Module Gnumed.pycommon.gmMatchProvider

Base classes for match providers.

They are used by business objects to give phrasewheels the ability to guess phrases.

Copyright (C) GNUMed developers license: GPL v2 or later

"""Base classes for match providers.

They are used by business objects to give
phrasewheels the ability to guess phrases.

Copyright (C) GNUMed developers
license: GPL v2 or later
"""
__author__  = "K.Hilbert <Karsten.Hilbert@gmx.net>, I.Haywood <ihaywood@gnu.org>, S.J.Tan <sjtan@bigpond.com>"

# std lib
import sys
import logging
import re as regex
import datetime as pydt


# GNUmed
if __name__ == "__main__":
        sys.path.insert(0, '../../')
from Gnumed.pycommon import gmPG2


_log = logging.getLogger('gm.ui')


# these are stripped from the fragment passed to the
# match provider before looking for matches:
default_ignored_chars = "[?!.'\\(){}\[\]<>~#*$%^_]+" + '"'

# these are used to detect word boundaries which is,
# in turn, used to normalize word boundaries in the
# input fragment
default_word_separators = '[- \t=+&:@]+'
#============================================================
class cMatchProvider(object):
        """Base class for match providing objects.

        Match sources might be:
        - database tables
        - flat files
        - previous input
        - config files
        - in-memory list created on the fly
        """
        print_queries = False
        #--------------------------------------------------------
        def __init__(self):
                self.setThresholds()

                self._context_vals = {}
                self.__ignored_chars = regex.compile(default_ignored_chars)
                # used to normalize word boundaries:
                self.__word_separators = regex.compile(default_word_separators)
        #--------------------------------------------------------
        # actions
        #--------------------------------------------------------
        def getMatches(self, aFragment = None):
                """Return matches according to aFragment and matching thresholds.

                FIXME: design decision: we dont worry about data source changes
                           during the lifetime of a MatchProvider
                FIXME: append _("*get all items*") on truncation
                """
                # sanity check
                if aFragment is None:
                        raise ValueError('Cannot find matches without a fragment.')

                # user explicitly wants all matches
                if aFragment == '*':
                        return self.getAllMatches()

                # case insensitivity
                tmpFragment = aFragment.casefold()
                # remove ignored chars
                if self.__ignored_chars is not None:
                        tmpFragment = self.__ignored_chars.sub('', tmpFragment)
                # normalize word separators
                if self.__word_separators is not None:
                        tmpFragment = ' '.join(self.__word_separators.split(tmpFragment))
                # length in number of significant characters only
                lngFragment = len(tmpFragment)

                # order is important !
                if lngFragment >= self.__threshold_substring:
                        return self.getMatchesBySubstr(tmpFragment)
                elif lngFragment >= self.__threshold_word:
                        return self.getMatchesByWord(tmpFragment)
                elif lngFragment >= self.__threshold_phrase:
                        return self.getMatchesByPhrase(tmpFragment)
                else:
                        return (False, [])
        #--------------------------------------------------------
        def getAllMatches(self):
                raise NotImplementedError
        #--------------------------------------------------------
        def getMatchesByPhrase(self, aFragment):
                raise NotImplementedError
        #--------------------------------------------------------
        def getMatchesByWord(self, aFragment):
                raise NotImplementedError
        #--------------------------------------------------------
        def getMatchesBySubstr(self, aFragment):
                raise NotImplementedError
        #--------------------------------------------------------
        def get_match_by_data(self, data=None):
                return None
        #--------------------------------------------------------
        # configuration
        #--------------------------------------------------------
        def setThresholds(self, aPhrase = 1, aWord = 3, aSubstring = 5):
                """Set match location thresholds.

                - the fragment passed to getMatches() must contain at least this many
                  characters before it triggers a match search at:
                  1) phrase_start - start of phrase (first word)
                  2) word_start - start of any word within phrase
                  3) in_word - _inside_ any word within phrase
                """
                # sanity checks
                if aSubstring < aWord:
                        _log.error('Setting substring threshold (%s) lower than word-start threshold (%s) does not make sense.' % (aSubstring, aWord))
                        return False

                if aWord < aPhrase:
                        _log.error('Setting word-start threshold (%s) lower than phrase-start threshold (%s) does not make sense.' % (aSubstring, aWord))
                        return False

                # now actually reassign thresholds
                self.__threshold_phrase = aPhrase
                self.__threshold_word   = aWord
                self.__threshold_substring      = aSubstring
                return True

        #--------------------------------------------------------
        def _set_word_separators(self, word_separators=None):
                if word_separators is None:
                        self.__word_separators = None
                else:
                        self.__word_separators = regex.compile(word_separators)

        def _get_word_separators(self):
                if self.__word_separators is None:
                        return None
                return self.__word_separators.pattern

        word_separators = property(_get_word_separators, _set_word_separators)
        #--------------------------------------------------------
        def _set_ignored_chars(self, ignored_chars=None):
                if ignored_chars is None:
                        self.__ignored_chars = None
                else:
                        self.__ignored_chars = regex.compile(ignored_chars)

        def _get_ignored_chars(self):
                if self.__ignored_chars is None:
                        return None
                return self.__ignored_chars.pattern

        ignored_chars = property(_get_ignored_chars, _set_ignored_chars)
        #--------------------------------------------------------
        def set_context (self, context=None, val=None):
                """Set value to provide context information     for matches.

                The matching code may ignore it depending on its exact
                implementation. Names and values of the context depend
                on what is being matched.

