def cat(filename, tokenizer, patterns, writer):
"""Parses file, then applies patterns on parsetree root before
passing it to writer."""
## Parsing:
root = parsetree.fromfile(filename, tokenizer, attr_type=dict)
## Applying patterns:
if patterns:
for node in root.preorder():
for pattern in patterns:
pattern.match(node)
## Writing:
writer.write_node(root)
from ptTools.patterns import AnyPattern as Any
from ptTools.patterns import LiteralPattern as Lit
from ptTools.patterns import TuplePattern
from ptTools.patterns import TuplePattern as Tup
from prettify import patterns as prettify
if __name__ == '__main__':
print(__doc__)
## Initializing writer for printing ParseTreeNodes:
writer = AnsiParseTreeWriter(sys.stdout)
## Creating a ParseTreeNode from this very file:
root = parsetree.fromfile(__file__, attr_type=dict)
## Creating a pattern that matches itself in this file:
_ = Any()
captures = []
X = _%captures.append
pattern = Tup(symbol.expr_stmt,
Tup(Lit(symbol.testlist_star_expr)
>> (token.NAME, 'pattern')),
(token.EQUAL, '='),
X)
## Matches parse tree node described by:
##
## (expr.stmt
## (testlist_star_expr
## (.. (NAME, 'pattern')),
## (EQUAL '='),
