# Django 2.1.8.dev20190330215650 documentation

# Source code for django.contrib.postgres.indexes

    from django.db.models import Index
    from django.utils.functional import cached_property

    __all__ = ['BrinIndex', 'GinIndex', 'GistIndex']

    class PostgresIndex(Index):

        @cached_property
        def max_name_length(self):
            # Allow an index name longer than 30 characters when the suffix is
            # longer than the usual 3 character limit. The 30 character limit for
            # cross-database compatibility isn't applicable to PostgreSQL-specific
            # indexes.
            return Index.max_name_length - len(Index.suffix) + len(self.suffix)

        def create_sql(self, model, schema_editor, using=''):
            statement = super().create_sql(model, schema_editor, using=' USING %s' % self.suffix)
            with_params = self.get_with_params()
            if with_params:
                statement.parts['extra'] = 'WITH (%s) %s' % (
                    ', '.join(with_params),
                    statement.parts['extra'],
                )
            return statement

        def get_with_params(self):
            return []

    class BrinIndex(PostgresIndex):
        suffix = 'brin'

        def __init__(self, *, pages_per_range=None, **kwargs):
            if pages_per_range is not None and pages_per_range <= 0:
                raise ValueError('pages_per_range must be None or a positive integer')
            self.pages_per_range = pages_per_range
            super().__init__(**kwargs)

        def deconstruct(self):
            path, args, kwargs = super().deconstruct()
            if self.pages_per_range is not None:
                kwargs['pages_per_range'] = self.pages_per_range
            return path, args, kwargs

        def get_with_params(self):
            with_params = []
            if self.pages_per_range is not None:
                with_params.append('pages_per_range = %d' % self.pages_per_range)
            return with_params

    class GinIndex(PostgresIndex):
        suffix = 'gin'

        def __init__(self, *, fastupdate=None, gin_pending_list_limit=None, **kwargs):
            self.fastupdate = fastupdate
            self.gin_pending_list_limit = gin_pending_list_limit
            super().__init__(**kwargs)

        def deconstruct(self):
            path, args, kwargs = super().deconstruct()
            if self.fastupdate is not None:
                kwargs['fastupdate'] = self.fastupdate
            if self.gin_pending_list_limit is not None:
                kwargs['gin_pending_list_limit'] = self.gin_pending_list_limit
            return path, args, kwargs

        def get_with_params(self):
            with_params = []
            if self.gin_pending_list_limit is not None:
                with_params.append('gin_pending_list_limit = %d' % self.gin_pending_list_limit)
            if self.fastupdate is not None:
                with_params.append('fastupdate = %s' % ('on' if self.fastupdate else 'off'))
            return with_params

    class GistIndex(PostgresIndex):
        suffix = 'gist'

        def __init__(self, *, buffering=None, fillfactor=None, **kwargs):
            self.buffering = buffering
            self.fillfactor = fillfactor
            super().__init__(**kwargs)

        def deconstruct(self):
            path, args, kwargs = super().deconstruct()
            if self.buffering is not None:
                kwargs['buffering'] = self.buffering
            if self.fillfactor is not None:
                kwargs['fillfactor'] = self.fillfactor
            return path, args, kwargs

        def get_with_params(self):
            with_params = []
            if self.buffering is not None:
                with_params.append('buffering = %s' % ('on' if self.buffering else 'off'))
            if self.fillfactor is not None:
                with_params.append('fillfactor = %d' % self.fillfactor)
            return with_params