EST_WFST.cc

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/*                Centre for Speech Technology Research                  */
/*                     University of Edinburgh, UK                       */
/*                         Copyright (c) 1997                            */
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/*************************************************************************/
/*                     Author :  Alan W Black                            */
/*                     Date   :  November 1997                           */
/*-----------------------------------------------------------------------*/
/*                                                                       */
/* A class for representing Weighted Finite State Transducers            */
/*                                                                       */
/* This is based on various papers by Mehryar Mohri but not forgetting   */
/* the Kay and Kaplan stuff as well as my own Koskenniemi implementation */
/* and finite state machine manipulations in my earlier lives            */
/*                                                                       */
/*=======================================================================*/

#include <iostream>
#include "EST_Pathname.h"
#include "EST_cutils.h"
#include "EST_Token.h"
#include "EST_FileType.h"
#include "EST_WFST.h"

#include "EST_TVector.h"

Declare_TList_T(EST_WFST_Transition *, EST_WFST_TransitionP)
Declare_TVector_Base_T(EST_WFST_State *, NULL, NULL, EST_WFST_StateP)


#if defined(INSTANTIATE_TEMPLATES)
#include "../base_class/EST_TList.cc"

Instantiate_TList_T(EST_WFST_Transition *, EST_WFST_TransitionP)

#include "../base_class/EST_TVector.cc"

Instantiate_TVector_T(EST_WFST_State *, EST_WFST_StateP)

#endif

using namespace std;

// Used for marking states duration traversing functions
int EST_WFST::traverse_tag = 0;

EST_WFST_State::EST_WFST_State(int name)
{
    p_name = name;
    p_type = wfst_error;
    p_tag = 0;
}

EST_WFST_State::EST_WFST_State(const EST_WFST_State &state)
{
    EST_Litem *p;

    p_name = state.p_name;
    p_type = state.p_type;
    p_tag = state.p_tag;
    for (p=state.transitions.head(); p != 0; p=p->next())
    transitions.append(new EST_WFST_Transition(*state.transitions(p)));
}

EST_WFST_State::~EST_WFST_State()
{
    EST_Litem *p;

    for (p=transitions.head(); p != 0; p=p->next())
    delete transitions(p);

}

EST_WFST_Transition *EST_WFST_State::add_transition(float w,
                            int end, 
                            int in,
                            int out)
{
    // Add new transition
    EST_WFST_Transition *s = new EST_WFST_Transition(w,end,in,out);
    transitions.append(s);
    return s;
}

EST_WFST::~EST_WFST()
{
    clear();
}

void EST_WFST::clear()
{

    // delete up to p_num_states, rather than p_states.length() as
    // only up to there is necessarily filled
    for (int i=0; i < p_num_states; ++i)
    delete p_states[i];
    p_num_states = 0;
    p_cumulate = 0;
}

EST_WFST::EST_WFST()
{
    p_num_states = 0;
    init(0);
    p_start_state = 0;
    current_tag = 0;
}

void EST_WFST::copy(const EST_WFST &wfst)
{
    clear();
    p_in_symbols = wfst.p_in_symbols;
    p_out_symbols = wfst.p_out_symbols;
    p_start_state = wfst.p_start_state;
    current_tag = wfst.current_tag;
    p_num_states = wfst.p_num_states;
    p_states.resize(p_num_states);
    for (int i=0; i < p_num_states; ++i)
    p_states[i] = new EST_WFST_State(*wfst.state(i));
}

void EST_WFST::init(int init_num_states)
{
    int i;

    clear();

    p_states.resize(init_num_states);
    for (i=0; i < p_states.length(); i++)
    p_states[i] = 0;
    p_num_states = init_num_states;

