////////////////// pub mod semiring; use semiring::Weight; //////////////////////////////////////////////////////////////////////////////// ////////// FST AND MUTABLE FST INTERFACES //////////////////////////////////////////////////////////////////////////////// // This interface is informed by Section 4.1 of: // Mehryar Mohri, Fernando Pereira, and Michael Riley. "The design // principles of a weighted finite-state transducer library." // Theoretical Computer Science 231.1 (2000): 17-32. pub type Label = usize; pub type StateId = usize; pub trait Fst<W: Weight>: Debug { type Arc: Arc<W>; type Iter: Iterator<Item=Self::Arc>; type Symtab: IntoIterator<Item=String>; fn get_start(&self) -> Option<StateId>; fn get_finalweight(&self, StateId) -> W; fn arc_iter(&self, StateId) -> Self::Iter; fn get_isyms(&self) -> Option<Self::Symtab>; fn get_osyms(&self) -> Option<Self::Symtab>; fn is_final(&self, StateId) -> bool; } // This interface defined by looking at OpenFST (C++ and Java // interfaces): pub trait MutableFst<W: Weight>: Fst<W> { fn new() -> Self; fn set_start(&mut self, id: StateId); fn add_state(&mut self, finalweight: W) -> StateId; fn del_state(&mut self, StateId); fn del_states<T: IntoIterator<Item=StateId>>(&mut self, states: T); fn add_arc(&mut self, source: StateId, target: StateId, ilabel: Label, olabel: Label, weight: W); fn set_finalweight(&mut self, id: StateId, finalweight: W); fn set_isyms<T: IntoIterator<Item=String>>(&mut self, symtab: T); fn set_osyms<T: IntoIterator<Item=String>>(&mut self, symtab: T); } pub trait ExpandedFst<W: Weight>: Fst<W> + Clone { fn get_numstates(&self) -> usize; } pub trait Arc<W: Weight>: PartialEq + Debug + Clone { fn ilabel(&self) -> Label; fn olabel(&self) -> Label; fn weight(&self) -> W; fn nextstate(&self) -> StateId; } //////////////////////////////////////////////////////////////////////////////// ////////// GENERIC FST ALGORITHMS //////////////////////////////////////////////////////////////////////////////// pub mod utils; pub mod algorithms; //////////////////////////////////////////////////////////////////////////////// ////////// SPECIFIC FST IMPLEMENTATIONS //////////////////////////////////////////////////////////////////////////////// pub mod wfst_vec;