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