[Python-checkins] r53675 - sandbox/trunk/2to3/fixes/find_pattern.py
guido.van.rossum
python-checkins at python.org
Thu Feb 8 23:32:36 CET 2007
Author: guido.van.rossum
Date: Thu Feb 8 23:32:35 2007
New Revision: 53675
Added:
sandbox/trunk/2to3/fixes/find_pattern.py (contents, props changed)
Log:
Helper script by Collin Winter.
Added: sandbox/trunk/2to3/fixes/find_pattern.py
==============================================================================
--- (empty file)
+++ sandbox/trunk/2to3/fixes/find_pattern.py Thu Feb 8 23:32:35 2007
@@ -0,0 +1,98 @@
+#!/usr/bin/env python2.5
+
+"""A script that makes determining PATTERN for a new fixer much, much easier.
+
+Figuring out exactly what PATTERN I want for a given fixer class is
+getting tedious. This script will step through each possible subtree
+for a given string, allowing you to select which one you want. It will
+then try to figure out an appropriate pattern to match that tree. This
+pattern will require some editing (it will be overly restrictive) but
+should provide a solid base to work with and handle the tricky parts.
+
+Usage:
+
+ python find_pattern.py "g.throw(E, V, T)"
+
+This will step through each subtree in the parse. To reject a
+candidate subtree, hit enter; to accept a candidate, hit "y" and
+enter. The pattern will be spit out to stdout.
+
+For example, the above will yield a succession of possible snippets,
+skipping all leaf-only trees. I accept
+
+'g.throw(E, V, T)'
+
+This causes find_pattern to spit out
+
+power< 'g' trailer< '.' 'throw' >
+ trailer< '(' arglist< 'E' ',' 'V' ',' 'T' > ')' > >
+
+
+Some minor tweaks later, I'm left with
+
+power< any trailer< '.' 'throw' >
+ trailer< '(' args=arglist< exc=any ',' val=any [',' tb=any] > ')' > >
+
+
+which is exactly what I was after.
+
+Larger snippets can be placed in a file (as opposed to a command-line
+arg) and processed with the -f option.
+"""
+
+__author__ = "Collin Winter <collinw at gmail.com>"
+
+# Python imports
+import optparse
+import sys
+from StringIO import StringIO
+
+# Local imports
+import pytree
+from pgen2 import driver
+from pygram import python_symbols, python_grammar
+
+driver = driver.Driver(python_grammar, convert=pytree.convert)
+
+def main(args):
+ parser = optparse.OptionParser(usage="find_pattern.py [options] [string]")
+ parser.add_option("-f", "--file", action="store",
+ help="Read a code snippet from the specified file")
+
+ # Parse command line arguments
+ options, args = parser.parse_args(args)
+ if options.file:
+ tree = driver.parse_file(options.file)
+ elif len(args) > 1:
+ tree = driver.parse_stream(StringIO(args[1] + "\n"))
+ else:
+ print >>sys.stderr, "You must specify an input file or an input string"
+ return 1
+
+ examine_tree(tree)
+ return 0
+
+def examine_tree(tree):
+ for node in tree.post_order():
+ if isinstance(node, pytree.Leaf):
+ continue
+ print repr(str(node))
+ verdict = raw_input()
+ if verdict.strip():
+ print find_pattern(node)
+ return
+
+def find_pattern(node):
+ if isinstance(node, pytree.Leaf):
+ return repr(node.value)
+
+ return find_symbol(node.type) + \
+ "< " + " ".join(find_pattern(n) for n in node.children) + " >"
+
+def find_symbol(sym):
+ for n, v in python_symbols.__dict__.items():
+ if v == sym:
+ return n
+
+if __name__ == "__main__":
+ sys.exit(main(sys.argv))
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