patternTable.py

#!/usr/bin/python3
# PyElly - rule-based tool for analyzing natural language (Python v3.8)
#
# patternTable.py : 04feb2020 CPM
# ------------------------------------------------------------------------------
# Copyright (c) 2019, Clinton Prentiss Mah
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"""
non-deterministic finite-state automaton (FSA) for inferring the syntactic type
of simple or hyphenated tokens
"""

import sys
import ellyChar
import ellyWildcard
import ellyException
import syntaxSpecification
import featureSpecification

class Link(object):

    """
    for defining FSA transitions with Elly pattern matching

    attributes:
        patn  - Elly pattern to match
        nxts  - next state on match
        catg  - syntactic category
        synf  - syntactic features
        semf  - semantic  features
        bias  - initial plausibility score
    """

    def __init__ ( self , syms , dfls ):

        """
        initialization

        arguments:
            self  -
            syms  - Elly grammatical symbol table
            dfls  - definition elements in list

        exceptions:
            FormatFailure on error
        """

#       print ( 'dfls=' , dfls )
        ne = len(dfls)
#       print ( 'ne=' , ne )
        if 3 > ne or ne > 5:                              # must have 3 to 5 elements
            raise ellyException.FormatFailure
        else:
            if dfls[0] == '\\0':
                self.patn = '\x00'                       # special nul pattern
            elif ellyWildcard.numSpaces(list(dfls[0])) > 0:
                print ( '** link pattern includes space:' , dfls[0] , file=sys.stderr )
                raise ellyException.FormatFailure
            else:
#               print ( 'do conversion' )
                self.patn = ellyWildcard.convert(dfls[0]) # encode Elly pattern
#               print ( 'patn=' , self.patn )
            if dfls[0] != '$':
                if self.patn == None or ellyWildcard.minMatch(self.patn) == 0:
                    print ( '** bad link pattern:' , dfls[0] , file=sys.stderr )
                    raise ellyException.FormatFailure
#               print ( 'appended patn=' , list(self.patn) , '=' , len(self.patn) )

            lastat = dfls[-1]
            self.catg = None                          # defaults
            self.synf = None                          #
            self.semf = None                          #
            self.bias = 0                             #
            sss = dfls[1].lower()                     # assumed not to be Unicode
#           print ( 'sss=' , sss )
            if sss != '-':                            # allow for no category
                syx = syntaxSpecification.SyntaxSpecification(syms,sss)
                if syx != None:
                    if not lastat in ['-1','-2']:     # not a stop state for matching
                        raise ellyException.FormatFailure # cannot have syntax here
                    self.catg = syx.catg              # syntactic category
                    self.synf = syx.synf.positive     # syntactic features

            if ne > 3:
                if lastat != '-1':                    # not a stop state for matching
                    raise ellyException.FormatFailure # cannot have semantics here
                sss = None if dfls[2] == '-' else dfls[2].lower()
            else:
                sss = None
#           print ( 'semantic features=' , sss )
            sem = featureSpecification.FeatureSpecification(syms,sss,True)
            self.semf = sem.positive                  # get semantic features
#           print ( 'semf=' , self.semf )

            if ne > 4:
                try:
                    self.bias = int(dfls[3])
                except ValueError:
                    raise ellyException.FormatFailure # unrecognizable bias

            try:
                n = int(lastat)                        # next state for link
            except ValueError:
                raise ellyException.FormatFailure      # unrecognizable number

#           print ( 'transition=' , n )

            if n < 0:                                  # final transition?
                if self.patn == '\x00':
                    raise ellyException.FormatFailure  # final state not allowed here
                if n == -1:
                    pe = self.patn[-1]                 # if so, get last pattern element
                    if ( pe != ellyWildcard.cALL and   # final pattern must end with * or $
                         pe != ellyWildcard.cEND ):
                        self.patn += ellyWildcard.cEND # default is $
                        print ( '** final $ added to pattern' , list(self.patn) , file=sys.stderr )

            self.nxts = n                              # specify next state

    def __str__ ( self ):

