/
FlowControl.py
1148 lines (970 loc) · 37.2 KB
/
FlowControl.py
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import cython
cython.declare(PyrexTypes=object, Naming=object, ExprNodes=object, Nodes=object,
Options=object, UtilNodes=object, ModuleNode=object,
LetNode=object, LetRefNode=object, TreeFragment=object,
TemplateTransform=object, EncodedString=object,
error=object, warning=object, copy=object)
import Builtin
import ExprNodes
import Nodes
from PyrexTypes import py_object_type
from Visitor import TreeVisitor, CythonTransform
from Errors import error, warning, InternalError
class TypedExprNode(ExprNodes.ExprNode):
# Used for declaring assignments of a specified type without a known entry.
def __init__(self, type, may_be_none=None):
self.type = type
self._may_be_none = may_be_none
def may_be_none(self):
return self._may_be_none != False
object_expr = TypedExprNode(py_object_type, may_be_none=True)
object_expr_not_none = TypedExprNode(py_object_type, may_be_none=False)
class ControlBlock(object):
"""Control flow graph node. Sequence of assignments and name references.
children set of children nodes
parents set of parent nodes
positions set of position markers
stats list of block statements
gen dict of assignments generated by this block
bounded set of entries that are definitely bounded in this block
Example:
a = 1
b = a + c # 'c' is already bounded or exception here
stats = [Assignment(a), NameReference(a), NameReference(c),
Assignment(b)]
gen = {Entry(a): Assignment(a), Entry(b): Assignment(b)}
bounded = set([Entry(a), Entry(c)])
"""
def __init__(self):
self.children = set()
self.parents = set()
self.positions = set()
self.stats = []
self.gen = {}
self.bounded = set()
self.i_input = 0
self.i_output = 0
self.i_gen = 0
self.i_kill = 0
self.i_state = 0
def empty(self):
return (not self.stats and not self.positions)
def detach(self):
"""Detach block from parents and children."""
for child in self.children:
child.parents.remove(self)
for parent in self.parents:
parent.children.remove(self)
self.parents.clear()
self.children.clear()
def add_child(self, block):
self.children.add(block)
block.parents.add(self)
class ExitBlock(ControlBlock):
"""Non-empty exit point block."""
def empty(self):
return False
class AssignmentList:
def __init__(self):
self.stats = []
class ControlFlow(object):
"""Control-flow graph.
entry_point ControlBlock entry point for this graph
exit_point ControlBlock normal exit point
block ControlBlock current block
blocks set children nodes
entries set tracked entries
loops list stack for loop descriptors
exceptions list stack for exception descriptors
"""
def __init__(self):
self.blocks = set()
self.entries = set()
self.loops = []
self.exceptions = []
self.entry_point = ControlBlock()
self.exit_point = ExitBlock()
self.blocks.add(self.exit_point)
self.block = self.entry_point
def newblock(self, parent=None):
"""Create floating block linked to `parent` if given.
NOTE: Block is NOT added to self.blocks
"""
block = ControlBlock()
self.blocks.add(block)
if parent:
parent.add_child(block)
return block
def nextblock(self, parent=None):
"""Create block children block linked to current or `parent` if given.
NOTE: Block is added to self.blocks
"""
block = ControlBlock()
self.blocks.add(block)
if parent:
parent.add_child(block)
elif self.block:
self.block.add_child(block)
self.block = block
return self.block
def is_tracked(self, entry):
if entry.is_anonymous:
return False
if (entry.type.is_array or entry.type.is_struct_or_union or
entry.type.is_cpp_class):
return False
return (entry.is_local or entry.is_pyclass_attr or entry.is_arg or
entry.from_closure or entry.in_closure or
entry.error_on_uninitialized)
def mark_position(self, node):
"""Mark position, will be used to draw graph nodes."""
if self.block:
self.block.positions.add(node.pos[:2])
def mark_assignment(self, lhs, rhs, entry):
if self.block:
if not self.is_tracked(entry):
return
assignment = NameAssignment(lhs, rhs, entry)
self.block.stats.append(assignment)
self.block.gen[entry] = assignment
self.entries.add(entry)
def mark_argument(self, lhs, rhs, entry):
if self.block and self.is_tracked(entry):
assignment = Argument(lhs, rhs, entry)
self.block.stats.append(assignment)
self.block.gen[entry] = assignment
self.entries.add(entry)
def mark_deletion(self, node, entry):
if self.block and self.is_tracked(entry):
assignment = NameAssignment(node, None, entry)
self.block.stats.append(assignment)
self.block.gen[entry] = Uninitialized
self.entries.add(entry)
def mark_reference(self, node, entry):
if self.block and self.is_tracked(entry):
self.block.stats.append(NameReference(node, entry))
# Local variable is definitely bound after this reference
if not node.allow_null:
self.block.bounded.add(entry)
self.entries.add(entry)
def normalize(self):
"""Delete unreachable and orphan blocks."""
