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1 """
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2 webcalc: a view with webob
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3 """
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4
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5 import math
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6 from pkg_resources import iter_entry_points
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7 from pkg_resources import resource_filename
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8 from webob import Request, Response, exc
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9
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10 class WebcalcView(object):
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11
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12 ### class level variables
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13 defaults = { 'formatter': 'text/plain' }
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14
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15 def __init__(self, **kw):
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16 for key in self.defaults:
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17 setattr(self, key, kw.get(key, self.defaults[key]))
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18 self.formatters = {}
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19 for entry_point in iter_entry_points('webcalc.formatters'):
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20 try:
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21 formatter = entry_point.load()
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22 except:
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23 continue
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24 self.formatters[entry_point.name] = formatter
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25
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26 assert self.formatter in self.formatters
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27
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28 self.response_functions = { 'GET': self.get,
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29 'POST': self.get,
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30 }
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31
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32 ### methods dealing with HTTP
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33 def __call__(self, environ, start_response):
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34 request = Request(environ)
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35 res = self.make_response(request)
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36 return res(environ, start_response)
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37
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38 def make_response(self, request):
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39 return self.response_functions.get(request.method, self.error)(request)
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40
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41 def get_response(self, text, content_type='text/html'):
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42 res = Response(content_type=content_type, body=text)
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43 return res
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44
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45 def get(self, request):
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46 """
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47 return response to a GET requst
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48 """
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49
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50
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51 equation = request.path_info.strip('/').strip()
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52 if not equation:
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53 return self.get_response('<html><body><form method="post"><input type="text" name="equation"/></form></body></html>')
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54
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55
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56 # limit scope of execution
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57 forbidden = set([';', '=', 'import', 'from', 'with'])
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58 forbidden.update(dir(__builtins__))
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59 assert not [ i for i in forbidden
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60 if i in equation ]
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61 math_globals = dict([(i, getattr(math, i))
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62 for i in dir(math)
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63 if not i.startswith('_')])
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64
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65 # get the range of variables
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66 variables = []
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67 assert 'result' not in request.GET
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68 for name, value in request.GET.items():
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69 if name == 'format':
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70 continue
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71 values = self.values(value)
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72 if variables:
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73 if len(values) == 1:
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74 for var in variables:
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75 var[name] = values[0]
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76 else:
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77 old_variables = [ i.copy() for i in variables[:] ]
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78 variables = []
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79 for val in values:
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80 row = [ i.copy() for i in old_variables ]
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81 for item in row:
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82 item[name] = val
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83 variables.extend(row)
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84 else:
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85 variables = [ { name: val }
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86 for val in values ]
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87
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88 # evaluate the equation
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89 if variables:
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90 for var in variables:
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91 result = float(eval(equation, math_globals, var))
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92 var['result'] = result
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93 else:
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94 result = float(eval(equation, math_globals, {}))
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95 variables = [{'result': result}]
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96
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97 # format the result
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98 format = request.params.get('format') or request.content_type or self.formatter
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99 formatter = self.formatters.get(format, self.formatters[self.formatter])
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100 return self.get_response(formatter(variables), format)
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101
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102 def post(self, request):
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103 """
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104 return response to a POST request
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105 """
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106 import pdb; pdb.set_trace()
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107
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108 return exc.HTTPOk("Ok")
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109
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110 def error(self, request):
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111 """deal with non-supported methods"""
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112 return exc.HTTPMethodNotAllowed("Only %r operations are allowed" % self.response_functions.keys())
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113
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114
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115 def values(self, string):
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116 """
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117 >>> values('1,2,3,4')
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118 [1,2,3,4]
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119 >>> values('1..0.2..2')
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120 [1,1.2,1.4,1.6,1.8,2]
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121 """
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122 retval = []
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123 tokens = [i.strip() for i in string.split(',')
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124 if i.strip()]
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125 for token in tokens:
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126 try:
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127 value = float(token)
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128 retval.append(value)
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129 continue
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130 except ValueError:
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131 pass
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132 start, step, end = token.split('..')
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133 start = float(start)
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134 step = float(step)
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135 end = float(end)
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136
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137 values = [ start ]
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138 npoints = (end - start)/step
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139 npoints = int(npoints)
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140 values.extend([i*step + start
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141 for i in range(1, npoints)])
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142 values.append(end)
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143 retval.extend(values)
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144 return retval
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