                <context> -- the *placeholder* key *inside* the context
                                         definition, not the context *definition* key
                """
                if context is None:
                        return False
                self._context_vals[context] = val
                return True
        #--------------------------------------------------------
        def unset_context(self, context=None):
                try:
                        del self._context_vals[context]
                except KeyError:
                        pass
#------------------------------------------------------------
# usable instances
#------------------------------------------------------------
class cMatchProvider_FixedList(cMatchProvider):
        """Match provider where all possible options can be held
           in a reasonably sized, pre-allocated list.
        """
        def __init__(self, aSeq = None):
                """aSeq must be a list of dicts. Each dict must have the keys (data, label, weight)
                """
                if not type(aSeq) in [type(None), list, tuple]:
                        _log.error('fixed list match provider argument must be a list/tuple of dicts/None')
                        raise TypeError('fixed list match provider argument must be a list/tuple of dicts/None')

                self.__items = aSeq
                cMatchProvider.__init__(self)

        #--------------------------------------------------------
        # internal matching algorithms
        #
        # if we end up here:
        #       - aFragment will not be "None"
        #   - aFragment will be lower case
        #       - we _do_ deliver matches (whether we find any is a different story)
        #--------------------------------------------------------
        def getMatchesByPhrase(self, aFragment):
                """Return matches for aFragment at start of phrases."""
                matches = []
                # look for matches
                for item in self.__items:
                        # at start of phrase, that is
                        if item['list_label'].casefold().startswith(aFragment.casefold()):
                                matches.append(item)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                #matches.sort(self.__cmp_items)
                matches.sort(key = lambda x: x['weight'], reverse = True)
                return (True, matches)

        #--------------------------------------------------------
        def getMatchesByWord(self, aFragment):
                """Return matches for aFragment at start of words inside phrases."""
                matches = []
                # look for matches
                for item in self.__items:
                        item_label = item['list_label'].casefold()
                        fragment_pos = item_label.find(aFragment.casefold())
                        # found at start of phrase
                        if fragment_pos == 0:
                                matches.append(item)
                        # found as a true substring
                        elif fragment_pos > 0:
                                # but use only if substring is at start of a word
                                if item_label[fragment_pos-1] == ' ':
                                        matches.append(item)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                #matches.sort(self.__cmp_items)
                matches.sort(key = lambda x: x['weight'], reverse = True)
                return (True, matches)

        #--------------------------------------------------------
        def getMatchesBySubstr(self, aFragment):
                """Return matches for aFragment as a true substring."""
                matches = []
                # look for matches
                for item in self.__items:
                        if item['list_label'].casefold().find(aFragment.casefold()) != -1:
                                matches.append(item)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                #matches.sort(self.__cmp_items)
                matches.sort(key = lambda x: x['weight'], reverse = True)
                return (True, matches)

        #--------------------------------------------------------
        def getAllMatches(self):
                """Return all items."""
                matches = self.__items
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                #matches.sort(self.__cmp_items)
                matches.sort(key = lambda x: x['weight'], reverse = True)
                return (True, matches)

        #--------------------------------------------------------
        def set_items(self, items):
                """items must be a list of dicts. Each dict must have the keys (data, list_label, weight)"""
                self.__items = items

#       #--------------------------------------------------------
#       def __cmp_items(self, item1, item2):
#               """Compare items based on weight."""
#               if item1['weight'] == item2['weight']:
#                       return 0
#
#               # do it the wrong way round to do sorting/reversing at once
#               if item1['weight'] < item2['weight']:
#                       return 1
#               if item1['weight'] > item2['weight']:
#                       return -1

# ===========================================================
class cMatchProvider_Func(cMatchProvider):
        """Match provider which searches matches
           in the results of a function call.
        """
        def __init__(self, get_candidates = None):
                """get_candidates() must return a list of strings."""
                if get_candidates is None:
                        _log.error('must define function to retrieve match candidates list')
                        raise ValueError('must define function to retrieve match candidates list')

                self._get_candidates = get_candidates
                cMatchProvider.__init__(self)
        #--------------------------------------------------------
        # internal matching algorithms
        #
        # if we end up here:
        #       - aFragment will not be "None"
        #   - aFragment will be lower case
        #       - we _do_ deliver matches (whether we find any is a different story)
        #--------------------------------------------------------
        def getMatchesByPhrase(self, aFragment):
                """Return matches for aFragment at start of phrases."""
                matches = []
                candidates = self._get_candidates()
                # look for matches
                for candidate in candidates:
                        # at start of phrase, that is
                        if aFragment.startswith(candidate['list_label'].casefold()):
                                matches.append(candidate)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                matches.sort(key = self.__cmp_candidates)
                return (True, matches)
        #--------------------------------------------------------
        def getMatchesByWord(self, aFragment):
                """Return matches for aFragment at start of words inside phrases."""
                matches = []
                candidates = self._get_candidates()
                # look for matches
                for candidate in candidates:
                        pos = candidate['list_label'].casefold().find(aFragment)
#                       pos = string.find(string.lower(candidate['list_label']), aFragment)
                        # found as a true substring
                        # but use only if substring is at start of a word
                        # FIXME: use word seps
                        if (pos == 0) or (candidate['list_label'][pos-1] == ' '):
                                matches.append(candidate)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                matches.sort(key = self.__cmp_candidates)
                return (True, matches)
        #--------------------------------------------------------
        def getMatchesBySubstr(self, aFragment):
                """Return matches for aFragment as a true substring."""
                matches = []
                candidates = self._get_candidates()
                # look for matches
                for candidate in candidates:
                        if candidate['list_label'].casefold().find(aFragment) != -1:
#                       if string.find(string.lower(candidate['list_label']), aFragment) != -1:
                                matches.append(candidate)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                matches.sort(key = self.__cmp_candidates)
                return (True, matches)
        #--------------------------------------------------------
        def getAllMatches(self):
                """Return all candidates."""
                return self._get_candidates()
        #--------------------------------------------------------
        #def __cmp_candidates(self, candidate1, candidate2):
        def __cmp_candidates(self, candidate):
                """naive ordering"""
                return 0
                # FIXME: do ordering
#               if candidate1 < candidate2:
#                       return -1
#               if candidate1 == candidate2:
#                       return 0
#               return 1

# ===========================================================
class cMatchProvider_SQL2(cMatchProvider):
        """Match provider which searches matches
           in possibly several database tables.

