ast_sample.py

# sample of ast module
# reference:
#   http://docs.python.jp/2.7/library/ast.html
#   http://stackoverflow.com/questions/1515357/simple-example-of-how-to-use-ast-nodevisitor

import ast
import sys
import logging


class SampleVisitor(ast.NodeVisitor):

    def generic_visit(self, node):
        print("type of node: {0}".format(type(node).__name__))
        ast.NodeVisitor.generic_visit(self, node)

    def visit_Load(self, node):
        pass

    def visit_Name(self, node):
        print("Name: {0}".format(node.id))

    def visit_Num(self, node):
        print("Num: {0}".format(node.n))


if len(sys.argv) != 2:
    logging.error("usage: ast_example.py [word]")
    sys.exit(1)

expr = sys.argv[1]
print("expression: {0}".format(expr))

tree = ast.parse(expr)
sv = SampleVisitor()

sv.visit(tree)