spaCy/spacy/tokenizer.pyx

# cython: embedsignature=True
# coding: utf8
from __future__ import unicode_literals

import ujson

from cython.operator cimport dereference as deref
from cython.operator cimport preincrement as preinc
from cymem.cymem cimport Pool
from preshed.maps cimport PreshMap

from .strings cimport hash_string
cimport cython

from . import util
from .tokens.doc cimport Doc


cdef class Tokenizer:
    """
    Segment text, and create Doc objects with the discovered segment boundaries.
    """
    @classmethod
    def load(cls, path, Vocab vocab, rules=None, prefix_search=None, suffix_search=None,
             infix_finditer=None, token_match=None):
        """
        Load a Tokenizer, reading unsupplied components from the path.

        Arguments:
            path (Path):
                The path to load from.
            vocab (Vocab):
                A storage container for lexical types.
            rules (dict):
                Exceptions and special-cases for the tokenizer.
            token_match:
                A boolean function matching strings that becomes tokens.
            prefix_search:
                Signature of re.compile(string).search
            suffix_search:
                Signature of re.compile(string).search
            infix_finditer:
                Signature of re.compile(string).finditer
        Returns Tokenizer
        """
        path = util.ensure_path(path)
        if rules is None:
            with (path / 'tokenizer' / 'specials.json').open('r', encoding='utf8') as file_:
                rules = ujson.load(file_)
        if prefix_search in (None, True):
            with (path / 'tokenizer' / 'prefix.txt').open() as file_:
                entries = file_.read().split('\n')
            prefix_search = util.compile_prefix_regex(entries).search
        if suffix_search in (None, True):
            with (path / 'tokenizer' / 'suffix.txt').open() as file_:
                entries = file_.read().split('\n')
            suffix_search = util.compile_suffix_regex(entries).search
        if infix_finditer in (None, True):
            with (path / 'tokenizer' / 'infix.txt').open() as file_:
                entries = file_.read().split('\n')
            infix_finditer = util.compile_infix_regex(entries).finditer
        return cls(vocab, rules, prefix_search, suffix_search, infix_finditer, token_match)

    def __init__(self, Vocab vocab, rules, prefix_search, suffix_search, infix_finditer, token_match=None):
        """
        Create a Tokenizer, to create Doc objects given unicode text.

        Arguments:
            vocab (Vocab):
                A storage container for lexical types.
            rules (dict):
                Exceptions and special-cases for the tokenizer.
            prefix_search:
                A function matching the signature of re.compile(string).search
                to match prefixes.
            suffix_search:
                A function matching the signature of re.compile(string).search
                to match suffixes.
            infix_finditer:
                A function matching the signature of re.compile(string).finditer
                to find infixes.
            token_match:
                A boolean function matching strings that becomes tokens.
        """
        self.mem = Pool()
        self._cache = PreshMap()
        self._specials = PreshMap()
        self.token_match = token_match
        self.prefix_search = prefix_search
        self.suffix_search = suffix_search
        self.infix_finditer = infix_finditer
        self.vocab = vocab
        self._rules = {}
        for chunk, substrings in sorted(rules.items()):
            self.add_special_case(chunk, substrings)

    def __reduce__(self):
        args = (self.vocab,
                self._rules,
                self._prefix_re,
                self._suffix_re,
                self._infix_re,
                self.token_match)

        return (self.__class__, args, None, None)

    cpdef Doc tokens_from_list(self, list strings):
        return Doc(self.vocab, words=strings)
        #raise NotImplementedError(
        #    "Method deprecated in 1.0.\n"
        #    "Old: tokenizer.tokens_from_list(strings)\n"
        #    "New: Doc(tokenizer.vocab, words=strings)")

    @cython.boundscheck(False)
    def __call__(self, unicode string):
        """
        Tokenize a string.