        queries:
                - a list of unicode strings
                - each string is a query
                - each string must contain: "... WHERE <column> %(fragment_condition)s ..."
                - each string can contain in the where clause: "... %(<ctxt_key1>)s ..."
                - each query must return (data, list_label, field_label)

        context definitions to be used in the queries, example:
                {'ctxt_key1': {'where_part': 'AND country = %(country)s', 'placeholder': 'country'}}

        client code using .set_context() must use the 'placeholder':
                <phrasewheel>/<match provider>.set_context('country', 'Germany')

        full example query:

                query = u" " "
                        SELECT DISTINCT ON (list_label)
                                pk_encounter
                                        AS data,
                                to_char(started, 'YYYY Mon DD (HH24:MI)') || ': ' || l10n_type || ' [#' || pk_encounter || ']'
                                        AS list_label,
                                to_char(started, 'YYYY Mon DD') || ': ' || l10n_type
                                        AS field_label
                        FROM
                                clin.v_pat_encounters
                        WHERE
                                (
                                        l10n_type %(fragment_condition)s
                                                OR
                                        type %(fragment_condition)s
                                )       %(ctxt_patient)s
                        ORDER BY
                                list_label
                        LIMIT
                                30
                " " "
                context = {'ctxt_patient': {
                        'where_part': u'AND pk_patient = %(PLACEHOLDER)s',
                        'placeholder': u'PLACEHOLDER'
                }}
                self.mp = gmMatchProvider.cMatchProvider_SQL2(queries = query, context = context)
                self.set_context(context = 'PLACEHOLDER', val = '<THE VALUE>')

        _SQL_data2match:
                SQL to retrieve a match by, say, primary key
                wherein the only keyword argument is 'pk'
        """
        def __init__(self, queries = None, context = None):

                cMatchProvider.__init__(self)

                if type(queries) == type([]):
                        self._queries = queries
                else:
                        self._queries = [queries]

                if context is None:
                        self._context = {}
                else:
                        self._context = context

                self._args = {}

                self._SQL_data2match = None

        #--------------------------------------------------------
        # internal matching algorithms
        #
        # if we end up here:
        #       - aFragment will not be "None"
        #   - aFragment will be lower case
        #       - we _do_ deliver matches (whether we find any is a different story)
        #--------------------------------------------------------
        def getMatchesByPhrase(self, aFragment):
                """Return matches for aFragment at start of phrases."""

                fragment_condition = "ILIKE %(fragment)s"
                self._args['fragment'] = "%s%%" % aFragment

                return self._find_matches(fragment_condition)

        #--------------------------------------------------------
        def getMatchesByWord(self, aFragment):
                """Return matches for aFragment at start of words inside phrases."""

                fragment_condition = "~* %(fragment)s"
                aFragment = gmPG2.sanitize_pg_regex(expression = aFragment, escape_all = False)
                self._args['fragment'] = "( %s)|(^%s)" % (aFragment, aFragment)

                return self._find_matches(fragment_condition)

        #--------------------------------------------------------
        def getMatchesBySubstr(self, aFragment):
                """Return matches for aFragment as a true substring."""

                fragment_condition = "ILIKE %(fragment)s"
                self._args['fragment'] = "%%%s%%" % aFragment

                return self._find_matches(fragment_condition)

        #--------------------------------------------------------
        def getAllMatches(self):
                """Return all items."""
                return self.getMatchesBySubstr('')

        #--------------------------------------------------------
        def get_match_by_data(self, data=None):
                if self._SQL_data2match is None:
                        return None

                query = {'cmd': self._SQL_data2match, 'args': {'pk': data}}
                try:
                        rows, idx = gmPG2.run_ro_queries(queries = [query], get_col_idx = False)
                except Exception:
                        _log.exception('[%s]: error running _SQL_data2match, dropping query', self.__class__.__name__)
                        self._SQL_data2match = None
                        return None

                # hopefully the most frequent case:
                if len(rows) == 1:
                        return rows[0]

                _log.error('[%s]: 0 or >1 rows found by running _SQL_data2match, ambiguous, ignoring', self.__class__.__name__)
                return None

        #--------------------------------------------------------
        def _rows2matches(self, rows):
                """Turns retrieved database values into a list
                   of dicts fit for phrasewheel use.

                   This method can be overridden to massage arbitrary
                   data into the proper list of dicts.
                """
                matches = []
                for row in rows:
                        # PRW wants a weight
                        match = {'weight': 0}
                        try:
                                match['data'] = row['data']
                        except KeyError:
                                match['data'] = row[0]
                        try:
                                match['list_label'] = row['list_label']
                        except KeyError:
                                match['list_label'] = row[1]
                        # explicit "field_label" in result ?
                        try:
                                match['field_label'] = row['field_label']
                        # no
                        except KeyError:
                                # but does row[2] exist ?
                                try:
                                        match['field_label'] = row[2]
                                # no: reuse "list_label"
                                except IndexError:
                                        match['field_label'] = match['list_label']
                        matches.append(match)

                return matches

        #--------------------------------------------------------
        def _find_matches(self, fragment_condition:str) -> tuple[bool, list]:
                """Loads matching data from PostgreSQL and turns them into
                   matches fit for consumption by a phrasewheel.
                """
                if self.print_queries:
                        print("----------------------")
                        print(pydt.datetime.now())

                matches = []
                for query in self._queries:
                        where_fragments = {'fragment_condition': fragment_condition}

                        for context_key, context_def in self._context.items():
                                try:
                                        placeholder = context_def['placeholder']
                                        where_part = context_def['where_part']
                                        self._args[placeholder] = self._context_vals[placeholder]
                                        # we do have a context value for this key, so add the where condition
                                        where_fragments[context_key] = where_part
                                        if self.print_queries:
                                                print("ctxt ph:", placeholder)
                                                print("ctxt where:", where_part)
                                                print("ctxt val:", self._context_vals[placeholder])
                                except KeyError:
                                        # we don't have a context value for this key, so skip the where condition
                                        where_fragments[context_key] = ''
                                        if self.print_queries:
                                                print("invalid ctxt key:", context_key)

                        cmd = query % where_fragments

                        if self.print_queries:
                                print("class:", self.__class__.__name__)
                                print("ctxt:", self._context_vals)
                                print("args:", self._args)
                                print("query:", cmd)

                        try:
                                rows, idx = gmPG2.run_ro_queries(queries = [{'cmd': cmd, 'args': self._args}], get_col_idx = False)
                        except gmPG2.PG_ERROR_EXCEPTION:
                                _log.exception('[%s]: error running match provider SQL, dropping query', self.__class__.__name__)
                                _log.error('SQL: %s', cmd)
                                idx = self._queries.index(query)
                                del self._queries[idx]
                                break
                        # no matches found: try next query
                        if len(rows) == 0:
                                continue
                        matches = self._rows2matches(rows)
                        return (True, matches)
                # none found whatsoever
                return (False, [])

#================================================================
if __name__ == '__main__':
        pass

Classes

class cMatchProvider

Base class for match providing objects.

