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"""Base classes for the store."""
from rdflib import Literal
from rdflib.graph import Graph, QuotedGraph
from rdflib.plugins.stores.regexmatching import REGEXTerm
from sqlalchemy.sql import expression
from rdflib_sqlalchemy.termutils import (
type_to_term_combination,
statement_to_term_combination,
)
class SQLGeneratorMixin(object):
"""SQL statement generator mixin for the SQLAlchemy store."""
def _build_type_sql_command(self, member, klass, context):
"""Build an insert command for a type table."""
# columns: member,klass,context
rt = self.tables["type_statements"].insert()
return rt, {
"member": member,
"klass": klass,
"context": context.identifier,
"termComb": int(type_to_term_combination(member, klass, context))
}
def _build_literal_triple_sql_command(self, subject, predicate, obj, context):
"""
Build an insert command for literal triples.
These triples correspond to RDF statements where the object is a Literal,
e.g. `rdflib.Literal`.
"""
triple_pattern = int(
statement_to_term_combination(subject, predicate, obj, context)
)
command = self.tables["literal_statements"].insert()
values = {
"subject": subject,
"predicate": predicate,
"object": obj,
"context": context.identifier,
"termComb": triple_pattern,
"objLanguage": isinstance(obj, Literal) and obj.language or None,
"objDatatype": isinstance(obj, Literal) and obj.datatype or None,
}
return command, values
def _build_triple_sql_command(self, subject, predicate, obj, context, quoted):
"""
Build an insert command for regular triple table.
"""
stmt_table = (
self.tables["quoted_statements"]
if quoted
else self.tables["asserted_statements"]
)
triple_pattern = statement_to_term_combination(
subject,
predicate,
obj,
context,
)
command = stmt_table.insert()
if quoted:
params = {
"subject": subject,
"predicate": predicate,
"object": obj,
"context": context.identifier,
"termComb": triple_pattern,
"objLanguage": isinstance(obj, Literal) and obj.language or None,
"objDatatype": isinstance(obj, Literal) and obj.datatype or None
}
else:
params = {
"subject": subject,
"predicate": predicate,
"object": obj,
"context": context.identifier,
"termComb": triple_pattern,
}
return command, params
def build_clause(self, table, subject, predicate, obj, context=None, typeTable=False):
"""Build WHERE clauses for the supplied terms and, context."""
if typeTable:
clauseList = [
self.build_type_member_clause(subject, table),
self.build_type_class_clause(obj, table),
self.build_context_clause(context, table)
]
else:
clauseList = [
self.build_subject_clause(subject, table),
self.build_predicate_clause(predicate, table),
self.build_object_clause(obj, table),
self.build_context_clause(context, table),
self.build_literal_datatype_clause(obj, table),
self.build_literal_language_clause(obj, table)
]
clauseList = [clause for clause in clauseList if clause is not None]
if clauseList:
return expression.and_(*clauseList)
else:
return None
def build_literal_datatype_clause(self, obj, table):
"""Build Literal and datatype clause."""
if isinstance(obj, Literal) and obj.datatype is not None:
return table.c.objDatatype == obj.datatype
else:
return None
def build_literal_language_clause(self, obj, table):
"""Build Literal and language clause."""
if isinstance(obj, Literal) and obj.language is not None:
return table.c.objLanguage == obj.language
else:
return None
# Where Clause utility Functions
# The predicate and object clause builders are modified in order
# to optimize subjects and objects utility functions which can
# take lists as their last argument (object, predicate - respectively)
def build_subject_clause(self, subject, table):
"""Build Subject clause."""
if isinstance(subject, REGEXTerm):
# TODO: this work only in mysql. Must adapt for postgres and sqlite
return table.c.subject.op("REGEXP")(subject)
elif isinstance(subject, list):
# clauseStrings = [] --- unused
return expression.or_(
*[self.build_subject_clause(s, table) for s in subject if s])
elif isinstance(subject, (QuotedGraph, Graph)):
return table.c.subject == subject.identifier
elif subject is not None:
return table.c.subject == subject
else:
return None
def build_predicate_clause(self, predicate, table):
"""
Build Predicate clause.
Capable of taking a list of predicates as well, in which case
subclauses are joined with 'OR'.
"""
if isinstance(predicate, REGEXTerm):
# TODO: this work only in mysql. Must adapt for postgres and sqlite
return table.c.predicate.op("REGEXP")(predicate)
elif isinstance(predicate, list):
return expression.or_(
*[self.build_predicate_clause(p, table) for p in predicate if p])
elif predicate is not None:
return table.c.predicate == predicate
else:
return None
def build_object_clause(self, obj, table):
"""
Build Object clause.
Capable of taking a list of objects as well, in which case subclauses
are joined with 'OR'.
"""
if isinstance(obj, REGEXTerm):
# TODO: this work only in mysql. Must adapt for postgres and sqlite
return table.c.object.op("REGEXP")(obj)
elif isinstance(obj, list):
return expression.or_(
*[self.build_object_clause(o, table) for o in obj if o])
elif isinstance(obj, (QuotedGraph, Graph)):
return table.c.object == obj.identifier
elif obj is not None:
return table.c.object == obj
else:
return None
def build_context_clause(self, context, table):
"""Build Context clause."""
if isinstance(context, REGEXTerm):
# TODO: this work only in mysql. Must adapt for postgres and sqlite
return table.c.context.op("regexp")(context.identifier)
elif context is not None and context.identifier is not None:
return table.c.context == context.identifier
else:
return None
def build_type_member_clause(self, subject, table):
"""Build Type Member clause."""
if isinstance(subject, REGEXTerm):
# TODO: this work only in mysql. Must adapt for postgres and sqlite
return table.c.member.op("regexp")(subject)
elif isinstance(subject, list):
return expression.or_(
*[self.build_type_member_clause(s, table) for s in subject if s])
elif subject is not None:
return table.c.member == subject
else:
return None
def build_type_class_clause(self, obj, table):
"""Build Type Class clause."""
if isinstance(obj, REGEXTerm):
# TODO: this work only in mysql. Must adapt for postgres and sqlite
return table.c.klass.op("regexp")(obj)
elif isinstance(obj, list):
return expression.or_(
*[self.build_type_class_clause(o, table) for o in obj if o])
elif obj is not None:
return obj and table.c.klass == obj
else:
return None
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