50 lines
1.4 KiB
Python
50 lines
1.4 KiB
Python
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#!/usr/bin/env python
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'''
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mavlink expression evaluation functions
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Copyright Andrew Tridgell 2011
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Released under GNU GPL version 3 or later
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'''
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import os
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# these imports allow for mavgraph and mavlogdump to use maths expressions more easily
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from math import *
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from .mavextra import *
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'''
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Support having a $HOME/.pymavlink/mavextra.py for extra graphing functions
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'''
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home = os.getenv('HOME')
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if home is not None:
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extra = os.path.join(home, '.pymavlink', 'mavextra.py')
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if os.path.exists(extra):
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import imp
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mavuser = imp.load_source('pymavlink.mavuser', extra)
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from pymavlink.mavuser import *
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def evaluate_expression(expression, vars, nocondition=False):
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'''evaluation an expression'''
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# first check for conditions which take the form EXPRESSION{CONDITION}
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if expression[-1] == '}':
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startidx = expression.rfind('{')
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if startidx == -1:
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return None
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condition=expression[startidx+1:-1]
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expression=expression[:startidx]
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try:
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v = eval(condition, globals(), vars)
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except Exception:
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return None
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if not nocondition and not v:
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return None
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try:
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v = eval(expression, globals(), vars)
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except NameError:
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return None
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except ZeroDivisionError:
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return None
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except IndexError:
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return None
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return v
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