Match sources might be: - database tables - flat files - previous input - config files - in-memory list created on the fly

Expand source code

class cMatchProvider(object):
        """Base class for match providing objects.

        Match sources might be:
        - database tables
        - flat files
        - previous input
        - config files
        - in-memory list created on the fly
        """
        print_queries = False
        #--------------------------------------------------------
        def __init__(self):
                self.setThresholds()

                self._context_vals = {}
                self.__ignored_chars = regex.compile(default_ignored_chars)
                # used to normalize word boundaries:
                self.__word_separators = regex.compile(default_word_separators)
        #--------------------------------------------------------
        # actions
        #--------------------------------------------------------
        def getMatches(self, aFragment = None):
                """Return matches according to aFragment and matching thresholds.

                FIXME: design decision: we dont worry about data source changes
                           during the lifetime of a MatchProvider
                FIXME: append _("*get all items*") on truncation
                """
                # sanity check
                if aFragment is None:
                        raise ValueError('Cannot find matches without a fragment.')

                # user explicitly wants all matches
                if aFragment == '*':
                        return self.getAllMatches()

                # case insensitivity
                tmpFragment = aFragment.casefold()
                # remove ignored chars
                if self.__ignored_chars is not None:
                        tmpFragment = self.__ignored_chars.sub('', tmpFragment)
                # normalize word separators
                if self.__word_separators is not None:
                        tmpFragment = ' '.join(self.__word_separators.split(tmpFragment))
                # length in number of significant characters only
                lngFragment = len(tmpFragment)

                # order is important !
                if lngFragment >= self.__threshold_substring:
                        return self.getMatchesBySubstr(tmpFragment)
                elif lngFragment >= self.__threshold_word:
                        return self.getMatchesByWord(tmpFragment)
                elif lngFragment >= self.__threshold_phrase:
                        return self.getMatchesByPhrase(tmpFragment)
                else:
                        return (False, [])
        #--------------------------------------------------------
        def getAllMatches(self):
                raise NotImplementedError
        #--------------------------------------------------------
        def getMatchesByPhrase(self, aFragment):
                raise NotImplementedError
        #--------------------------------------------------------
        def getMatchesByWord(self, aFragment):
                raise NotImplementedError
        #--------------------------------------------------------
        def getMatchesBySubstr(self, aFragment):
                raise NotImplementedError
        #--------------------------------------------------------
        def get_match_by_data(self, data=None):
                return None
        #--------------------------------------------------------
        # configuration
        #--------------------------------------------------------
        def setThresholds(self, aPhrase = 1, aWord = 3, aSubstring = 5):
                """Set match location thresholds.

                - the fragment passed to getMatches() must contain at least this many
                  characters before it triggers a match search at:
                  1) phrase_start - start of phrase (first word)
                  2) word_start - start of any word within phrase
                  3) in_word - _inside_ any word within phrase
                """
                # sanity checks
                if aSubstring < aWord:
                        _log.error('Setting substring threshold (%s) lower than word-start threshold (%s) does not make sense.' % (aSubstring, aWord))
                        return False

                if aWord < aPhrase:
                        _log.error('Setting word-start threshold (%s) lower than phrase-start threshold (%s) does not make sense.' % (aSubstring, aWord))
                        return False

                # now actually reassign thresholds
                self.__threshold_phrase = aPhrase
                self.__threshold_word   = aWord
                self.__threshold_substring      = aSubstring
                return True

        #--------------------------------------------------------
        def _set_word_separators(self, word_separators=None):
                if word_separators is None:
                        self.__word_separators = None
                else:
                        self.__word_separators = regex.compile(word_separators)

        def _get_word_separators(self):
                if self.__word_separators is None:
                        return None
                return self.__word_separators.pattern

        word_separators = property(_get_word_separators, _set_word_separators)
        #--------------------------------------------------------
        def _set_ignored_chars(self, ignored_chars=None):
                if ignored_chars is None:
                        self.__ignored_chars = None
                else:
                        self.__ignored_chars = regex.compile(ignored_chars)

        def _get_ignored_chars(self):
                if self.__ignored_chars is None:
                        return None
                return self.__ignored_chars.pattern

        ignored_chars = property(_get_ignored_chars, _set_ignored_chars)
        #--------------------------------------------------------
        def set_context (self, context=None, val=None):
                """Set value to provide context information     for matches.

                The matching code may ignore it depending on its exact
                implementation. Names and values of the context depend
                on what is being matched.

                <context> -- the *placeholder* key *inside* the context
                                         definition, not the context *definition* key
                """
                if context is None:
                        return False
                self._context_vals[context] = val
                return True
        #--------------------------------------------------------
        def unset_context(self, context=None):
                try:
                        del self._context_vals[context]
                except KeyError:
                        pass

Subclasses

• cMatchProvider_FixedList
• cMatchProvider_Func
• cMatchProvider_SQL2

Class variables

var print_queries

Instance variables

var ignored_chars

Expand source code

def _get_ignored_chars(self):
        if self.__ignored_chars is None:
                return None
        return self.__ignored_chars.pattern

var word_separators

Expand source code

def _get_word_separators(self):
        if self.__word_separators is None:
                return None
        return self.__word_separators.pattern

Methods

def getAllMatches(self)

Expand source code

def getAllMatches(self):
        raise NotImplementedError

def getMatches(self, aFragment=None)

Return matches according to aFragment and matching thresholds.

FIXME: design decision: we dont worry about data source changes during the lifetime of a MatchProvider FIXME: append _("get all items") on truncation

Expand source code

def getMatches(self, aFragment = None):
        """Return matches according to aFragment and matching thresholds.

        FIXME: design decision: we dont worry about data source changes
                   during the lifetime of a MatchProvider
        FIXME: append _("*get all items*") on truncation
        """
        # sanity check
        if aFragment is None:
                raise ValueError('Cannot find matches without a fragment.')