        """
        string representation of link

        arguments:
            self

        returns:
            string for printing out
        """

        if self.patn == None:
            return 'None'
        else:
            p = '{0:<24}'.format(ellyWildcard.deconvert(self.patn))
            c = str(self.catg)
            x = '' if self.synf == None else self.synf.hexadecimal(False)
            m = '' if self.semf == None else self.semf.hexadecimal(False)
            b = str(self.bias)
            n = ' next=' + str(self.nxts) if self.nxts >= 0 else ' stop'
            if self.nxts == -2: n += '+breaking'
            return p + ' ' + ' ' + c + ' ' + x + ' ' + m + ' ' + b + n

    def shortcode ( self ):

        """
        short description of FSA link

        arguments:
            self

        returns:
            state and link pattern as a string
        """

        return str(self.nxts) + ': ' + ellyWildcard.deconvert(self.patn)

#
#### main code section
#

Trmls = ellyWildcard.Trmls

def bound ( segm ):

    """
    get maximum limit on string for pattern matching
    (override this method if necessary)

    arguments:
        segm  - text segment to match against

    returns:
        char count
    """

#   print ( 'segm=' , segm )
    lm = len(segm)   # limit can be up to total length of text for matching
    ll = 0
    while ll < lm:   # look for first space in text segment
        if segm[ll] == ' ': break
        ll += 1
#   print ( 'll=' , ll , ', lm=' , lm )
    ll -= 1
    while ll > 0:    # exclude trailing non-alphanumeric from matching
                     # except for '.', Unicode prime, or  '*' and bracketing
        c = segm[ll]
#       print ( 'bound c=' , c , '{:x}'.format(ord(c)) )
        if (c in Trmls or c in [ '*' , '\u2032' , '+' ]
            or ellyChar.isLetterOrDigit(c)): break
        ll -= 1
#   print ( 'limit=' , ll + 1 )
    return ll + 1

class PatternTable(object):

    """
    non-deterministic FSA with Elly patterns to determine syntax types

    attributes:
        indx      - for FSA states and their links

        _errcount - running input error count
     """

    def __init__ ( self , syms=None , fsa=None ):

        """
        initialize

        arguments:
            self  -
            syms  - symbol table for syntax categories and features
            fsa   - EllyDefinitionReader for FSA patterns plus syntax specifications

        exceptions:
            TableFailure on error
        """

        self.indx = [ ]     # start empty
        self._errcount = 0  # no errors yet
        if fsa != None and syms != None:
            self.load(syms,fsa)

    def _err ( self , s='malformed FSA transition' , l='' ):

        """
        for error handling

        arguments:
            self  -
            s     - error message
            l     - problem line
        """

        self._errcount += 1
        print ( '** pattern error:' , s , file=sys.stderr )
        if l != '':
            print ( '*  at [' , l , ']' , file=sys.stderr )

    def load ( self , syms , fsa ):

        """
        convert text input to get FSA with encoded syntax

        arguments:
            self  -
            syms  - symbol table for syntax categories and features
            fsa   - FSA link input from Elly definition reader

        exceptions:
            TableFailure on error
        """

                        # for error checking
        ins = [ 0 ]     # states with incoming links
        sss = [   ]     # starting states
        lss = [ 0 ]     # all defined states

        nm = 0                               # states producing matches
#       print ( 'FSA definition line count=' , fsa.linecount() )
        while True: # read all input from ellyDefinitionReader
            line = fsa.readline()
#           print ( 'input line=[' , line , '], len=' , len(line) )
            if len(line) == 0: break         # EOF check
            ls = line.strip().split(' ')     # get link definition as list
#           print ( 'ls=' , ls )
            sts = ls.pop(0)                  # starting state for FSA link
            try:
                stn = int(sts)               # numerical starting state
            except ValueError:
                self._err('bad start state',line)
                continue
            n = len(self.indx)

            while stn >= n:                  # make sure state index has enough slots
                self.indx.append([ ])
                n += 1