}

void EST_WFST::init(LISP in_alphabet,LISP out_alphabet)
{
    EST_StrList in,out;
    LISP iin,oout;

    in.append("__epsilon__");
    in.append("=");
    for (iin=in_alphabet; iin != NIL; iin=cdr(iin))
    if ((!streq(get_c_string(car(iin)),"__epsilon__")) &&
        (!streq(get_c_string(car(iin)),"=")))
        in.append(get_c_string(car(iin)));

    out.append("__epsilon__");
    out.append("=");
    for (oout=out_alphabet; oout != NIL; oout=cdr(oout))
    if ((!streq(get_c_string(car(oout)),"__epsilon__")) &&
        (!streq(get_c_string(car(oout)),"=")))
        out.append(get_c_string(car(oout)));

    p_in_symbols.init(in);
    p_out_symbols.init(out);

}

int EST_WFST::transduce(int state,const EST_String &in,EST_String &out) const
{
    int nstate;
    int in_i = p_in_symbols.name(in);
    int out_i=0;

    if (in_i == -1)
    {
    cerr << "WFST transduce: \"" << in << "\" not in alphabet" << endl;
    return WFST_ERROR_STATE;
    }
    
    nstate = transduce(state,in_i,out_i);

    out = p_out_symbols.name(out_i);

    return nstate;
}

void EST_WFST::transduce(int state,int in,wfst_translist &out) const
{
    EST_WFST_State *s = p_states(state);
    EST_Litem *i;

    for (i=s->transitions.head(); i != 0; i=i->next())
    {
    if (in == s->transitions(i)->in_symbol())
    {
        if (cumulate())
        s->transitions(i)->set_weight(1+s->transitions(i)->weight());
        out.append(s->transitions(i));
    }
    }

    // could return if any transitions were found
}

int EST_WFST::transduce(int state,int in,int &out) const
{
    EST_WFST_State *s = p_states(state);
    EST_Litem *i;

    for (i=s->transitions.head(); i != 0; i=i->next())
    {
    if (in == s->transitions(i)->in_symbol())
    {
        out = s->transitions(i)->out_symbol();
        return s->transitions(i)->state();
    }
    }

    return WFST_ERROR_STATE; // no match
}

int EST_WFST::transition(int state,const EST_String &inout) const
{
    if (inout.contains("/"))
    return transition(state,inout.before("/"),inout.after("/"));
    else
    return transition(state,inout,inout);
}

int EST_WFST::transition(int state,const EST_String &in,
             const EST_String &out) const
{
    int in_i = p_in_symbols.name(in);
    int out_i = p_out_symbols.name(out);

    if ((in_i == -1) || (out_i == -1))
    {
    cerr << "WFST: one of " << in << "/" << out << " not in alphabet"
        << endl;
    return WFST_ERROR_STATE;
    }

    return transition(state,in_i,out_i);
}

int EST_WFST::transition(int state,int in, int out) const
{
    // Finds first transition (hopefully deterministic)
    float prob;
    return transition(state,in,out,prob);
}

EST_WFST_Transition *EST_WFST::find_transition(int state,int in, int out) const
{
    // Finds first transition (hopefully deterministic)
    EST_WFST_State *s = p_states(state);
    EST_Litem *i;

    for (i=s->transitions.head(); i != 0; i=i->next())
    {
    if ((in == s->transitions(i)->in_symbol()) &&
        (out == s->transitions(i)->out_symbol()))
    {
        if (cumulate())
        s->transitions(i)->set_weight(1+s->transitions(i)->weight());
        return s->transitions(i);
    }
    }

    return 0; // no match
}

int EST_WFST::transition(int state,int in, int out,float &prob) const
{
    // Finds first transition (hopefully deterministic)
    EST_WFST_Transition *trans = find_transition(state,in,out);

    if (trans == 0)
    {
    prob = 0;
    return WFST_ERROR_STATE;
    }
    else
    {
    prob = trans->weight();
    return trans->state();
    }
}