        # user explicitly wants all matches
        if aFragment == '*':
                return self.getAllMatches()

        # case insensitivity
        tmpFragment = aFragment.casefold()
        # remove ignored chars
        if self.__ignored_chars is not None:
                tmpFragment = self.__ignored_chars.sub('', tmpFragment)
        # normalize word separators
        if self.__word_separators is not None:
                tmpFragment = ' '.join(self.__word_separators.split(tmpFragment))
        # length in number of significant characters only
        lngFragment = len(tmpFragment)

        # order is important !
        if lngFragment >= self.__threshold_substring:
                return self.getMatchesBySubstr(tmpFragment)
        elif lngFragment >= self.__threshold_word:
                return self.getMatchesByWord(tmpFragment)
        elif lngFragment >= self.__threshold_phrase:
                return self.getMatchesByPhrase(tmpFragment)
        else:
                return (False, [])

def getMatchesByPhrase(self, aFragment)

Expand source code

def getMatchesByPhrase(self, aFragment):
        raise NotImplementedError

def getMatchesBySubstr(self, aFragment)

Expand source code

def getMatchesBySubstr(self, aFragment):
        raise NotImplementedError

def getMatchesByWord(self, aFragment)

Expand source code

def getMatchesByWord(self, aFragment):
        raise NotImplementedError

def get_match_by_data(self, data=None)

Expand source code

def get_match_by_data(self, data=None):
        return None

def setThresholds(self, aPhrase=1, aWord=3, aSubstring=5)

Set match location thresholds.

• the fragment passed to getMatches() must contain at least this many characters before it triggers a match search at: 1) phrase_start - start of phrase (first word) 2) word_start - start of any word within phrase 3) in_word - inside any word within phrase

Expand source code

def setThresholds(self, aPhrase = 1, aWord = 3, aSubstring = 5):
        """Set match location thresholds.

        - the fragment passed to getMatches() must contain at least this many
          characters before it triggers a match search at:
          1) phrase_start - start of phrase (first word)
          2) word_start - start of any word within phrase
          3) in_word - _inside_ any word within phrase
        """
        # sanity checks
        if aSubstring < aWord:
                _log.error('Setting substring threshold (%s) lower than word-start threshold (%s) does not make sense.' % (aSubstring, aWord))
                return False

        if aWord < aPhrase:
                _log.error('Setting word-start threshold (%s) lower than phrase-start threshold (%s) does not make sense.' % (aSubstring, aWord))
                return False

        # now actually reassign thresholds
        self.__threshold_phrase = aPhrase
        self.__threshold_word   = aWord
        self.__threshold_substring      = aSubstring
        return True

def set_context(self, context=None, val=None)

Set value to provide context information for matches.

The matching code may ignore it depending on its exact implementation. Names and values of the context depend on what is being matched.

– the placeholder key inside the context definition, not the context definition key

Expand source code

def set_context (self, context=None, val=None):
        """Set value to provide context information     for matches.

        The matching code may ignore it depending on its exact
        implementation. Names and values of the context depend
        on what is being matched.

        <context> -- the *placeholder* key *inside* the context
                                 definition, not the context *definition* key
        """
        if context is None:
                return False
        self._context_vals[context] = val
        return True

def unset_context(self, context=None)

Expand source code

def unset_context(self, context=None):
        try:
                del self._context_vals[context]
        except KeyError:
                pass

class cMatchProvider_FixedList (aSeq=None)

Match provider where all possible options can be held in a reasonably sized, pre-allocated list.

aSeq must be a list of dicts. Each dict must have the keys (data, label, weight)

Expand source code

class cMatchProvider_FixedList(cMatchProvider):
        """Match provider where all possible options can be held
           in a reasonably sized, pre-allocated list.
        """
        def __init__(self, aSeq = None):
                """aSeq must be a list of dicts. Each dict must have the keys (data, label, weight)
                """
                if not type(aSeq) in [type(None), list, tuple]:
                        _log.error('fixed list match provider argument must be a list/tuple of dicts/None')
                        raise TypeError('fixed list match provider argument must be a list/tuple of dicts/None')

                self.__items = aSeq
                cMatchProvider.__init__(self)

        #--------------------------------------------------------
        # internal matching algorithms
        #
        # if we end up here:
        #       - aFragment will not be "None"
        #   - aFragment will be lower case
        #       - we _do_ deliver matches (whether we find any is a different story)
        #--------------------------------------------------------
        def getMatchesByPhrase(self, aFragment):
                """Return matches for aFragment at start of phrases."""
                matches = []
                # look for matches
                for item in self.__items:
                        # at start of phrase, that is
                        if item['list_label'].casefold().startswith(aFragment.casefold()):
                                matches.append(item)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                #matches.sort(self.__cmp_items)
                matches.sort(key = lambda x: x['weight'], reverse = True)
                return (True, matches)

        #--------------------------------------------------------
        def getMatchesByWord(self, aFragment):
                """Return matches for aFragment at start of words inside phrases."""
                matches = []
                # look for matches
                for item in self.__items:
                        item_label = item['list_label'].casefold()
                        fragment_pos = item_label.find(aFragment.casefold())
                        # found at start of phrase
                        if fragment_pos == 0:
                                matches.append(item)
                        # found as a true substring
                        elif fragment_pos > 0:
                                # but use only if substring is at start of a word
                                if item_label[fragment_pos-1] == ' ':
                                        matches.append(item)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                #matches.sort(self.__cmp_items)
                matches.sort(key = lambda x: x['weight'], reverse = True)
                return (True, matches)

        #--------------------------------------------------------
        def getMatchesBySubstr(self, aFragment):
                """Return matches for aFragment as a true substring."""
                matches = []
                # look for matches
                for item in self.__items:
                        if item['list_label'].casefold().find(aFragment.casefold()) != -1:
                                matches.append(item)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                #matches.sort(self.__cmp_items)
                matches.sort(key = lambda x: x['weight'], reverse = True)
                return (True, matches)

        #--------------------------------------------------------
        def getAllMatches(self):
                """Return all items."""
                matches = self.__items
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                #matches.sort(self.__cmp_items)
                matches.sort(key = lambda x: x['weight'], reverse = True)
                return (True, matches)

        #--------------------------------------------------------
        def set_items(self, items):
                """items must be a list of dicts. Each dict must have the keys (data, list_label, weight)"""
                self.__items = items

Ancestors

• cMatchProvider

Methods

def getAllMatches(self)

Return all items.

