def _update_cardinality_in_derived(ptrcls: s_pointers.Pointer, *,
env: context.Environment) -> None:
children = env.pointer_derivation_map.get(ptrcls)
if children:
ptrcls_cardinality = ptrcls.get_cardinality(env.schema)
ptrcls_required = ptrcls.get_required(env.schema)
assert ptrcls_cardinality.is_known()
for child in children:
env.schema = child.set_field_value(env.schema, 'cardinality',
ptrcls_cardinality)
env.schema = child.set_field_value(env.schema, 'required',
ptrcls_required)
_update_cardinality_in_derived(child, env=env)
def _infer_pointer_cardinality(
*,
ptrcls: s_pointers.Pointer,
ptrref: Optional[irast.BasePointerRef],
irexpr: irast.Base,
specified_required: Optional[bool] = None,
specified_card: Optional[qltypes.SchemaCardinality] = None,
is_mut_assignment: bool = False,
shape_op: qlast.ShapeOp = qlast.ShapeOp.ASSIGN,
source_ctx: Optional[parsing.ParserContext] = None,
scope_tree: irast.ScopeTreeNode,
ctx: inference_context.InfCtx,
) -> None:
env = ctx.env
if specified_required is None:
spec_lower_bound = None
else:
spec_lower_bound = CardinalityBound.from_required(specified_required)
if specified_card is None:
spec_upper_bound = None
else:
spec_upper_bound = CardinalityBound.from_schema_value(specified_card)
expr_card = infer_cardinality(irexpr, scope_tree=scope_tree, ctx=ctx)
ptrcls_schema_card = ptrcls.get_cardinality(env.schema)
# Infer cardinality and convert it back to schema values of "ONE/MANY".
if shape_op is qlast.ShapeOp.APPEND:
# += in shape always means MANY
inferred_card = qltypes.Cardinality.MANY
elif shape_op is qlast.ShapeOp.SUBTRACT:
# -= does not increase cardinality, but it may result in an empty set,
# hence AT_MOST_ONE.
inferred_card = qltypes.Cardinality.AT_MOST_ONE
else:
# Pull cardinality from the ptrcls, if it exists.
# (This generally will have been populated by the source_map
# handling in infer_toplevel_cardinality().)
if ptrcls_schema_card.is_known():
inferred_card = qltypes.Cardinality.from_schema_value(
not expr_card.can_be_zero(), ptrcls_schema_card)
else:
inferred_card = expr_card
if spec_upper_bound is None and spec_lower_bound is None:
# Common case of no explicit specifier and no overloading.
ptr_card = inferred_card
else:
# Verify that the explicitly specified (or inherited) cardinality is
# within the cardinality bounds inferred from the expression, except
# for mutations we punt the lower cardinality bound check to the
# runtime DML constraint as that would produce a more meaningful error.
inf_lower_bound, inf_upper_bound = _card_to_bounds(inferred_card)
if spec_upper_bound is None:
upper_bound = inf_upper_bound
else:
if inf_upper_bound > spec_upper_bound:
desc = ptrcls.get_verbosename(env.schema)
if not is_mut_assignment:
desc = f"computed {desc}"
raise errors.QueryError(
f"possibly more than one element returned by an "
f"expression for a {desc} declared as 'single'",
context=source_ctx,
)
upper_bound = spec_upper_bound
if spec_lower_bound is None:
lower_bound = inf_lower_bound
else:
if inf_lower_bound < spec_lower_bound:
if is_mut_assignment:
lower_bound = inf_lower_bound
else:
desc = f"computed {ptrcls.get_verbosename(env.schema)}"
raise errors.QueryError(
f"possibly an empty set returned by an "
f"expression for a {desc} declared as 'required'",
context=source_ctx,
)
else:
lower_bound = spec_lower_bound
ptr_card = _bounds_to_card(lower_bound, upper_bound)
if (not ptrcls_schema_card.is_known()
or ptrcls in ctx.env.pointer_specified_info):
if ptrcls_schema_card.is_known():