            try:
                lk = Link(syms,ls)           # allocate new link
            except ellyException.FormatFailure:
                self._err('bad FSA option',line)
                continue
#           print ( 'load lk=' , lk )

            if lk.nxts < 0:                  # final state?
                if lk.catg != None:
                    nm += 1                  # count link category for match
                else:
                    self._err('missing category for final state',line)
                    continue
            elif lk.catg != None:
                self._err('unexpected category for non-final state' , line)

            if not stn in lss: lss.append(stn)
            if not stn in sss: sss.append(stn)
            if lk.nxts >= 0:                 # -1 is stop, not state
                if not lk.nxts in lss: lss.append(lk.nxts)
                if not lk.nxts in ins: ins.append(lk.nxts)
            elif lk.nxts < -2:
                self._err('bad final state' , line)
                continue

            self.indx[stn].append(lk)        # add to its slot in FSA state index
#           print ( '=' , self.indx[stn] )

        if len(self.indx) == 0 and self._errcount == 0:
            return                           # in case of empty definition file

        if nm == 0:                          # FSA must have at least one match state
            self._err('no match states')
#       print ( 'ins=' , ins )
#       print ( 'lss=' , lss)

        ns = len(lss)                        # total number of states
        if len(ins) != ns:
            self._err('some states unreachable')
        if len(sss) != ns:
            self._err('some non-stop states are dead ends')

        if self._errcount > 0:
            print ( '**' , self._errcount , 'pattern errors in all' , file=sys.stderr )
            print ( 'pattern table definition FAILed' , file=sys.stderr )
            raise ellyException.TableFailure

    def match ( self , segm , tree ):

        """
        compare text segment against all FSA patterns from state 0

        arguments:
            self  -
            segm  - segment to match against
            tree  - parse tree in which to put leaf nodes for final matches

        returns:
            text length matched by FSA
        """

#       print ( 'comparing' , segm )

        if len(self.indx) == 0: return 0  # no matches if FSA is empty

        if len(segm) == 0: return 0       # string is empty

        lim = bound(segm)                 # get text limit for matching

        mtl  = 0        # accumulated match length
        mtls = 0        # saved final match length

        state = 0       # set to mandatory initial state for FSA

        stk = [ ]       # for tracking possible multiple matches

        ls = self.indx[state]       # for state 0!
        ix = 0                      # index into current possible transitions
        sg = segm[:lim] # text subsegment for matching
#       print ( 'initial sg=' , sg )
#       print ( len(ls) , 'transitions from state 0' )
        capd = False if len(sg) == 0 else ellyChar.isUpperCaseLetter(sg[0])

        while True:                 # run FSA to find all possible matches
#           print ( 'state=' , state )
#           print ( 'count=' , mtl , 'matched so far' )
#           print ( 'links=' , len(ls) , 'ix=' , ix )
            nls = len(ls)           # how many links from current state

            if ix == nls:           # if none, then must back up
                if len(stk) == 0: break
                r = stk.pop()       # restore match status
#               print ( 'pop r= [' , r[0] , r[1][0].shortcode() , ']' )
                state = r[0]        # FSA state
                ls  = r[1]          # remaining links to check
                sg  = r[2]          # input string
                mtl = r[3]          # total match length
                ix = 0
#               print ( 'pop sg=' , sg )
                continue

#           print ( 'substring to match, sg=' , sg , 'nls=' , nls )
            m = 0
            while ix < nls:
                lk = ls[ix]         # get next link at current state
                ix += 1             # and increment link index
#               print ( '@' , state , 'lk= [' , str(lk), ']' , 'ix=' , ix )
#               print ( 'patn=' , lk.patn )
                po = lk.patn[0]
                if po == '\x00':   # do state change without matching?
                    m = 0           # no match length
                elif po != ellyWildcard.cEND:
#                   print ( 'po=' , po )
                    bds = ellyWildcard.match(lk.patn,sg)
#                   print ( 'bds=' , bds )
                    if bds == None: continue
                    m = bds[0]      # get match length, ignore wildcard bindings
                elif (len(sg) > 0 and
                        (ellyChar.isLetterOrDigit(sg[0]) or sg[0] == ellyChar.PRME)):
#                   print ( 'unmatched solitary $' )
                    continue
                else:
#                   print ( 'matched solitary $, state=' , state )
                    m = 0