Expand source code

def getAllMatches(self):
        """Return all items."""
        matches = self.__items
        # no matches found
        if len(matches) == 0:
                return (False, [])

        #matches.sort(self.__cmp_items)
        matches.sort(key = lambda x: x['weight'], reverse = True)
        return (True, matches)

def getMatchesByPhrase(self, aFragment)

Return matches for aFragment at start of phrases.

Expand source code

def getMatchesByPhrase(self, aFragment):
        """Return matches for aFragment at start of phrases."""
        matches = []
        # look for matches
        for item in self.__items:
                # at start of phrase, that is
                if item['list_label'].casefold().startswith(aFragment.casefold()):
                        matches.append(item)
        # no matches found
        if len(matches) == 0:
                return (False, [])

        #matches.sort(self.__cmp_items)
        matches.sort(key = lambda x: x['weight'], reverse = True)
        return (True, matches)

def getMatchesBySubstr(self, aFragment)

Return matches for aFragment as a true substring.

Expand source code

def getMatchesBySubstr(self, aFragment):
        """Return matches for aFragment as a true substring."""
        matches = []
        # look for matches
        for item in self.__items:
                if item['list_label'].casefold().find(aFragment.casefold()) != -1:
                        matches.append(item)
        # no matches found
        if len(matches) == 0:
                return (False, [])

        #matches.sort(self.__cmp_items)
        matches.sort(key = lambda x: x['weight'], reverse = True)
        return (True, matches)

def getMatchesByWord(self, aFragment)

Return matches for aFragment at start of words inside phrases.

Expand source code

def getMatchesByWord(self, aFragment):
        """Return matches for aFragment at start of words inside phrases."""
        matches = []
        # look for matches
        for item in self.__items:
                item_label = item['list_label'].casefold()
                fragment_pos = item_label.find(aFragment.casefold())
                # found at start of phrase
                if fragment_pos == 0:
                        matches.append(item)
                # found as a true substring
                elif fragment_pos > 0:
                        # but use only if substring is at start of a word
                        if item_label[fragment_pos-1] == ' ':
                                matches.append(item)
        # no matches found
        if len(matches) == 0:
                return (False, [])

        #matches.sort(self.__cmp_items)
        matches.sort(key = lambda x: x['weight'], reverse = True)
        return (True, matches)

def set_items(self, items)

items must be a list of dicts. Each dict must have the keys (data, list_label, weight)

Expand source code

def set_items(self, items):
        """items must be a list of dicts. Each dict must have the keys (data, list_label, weight)"""
        self.__items = items

Inherited members

• cMatchProvider:
  • getMatches
  • setThresholds
  • set_context

class cMatchProvider_Func (get_candidates=None)

Match provider which searches matches in the results of a function call.

get_candidates() must return a list of strings.

Expand source code

class cMatchProvider_Func(cMatchProvider):
        """Match provider which searches matches
           in the results of a function call.
        """
        def __init__(self, get_candidates = None):
                """get_candidates() must return a list of strings."""
                if get_candidates is None:
                        _log.error('must define function to retrieve match candidates list')
                        raise ValueError('must define function to retrieve match candidates list')

                self._get_candidates = get_candidates
                cMatchProvider.__init__(self)
        #--------------------------------------------------------
        # internal matching algorithms
        #
        # if we end up here:
        #       - aFragment will not be "None"
        #   - aFragment will be lower case
        #       - we _do_ deliver matches (whether we find any is a different story)
        #--------------------------------------------------------
        def getMatchesByPhrase(self, aFragment):
                """Return matches for aFragment at start of phrases."""
                matches = []
                candidates = self._get_candidates()
                # look for matches
                for candidate in candidates:
                        # at start of phrase, that is
                        if aFragment.startswith(candidate['list_label'].casefold()):
                                matches.append(candidate)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                matches.sort(key = self.__cmp_candidates)
                return (True, matches)
        #--------------------------------------------------------
        def getMatchesByWord(self, aFragment):
                """Return matches for aFragment at start of words inside phrases."""
                matches = []
                candidates = self._get_candidates()
                # look for matches
                for candidate in candidates:
                        pos = candidate['list_label'].casefold().find(aFragment)
#                       pos = string.find(string.lower(candidate['list_label']), aFragment)
                        # found as a true substring
                        # but use only if substring is at start of a word
                        # FIXME: use word seps
                        if (pos == 0) or (candidate['list_label'][pos-1] == ' '):
                                matches.append(candidate)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                matches.sort(key = self.__cmp_candidates)
                return (True, matches)
        #--------------------------------------------------------
        def getMatchesBySubstr(self, aFragment):
                """Return matches for aFragment as a true substring."""
                matches = []
                candidates = self._get_candidates()
                # look for matches
                for candidate in candidates:
                        if candidate['list_label'].casefold().find(aFragment) != -1:
#                       if string.find(string.lower(candidate['list_label']), aFragment) != -1:
                                matches.append(candidate)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                matches.sort(key = self.__cmp_candidates)
                return (True, matches)
        #--------------------------------------------------------
        def getAllMatches(self):
                """Return all candidates."""
                return self._get_candidates()
        #--------------------------------------------------------
        #def __cmp_candidates(self, candidate1, candidate2):
        def __cmp_candidates(self, candidate):
                """naive ordering"""
                return 0
                # FIXME: do ordering

Ancestors

• cMatchProvider

Methods

def getAllMatches(self)

Return all candidates.

Expand source code

def getAllMatches(self):
        """Return all candidates."""
        return self._get_candidates()

def getMatchesByPhrase(self, aFragment)

Return matches for aFragment at start of phrases.

Expand source code

def getMatchesByPhrase(self, aFragment):
        """Return matches for aFragment at start of phrases."""
        matches = []
        candidates = self._get_candidates()
        # look for matches
        for candidate in candidates:
                # at start of phrase, that is
                if aFragment.startswith(candidate['list_label'].casefold()):
                        matches.append(candidate)
        # no matches found
        if len(matches) == 0:
                return (False, [])

        matches.sort(key = self.__cmp_candidates)
        return (True, matches)

def getMatchesBySubstr(self, aFragment)

Return matches for aFragment as a true substring.