queue = set([self.entry_point])
visited = set()
while queue:
root = queue.pop()
visited.add(root)
for child in root.children:
if child not in visited:
queue.add(child)
unreachable = self.blocks - visited
for block in unreachable:
block.detach()
visited.remove(self.entry_point)
for block in visited:
if block.empty():
for parent in block.parents: # Re-parent
for child in block.children:
parent.add_child(child)
block.detach()
unreachable.add(block)
self.blocks -= unreachable
def initialize(self):
"""Set initial state, map assignments to bits."""
self.assmts = {}
offset = 0
for entry in self.entries:
assmts = AssignmentList()
assmts.bit = 1 << offset
assmts.mask = assmts.bit
self.assmts[entry] = assmts
offset += 1
for block in self.blocks:
for stat in block.stats:
if isinstance(stat, NameAssignment):
stat.bit = 1 << offset
assmts = self.assmts[stat.entry]
assmts.stats.append(stat)
assmts.mask |= stat.bit
offset += 1
for block in self.blocks:
for entry, stat in block.gen.items():
assmts = self.assmts[entry]
if stat is Uninitialized:
block.i_gen |= assmts.bit
else:
block.i_gen |= stat.bit
block.i_kill |= assmts.mask
block.i_output = block.i_gen
for entry in block.bounded:
block.i_kill |= self.assmts[entry].bit
for assmts in self.assmts.itervalues():
self.entry_point.i_gen |= assmts.bit
self.entry_point.i_output = self.entry_point.i_gen
def map_one(self, istate, entry):
ret = set()
assmts = self.assmts[entry]
if istate & assmts.bit:
ret.add(Uninitialized)
for assmt in assmts.stats:
if istate & assmt.bit:
ret.add(assmt)
return ret
def reaching_definitions(self):
"""Per-block reaching definitions analysis."""
dirty = True
while dirty:
dirty = False
for block in self.blocks:
i_input = 0
for parent in block.parents:
i_input |= parent.i_output
i_output = (i_input & ~block.i_kill) | block.i_gen
if i_output != block.i_output:
dirty = True
block.i_input = i_input
block.i_output = i_output
class LoopDescr(object):
def __init__(self, next_block, loop_block):
self.next_block = next_block
self.loop_block = loop_block
self.exceptions = []
class ExceptionDescr(object):
"""Exception handling helper.
entry_point ControlBlock Exception handling entry point
finally_enter ControlBlock Normal finally clause entry point
finally_exit ControlBlock Normal finally clause exit point
"""
def __init__(self, entry_point, finally_enter=None, finally_exit=None):
self.entry_point = entry_point
self.finally_enter = finally_enter
self.finally_exit = finally_exit
class NameAssignment(object):
def __init__(self, lhs, rhs, entry):
if lhs.cf_state is None:
lhs.cf_state = set()
self.lhs = lhs
self.rhs = rhs
self.entry = entry
self.pos = lhs.pos
self.refs = set()
self.is_arg = False
def __repr__(self):
return '%s(entry=%r)' % (self.__class__.__name__, self.entry)
class Argument(NameAssignment):
def __init__(self, lhs, rhs, entry):
NameAssignment.__init__(self, lhs, rhs, entry)
self.is_arg = True
class Uninitialized(object):
pass
class NameReference(object):
def __init__(self, node, entry):
if node.cf_state is None:
node.cf_state = set()
self.node = node
self.entry = entry
self.pos = node.pos
def __repr__(self):
return '%s(entry=%r)' % (self.__class__.__name__, self.entry)
class ControlFlowState(list):
# Keeps track of Node's entry assignments
#
# cf_is_null [boolean] It is uninitialized
# cf_maybe_null [boolean] May be uninitialized
# is_single [boolean] Has only one assignment at this point
cf_maybe_null = False
cf_is_null = False
is_single = False
def __init__(self, state):
if Uninitialized in state:
state.discard(Uninitialized)
self.cf_maybe_null = True
if not state:
self.cf_is_null = True
else:
if len(state) == 1:
self.is_single = True
super(ControlFlowState, self).__init__(state)
def one(self):
return self[0]
class GVContext(object):
"""Graphviz subgraph object."""
