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 ESC[4;38;5;81mBaseFix(ESC[4;38;5;149mobject):
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 ESC[4;38;5;81mConditionalFix(ESC[4;38;5;149mBaseFix):
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