Expand source code

        def getMatchesBySubstr(self, aFragment):
                """Return matches for aFragment as a true substring."""
                matches = []
                candidates = self._get_candidates()
                # look for matches
                for candidate in candidates:
                        if candidate['list_label'].casefold().find(aFragment) != -1:
#                       if string.find(string.lower(candidate['list_label']), aFragment) != -1:
                                matches.append(candidate)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                matches.sort(key = self.__cmp_candidates)
                return (True, matches)

def getMatchesByWord(self, aFragment)

Return matches for aFragment at start of words inside phrases.

Expand source code

        def getMatchesByWord(self, aFragment):
                """Return matches for aFragment at start of words inside phrases."""
                matches = []
                candidates = self._get_candidates()
                # look for matches
                for candidate in candidates:
                        pos = candidate['list_label'].casefold().find(aFragment)
#                       pos = string.find(string.lower(candidate['list_label']), aFragment)
                        # found as a true substring
                        # but use only if substring is at start of a word
                        # FIXME: use word seps
                        if (pos == 0) or (candidate['list_label'][pos-1] == ' '):
                                matches.append(candidate)
                # no matches found
                if len(matches) == 0:
                        return (False, [])

                matches.sort(key = self.__cmp_candidates)
                return (True, matches)

Inherited members

• cMatchProvider:
  • getMatches
  • setThresholds
  • set_context

class cMatchProvider_SQL2 (queries=None, context=None)

Match provider which searches matches in possibly several database tables.

queries: - a list of unicode strings - each string is a query - each string must contain: "… WHERE %(fragment_condition)s …" - each string can contain in the where clause: "… %()s …" - each query must return (data, list_label, field_label)

context definitions to be used in the queries, example: {'ctxt_key1': {'where_part': 'AND country = %(country)s', 'placeholder': 'country'}}

client code using .set_context() must use the 'placeholder': /.set_context('country', 'Germany')

full example query:

    query = u" " "
            SELECT DISTINCT ON (list_label)
                    pk_encounter
                            AS data,
                    to_char(started, 'YYYY Mon DD (HH24:MI)') || ': ' || l10n_type || ' [#' || pk_encounter || ']'
                            AS list_label,
                    to_char(started, 'YYYY Mon DD') || ': ' || l10n_type
                            AS field_label
            FROM
                    clin.v_pat_encounters
            WHERE
                    (
                            l10n_type %(fragment_condition)s
                                    OR
                            type %(fragment_condition)s
                    )       %(ctxt_patient)s
            ORDER BY
                    list_label
            LIMIT
                    30
    " " "
    context = {'ctxt_patient': {
            'where_part': u'AND pk_patient = %(PLACEHOLDER)s',
            'placeholder': u'PLACEHOLDER'
    }}
    self.mp = gmMatchProvider.cMatchProvider_SQL2(queries = query, context = context)
    self.set_context(context = 'PLACEHOLDER', val = '<THE VALUE>')

_SQL_data2match: SQL to retrieve a match by, say, primary key wherein the only keyword argument is 'pk'

Expand source code

class cMatchProvider_SQL2(cMatchProvider):
        """Match provider which searches matches
           in possibly several database tables.

        queries:
                - a list of unicode strings
                - each string is a query
                - each string must contain: "... WHERE <column> %(fragment_condition)s ..."
                - each string can contain in the where clause: "... %(<ctxt_key1>)s ..."
                - each query must return (data, list_label, field_label)

        context definitions to be used in the queries, example:
                {'ctxt_key1': {'where_part': 'AND country = %(country)s', 'placeholder': 'country'}}

        client code using .set_context() must use the 'placeholder':
                <phrasewheel>/<match provider>.set_context('country', 'Germany')

        full example query:

                query = u" " "
                        SELECT DISTINCT ON (list_label)
                                pk_encounter
                                        AS data,
                                to_char(started, 'YYYY Mon DD (HH24:MI)') || ': ' || l10n_type || ' [#' || pk_encounter || ']'
                                        AS list_label,
                                to_char(started, 'YYYY Mon DD') || ': ' || l10n_type
                                        AS field_label
                        FROM
                                clin.v_pat_encounters
                        WHERE
                                (
                                        l10n_type %(fragment_condition)s
                                                OR
                                        type %(fragment_condition)s
                                )       %(ctxt_patient)s
                        ORDER BY
                                list_label
                        LIMIT
                                30
                " " "
                context = {'ctxt_patient': {
                        'where_part': u'AND pk_patient = %(PLACEHOLDER)s',
                        'placeholder': u'PLACEHOLDER'
                }}
                self.mp = gmMatchProvider.cMatchProvider_SQL2(queries = query, context = context)
                self.set_context(context = 'PLACEHOLDER', val = '<THE VALUE>')

        _SQL_data2match:
                SQL to retrieve a match by, say, primary key
                wherein the only keyword argument is 'pk'
        """
        def __init__(self, queries = None, context = None):

                cMatchProvider.__init__(self)

                if type(queries) == type([]):
                        self._queries = queries
                else:
                        self._queries = [queries]

                if context is None:
                        self._context = {}
                else:
                        self._context = context

                self._args = {}

                self._SQL_data2match = None

        #--------------------------------------------------------
        # internal matching algorithms
        #
        # if we end up here:
        #       - aFragment will not be "None"
        #   - aFragment will be lower case
        #       - we _do_ deliver matches (whether we find any is a different story)
        #--------------------------------------------------------
        def getMatchesByPhrase(self, aFragment):
                """Return matches for aFragment at start of phrases."""

                fragment_condition = "ILIKE %(fragment)s"
                self._args['fragment'] = "%s%%" % aFragment

                return self._find_matches(fragment_condition)

        #--------------------------------------------------------
        def getMatchesByWord(self, aFragment):
                """Return matches for aFragment at start of words inside phrases."""

                fragment_condition = "~* %(fragment)s"
                aFragment = gmPG2.sanitize_pg_regex(expression = aFragment, escape_all = False)
                self._args['fragment'] = "( %s)|(^%s)" % (aFragment, aFragment)

                return self._find_matches(fragment_condition)

        #--------------------------------------------------------
        def getMatchesBySubstr(self, aFragment):
                """Return matches for aFragment as a true substring."""

                fragment_condition = "ILIKE %(fragment)s"
                self._args['fragment'] = "%%%s%%" % aFragment

                return self._find_matches(fragment_condition)

        #--------------------------------------------------------
        def getAllMatches(self):
                """Return all items."""
                return self.getMatchesBySubstr('')

        #--------------------------------------------------------
        def get_match_by_data(self, data=None):
                if self._SQL_data2match is None:
                        return None

                query = {'cmd': self._SQL_data2match, 'args': {'pk': data}}
                try:
                        rows, idx = gmPG2.run_ro_queries(queries = [query], get_col_idx = False)
                except Exception:
                        _log.exception('[%s]: error running _SQL_data2match, dropping query', self.__class__.__name__)
                        self._SQL_data2match = None
                        return None

                # hopefully the most frequent case:
                if len(rows) == 1:
                        return rows[0]

                _log.error('[%s]: 0 or >1 rows found by running _SQL_data2match, ambiguous, ignoring', self.__class__.__name__)
                return None

        #--------------------------------------------------------
        def _rows2matches(self, rows):
                """Turns retrieved database values into a list
                   of dicts fit for phrasewheel use.

