diff dml-cla/python/json_wrapper.py @ 0:718306e29690 tip

commiting public release

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dml-cla/python/json_wrapper.py	Tue Feb 09 21:05:06 2016 +0100
@@ -0,0 +1,52 @@
+#!/usr/bin/env python
+# Part of DML (Digital Music Laboratory)
+# Copyright 2014-2015 Samer Abdallah, University College London
+ 
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+# -*- coding: utf-8 -*-
+__author__="samer"
+
+import sys
+import json
+
+# Does computation described in spec, with following fields:
+# "module" : string   ~ module names to import
+# "function": string  ~ name of function to call
+# "arguments" : list  ~ list of arguments to function
+def import_and_apply(spec): 
+    exec "from %s import %s" % (spec['module'], spec['function']) 
+    return eval(spec['function'])(*spec['arguments'])
+
+# call fn with input coverted from JSON on standard input and output
+# written as JSON to standard output. 
+# Success produces { "tag":"ok", "value":ReturnValue }.
+# Error produces { "tag":"error", "value":Description }
+def wrap(fn):
+    # Function to convert unicode dict keys to ordinary strings.
+    # Note that dict values are kept as unicode.
+    def stringify(input):
+        if isinstance(input, dict):
+            return {key.encode('utf-8'):stringify(value) for key,value in input.iteritems()}
+        elif isinstance(input, list):
+            return [stringify(element) for element in input]
+        else: return input
+
+    try: reply = json.dumps({'tag':'ok', 'value':fn(stringify(json.load(sys.stdin)))})
+    except Exception as e:
+        reply = json.dumps({'tag':'error', 'value':str(e)})
+    print(reply)
+    
+if __name__ == "__main__": wrap(import_and_apply)