def generate_For(self, context, node):
context.stmts.append("for (")
orig_end_stmt = context.end_stmt
context.end_stmt = "; "
context.visit(node.init)
init = context.body.pop()
guard = context.visit(node.guard)
context.stmts.append((guard.code, "; "))
context.end_stmt = (") {\n", context.tab)
context.visit(node.update_stmt)
update_stmt = context.body.pop()
context.end_stmt = orig_end_stmt
parent_body = context.body
body = context.body = []
for stmt in node.body:
context.visit(stmt)
context.body = parent_body
context.stmts.append((context.untab, "}\n"))
context.body.append(
astx.copy_node(
node,
target=astx.deep_copy_node(node.target),
iter=astx.copy_node(node.iter),
body=body,
orelse=[],
init=init,
guard=guard,
update_stmt=update_stmt))
def visit_For(self, node):
if node.orelse:
raise InvalidOperationError(
"else clauses on for loops are not supported.", node)
# We only support the standard for x in ([start, ]stop[, step]) syntax
# with positive step sizes.
# insert missing iteration bounds if not specified
iter = astx.deep_copy_node(node.iter)
if isinstance(iter, _ast.Tuple):
elts = iter.elts
n_elts = len(elts)
if n_elts == 1:
start = _ast.Num(n=0)
stop = elts[0]
step = _ast.Num(n=1)
elif n_elts == 2:
start = elts[0]
stop = elts[1]
step = _ast.Num(n=1)
elif n_elts == 3:
start = elts[0]
stop = elts[1]
step = elts[2]
else:
raise InvalidOperationError(
"Invalid number of elements specified in for-loop index.", node)
else:
start = _ast.Num(n=0)
stop = iter
step = _ast.Num(n=1)
# visit target
target = node.target
if not isinstance(target, _ast.Name):
raise InvalidOperationError(
"Invalid target -- only named variables are supported.")
target = astx.copy_node(target)
init = self.visit(_ast.Assign(targets=[target], value=start))
# to create the guard operation, we need a Load version of the target
target_load = astx.copy_node(target, ctx=_ast.Load())
guard = self.visit(_ast.Compare(left=target_load, comparators=[stop],
ops=[_ast.Lt()]))
# Create an update statement
update_stmt = self.visit(
_ast.AugAssign(
target=target,
op=_ast.Add(),
value=step
)
)
return astx.copy_node(node,
target=target,
iter=iter,
body=[self.visit(stmt) for stmt in node.body],
orelse=[],
init=init,
guard=guard,
update_stmt=update_stmt
)