def __init__(self):
self.blockids = {}
self.nextid = 0
self.children = []
self.sources = {}
def add(self, child):
self.children.append(child)
def nodeid(self, block):
if block not in self.blockids:
self.blockids[block] = 'block%d' % self.nextid
self.nextid += 1
return self.blockids[block]
def extract_sources(self, block):
if not block.positions:
return ''
start = min(block.positions)
stop = max(block.positions)
srcdescr = start[0]
if not srcdescr in self.sources:
self.sources[srcdescr] = list(srcdescr.get_lines())
lines = self.sources[srcdescr]
return '\\n'.join([l.strip() for l in lines[start[1] - 1:stop[1]]])
def render(self, fp, name, annotate_defs=False):
"""Render graphviz dot graph"""
fp.write('digraph %s {\n' % name)
fp.write(' node [shape=box];\n')
for child in self.children:
child.render(fp, self, annotate_defs)
fp.write('}\n')
def escape(self, text):
return text.replace('"', '\\"').replace('\n', '\\n')
class GV(object):
"""Graphviz DOT renderer."""
def __init__(self, name, flow):
self.name = name
self.flow = flow
def render(self, fp, ctx, annotate_defs=False):
fp.write(' subgraph %s {\n' % self.name)
for block in self.flow.blocks:
label = ctx.extract_sources(block)
if annotate_defs:
for stat in block.stats:
if isinstance(stat, NameAssignment):
label += '\n %s [definition]' % stat.entry.name
elif isinstance(stat, NameReference):
if stat.entry:
label += '\n %s [reference]' % stat.entry.name
if not label:
label = 'empty'
pid = ctx.nodeid(block)
fp.write(' %s [label="%s"];\n' % (pid, ctx.escape(label)))
for block in self.flow.blocks:
pid = ctx.nodeid(block)
for child in block.children:
fp.write(' %s -> %s;\n' % (pid, ctx.nodeid(child)))
fp.write(' }\n')
class MessageCollection:
"""Collect error/warnings messages first then sort"""
def __init__(self):
self.messages = []
def error(self, pos, message):
self.messages.append((pos, True, message))
def warning(self, pos, message):
self.messages.append((pos, False, message))
def report(self):
self.messages.sort()
for pos, is_error, message in self.messages:
if is_error:
error(pos, message)
else:
warning(pos, message, 2)
def check_definitions(flow, compiler_directives):
flow.initialize()
flow.reaching_definitions()
# Track down state
assignments = set()
# Node to entry map
references = {}
assmt_nodes = set()
for block in flow.blocks:
i_state = block.i_input
for stat in block.stats:
i_assmts = flow.assmts[stat.entry]
state = flow.map_one(i_state, stat.entry)
if isinstance(stat, NameAssignment):
stat.lhs.cf_state.update(state)
assmt_nodes.add(stat.lhs)
i_state = i_state & ~i_assmts.mask
if stat.rhs:
i_state |= stat.bit
else:
i_state |= i_assmts.bit
assignments.add(stat)
stat.entry.cf_assignments.append(stat)
elif isinstance(stat, NameReference):
references[stat.node] = stat.entry
stat.entry.cf_references.append(stat)
stat.node.cf_state.update(state)
if not stat.node.allow_null:
i_state &= ~i_assmts.bit
state.discard(Uninitialized)
for assmt in state:
assmt.refs.add(stat)
# Check variable usage
warn_maybe_uninitialized = compiler_directives['warn.maybe_uninitialized']
warn_unused_result = compiler_directives['warn.unused_result']
warn_unused = compiler_directives['warn.unused']
warn_unused_arg = compiler_directives['warn.unused_arg']
messages = MessageCollection()
# assignment hints
for node in assmt_nodes:
if Uninitialized in node.cf_state:
node.cf_maybe_null = True
if len(node.cf_state) == 1:
node.cf_is_null = True
else:
node.cf_is_null = False
else:
node.cf_is_null = False
node.cf_maybe_null = False
# Find uninitialized references and cf-hints
for node, entry in references.iteritems():
if Uninitialized in node.cf_state:
node.cf_maybe_null = True
if not entry.from_closure and len(node.cf_state) == 1:
node.cf_is_null = True
if node.allow_null or entry.from_closure or entry.is_pyclass_attr:
pass # Can be uninitialized here
elif node.cf_is_null:
if (entry.type.is_pyobject or entry.type.is_unspecified or
entry.error_on_uninitialized):
messages.error(
node.pos,
"local variable '%s' referenced before assignment"
