def make_while_from_for(for_node):
"Create a While from a For. The 'test' (loop condition) must still be set."
while_node = nodes.While(test=None,
body=for_node.body,
orelse=for_node.orelse)
copy_basic_blocks(for_node, while_node)
while_node = nodes.build_while(**vars(while_node))
return while_node
def make_while_from_for(for_node):
"Create a While from a For. The 'test' (loop condition) must still be set."
while_node = nodes.While(test=None,
body=for_node.body,
orelse=for_node.orelse)
copy_basic_blocks(for_node, while_node)
while_node = nodes.build_while(**vars(while_node))
return while_node
def visit_While(self, node):
node.cond_block = self.flow.nextblock(label='while_condition',
pos=node.test)
node.exit_block = self.flow.exit_block(label='exit_while', pos=node)
# Condition block
self.flow.loops.append(LoopDescr(node.exit_block, node.cond_block))
node.test = self.visit(node.test)
self._visit_loop_body(node)
return nodes.build_while(**vars(node))
def visit_While(self, node):
node.cond_block = self.flow.nextblock(label='while_condition',
pos=node.test)
node.exit_block = self.flow.exit_block(label='exit_while', pos=node)
# Condition block
self.flow.loops.append(LoopDescr(node.exit_block, node.cond_block))
node.test = self.visit(node.test)
self._visit_loop_body(node)
return nodes.build_while(**vars(node))
def rewrite_range_iteration(self, node):
"""
Handle range iteration:
for i in range(start, stop, step):
...
becomes
nsteps = compute_nsteps(start, stop, step)
temp = 0
while temp < nsteps:
target = start + temp * step
...
temp += 1
"""
self.generic_visit(node)
temp = nodes.TempNode(node.target.type, 'target_temp')
nsteps = nodes.TempNode(Py_ssize_t, 'nsteps')
start, stop, step = unpack_range_args(node.iter)
if isinstance(step, nodes.ConstNode):
have_step = step.pyval != 1
else:
have_step = True
start, stop, step = [
nodes.CloneableNode(n) for n in (start, stop, step)
]
if have_step:
compute_nsteps = """
$length = {{stop}} - {{start}}
{{nsteps}} = $length / {{step}}
if {{nsteps_load}} * {{step}} != $length: #$length % {{step}}:
# Test for truncation
{{nsteps}} = {{nsteps_load}} + 1
# print "nsteps", {{nsteps_load}}
"""
else:
compute_nsteps = "{{nsteps}} = {{stop}} - {{start}}"
if node.orelse:
else_clause = "else: {{else_body}}"
else:
else_clause = ""
templ = textwrap.dedent("""
%s
{{temp}} = 0
while {{temp_load}} < {{nsteps_load}}:
{{target}} = {{start}} + {{temp_load}} * {{step}}
{{body}}
{{temp}} = {{temp_load}} + 1
%s
""") % (textwrap.dedent(compute_nsteps), else_clause)
# Leave the bodies empty, they are already analyzed
body = ast.Suite(body=[])
else_body = ast.Suite(body=[])
#--------------------------------------------------------------------
# Substitute template and infer types
#--------------------------------------------------------------------
result = self.run_template(templ,
vars=dict(length=Py_ssize_t),
start=start,
stop=stop,
step=step,
nsteps=nsteps.store(),
nsteps_load=nsteps.load(),
temp=temp.store(),
temp_load=temp.load(),
target=node.target,
body=body,
else_body=else_body)
#--------------------------------------------------------------------
# Patch the body and else clause
#--------------------------------------------------------------------
body.body.extend(node.body)
else_body.body.extend(node.orelse)
while_node = result.body[-1]
assert isinstance(while_node, ast.While)
target_increment = while_node.body[-1]
assert isinstance(target_increment, ast.Assign)
# Add target variable increment basic block
node.incr_block.body = [target_increment]
while_node.body[-1] = node.incr_block
#--------------------------------------------------------------------
# Create a While with the ForNode's cfg blocks merged in
#--------------------------------------------------------------------
while_node = make_while_loop(while_node)
copy_basic_blocks(node, while_node)
while_node = nodes.build_while(**vars(while_node))
# Create the place to jump to for 'continue'
while_node.continue_block = node.incr_block
# Set the new while loop in the templated Suite
result.body[-1] = while_node
return result
def rewrite_range_iteration(self, node):
"""
Handle range iteration:
for i in range(start, stop, step):
...