EST_write_status EST_WFST::save_binary(FILE *fd)
{
    int i;
    EST_Litem *j;
    int num_transitions, type, in, out, next_state;
    float weight;
    
    for (i=0; i<p_num_states; i++)
    {
    num_transitions = p_states[i]->num_transitions();
    fwrite(&num_transitions,4,1,fd);
    if (p_states[i]->type() == wfst_final)
        type = WFST_FINAL;
    else if (p_states[i]->type() == wfst_nonfinal)
        type = WFST_NONFINAL;
    else if (p_states[i]->type() == wfst_licence)
        type = WFST_LICENCE;
    else
        type = WFST_ERROR;
    fwrite(&type,4,1,fd);
    for (j=p_states[i]->transitions.head(); j != 0; j=j->next())
    {
        in = p_states[i]->transitions(j)->in_symbol();
        out = p_states[i]->transitions(j)->out_symbol();
        next_state = p_states[i]->transitions(j)->state();
        weight = p_states[i]->transitions(j)->weight();

        if (in == out)
        {
        in *= -1;
        fwrite(&in,4,1,fd);
        }
        else
        {
        fwrite(&in,4,1,fd);
        fwrite(&out,4,1,fd);
        }
        fwrite(&next_state,4,1,fd);
        fwrite(&weight,4,1,fd);
    }
    }

    return write_ok;
}

EST_write_status EST_WFST::save(const EST_String &filename,
                const EST_String type)
{
    FILE *ofd;
    int i;
    static EST_Regex needquotes(".*[()'\";., \t\n\r].*");
    EST_Litem *j;

    if (filename == "-")
    ofd = stdout;
    else if ((ofd = fopen(filename,"wb")) == NULL)
    {
    cerr << "WFST: cannot write to file \"" << filename << "\"" << endl;
    return misc_write_error;
    }
    
    fprintf(ofd,"EST_File fst\n");
    fprintf(ofd,"DataType %s\n",(const char *)type);
    fprintf(ofd,"in %s\n",
      (const char *)quote_string(EST_String("(")+
                 p_in_symbols.print_to_string(TRUE)+")",
                 "\"","\\",1));
    fprintf(ofd,"out %s\n",
      (const char *)quote_string(EST_String("(")+
                 p_out_symbols.print_to_string(TRUE)+")",
                 "\"","\\",1));
    fprintf(ofd,"NumStates %d\n",p_num_states);
    fprintf(ofd, "ByteOrder %s\n", ((EST_NATIVE_BO == bo_big) ? "10" : "01"));
    fprintf(ofd,"EST_Header_End\n");

    if (type == "binary")
    save_binary(ofd);
    else
    {
    for (i=0; i < p_num_states; i++)
    {
        EST_WFST_State *s=p_states[i];
        fprintf(ofd,"((%d ",s->name());
        switch(s->type())
        {
        case wfst_final: 
        fprintf(ofd,"final ");
        break;
        case wfst_nonfinal: 
        fprintf(ofd,"nonfinal ");
        break;
        case wfst_licence: 
        fprintf(ofd,"licence ");
        break;
        default: 
        fprintf(ofd,"error ");
        }
        fprintf(ofd,"%d)\n",s->num_transitions());
        for (j=s->transitions.head(); j != 0; j=j->next())
        {
        EST_String in = p_in_symbols.name(s->transitions(j)->in_symbol());
        EST_String out=p_out_symbols.name(s->transitions(j)->out_symbol());
        if (in.matches(needquotes))
            fprintf(ofd,"  (%s ",(const char *)quote_string(in,"\"","\\",1));
        else
            fprintf(ofd,"  (%s ",(const char *)in);
        if (out.matches(needquotes))
            fprintf(ofd," %s ",(const char *)quote_string(out,"\"","\\",1));
        else
            fprintf(ofd," %s ",(const char *)out);
        fprintf(ofd,"%d %g)\n",
            s->transitions(j)->state(),
            s->transitions(j)->weight());
        }
        fprintf(ofd,")\n");
    }
    }
    if (ofd != stdout)
    fclose(ofd);

    return write_ok;
}

static float get_float(FILE *fd,int swap)
{
    float f;
    if (fread(&f,4,1,fd) != 1)
    {
        cerr << "Could not get float from WFST" << endl;
        return 0;
    }
    if (swap) swapfloat(&f);
    return f;
}

static int get_int(FILE *fd,int swap)
{
    int i;
    if (fread(&i,4,1,fd) != 1)
    {
        cerr << "Could not get int from WFST" << endl;
        return 0;
    }
    if (swap) 
    return SWAPINT(i);
    else
    return i;
}