        Arguments:
            string (unicode): The string to tokenize.
        Returns:
            Doc A container for linguistic annotations.
        """
        if len(string) >= (2 ** 30):
            raise ValueError(
                "String is too long: %d characters. Max is 2**30." % len(string)
            )
        cdef int length = len(string)
        cdef Doc tokens = Doc(self.vocab)
        if length == 0:
            return tokens
        cdef int i = 0
        cdef int start = 0
        cdef bint cache_hit
        cdef bint in_ws = string[0].isspace()
        cdef unicode span
        # The task here is much like string.split, but not quite
        # We find spans of whitespace and non-space characters, and ignore
        # spans that are exactly ' '. So, our sequences will all be separated
        # by either ' ' or nothing.
        for uc in string:
            if uc.isspace() != in_ws:
                if start < i:
                    # When we want to make this fast, get the data buffer once
                    # with PyUnicode_AS_DATA, and then maintain a start_byte
                    # and end_byte, so we can call hash64 directly. That way
                    # we don't have to create the slice when we hit the cache.
                    span = string[start:i]
                    key = hash_string(span)
                    cache_hit = self._try_cache(key, tokens)
                    if not cache_hit:
                        self._tokenize(tokens, span, key)
                if uc == ' ':
                    tokens.c[tokens.length - 1].spacy = True
                    start = i + 1
                else:
                    start = i
                in_ws = not in_ws
            i += 1
        if start < i:
            span = string[start:]
            key = hash_string(span)
            cache_hit = self._try_cache(key, tokens)
            if not cache_hit:
                self._tokenize(tokens, span, key)
            tokens.c[tokens.length - 1].spacy = string[-1] == ' ' and not in_ws
        return tokens

    def pipe(self, texts, batch_size=1000, n_threads=2):
        """
        Tokenize a stream of texts.

        Arguments:
            texts: A sequence of unicode texts.
            batch_size (int):
                The number of texts to accumulate in an internal buffer.
            n_threads (int):
                The number of threads to use, if the implementation supports
                multi-threading. The default tokenizer is single-threaded.
        Yields:
            Doc A sequence of Doc objects, in order.
        """
        for text in texts:
            yield self(text)

    cdef int _try_cache(self, hash_t key, Doc tokens) except -1:
        cached = <_Cached*>self._cache.get(key)
        if cached == NULL:
            return False
        cdef int i
        if cached.is_lex:
            for i in range(cached.length):
                tokens.push_back(cached.data.lexemes[i], False)
        else:
            for i in range(cached.length):
                tokens.push_back(&cached.data.tokens[i], False)
        return True

    cdef int _tokenize(self, Doc tokens, unicode span, hash_t orig_key) except -1:
        cdef vector[LexemeC*] prefixes
        cdef vector[LexemeC*] suffixes
        cdef int orig_size
        orig_size = tokens.length
        span = self._split_affixes(tokens.mem, span, &prefixes, &suffixes)
        self._attach_tokens(tokens, span, &prefixes, &suffixes)
        self._save_cached(&tokens.c[orig_size], orig_key, tokens.length - orig_size)

    cdef unicode _split_affixes(self, Pool mem, unicode string,
                                vector[const LexemeC*] *prefixes,
                                vector[const LexemeC*] *suffixes):
        cdef size_t i
        cdef unicode prefix
        cdef unicode suffix
        cdef unicode minus_pre
        cdef unicode minus_suf
        cdef size_t last_size = 0
        while string and len(string) != last_size:
            if self.token_match and self.token_match(string):
                break
            last_size = len(string)
            pre_len = self.find_prefix(string)
            if pre_len != 0:
                prefix = string[:pre_len]
                minus_pre = string[pre_len:]
                # Check whether we've hit a special-case
                if minus_pre and self._specials.get(hash_string(minus_pre)) != NULL:
                    string = minus_pre
                    prefixes.push_back(self.vocab.get(mem, prefix))
                    break
                if self.token_match and self.token_match(string):
                    break
            suf_len = self.find_suffix(string)
            if suf_len != 0:
                suffix = string[-suf_len:]
                minus_suf = string[:-suf_len]
                # Check whether we've hit a special-case
                if minus_suf and (self._specials.get(hash_string(minus_suf)) != NULL):
                    string = minus_suf
                    suffixes.push_back(self.vocab.get(mem, suffix))
                    break
            if pre_len and suf_len and (pre_len + suf_len) <= len(string):
                string = string[pre_len:-suf_len]
                prefixes.push_back(self.vocab.get(mem, prefix))
                suffixes.push_back(self.vocab.get(mem, suffix))
            elif pre_len:
                string = minus_pre
                prefixes.push_back(self.vocab.get(mem, prefix))
            elif suf_len:
                string = minus_suf
                suffixes.push_back(self.vocab.get(mem, suffix))
            if string and (self._specials.get(hash_string(string)) != NULL):
                break
        return string

