1# Copyright 2006 Google, Inc. All Rights Reserved. 2# Licensed to PSF under a Contributor Agreement. 3 4"""Base class for fixers (optional, but recommended).""" 5 6# Python imports 7import logging 8import itertools 9 10# Local imports 11from .patcomp import PatternCompiler 12from . import pygram 13from .fixer_util import does_tree_import 14 15class BaseFix(object): 16 17 """Optional base class for fixers. 18 19 The subclass name must be FixFooBar where FooBar is the result of 20 removing underscores and capitalizing the words of the fix name. 21 For example, the class name for a fixer named 'has_key' should be 22 FixHasKey. 23 """ 24 25 PATTERN = None # Most subclasses should override with a string literal 26 pattern = None # Compiled pattern, set by compile_pattern() 27 pattern_tree = None # Tree representation of the pattern 28 options = None # Options object passed to initializer 29 filename = None # The filename (set by set_filename) 30 logger = None # A logger (set by set_filename) 31 numbers = itertools.count(1) # For new_name() 32 used_names = set() # A set of all used NAMEs 33 order = "post" # Does the fixer prefer pre- or post-order traversal 34 explicit = False # Is this ignored by refactor.py -f all? 35 run_order = 5 # Fixers will be sorted by run order before execution 36 # Lower numbers will be run first. 37 _accept_type = None # [Advanced and not public] This tells RefactoringTool 38 # which node type to accept when there's not a pattern. 39 40 keep_line_order = False # For the bottom matcher: match with the 41 # original line order 42 BM_compatible = False # Compatibility with the bottom matching 43 # module; every fixer should set this 44 # manually 45 46 # Shortcut for access to Python grammar symbols 47 syms = pygram.python_symbols 48 49 def __init__(self, options, log): 50 """Initializer. Subclass may override. 51 52 Args: 53 options: an dict containing the options passed to RefactoringTool 54 that could be used to customize the fixer through the command line. 55 log: a list to append warnings and other messages to. 56 """ 57 self.options = options 58 self.log = log 59 self.compile_pattern() 60 61 def compile_pattern(self): 62 """Compiles self.PATTERN into self.pattern. 63 64 Subclass may override if it doesn't want to use 65 self.{pattern,PATTERN} in .match(). 66 """ 67 if self.PATTERN is not None: 68 PC = PatternCompiler() 69 self.pattern, self.pattern_tree = PC.compile_pattern(self.PATTERN, 70 with_tree=True) 71 72 def set_filename(self, filename): 73 """Set the filename, and a logger derived from it. 74 75 The main refactoring tool should call this. 76 """ 77 self.filename = filename 78 self.logger = logging.getLogger(filename) 79 80 def match(self, node): 81 """Returns match for a given parse tree node. 82 83 Should return a true or false object (not necessarily a bool). 84 It may return a non-empty dict of matching sub-nodes as 85 returned by a matching pattern. 86 87 Subclass may override. 88 """ 89 results = {"node": node} 90 return self.pattern.match(node, results) and results 91 92 def transform(self, node, results): 93 """Returns the transformation for a given parse tree node. 94 95 Args: 96 node: the root of the parse tree that matched the fixer. 97 results: a dict mapping symbolic names to part of the match. 98 99 Returns: 100 None, or a node that is a modified copy of the 101 argument node. The node argument may also be modified in-place to 102 effect the same change. 103 104 Subclass *must* override. 105 """ 106 raise NotImplementedError() 107 108 def new_name(self, template=u"xxx_todo_changeme"): 109 """Return a string suitable for use as an identifier 110 111 The new name is guaranteed not to conflict with other identifiers. 112 """ 113 name = template 114 while name in self.used_names: 115 name = template + unicode(self.numbers.next()) 116 self.used_names.add(name) 117 return name 118 119 def log_message(self, message): 120 if self.first_log: 121 self.first_log = False 122 self.log.append("### In file %s ###" % self.filename) 123 self.log.append(message) 124 125 def cannot_convert(self, node, reason=None): 126 """Warn the user that a given chunk of code is not valid Python 3, 127 but that it cannot be converted automatically. 128 129 First argument is the top-level node for the code in question. 130 Optional second argument is why it can't be converted. 131 """ 132 lineno = node.get_lineno() 133 for_output = node.clone() 134 for_output.prefix = u"" 135 msg = "Line %d: could not convert: %s" 136 self.log_message(msg % (lineno, for_output)) 137 if reason: 138 self.log_message(reason) 139 140 def warning(self, node, reason): 141 """Used for warning the user about possible uncertainty in the 142 translation. 143 144 First argument is the top-level node for the code in question. 145 Optional second argument is why it can't be converted. 146 """ 147 lineno = node.get_lineno() 148 self.log_message("Line %d: %s" % (lineno, reason)) 149 150 def start_tree(self, tree, filename): 151 """Some fixers need to maintain tree-wide state. 152 This method is called once, at the start of tree fix-up. 153 154 tree - the root node of the tree to be processed. 155 filename - the name of the file the tree came from. 156 """ 157 self.used_names = tree.used_names 158 self.set_filename(filename) 159 self.numbers = itertools.count(1) 160 self.first_log = True 161 162 def finish_tree(self, tree, filename): 163 """Some fixers need to maintain tree-wide state. 164 This method is called once, at the conclusion of tree fix-up. 165 166 tree - the root node of the tree to be processed. 167 filename - the name of the file the tree came from. 168 """ 169 pass 170 171 172class ConditionalFix(BaseFix): 173 """ Base class for fixers which not execute if an import is found. """ 174 175 # This is the name of the import which, if found, will cause the test to be skipped 176 skip_on = None 177 178 def start_tree(self, *args): 179 super(ConditionalFix, self).start_tree(*args) 180 self._should_skip = None 181 182 def should_skip(self, node): 183 if self._should_skip is not None: 184 return self._should_skip 185 pkg = self.skip_on.split(".") 186 name = pkg[-1] 187 pkg = ".".join(pkg[:-1]) 188 self._should_skip = does_tree_import(pkg, name, node) 189 return self._should_skip 190