Initial commit. Basic models mostly done.

venv/lib/python3.8/site-packages/django/db/models/indexes.py

@@ -0,0 +1,115 @@
+from django.db.backends.utils import names_digest, split_identifier
+from django.db.models.query_utils import Q
+from django.db.models.sql import Query
+
+__all__ = ['Index']
+
+
+class Index:
+    suffix = 'idx'
+    # The max length of the name of the index (restricted to 30 for
+    # cross-database compatibility with Oracle)
+    max_name_length = 30
+
+    def __init__(self, *, fields=(), name=None, db_tablespace=None, opclasses=(), condition=None):
+        if opclasses and not name:
+            raise ValueError('An index must be named to use opclasses.')
+        if not isinstance(condition, (type(None), Q)):
+            raise ValueError('Index.condition must be a Q instance.')
+        if condition and not name:
+            raise ValueError('An index must be named to use condition.')
+        if not isinstance(fields, (list, tuple)):
+            raise ValueError('Index.fields must be a list or tuple.')
+        if not isinstance(opclasses, (list, tuple)):
+            raise ValueError('Index.opclasses must be a list or tuple.')
+        if opclasses and len(fields) != len(opclasses):
+            raise ValueError('Index.fields and Index.opclasses must have the same number of elements.')
+        if not fields:
+            raise ValueError('At least one field is required to define an index.')
+        self.fields = list(fields)
+        # A list of 2-tuple with the field name and ordering ('' or 'DESC').
+        self.fields_orders = [
+            (field_name[1:], 'DESC') if field_name.startswith('-') else (field_name, '')
+            for field_name in self.fields
+        ]
+        self.name = name or ''
+        self.db_tablespace = db_tablespace
+        self.opclasses = opclasses
+        self.condition = condition
+
+    def _get_condition_sql(self, model, schema_editor):
+        if self.condition is None:
+            return None
+        query = Query(model=model)
+        where = query.build_where(self.condition)
+        compiler = query.get_compiler(connection=schema_editor.connection)
+        sql, params = where.as_sql(compiler, schema_editor.connection)
+        return sql % tuple(schema_editor.quote_value(p) for p in params)
+
+    def create_sql(self, model, schema_editor, using='', **kwargs):
+        fields = [model._meta.get_field(field_name) for field_name, _ in self.fields_orders]
+        col_suffixes = [order[1] for order in self.fields_orders]
+        condition = self._get_condition_sql(model, schema_editor)
+        return schema_editor._create_index_sql(
+            model, fields, name=self.name, using=using, db_tablespace=self.db_tablespace,
+            col_suffixes=col_suffixes, opclasses=self.opclasses, condition=condition,
+            **kwargs,
+        )
+
+    def remove_sql(self, model, schema_editor, **kwargs):
+        return schema_editor._delete_index_sql(model, self.name, **kwargs)
+
+    def deconstruct(self):
+        path = '%s.%s' % (self.__class__.__module__, self.__class__.__name__)
+        path = path.replace('django.db.models.indexes', 'django.db.models')
+        kwargs = {'fields': self.fields, 'name': self.name}
+        if self.db_tablespace is not None:
+            kwargs['db_tablespace'] = self.db_tablespace
+        if self.opclasses:
+            kwargs['opclasses'] = self.opclasses
+        if self.condition:
+            kwargs['condition'] = self.condition
+        return (path, (), kwargs)
+
+    def clone(self):
+        """Create a copy of this Index."""
+        _, _, kwargs = self.deconstruct()
+        return self.__class__(**kwargs)
+
+    def set_name_with_model(self, model):
+        """
+        Generate a unique name for the index.
+
+        The name is divided into 3 parts - table name (12 chars), field name
+        (8 chars) and unique hash + suffix (10 chars). Each part is made to
+        fit its size by truncating the excess length.
+        """
+        _, table_name = split_identifier(model._meta.db_table)
+        column_names = [model._meta.get_field(field_name).column for field_name, order in self.fields_orders]
+        column_names_with_order = [
+            (('-%s' if order else '%s') % column_name)
+            for column_name, (field_name, order) in zip(column_names, self.fields_orders)
+        ]
+        # The length of the parts of the name is based on the default max
+        # length of 30 characters.
+        hash_data = [table_name] + column_names_with_order + [self.suffix]
+        self.name = '%s_%s_%s' % (
+            table_name[:11],
+            column_names[0][:7],
+            '%s_%s' % (names_digest(*hash_data, length=6), self.suffix),
+        )
+        assert len(self.name) <= self.max_name_length, (
+            'Index too long for multiple database support. Is self.suffix '
+            'longer than 3 characters?'
+        )
+        if self.name[0] == '_' or self.name[0].isdigit():
+            self.name = 'D%s' % self.name[1:]
+
+    def __repr__(self):
+        return "<%s: fields='%s'%s>" % (
+            self.__class__.__name__, ', '.join(self.fields),
+            '' if self.condition is None else ', condition=%s' % self.condition,
+        )
+
+    def __eq__(self, other):
+        return (self.__class__ == other.__class__) and (self.deconstruct() == other.deconstruct())