    cdef int _attach_tokens(self, Doc tokens, unicode string,
                            vector[const LexemeC*] *prefixes,
                            vector[const LexemeC*] *suffixes) except -1:
        cdef bint cache_hit
        cdef int split, end
        cdef const LexemeC* const* lexemes
        cdef const LexemeC* lexeme
        cdef unicode span
        cdef int i
        if prefixes.size():
            for i in range(prefixes.size()):
                tokens.push_back(prefixes[0][i], False)
        if string:
            cache_hit = self._try_cache(hash_string(string), tokens)
            if cache_hit:
                pass
            elif self.token_match and self.token_match(string):
                # We're always saying 'no' to spaces here -- the caller will
                # fix up the outermost one, with reference to the original.
                # See Issue #859
                tokens.push_back(self.vocab.get(tokens.mem, string), False)
            else:
                matches = self.find_infix(string)
                if not matches:
                    tokens.push_back(self.vocab.get(tokens.mem, string), False)
                else:
                    # let's say we have dyn-o-mite-dave
                    # the regex finds the start and end positions of the hyphens
                    start = 0
                    for match in matches:
                        infix_start = match.start()
                        infix_end = match.end()
                        if infix_start == start:
                            continue

                        span = string[start:infix_start]
                        tokens.push_back(self.vocab.get(tokens.mem, span), False)

                        if infix_start != infix_end:
                            # If infix_start != infix_end, it means the infix
                            # token is non-empty. Empty infix tokens are useful
                            # for tokenization in some languages (see
                            # https://github.com/explosion/spaCy/issues/768)
                            infix_span = string[infix_start:infix_end]
                            tokens.push_back(self.vocab.get(tokens.mem, infix_span), False)

                        start = infix_end
                    span = string[start:]
                    tokens.push_back(self.vocab.get(tokens.mem, span), False)
        cdef vector[const LexemeC*].reverse_iterator it = suffixes.rbegin()
        while it != suffixes.rend():
            lexeme = deref(it)
            preinc(it)
            tokens.push_back(lexeme, False)

    cdef int _save_cached(self, const TokenC* tokens, hash_t key, int n) except -1:
        cdef int i
        for i in range(n):
            if tokens[i].lex.id == 0:
                return 0
        cached = <_Cached*>self.mem.alloc(1, sizeof(_Cached))
        cached.length = n
        cached.is_lex = True
        lexemes = <const LexemeC**>self.mem.alloc(n, sizeof(LexemeC**))
        for i in range(n):
            lexemes[i] = tokens[i].lex
        cached.data.lexemes = <const LexemeC* const*>lexemes
        self._cache.set(key, cached)

    def find_infix(self, unicode string):
        """
        Find internal split points of the string, such as hyphens.

        string (unicode): The string to segment.

        Returns List[re.MatchObject]
            A list of objects that have .start() and .end() methods, denoting the
            placement of internal segment separators, e.g. hyphens.
        """
        if self.infix_finditer is None:
            return 0
        return list(self.infix_finditer(string))

    def find_prefix(self, unicode string):
        """
        Find the length of a prefix that should be segmented from the string,
        or None if no prefix rules match.

        Arguments:
            string (unicode): The string to segment.
        Returns (int or None): The length of the prefix if present, otherwise None.
        """
        if self.prefix_search is None:
            return 0
        match = self.prefix_search(string)
        return (match.end() - match.start()) if match is not None else 0

    def find_suffix(self, unicode string):
        """
        Find the length of a suffix that should be segmented from the string,
        or None if no suffix rules match.

        Arguments:
            string (unicode): The string to segment.
        Returns (int or None): The length of the suffix if present, otherwise None.
        """
        if self.suffix_search is None:
            return 0
        match = self.suffix_search(string)
        return (match.end() - match.start()) if match is not None else 0

    def _load_special_tokenization(self, special_cases):
        """
        Add special-case tokenization rules.
        """
        for chunk, substrings in sorted(special_cases.items()):
            self.add_special_case(chunk, substrings)

    def add_special_case(self, unicode string, substrings):
        """
        Add a special-case tokenization rule.

        Arguments:
            string (unicode): The string to specially tokenize.
            token_attrs:
                A sequence of dicts, where each dict describes a token and its
                attributes. The ORTH fields of the attributes must exactly match
                the string when they are concatenated.
        Returns None
        """
        substrings = list(substrings)
        cached = <_Cached*>self.mem.alloc(1, sizeof(_Cached))
        cached.length = len(substrings)
        cached.is_lex = False
        cached.data.tokens = self.vocab.make_fused_token(substrings)
        key = hash_string(string)
        self._specials.set(key, cached)
        self._cache.set(key, cached)
        self._rules[string] = substrings