# If we are overloading an existing pointer, take the _maximum_
# of the cardinalities. In practice this only means that we might
# raise the lower bound, since the other redefinitions of bounds
# are prohibited above and in viewgen.
ptrcls_card = qltypes.Cardinality.from_schema_value(
ptrcls.get_required(env.schema),
ptrcls_schema_card,
)
if is_mut_assignment:
ptr_card = cartesian_cardinality((ptrcls_card, ptr_card))
else:
ptr_card = max_cardinality((ptrcls_card, ptr_card))
required, card = ptr_card.to_schema_value()
env.schema = ptrcls.set_field_value(env.schema, 'cardinality', card)
env.schema = ptrcls.set_field_value(env.schema, 'required', required)
_update_cardinality_in_derived(ptrcls, env=ctx.env)
if ptrref:
out_card, in_card = typeutils.cardinality_from_ptrcls(
env.schema, ptrcls)
assert in_card is not None
assert out_card is not None
ptrref.in_cardinality = in_card
ptrref.out_cardinality = out_card
def _infer_pointer_cardinality(
*,
ptrcls: s_pointers.Pointer,
ptrref: irast.BasePointerRef,
irexpr: irast.Base,
specified_required: bool = False,
specified_card: Optional[qltypes.SchemaCardinality] = None,
is_mut_assignment: bool = False,
shape_op: qlast.ShapeOp = qlast.ShapeOp.ASSIGN,
source_ctx: Optional[parsing.ParserContext] = None,
scope_tree: irast.ScopeTreeNode,
ctx: inference_context.InfCtx,
) -> None:
env = ctx.env
# Convert the SchemaCardinality into Cardinality used for inference.
if not specified_required and specified_card is None:
ir_specified_card = None
else:
ir_specified_card = qltypes.Cardinality.from_schema_value(
specified_required, specified_card
or qltypes.SchemaCardinality.One)
expr_card = infer_cardinality(irexpr, scope_tree=scope_tree, ctx=ctx)
# Infer cardinality and convert it back to schema values of "ONE/MANY".
if shape_op is qlast.ShapeOp.APPEND:
# += in shape always means MANY
inferred_card = qltypes.Cardinality.MANY
elif shape_op is qlast.ShapeOp.SUBTRACT:
# -= does not increase cardinality, but it may result in an empty set,
# hence AT_MOST_ONE.
inferred_card = qltypes.Cardinality.AT_MOST_ONE
else:
inferred_card = expr_card
if ir_specified_card is None:
ptr_card = inferred_card
else:
if is_subset_cardinality(inferred_card, ir_specified_card):
# The inferred cardinality is within the boundaries of
# specified cardinality, use the maximum lower and upper bounds.
ptr_card = max_cardinality((ir_specified_card, inferred_card), )
else:
sp_req, sp_card = ir_specified_card.to_schema_value()
ic_req, ic_card = inferred_card.to_schema_value()
# Specified cardinality is stricter than inferred (e.g.
# ONE vs MANY), this is an error.
if sp_req and not ic_req:
if is_mut_assignment:
# For mutations we punt the lower cardinality bound
# check to the runtime constraint. Doing it statically
# is impractical because it is impossible to prove
# non-emptiness of object-selecting expressions bound
# for required links.
ptr_card = cartesian_cardinality(
(ir_specified_card, inferred_card), )
else:
raise errors.QueryError(
f'possibly an empty set returned by an '
f'expression for a computable '
f'{ptrcls.get_verbosename(env.schema)} '
f"declared as 'required'",
context=source_ctx)
else:
raise errors.QueryError(
f'possibly more than one element returned by an '
f'expression for a computable '
f'{ptrcls.get_verbosename(env.schema)} '
f"declared as 'single'",
context=source_ctx)
ptrcls_schema_card = ptrcls.get_cardinality(env.schema)
if (not ptrcls_schema_card.is_known()
or ptrcls in ctx.env.pointer_specified_info):
if ptrcls_schema_card.is_known():
# If we are overloading an existing pointer, take the _maximum_
# of the cardinalities. In practice this only means that we might
# raise the lower bound, since the other redefinitions of bounds
# are prohibited above and in viewgen.
ptrcls_card = qltypes.Cardinality.from_schema_value(
ptrcls.get_required(env.schema),
ptrcls_schema_card,
)
if is_mut_assignment:
ptr_card = cartesian_cardinality((ptrcls_card, ptr_card))
else:
ptr_card = max_cardinality((ptrcls_card, ptr_card))
required, card = ptr_card.to_schema_value()
env.schema = ptrcls.set_field_value(env.schema, 'cardinality', card)
env.schema = ptrcls.set_field_value(env.schema, 'required', required)
_update_cardinality_in_derived(ptrcls, env=ctx.env)
out_card, dir_card = typeutils.cardinality_from_ptrcls(
env.schema, ptrcls, direction=ptrref.direction)
assert dir_card is not None
assert out_card is not None
ptrref.dir_cardinality = dir_card
ptrref.out_cardinality = out_card