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# Authors R. W. Ford, A. R. Porter, S. Siso and N. Nobre, STFC Daresbury Lab
# I. Kavcic, Met Office
# J. Henrichs, Bureau of Meteorology
# -----------------------------------------------------------------------------
''' This module contains the IfBlock node implementation.'''
from psyclone.core import VariablesAccessMap
from psyclone.errors import InternalError, GenerationError
from psyclone.psyir.nodes.datanode import DataNode
from psyclone.psyir.nodes.schedule import Schedule
from psyclone.psyir.nodes.statement import Statement
[docs]
class IfBlock(Statement):
'''
Node representing an if-block within the PSyIR. It has two mandatory
children: the first one represents the if-condition and the second one
the if-body; and an optional third child representing the else-body.
'''
# The valid annotations for this If node:
# 'was_elseif' to tag nested ifs originally written with the 'else if'
# language syntactic construct;
# 'was_single_stmt' to tag ifs with a 1-statement body which were
# originally written in a single line;
# 'was_case' to tag a conditional structure which was originally written
# with the Fortran 'case' or C 'switch' syntactic constructs;
# 'was_where' - a conditional structure originally implied by a Fortran
# WHERE construct.
# 'was_type_is' to tag a conditional structure originally
# written with the Fortran 'select type' construct with a 'type
# is' clause.
# 'was_class_is' to tag a conditional structure originally
# written with the Fortran 'select type' construct with a 'class
# is' clause.
valid_annotations = ('was_elseif', 'was_single_stmt', 'was_case',
'was_where', 'was_type_is', 'was_class_is')
# Textual description of the node.
_children_valid_format = "DataNode, Schedule [, Schedule]"
_text_name = "If"
_colour = "red"
@staticmethod
def _validate_child(position, child):
'''
:param int position: the position to be validated.
:param child: a child to be validated.
:type child: :py:class:`psyclone.psyir.nodes.Node`
:return: whether the given child and position are valid for this node.
:rtype: bool
'''
return (position == 0 and isinstance(child, DataNode)) or (
position in (1, 2) and isinstance(child, Schedule))
@property
def condition(self):
''' Return the PSyIR Node representing the conditional expression
of this IfBlock.
:returns: IfBlock conditional expression.
:rtype: :py:class:`psyclone.psyir.nodes.Node`
:raises InternalError: If the IfBlock node does not have the correct \
number of children.
'''
if len(self.children) < 2:
raise InternalError(
f"IfBlock malformed or incomplete. It should have at least 2 "
f"children, but found {len(self.children)}.")
return self._children[0]
@property
def if_body(self):
''' Return the Schedule executed when the IfBlock evaluates to True.
:returns: Schedule to be executed when IfBlock evaluates to True.
:rtype: :py:class:`psyclone.psyir.nodes.Schedule`
:raises InternalError: If the IfBlock node does not have the correct \
number of children.
'''
if len(self.children) < 2:
raise InternalError(
f"IfBlock malformed or incomplete. It should have at least 2 "
f"children, but found {len(self.children)}.")
return self._children[1]
@property
def else_body(self):
''' If available return the Schedule executed when the IfBlock
evaluates to False, otherwise return None.
:returns: Schedule to be executed when IfBlock evaluates \
to False, if it doesn't exist returns None.
:rtype: :py:class:`psyclone.psyir.nodes.Schedule` or NoneType
'''
if len(self._children) == 3:
return self._children[2]
return None
[docs]
@staticmethod
def create(if_condition, if_body, else_body=None):
'''Create an IfBlock instance given valid instances of an
if_condition, an if_body and an optional else_body.
:param if_condition: the PSyIR node containing the if \
condition of the if block.
:type if_condition: :py:class:`psyclone.psyir.nodes.Node`
:param if_body: the PSyIR nodes representing the if body of \
the if block.
:type if_body: List[:py:class:`psyclone.psyir.nodes.Node`]
:param else_body: PSyIR nodes representing the else body of the \
if block or None if there is no else body (defaults to None).
:type else_body: Optional[List[:py:class:`psyclone.psyir.nodes.Node`]]
:returns: an IfBlock instance.
:rtype: :py:class:`psyclone.psyir.nodes.IfBlock`
:raises GenerationError: if the arguments to the create method \
are not of the expected type.
'''
if not isinstance(if_body, list):
raise GenerationError(
f"if_body argument in create method of IfBlock class should "
f"be a list but found '{type(if_body).__name__}'.")
if else_body is not None and not isinstance(else_body, list):
raise GenerationError(
f"else_body argument in create method of IfBlock class should "
f"be a list but found '{type(else_body).__name__}'.")
if_stmt = IfBlock()
if_schedule = Schedule(parent=if_stmt, children=if_body)
if else_body is not None:
else_schedule = Schedule(parent=if_stmt, children=else_body)
if_stmt.children = [if_condition, if_schedule, else_schedule]
else:
if_stmt.children = [if_condition, if_schedule]
return if_stmt
def __str__(self):
name = self._text_name
result = name + "[]\n"
for entity in self._children:
result += str(entity)
result += "End " + name
return result
[docs]
def reference_accesses(self) -> VariablesAccessMap:
'''
:returns: a map of all the symbol accessed inside this node, the
keys are Signatures (unique identifiers to a symbol and its
structure accessors) and the values are AccessSequence
(a sequence of AccessTypes).
'''
var_accesses = self.condition.reference_accesses()
var_accesses.update(self.if_body.reference_accesses())
if self.else_body:
var_accesses.update(self.else_body.reference_accesses())
return var_accesses