EST_read_status EST_WFST::load_binary(FILE *fd,
                      EST_Option &hinfo,
                      int num_states,
                      int swap)
{
    (void)hinfo;
    EST_read_status r;
    int i,j, s;
    int num_trans, state_type;
    int in_sym, out_sym, next_state;
    float trans_cost;

    r = format_ok;

    for (i=0; i < num_states; i++)
    {
    num_trans = get_int(fd,swap);
    state_type = get_int(fd,swap);
    
    if (state_type == WFST_FINAL)
        s = add_state(wfst_final);
    else if (state_type == WFST_NONFINAL)
        s = add_state(wfst_nonfinal);
    else if (state_type == WFST_LICENCE)
        s = add_state(wfst_licence);
    else if (state_type == WFST_ERROR)
        s = add_state(wfst_error);
    else
    {
        cerr << "WFST load: unknown state type \"" << 
        state_type << "\"" << endl;
        r = read_format_error;
        break;
    }

    if (s != i)
    {
        cerr << "WFST load: internal error: unexpected state misalignment"
         << endl;
        r = read_format_error;
        break;
    }

    for (j=0; j < num_trans; j++)
    {
        in_sym = get_int(fd,swap);
        if (in_sym < 0)
        {
        in_sym *= -1;
        out_sym = in_sym;
        }
        else
        out_sym = get_int(fd,swap);
        next_state = get_int(fd,swap);
        trans_cost = get_float(fd,swap);

        p_states[i]->add_transition(trans_cost,next_state,in_sym,out_sym);
    }
    }

    return r;
}


EST_read_status EST_WFST::load(const EST_String &filename)
{
    // Load a WFST from a file
    FILE *fd;
    EST_TokenStream ts;
    EST_Option hinfo;
    bool ascii;
    EST_EstFileType t;
    EST_read_status r;
    int i,s;
    int swap;

    if ((fd=fopen(filename,"r")) == NULL)
    {
    cerr << "WFST load: unable to open \"" << filename 
        << "\" for reading" << endl;
    return read_error;
    }
    ts.open(fd,FALSE);
    ts.set_quotes('"','\\');

    if (((r = read_est_header(ts, hinfo, ascii, t)) != format_ok) ||
    (t != est_file_fst))
    {
    cerr << "WFST load: not a WFST file \"" << filename << "\"" <<endl;
    return misc_read_error;
    }

    // Value is a quoted quoted s-expression.  Two reads is the 
    // safest way to unquote them
    LISP inalpha = 
    read_from_string(get_c_string(read_from_string(hinfo.val("in"))));
    LISP outalpha = 
    read_from_string(get_c_string(read_from_string(hinfo.val("out"))));
    p_start_state = 0;

    clear();
    init(inalpha,outalpha);

    int num_states = hinfo.ival("NumStates");
    r = format_ok;

