rosjson.py
Go to the documentation of this file.00001 #!/usr/bin/env python 00002 # Software License Agreement (BSD License) 00003 # 00004 # Copyright (c) 2009, Willow Garage, Inc. 00005 # All rights reserved. 00006 # 00007 # Redistribution and use in source and binary forms, with or without 00008 # modification, are permitted provided that the following conditions 00009 # are met: 00010 # 00011 # * Redistributions of source code must retain the above copyright 00012 # notice, this list of conditions and the following disclaimer. 00013 # * Redistributions in binary form must reproduce the above 00014 # copyright notice, this list of conditions and the following 00015 # disclaimer in the documentation and/or other materials provided 00016 # with the distribution. 00017 # * Neither the name of Willow Garage, Inc. nor the names of its 00018 # contributors may be used to endorse or promote products derived 00019 # from this software without specific prior written permission. 00020 # 00021 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 00022 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00023 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 00024 # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 00025 # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 00026 # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 00027 # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00028 # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 00029 # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 00030 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 00031 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00032 # POSSIBILITY OF SUCH DAMAGE. 00033 # 00034 # Revision $Id: rosweb.py 4149 2009-04-13 17:00:09Z sfkwc $ 00035 00036 import roslib; roslib.load_manifest('rosjson') 00037 00038 import cStringIO 00039 import os 00040 00041 import rospy 00042 import genpy 00043 00044 class ROSJSONException(rospy.ROSException): pass 00045 00046 _JSON_ESCAPE = {'\\':r'\\', '"':'\\"', '\b':r'\b', '\f':r'\f', '\n':r'\n', '\r':r'\r', '\t':r'\t'} 00047 00048 ## Convert value to JSON representation 00049 ## @param v Any: value to convert to JSON. Supported types are Python primitives (str, int, float, long, bool) as well as rospy Message-related types (Message, Time, Duration). 00050 ## @return str: JSON string representation of \a v 00051 ## @throws ROSJSONException if \a msg cannot be converted to JSON 00052 def value_to_json(v): 00053 if type(v) == str: 00054 buff = cStringIO.StringIO() 00055 00056 buff.write('"') 00057 for c in v: 00058 if c in _JSON_ESCAPE: 00059 buff.write(_JSON_ESCAPE[c]) 00060 else: 00061 buff.write(c) 00062 buff.write('"') 00063 00064 return buff.getvalue() 00065 elif type(v) in (int, float, long): 00066 return "%s"%v 00067 elif type(v) in (list, tuple): 00068 return '['+','.join([value_to_json(x) for x in v]) + ']' 00069 elif type(v) == bool: 00070 if v: 00071 return 'true' 00072 else: 00073 return 'false' 00074 elif isinstance(v, rospy.Message): 00075 return ros_message_to_json(v) 00076 elif isinstance(v, (genpy.rostime.Time, genpy.rostime.Duration)): 00077 return v.to_sec() 00078 else: 00079 raise ROSJSONException("unknown type: %s"%type(v)) 00080 00081 ## Convert ROS message to JSON representation. JSON representation is 00082 ## a simple dictionary of dictionaries, where a dictionary represents 00083 ## a ROS message. Time and duration are represented by their float value 00084 ## in seconds. 00085 ## 00086 ## @param msg rospy.Message: message instance to convert 00087 ## @throws ROSJSONException if \a msg cannot be converted to JSON 00088 def ros_message_to_json(msg): 00089 if not isinstance(msg, rospy.Message): 00090 raise ROSJSONException("not a valid rospy Message instance: %s"%msg.__class__.__name__) 00091 buff = cStringIO.StringIO() 00092 buff.write('{') 00093 buff.write(','.join(['"%s": %s'%(f, value_to_json(getattr(msg, f))) for f in msg.__slots__])) 00094 buff.write('}') 00095 return buff.getvalue()