#               print ( 'm=' , m )

                if lk.nxts < 0: # final state?
                    if lk.nxts == -2: m = 0  # last part of match not counted
#                   print ( 'state=' , state , str(lk) )
#                   print ( 'flags=' , lk.synf , '/' , lk.semf )
                    if tree.addLiteralPhraseWithSemantics(
                            lk.catg,lk.synf,lk.semf,lk.bias,cap=capd): # make phrase
                        ml = mtl + m
                        if mtls < ml: mtls = ml
#                       print ( 'success!' , 'mtls=' , mtls )
                        tree.lastph.lens = mtls                    # save its length
#                       print ( 'match state=' , state , 'length=' , mtls )

#               print ( 'ix=' , ix , 'nls=' , nls )
                if ix < nls:        # any links not yet checked?
                    r = [ state , ls[ix:] , sg , mtl ]
#                   print ( 'saved r= ' , state , end=' ' )
#                   print ( [ x.shortcode() for x in ls[ix:] ] )
                    stk.append(r)   # if not, save info for later continuation

                mtl += m            # update match length
                break               # leave loop at this state, go to next state
            else:
#               print ( 'no matches' )
                continue            # all patterns exhausted for state

            ix = 0
            sg = sg[m:]             # move up in text input
            state = lk.nxts         # next state
            if state < 0:
                ls = [ ]
            else:
                ls = self.indx[state]
#           print ( 'sg=' , sg )
#           print ( 'state=' , state )
#           print ( 'len(ls)=' , len(ls) )

#       print ( 'mtls=' , mtls )
        return mtls

    def dump ( self ):

        """
        show contents of pattern table

        arguments:
            self
        """

        nn = 0   # nul pattern count
        for k in range(len(self.indx)):
            lks = self.indx[k]
            if lks == None or lks == [ ]:
                continue
            print ( '[state ' + str(k) + ']' )
            for lk in lks:
                print ( '  ' + str(lk) )
                if lk.patn == '\x00': nn += 1
        print ( nn , 'nul pattern(s)' )
        print ()

#
# unit test
#

if __name__ == '__main__':

    import ellyConfiguration
    import ellyDefinitionReader
    import dumpEllyGrammar
    import parseTest
    import stat
    import os

    mode = os.fstat(0).st_mode       # to check for redirection of stdin (=0)
    interact = not ( stat.S_ISFIFO(mode) or stat.S_ISREG(mode) )

    ctx = parseTest.Context()        # dummy interpretive context for testing
    tre = parseTest.Tree(ctx.syms)   # dummy parse tree for testing
    print ()

    basn = ellyConfiguration.baseSource + '/'
    filn = sys.argv[1] if len(sys.argv) > 1 else 'test' # which FSA definition to use
    inp = ellyDefinitionReader.EllyDefinitionReader(basn + filn + '.p.elly')

    print ( 'pattern test with' , '<' + filn + '>' )

    if inp.error != None:
        print ( inp.error )
        sys.exit(1)

    patn = None
    try:
        patn = PatternTable(ctx.syms,inp) # try to define FSA
    except ellyException.TableFailure:
        print ( 'no pattern table generated' )
        sys.exit(1)

    print ( len(patn.indx) , 'distinct FSA state(s)' )

    print ()
    dumpEllyGrammar.dumpCategories(ctx.syms)
    print ()
    patn.dump()

    print ( 'enter tokens in context to recognize' )

    while True: # try FSA with test examples

        if interact:
            sys.stdout.write('> ')
            sys.stdout.flush()
        t = sys.stdin.readline().strip()
        if len(t) == 0: break
        print ( 'text=' , '[' , t , ']' )
        nma = patn.match(list(t),tre)

    if interact: sys.stdout.write('\n')

    tre.showQueue()