becomes
nsteps = compute_nsteps(start, stop, step)
temp = 0
while temp < nsteps:
target = start + temp * step
...
temp += 1
"""
self.generic_visit(node)
temp = nodes.TempNode(node.target.type, 'target_temp')
nsteps = nodes.TempNode(Py_ssize_t, 'nsteps')
start, stop, step = unpack_range_args(node.iter)
if isinstance(step, nodes.ConstNode):
have_step = step.pyval != 1
else:
have_step = True
start, stop, step = map(nodes.CloneableNode, (start, stop, step))
if have_step:
templ = textwrap.dedent("""
{{temp}} = 0
{{nsteps}} = ({{stop}} - {{start}} + {{step}} -
(1 if {{step}} >= 0 else -1)) / {{step}}
while {{temp_load}} < {{nsteps_load}}:
{{target}} = {{start}} + {{temp_load}} * {{step}}
{{temp}} = {{temp_load}} + 1
{{body}}
""")
else:
templ = textwrap.dedent("""
{{temp}} = {{start}}
{{nsteps}} = {{stop}}
while {{temp_load}} < {{nsteps_load}}:
{{target}} = {{temp_load}}
{{temp}} = {{temp_load}} + 1
{{body}}
""")
if node.orelse:
templ += "\nelse: {{else_body}}"
# Leave the bodies empty, they are already analyzed
body = ast.Suite(body=[])
else_body = ast.Suite(body=[])
#--------------------------------------------------------------------
# Substitute template and infer types
#--------------------------------------------------------------------
result = self.run_template(templ,
vars=dict(length=Py_ssize_t),
start=start,
stop=stop,
step=step,
nsteps=nsteps.store(),
nsteps_load=nsteps.load(),
temp=temp.store(),
temp_load=temp.load(),
target=node.target,
body=body,
else_body=else_body)
ast.copy_location(result, node)
if hasattr(node, 'lineno'):
visitor = missing.FixMissingLocations(node.lineno,
node.col_offset,
override=True)
visitor.visit(result)
#--------------------------------------------------------------------
# Patch the body and else clause
#--------------------------------------------------------------------
body.body.extend(node.body)
else_body.body.extend(node.orelse)
while_node = result.body[-1]
assert isinstance(while_node, ast.While)
#--------------------------------------------------------------------
# Create a While with the ForNode's cfg blocks merged in
#--------------------------------------------------------------------
while_node = make_while_loop(while_node)
copy_basic_blocks(node, while_node)
while_node = nodes.build_while(**vars(while_node))
# Create the place to jump to for 'continue'
while_node.continue_block = node.cond_block
# Set the new while loop in the templated Suite
result.body[-1] = while_node
return result
def rewrite_range_iteration(self, node):
"""
Handle range iteration:
for i in range(start, stop, step):
...
becomes
nsteps = compute_nsteps(start, stop, step)
temp = 0
while temp < nsteps:
target = start + temp * step
...
