JezK
Edit File: fix_except.py
"""Fixer for except statements with named exceptions. The following cases will be converted: - "except E, T:" where T is a name: except E as T: - "except E, T:" where T is not a name, tuple or list: except E as t: T = t This is done because the target of an "except" clause must be a name. - "except E, T:" where T is a tuple or list literal: except E as t: T = t.args """ # Author: Collin Winter # Local imports from .. import pytree from ..pgen2 import token from .. import fixer_base from ..fixer_util import Assign, Attr, Name, is_tuple, is_list, syms def find_excepts(nodes): for i, n in enumerate(nodes): if n.type == syms.except_clause: if n.children[0].value == 'except': yield (n, nodes[i+2]) class FixExcept(fixer_base.BaseFix): BM_compatible = True PATTERN = """ try_stmt< 'try' ':' (simple_stmt | suite) cleanup=(except_clause ':' (simple_stmt | suite))+ tail=(['except' ':' (simple_stmt | suite)] ['else' ':' (simple_stmt | suite)] ['finally' ':' (simple_stmt | suite)]) > """ def transform(self, node, results): syms = self.syms tail = [n.clone() for n in results["tail"]] try_cleanup = [ch.clone() for ch in results["cleanup"]] for except_clause, e_suite in find_excepts(try_cleanup): if len(except_clause.children) == 4: (E, comma, N) = except_clause.children[1:4] comma.replace(Name("as", prefix=" ")) if N.type != token.NAME: # Generate a new N for the except clause new_N = Name(self.new_name(), prefix=" ") target = N.clone() target.prefix = "" N.replace(new_N) new_N = new_N.clone() # Insert "old_N = new_N" as the first statement in # the except body. This loop skips leading whitespace # and indents #TODO(cwinter) suite-cleanup suite_stmts = e_suite.children for i, stmt in enumerate(suite_stmts): if isinstance(stmt, pytree.Node): break # The assignment is different if old_N is a tuple or list # In that case, the assignment is old_N = new_N.args if is_tuple(N) or is_list(N): assign = Assign(target, Attr(new_N, Name('args'))) else: assign = Assign(target, new_N) #TODO(cwinter) stopgap until children becomes a smart list for child in reversed(suite_stmts[:i]): e_suite.insert_child(0, child) e_suite.insert_child(i, assign) elif N.prefix == "": # No space after a comma is legal; no space after "as", # not so much. N.prefix = " " #TODO(cwinter) fix this when children becomes a smart list children = [c.clone() for c in node.children[:3]] + try_cleanup + tail return pytree.Node(node.type, children)