Daniel@0: #!/usr/bin/env python
Daniel@0: # Part of DML (Digital Music Laboratory)
Daniel@0: # Copyright 2014-2015 Samer Abdallah, University College London
Daniel@0:  
Daniel@0: # This program is free software; you can redistribute it and/or
Daniel@0: # modify it under the terms of the GNU General Public License
Daniel@0: # as published by the Free Software Foundation; either version 2
Daniel@0: # of the License, or (at your option) any later version.
Daniel@0: # 
Daniel@0: # This program is distributed in the hope that it will be useful,
Daniel@0: # but WITHOUT ANY WARRANTY; without even the implied warranty of
Daniel@0: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Daniel@0: # GNU General Public License for more details.
Daniel@0: # 
Daniel@0: # You should have received a copy of the GNU General Public
Daniel@0: # License along with this library; if not, write to the Free Software
Daniel@0: # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
Daniel@0: 
Daniel@0: # -*- coding: utf-8 -*-
Daniel@0: __author__="samer"
Daniel@0: 
Daniel@0: import sys
Daniel@0: import json
Daniel@0: 
Daniel@0: # Does computation described in spec, with following fields:
Daniel@0: # "module" : string   ~ module names to import
Daniel@0: # "function": string  ~ name of function to call
Daniel@0: # "arguments" : list  ~ list of arguments to function
Daniel@0: def import_and_apply(spec): 
Daniel@0:     exec "from %s import %s" % (spec['module'], spec['function']) 
Daniel@0:     return eval(spec['function'])(*spec['arguments'])
Daniel@0: 
Daniel@0: # call fn with input coverted from JSON on standard input and output
Daniel@0: # written as JSON to standard output. 
Daniel@0: # Success produces { "tag":"ok", "value":ReturnValue }.
Daniel@0: # Error produces { "tag":"error", "value":Description }
Daniel@0: def wrap(fn):
Daniel@0:     # Function to convert unicode dict keys to ordinary strings.
Daniel@0:     # Note that dict values are kept as unicode.
Daniel@0:     def stringify(input):
Daniel@0:         if isinstance(input, dict):
Daniel@0:             return {key.encode('utf-8'):stringify(value) for key,value in input.iteritems()}
Daniel@0:         elif isinstance(input, list):
Daniel@0:             return [stringify(element) for element in input]
Daniel@0:         else: return input
Daniel@0: 
Daniel@0:     try: reply = json.dumps({'tag':'ok', 'value':fn(stringify(json.load(sys.stdin)))})
Daniel@0:     except Exception as e:
Daniel@0:         reply = json.dumps({'tag':'error', 'value':str(e)})
Daniel@0:     print(reply)
Daniel@0:     
Daniel@0: if __name__ == "__main__": wrap(import_and_apply)