temp += 1
"""
self.generic_visit(node)
temp = nodes.TempNode(node.target.type, 'target_temp')
nsteps = nodes.TempNode(Py_ssize_t, 'nsteps')
start, stop, step = unpack_range_args(node.iter)
if isinstance(step, nodes.ConstNode):
have_step = step.pyval != 1
else:
have_step = True
start, stop, step = [nodes.CloneableNode(n)
for n in (start, stop, step)]
if have_step:
compute_nsteps = """
$length = {{stop}} - {{start}}
{{nsteps}} = $length / {{step}}
if {{nsteps_load}} * {{step}} != $length: #$length % {{step}}:
# Test for truncation
{{nsteps}} = {{nsteps_load}} + 1
# print "nsteps", {{nsteps_load}}
"""
else:
compute_nsteps = "{{nsteps}} = {{stop}} - {{start}}"
if node.orelse:
else_clause = "else: {{else_body}}"
else:
else_clause = ""
templ = textwrap.dedent("""
%s
{{temp}} = 0
while {{temp_load}} < {{nsteps_load}}:
{{target}} = {{start}} + {{temp_load}} * {{step}}
{{body}}
{{temp}} = {{temp_load}} + 1
%s
""") % (textwrap.dedent(compute_nsteps), else_clause)
# Leave the bodies empty, they are already analyzed
body = ast.Suite(body=[])
else_body = ast.Suite(body=[])
#--------------------------------------------------------------------
# Substitute template and infer types
#--------------------------------------------------------------------
result = self.run_template(
templ, vars=dict(length=Py_ssize_t),
start=start, stop=stop, step=step,
nsteps=nsteps.store(), nsteps_load=nsteps.load(),
temp=temp.store(), temp_load=temp.load(),
target=node.target,
body=body, else_body=else_body)
#--------------------------------------------------------------------
# Patch the body and else clause
#--------------------------------------------------------------------
body.body.extend(node.body)
else_body.body.extend(node.orelse)
while_node = result.body[-1]
assert isinstance(while_node, ast.While)
target_increment = while_node.body[-1]
assert isinstance(target_increment, ast.Assign)
# Add target variable increment basic block
node.incr_block.body = [target_increment]
while_node.body[-1] = node.incr_block
#--------------------------------------------------------------------
# Create a While with the ForNode's cfg blocks merged in
#--------------------------------------------------------------------
while_node = make_while_loop(while_node)
copy_basic_blocks(node, while_node)
while_node = nodes.build_while(**vars(while_node))
# Create the place to jump to for 'continue'
while_node.continue_block = node.incr_block
# Set the new while loop in the templated Suite
result.body[-1] = while_node
return result
def rewrite_range_iteration(self, node):
"""
Handle range iteration:
for i in range(start, stop, step):
...
becomes
nsteps = compute_nsteps(start, stop, step)
temp = 0
while temp < nsteps:
target = start + temp * step
...
temp += 1
"""
self.generic_visit(node)
temp = nodes.TempNode(node.target.type, 'target_temp')
nsteps = nodes.TempNode(Py_ssize_t, 'nsteps')
start, stop, step = unpack_range_args(node.iter)
if isinstance(step, nodes.ConstNode):
have_step = step.pyval != 1
else:
have_step = True
start, stop, step = map(nodes.CloneableNode, (start, stop, step))
if have_step:
templ = textwrap.dedent("""
{{temp}} = 0
{{nsteps}} = ({{stop}} - {{start}} + {{step}} -
(1 if {{step}} >= 0 else -1)) / {{step}}
while {{temp_load}} < {{nsteps_load}}:
{{target}} = {{start}} + {{temp_load}} * {{step}}
{{temp}} = {{temp_load}} + 1
{{body}}
""")
else:
templ = textwrap.dedent("""
{{temp}} = {{start}}
{{nsteps}} = {{stop}}
while {{temp_load}} < {{nsteps_load}}:
{{target}} = {{temp_load}}
{{temp}} = {{temp_load}} + 1
{{body}}
""")
if node.orelse:
templ += "\nelse: {{else_body}}"
# Leave the bodies empty, they are already analyzed
body = ast.Suite(body=[])
else_body = ast.Suite(body=[])
#--------------------------------------------------------------------
# Substitute template and infer types
#--------------------------------------------------------------------
result = self.run_template(
templ, vars=dict(length=Py_ssize_t),
start=start, stop=stop, step=step,
nsteps=nsteps.store(), nsteps_load=nsteps.load(),
temp=temp.store(), temp_load=temp.load(),
target=node.target,
body=body, else_body=else_body)
ast.copy_location(result, node)
if hasattr(node, 'lineno'):
visitor = missing.FixMissingLocations(node.lineno, node.col_offset,
override=True)
visitor.visit(result)
#--------------------------------------------------------------------
# Patch the body and else clause
#--------------------------------------------------------------------
body.body.extend(node.body)
else_body.body.extend(node.orelse)
while_node = result.body[-1]
assert isinstance(while_node, ast.While)
#--------------------------------------------------------------------
# Create a While with the ForNode's cfg blocks merged in
#--------------------------------------------------------------------
while_node = make_while_loop(while_node)
copy_basic_blocks(node, while_node)
while_node = nodes.build_while(**vars(while_node))
# Create the place to jump to for 'continue'
while_node.continue_block = node.cond_block
# Set the new while loop in the templated Suite
result.body[-1] = while_node
return result