% entry.name)
else:
messages.warning(
node.pos,
"local variable '%s' referenced before assignment"
% entry.name)
elif warn_maybe_uninitialized:
messages.warning(
node.pos,
"local variable '%s' might be referenced before assignment"
% entry.name)
else:
node.cf_is_null = False
node.cf_maybe_null = False
# Unused result
for assmt in assignments:
if (not assmt.refs and not assmt.entry.is_pyclass_attr
and not assmt.entry.in_closure):
if assmt.entry.cf_references and warn_unused_result:
if assmt.is_arg:
messages.warning(assmt.pos, "Unused argument value '%s'" %
assmt.entry.name)
else:
messages.warning(assmt.pos, "Unused result in '%s'" %
assmt.entry.name)
assmt.lhs.cf_used = False
# Unused entries
for entry in flow.entries:
if (not entry.cf_references and not entry.is_pyclass_attr
and not entry.in_closure):
if entry.is_arg:
if warn_unused_arg:
messages.warning(entry.pos, "Unused argument '%s'" %
entry.name)
else:
if warn_unused:
messages.warning(entry.pos, "Unused entry '%s'" %
entry.name)
entry.cf_used = False
messages.report()
for node in assmt_nodes:
node.cf_state = ControlFlowState(node.cf_state)
for node in references:
node.cf_state = ControlFlowState(node.cf_state)
class AssignmentCollector(TreeVisitor):
def __init__(self):
super(AssignmentCollector, self).__init__()
self.assignments = []
def visit_Node(self):
self.visitchildren(self)
def visit_SingleAssignmentNode(self, node):
self.assignments.append((node.lhs, node.rhs))
def visit_CascadedAssignmentNode(self, node):
for lhs in node.lhs_list:
self.assignments.append((lhs, node.rhs))
class ControlFlowAnalysis(CythonTransform):
in_inplace_assignment = False
def visit_ModuleNode(self, node):
self.gv_ctx = GVContext()
# Set of NameNode reductions
self.reductions = set()
self.env_stack = []
self.env = node.scope
self.stack = []
self.flow = ControlFlow()
self.visitchildren(node)
check_definitions(self.flow, self.current_directives)
dot_output = self.current_directives['control_flow.dot_output']
if dot_output:
annotate_defs = self.current_directives['control_flow.dot_annotate_defs']
fp = open(dot_output, 'wt')
try:
self.gv_ctx.render(fp, 'module', annotate_defs=annotate_defs)
finally:
fp.close()
return node
def visit_FuncDefNode(self, node):
for arg in node.args:
if arg.default:
self.visitchildren(arg)
self.visitchildren(node, attrs=('decorators',))
self.env_stack.append(self.env)
self.env = node.local_scope
self.stack.append(self.flow)
self.flow = ControlFlow()
# Collect all entries
for entry in node.local_scope.entries.values():
if self.flow.is_tracked(entry):
self.flow.entries.add(entry)
self.mark_position(node)
# Function body block
self.flow.nextblock()
for arg in node.args:
self.visit(arg)
if node.star_arg:
self.flow.mark_argument(node.star_arg,
TypedExprNode(Builtin.tuple_type,
may_be_none=False),
node.star_arg.entry)
if node.starstar_arg:
self.flow.mark_argument(node.starstar_arg,
TypedExprNode(Builtin.dict_type,
may_be_none=False),
node.starstar_arg.entry)
self.visit(node.body)
# Workaround for generators
if node.is_generator:
self.visit(node.gbody.body)
# Exit point
if self.flow.block:
self.flow.block.add_child(self.flow.exit_point)
# Cleanup graph
self.flow.normalize()
check_definitions(self.flow, self.current_directives)
self.flow.blocks.add(self.flow.entry_point)
self.gv_ctx.add(GV(node.local_scope.name, self.flow))
self.flow = self.stack.pop()
self.env = self.env_stack.pop()
return node
def visit_DefNode(self, node):
node.used = True
return self.visit_FuncDefNode(node)
def visit_GeneratorBodyDefNode(self, node):
return node
def visit_CTypeDefNode(self, node):
return node
def mark_assignment(self, lhs, rhs=None):
if not self.flow.block:
return
if self.flow.exceptions:
exc_descr = self.flow.exceptions[-1]
self.flow.block.add_child(exc_descr.entry_point)
self.flow.nextblock()
if not rhs:
rhs = object_expr
if lhs.is_name:
if lhs.entry is not None:
entry = lhs.entry
else:
entry = self.env.lookup(lhs.name)
if entry is None: # TODO: This shouldn't happen...
