a sample for parsing a nginx-like conf

pyparse-sample.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# filename   : ustack.py
# created at : 2013-06-15 21:05:10
# author     : Jianing Yang <jianingy.yang AT gmail DOT com>

__author__ = 'Jianing Yang <jianingy.yang AT gmail DOT com>'

from pyparsing import *
import sys

BUILTIN_VARS = dict(total_instance=200)


def load_variable(*fns, **kwargs):
    token = fns[-1][0][1:]
    if token not in BUILTIN_VARS:
        print >>sys.stderr, "Unknown variable: %s!" % token
        return ""

    return BUILTIN_VARS[token]


def parse(input):

    LBRACE, RBRACE, SEMI, QUOTE = map(Suppress, '{};"')
    LPAREN, RPAREN = map(Suppress, '()')

    string = (QuotedString('"', "\\") | QuotedString("'", "\\") |
              Word(alphanums + "_-"))
    number = Combine(Optional('-') + ('0' | Word('123456789', nums)) +
                     Optional('.' + Word(nums)))

    ident = Word(alphanums + "_")
    var = Combine(Word("$") + ident).setParseAction(load_variable)
    fun = ident + LPAREN + RPAREN
    value = (string | number | var | fun)
    simple_stmt = ident.setResultsName("key") + \
        value.setResultsName("value") + SEMI

    stmt = simple_stmt

    section = ident.setResultsName("section") + \
        LBRACE + Dict(ZeroOrMore(Group(stmt))).setResultsName("stmt") + RBRACE

    for recipe in section.searchString(input):
        print "section =", recipe.section
        for stmt in recipe.stmt:
            print "    ", stmt.key, "=", stmt.value

    return True
case = """service {
  name     'mysql';
  instance $total_instance;
}
application {
  service mysql;
  service apache;
}
"""

print parse(case)