    if (!ascii)
    {
    if (!hinfo.present("ByteOrder"))
        swap = FALSE;  // ascii or not there for some reason
    else if (((hinfo.val("ByteOrder") == "01") ? bo_little : bo_big) 
         != EST_NATIVE_BO)
        swap = TRUE;
    else
        swap = FALSE;
    r = load_binary(fd,hinfo,num_states,swap);
    }
    else
    {
    for (i=0; i < num_states; i++)
    {
        LISP sd = lreadf(fd);
        if (i != get_c_int(car(car(sd))))
        {
        cerr << "WFST load: expected description of state " << i <<
            " but found \"" << siod_sprint(sd) << "\"" << endl;
        r = read_format_error;
        break;
        }
        if (streq("final",get_c_string(car(cdr(car(sd))))))
        s = add_state(wfst_final);
        else if (streq("nonfinal",get_c_string(car(cdr(car(sd))))))
        s = add_state(wfst_nonfinal);
        else if (streq("licence",get_c_string(car(cdr(car(sd))))))
        s = add_state(wfst_licence);
        else
        {
        cerr << "WFST load: unknown state type \"" << 
            siod_sprint(car(cdr(car(sd)))) << "\"" << endl;
        r = read_format_error;
        break;
        }
        
        if (s != i)
        {
        cerr << "WFST load: internal error: unexpected state misalignment"
             << endl;
        r = read_format_error;
        break;
        }
        if (load_transitions_from_lisp(s,cdr(sd)) != format_ok)
        {
        r = read_format_error;
        break;
        }
    }
    }

    fclose(fd);
    
    return r;
}

EST_read_status EST_WFST::load_transitions_from_lisp(int s, LISP trans)
{
    LISP t;

    for (t=trans; t != NIL; t=cdr(t))
    {
    float w = get_c_float(siod_nth(3,car(t)));
    int end = get_c_int(siod_nth(2,car(t)));
    int in = p_in_symbols.name(get_c_string(siod_nth(0,car(t))));
    int out = p_out_symbols.name(get_c_string(siod_nth(1,car(t))));

    if ((in == -1) || (out == -1))
    {
        cerr << "WFST load: unknown vocabulary in state transition" 
        << endl;
        cerr << "WFST load:  " << siod_sprint(car(t)) << endl;
        ssize_t i;
        /* Remove all added transitions: */
        for (i=0;i<p_states[s]->transitions.length();i++)
            delete (p_states[s]->transitions).nth(i);
        return read_format_error;
    }
    p_states[s]->add_transition(w,end,in,out);
    }
    return format_ok;
}

EST_String EST_WFST::summary() const
{
    int i;
    int tt=0;

    for (i=0; i < p_num_states; i++)
    tt += p_states(i)->transitions.length();

    return EST_String("WFST ")+itoString(p_num_states)+" states "+
    itoString(tt)+" transitions ";
}
    

void EST_WFST::more_states(int new_max)
{
    int i;

    p_states.resize(new_max);
    for (i=p_num_states; i < new_max; i++)
    p_states[i] = 0;
}

int EST_WFST::add_state(enum wfst_state_type state_type)
{
    // Add new state of given type
    EST_WFST_State *s = new EST_WFST_State(p_num_states);

    if (p_num_states >= p_states.length())
    {
    // Need more space for states
    more_states((int)((float)(p_states.length()+1)*1.5));
    }

    p_states[p_num_states] = s;
    s->set_type(state_type);
    p_num_states++;

    return s->name();
}

void EST_WFST::start_cumulate(void)
{
    // cumulate transitions during recognition
    EST_Litem *j;
    int i;

    p_cumulate = 1;
    for (i=0; i < p_num_states; i++)
    {
    EST_WFST_State *s=p_states[i];
    for (j=s->transitions.head(); j !=0; j=j->next())
        s->transitions(j)->set_weight(0);
    }
}

void EST_WFST::stop_cumulate(void)
{
    EST_Litem *j;
    int i;
    float t;

    p_cumulate = 0;
    for (i=0; i < p_num_states; i++)
    {
    EST_WFST_State *s=p_states[i];
    for (t=0,j=s->transitions.head(); j !=0; j=j->next())
        t += s->transitions(j)->weight();
    if (t > 0)
        for (j=s->transitions.head(); j !=0; j=j->next())
        s->transitions(j)->set_weight(s->transitions(j)->weight()/t);
    }
}