return
self.flow.mark_assignment(lhs, rhs, entry)
elif isinstance(lhs, ExprNodes.SequenceNode):
for arg in lhs.args:
self.mark_assignment(arg)
else:
self.visit(lhs)
if self.flow.exceptions:
exc_descr = self.flow.exceptions[-1]
self.flow.block.add_child(exc_descr.entry_point)
self.flow.nextblock()
def mark_position(self, node):
"""Mark position if DOT output is enabled."""
if self.current_directives['control_flow.dot_output']:
self.flow.mark_position(node)
def visit_FromImportStatNode(self, node):
for name, target in node.items:
if name != "*":
self.mark_assignment(target)
self.visitchildren(node)
return node
def visit_AssignmentNode(self, node):
raise InternalError, "Unhandled assignment node"
def visit_SingleAssignmentNode(self, node):
self.visit(node.rhs)
self.mark_assignment(node.lhs, node.rhs)
return node
def visit_CascadedAssignmentNode(self, node):
self.visit(node.rhs)
for lhs in node.lhs_list:
self.mark_assignment(lhs, node.rhs)
return node
def visit_ParallelAssignmentNode(self, node):
collector = AssignmentCollector()
collector.visitchildren(node)
for lhs, rhs in collector.assignments:
self.visit(rhs)
for lhs, rhs in collector.assignments:
self.mark_assignment(lhs, rhs)
return node
def visit_InPlaceAssignmentNode(self, node):
self.in_inplace_assignment = True
self.visitchildren(node)
self.in_inplace_assignment = False
self.mark_assignment(node.lhs, node.create_binop_node())
return node
def visit_DelStatNode(self, node):
for arg in node.args:
if arg.is_name:
entry = arg.entry or self.env.lookup(arg.name)
if entry.in_closure or entry.from_closure:
error(arg.pos,
"can not delete variable '%s' "
"referenced in nested scope" % entry.name)
# Mark reference
self.visit(arg)
self.flow.mark_deletion(arg, entry)
return node
def visit_CArgDeclNode(self, node):
entry = self.env.lookup(node.name)
if entry:
may_be_none = not node.not_none
self.flow.mark_argument(node, TypedExprNode(entry.type, may_be_none), entry)
return node
def visit_NameNode(self, node):
if self.flow.block:
entry = node.entry or self.env.lookup(node.name)
if entry:
self.flow.mark_reference(node, entry)
if entry in self.reductions and not self.in_inplace_assignment:
error(node.pos,
"Cannot read reduction variable in loop body")
return node
def visit_StatListNode(self, node):
if self.flow.block:
for stat in node.stats:
self.visit(stat)
if not self.flow.block:
stat.is_terminator = True
break
return node
def visit_Node(self, node):
self.visitchildren(node)
self.mark_position(node)
return node
def visit_IfStatNode(self, node):
next_block = self.flow.newblock()
parent = self.flow.block
# If clauses
for clause in node.if_clauses:
parent = self.flow.nextblock(parent)
self.visit(clause.condition)
self.flow.nextblock()
self.visit(clause.body)
if self.flow.block:
self.flow.block.add_child(next_block)
# Else clause
if node.else_clause:
self.flow.nextblock(parent=parent)
self.visit(node.else_clause)
if self.flow.block:
self.flow.block.add_child(next_block)
else:
parent.add_child(next_block)
if next_block.parents:
self.flow.block = next_block
else:
self.flow.block = None
return node
def visit_WhileStatNode(self, node):
condition_block = self.flow.nextblock()
next_block = self.flow.newblock()
# Condition block
self.flow.loops.append(LoopDescr(next_block, condition_block))
self.visit(node.condition)
# Body block
self.flow.nextblock()
self.visit(node.body)
self.flow.loops.pop()
# Loop it
if self.flow.block:
self.flow.block.add_child(condition_block)
self.flow.block.add_child(next_block)
# Else clause
if node.else_clause:
self.flow.nextblock(parent=condition_block)
self.visit(node.else_clause)
if self.flow.block:
self.flow.block.add_child(next_block)
else:
condition_block.add_child(next_block)
if next_block.parents:
self.flow.block = next_block
else:
self.flow.block = None
return node
def visit_ForInStatNode(self, node):
condition_block = self.flow.nextblock()
next_block = self.flow.newblock()