                   This method can be overridden to massage arbitrary
                   data into the proper list of dicts.
                """
                matches = []
                for row in rows:
                        # PRW wants a weight
                        match = {'weight': 0}
                        try:
                                match['data'] = row['data']
                        except KeyError:
                                match['data'] = row[0]
                        try:
                                match['list_label'] = row['list_label']
                        except KeyError:
                                match['list_label'] = row[1]
                        # explicit "field_label" in result ?
                        try:
                                match['field_label'] = row['field_label']
                        # no
                        except KeyError:
                                # but does row[2] exist ?
                                try:
                                        match['field_label'] = row[2]
                                # no: reuse "list_label"
                                except IndexError:
                                        match['field_label'] = match['list_label']
                        matches.append(match)

                return matches

        #--------------------------------------------------------
        def _find_matches(self, fragment_condition:str) -> tuple[bool, list]:
                """Loads matching data from PostgreSQL and turns them into
                   matches fit for consumption by a phrasewheel.
                """
                if self.print_queries:
                        print("----------------------")
                        print(pydt.datetime.now())

                matches = []
                for query in self._queries:
                        where_fragments = {'fragment_condition': fragment_condition}

                        for context_key, context_def in self._context.items():
                                try:
                                        placeholder = context_def['placeholder']
                                        where_part = context_def['where_part']
                                        self._args[placeholder] = self._context_vals[placeholder]
                                        # we do have a context value for this key, so add the where condition
                                        where_fragments[context_key] = where_part
                                        if self.print_queries:
                                                print("ctxt ph:", placeholder)
                                                print("ctxt where:", where_part)
                                                print("ctxt val:", self._context_vals[placeholder])
                                except KeyError:
                                        # we don't have a context value for this key, so skip the where condition
                                        where_fragments[context_key] = ''
                                        if self.print_queries:
                                                print("invalid ctxt key:", context_key)

                        cmd = query % where_fragments

                        if self.print_queries:
                                print("class:", self.__class__.__name__)
                                print("ctxt:", self._context_vals)
                                print("args:", self._args)
                                print("query:", cmd)

                        try:
                                rows, idx = gmPG2.run_ro_queries(queries = [{'cmd': cmd, 'args': self._args}], get_col_idx = False)
                        except gmPG2.PG_ERROR_EXCEPTION:
                                _log.exception('[%s]: error running match provider SQL, dropping query', self.__class__.__name__)
                                _log.error('SQL: %s', cmd)
                                idx = self._queries.index(query)
                                del self._queries[idx]
                                break
                        # no matches found: try next query
                        if len(rows) == 0:
                                continue
                        matches = self._rows2matches(rows)
                        return (True, matches)
                # none found whatsoever
                return (False, [])

Ancestors

• cMatchProvider

Subclasses

• cEpisodeMatchProvider
• cFormTemplateNameLong_MatchProvider
• cFormTemplateNameShort_MatchProvider
• cFormTemplateType_MatchProvider
• cLOINCMatchProvider
• cDrugComponentMatchProvider
• cProductOrSubstanceMatchProvider
• cSubstanceDoseMatchProvider
• cSubstanceIntakeObjectMatchProvider
• cMatchProvider_Provider

Methods

def getAllMatches(self)

Return all items.

Expand source code

def getAllMatches(self):
        """Return all items."""
        return self.getMatchesBySubstr('')

def getMatchesByPhrase(self, aFragment)

Return matches for aFragment at start of phrases.

Expand source code

def getMatchesByPhrase(self, aFragment):
        """Return matches for aFragment at start of phrases."""

        fragment_condition = "ILIKE %(fragment)s"
        self._args['fragment'] = "%s%%" % aFragment

        return self._find_matches(fragment_condition)

def getMatchesBySubstr(self, aFragment)

Return matches for aFragment as a true substring.

Expand source code

def getMatchesBySubstr(self, aFragment):
        """Return matches for aFragment as a true substring."""

        fragment_condition = "ILIKE %(fragment)s"
        self._args['fragment'] = "%%%s%%" % aFragment

        return self._find_matches(fragment_condition)

def getMatchesByWord(self, aFragment)

Return matches for aFragment at start of words inside phrases.

Expand source code

def getMatchesByWord(self, aFragment):
        """Return matches for aFragment at start of words inside phrases."""

        fragment_condition = "~* %(fragment)s"
        aFragment = gmPG2.sanitize_pg_regex(expression = aFragment, escape_all = False)
        self._args['fragment'] = "( %s)|(^%s)" % (aFragment, aFragment)

        return self._find_matches(fragment_condition)

def get_match_by_data(self, data=None)

Expand source code

def get_match_by_data(self, data=None):
        if self._SQL_data2match is None:
                return None

        query = {'cmd': self._SQL_data2match, 'args': {'pk': data}}
        try:
                rows, idx = gmPG2.run_ro_queries(queries = [query], get_col_idx = False)
        except Exception:
                _log.exception('[%s]: error running _SQL_data2match, dropping query', self.__class__.__name__)
                self._SQL_data2match = None
                return None

        # hopefully the most frequent case:
        if len(rows) == 1:
                return rows[0]

        _log.error('[%s]: 0 or >1 rows found by running _SQL_data2match, ambiguous, ignoring', self.__class__.__name__)
        return None

Inherited members

• cMatchProvider:
  • getMatches
  • setThresholds
  • set_context