copy lib2to3 from the trunk
diff --git a/Lib/lib2to3/fixer_base.py b/Lib/lib2to3/fixer_base.py
new file mode 100644
index 0000000..16887aa
--- /dev/null
+++ b/Lib/lib2to3/fixer_base.py
@@ -0,0 +1,180 @@
+# Copyright 2006 Google, Inc. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+"""Base class for fixers (optional, but recommended)."""
+
+# Python imports
+import logging
+import itertools
+
+# Local imports
+from .patcomp import PatternCompiler
+from . import pygram
+from .fixer_util import does_tree_import
+
+class BaseFix(object):
+
+ """Optional base class for fixers.
+
+ The subclass name must be FixFooBar where FooBar is the result of
+ removing underscores and capitalizing the words of the fix name.
+ For example, the class name for a fixer named 'has_key' should be
+ FixHasKey.
+ """
+
+ PATTERN = None # Most subclasses should override with a string literal
+ pattern = None # Compiled pattern, set by compile_pattern()
+ options = None # Options object passed to initializer
+ filename = None # The filename (set by set_filename)
+ logger = None # A logger (set by set_filename)
+ numbers = itertools.count(1) # For new_name()
+ used_names = set() # A set of all used NAMEs
+ order = "post" # Does the fixer prefer pre- or post-order traversal
+ explicit = False # Is this ignored by refactor.py -f all?
+ run_order = 5 # Fixers will be sorted by run order before execution
+ # Lower numbers will be run first.
+ _accept_type = None # [Advanced and not public] This tells RefactoringTool
+ # which node type to accept when there's not a pattern.
+
+ # Shortcut for access to Python grammar symbols
+ syms = pygram.python_symbols
+
+ def __init__(self, options, log):
+ """Initializer. Subclass may override.
+
+ Args:
+ options: an dict containing the options passed to RefactoringTool
+ that could be used to customize the fixer through the command line.
+ log: a list to append warnings and other messages to.
+ """
+ self.options = options
+ self.log = log
+ self.compile_pattern()
+
+ def compile_pattern(self):
+ """Compiles self.PATTERN into self.pattern.
+
+ Subclass may override if it doesn't want to use
+ self.{pattern,PATTERN} in .match().
+ """
+ if self.PATTERN is not None:
+ self.pattern = PatternCompiler().compile_pattern(self.PATTERN)
+
+ def set_filename(self, filename):
+ """Set the filename, and a logger derived from it.
+
+ The main refactoring tool should call this.
+ """
+ self.filename = filename
+ self.logger = logging.getLogger(filename)
+
+ def match(self, node):
+ """Returns match for a given parse tree node.
+
+ Should return a true or false object (not necessarily a bool).
+ It may return a non-empty dict of matching sub-nodes as
+ returned by a matching pattern.
+
+ Subclass may override.
+ """
+ results = {"node": node}
+ return self.pattern.match(node, results) and results
+
+ def transform(self, node, results):
+ """Returns the transformation for a given parse tree node.
+
+ Args:
+ node: the root of the parse tree that matched the fixer.
+ results: a dict mapping symbolic names to part of the match.
+
+ Returns:
+ None, or a node that is a modified copy of the
+ argument node. The node argument may also be modified in-place to
+ effect the same change.
+
+ Subclass *must* override.
+ """
+ raise NotImplementedError()
+
+ def new_name(self, template=u"xxx_todo_changeme"):
+ """Return a string suitable for use as an identifier
+
+ The new name is guaranteed not to conflict with other identifiers.
+ """
+ name = template
+ while name in self.used_names:
+ name = template + unicode(self.numbers.next())
+ self.used_names.add(name)
+ return name
+
+ def log_message(self, message):
+ if self.first_log:
+ self.first_log = False
+ self.log.append("### In file %s ###" % self.filename)
+ self.log.append(message)
+
+ def cannot_convert(self, node, reason=None):
+ """Warn the user that a given chunk of code is not valid Python 3,
+ but that it cannot be converted automatically.
+
+ First argument is the top-level node for the code in question.
+ Optional second argument is why it can't be converted.
+ """
+ lineno = node.get_lineno()
+ for_output = node.clone()
+ for_output.prefix = u""
+ msg = "Line %d: could not convert: %s"
+ self.log_message(msg % (lineno, for_output))
+ if reason:
+ self.log_message(reason)
+
+ def warning(self, node, reason):
+ """Used for warning the user about possible uncertainty in the
+ translation.
+
+ First argument is the top-level node for the code in question.
+ Optional second argument is why it can't be converted.
+ """
+ lineno = node.get_lineno()
+ self.log_message("Line %d: %s" % (lineno, reason))
+
+ def start_tree(self, tree, filename):
+ """Some fixers need to maintain tree-wide state.
+ This method is called once, at the start of tree fix-up.
+
+ tree - the root node of the tree to be processed.
+ filename - the name of the file the tree came from.
+ """
+ self.used_names = tree.used_names
+ self.set_filename(filename)
+ self.numbers = itertools.count(1)
+ self.first_log = True
+
+ def finish_tree(self, tree, filename):
+ """Some fixers need to maintain tree-wide state.
+ This method is called once, at the conclusion of tree fix-up.
+
+ tree - the root node of the tree to be processed.
+ filename - the name of the file the tree came from.
+ """
+ pass
+
+
+class ConditionalFix(BaseFix):
+ """ Base class for fixers which not execute if an import is found. """
+
+ # This is the name of the import which, if found, will cause the test to be skipped
+ skip_on = None
+
+ def start_tree(self, *args):
+ super(ConditionalFix, self).start_tree(*args)
+ self._should_skip = None
+
+ def should_skip(self, node):
+ if self._should_skip is not None:
+ return self._should_skip
+ pkg = self.skip_on.split(".")
+ name = pkg[-1]
+ pkg = ".".join(pkg[:-1])
+ self._should_skip = does_tree_import(pkg, name, node)
+ return self._should_skip