# Condition with iterator
self.flow.loops.append(LoopDescr(next_block, condition_block))
self.visit(node.iterator)
# Target assignment
self.flow.nextblock()
self.mark_assignment(node.target)
# Body block
if isinstance(node, Nodes.ParallelRangeNode):
# In case of an invalid
self._delete_privates(node, exclude=node.target.entry)
self.flow.nextblock()
self.visit(node.body)
self.flow.loops.pop()
# Loop it
if self.flow.block:
self.flow.block.add_child(condition_block)
# Else clause
if node.else_clause:
self.flow.nextblock(parent=condition_block)
self.visit(node.else_clause)
if self.flow.block:
self.flow.block.add_child(next_block)
else:
condition_block.add_child(next_block)
if next_block.parents:
self.flow.block = next_block
else:
self.flow.block = None
return node
def _delete_privates(self, node, exclude=None):
for private_node in node.assigned_nodes:
if not exclude or private_node.entry is not exclude:
self.flow.mark_deletion(private_node, private_node.entry)
def visit_ParallelRangeNode(self, node):
reductions = self.reductions
# if node.target is None or not a NameNode, an error will have
# been previously issued
if hasattr(node.target, 'entry'):
self.reductions = set(reductions)
for private_node in node.assigned_nodes:
private_node.entry.error_on_uninitialized = True
pos, reduction = node.assignments[private_node.entry]
if reduction:
self.reductions.add(private_node.entry)
node = self.visit_ForInStatNode(node)
self.reductions = reductions
return node
def visit_ParallelWithBlockNode(self, node):
for private_node in node.assigned_nodes:
private_node.entry.error_on_uninitialized = True
self._delete_privates(node)
self.visitchildren(node)
self._delete_privates(node)
return node
def visit_ForFromStatNode(self, node):
condition_block = self.flow.nextblock()
next_block = self.flow.newblock()
# Condition with iterator
self.flow.loops.append(LoopDescr(next_block, condition_block))
self.visit(node.bound1)
self.visit(node.bound2)
if node.step:
self.visit(node.step)
# Target assignment
self.flow.nextblock()
self.mark_assignment(node.target)
# Body block
self.flow.nextblock()
self.visit(node.body)
self.flow.loops.pop()
# Loop it
if self.flow.block:
self.flow.block.add_child(condition_block)
# Else clause
if node.else_clause:
self.flow.nextblock(parent=condition_block)
self.visit(node.else_clause)
if self.flow.block:
self.flow.block.add_child(next_block)
else:
condition_block.add_child(next_block)
if next_block.parents:
self.flow.block = next_block
else:
self.flow.block = None
return node
def visit_LoopNode(self, node):
raise InternalError, "Generic loops are not supported"
def visit_WithTargetAssignmentStatNode(self, node):
self.mark_assignment(node.lhs, node.rhs)
return node
def visit_WithStatNode(self, node):
self.visit(node.manager)
self.visit(node.enter_call)
self.visit(node.body)
return node
def visit_TryExceptStatNode(self, node):
# After exception handling
next_block = self.flow.newblock()
# Body block
self.flow.newblock()
# Exception entry point
entry_point = self.flow.newblock()
self.flow.exceptions.append(ExceptionDescr(entry_point))
self.flow.nextblock()
## XXX: links to exception handling point should be added by
## XXX: children nodes
self.flow.block.add_child(entry_point)
self.visit(node.body)
self.flow.exceptions.pop()
# After exception
if self.flow.block:
if node.else_clause:
self.flow.nextblock()
self.visit(node.else_clause)
if self.flow.block:
self.flow.block.add_child(next_block)
for clause in node.except_clauses:
self.flow.block = entry_point
if clause.pattern:
for pattern in clause.pattern:
self.visit(pattern)
else:
# TODO: handle * pattern
pass
entry_point = self.flow.newblock(parent=self.flow.block)
self.flow.nextblock()
if clause.target:
self.mark_assignment(clause.target)
self.visit(clause.body)
if self.flow.block:
self.flow.block.add_child(next_block)
if self.flow.exceptions:
entry_point.add_child(self.flow.exceptions[-1].entry_point)