lib/reinteract/statement.py

   1 #!/usr/bin/python
   2
   3 import copy
   4 import sys
   5
   6 import rewrite
   7 from custom_result import CustomResult
   8
   9 # A wrapper so we don't have to trap all exceptions when running statement.Execute
  10 class ExecutionError(Exception):
  11     def __init__(self, type, value, traceback):
  12         self.type = type
  13         self.value = value
  14         self.traceback = traceback
  15
  16     def __str__(self):
  17         return "ExecutionError: " + str(self.cause)
  18
  19 class WarningResult(object):
  20     def __init__(self, message):
  21         self.message = message
  22
  23 class Statement:
  24     def __init__(self, text, worksheet, parent = None):
  25         self.__text = text
  26         self.__worksheet = worksheet
  27         self.result_scope = None
  28         self.results = None
  29
  30         # May raise SyntaxError
  31         self.__compiled, self.__mutated = rewrite.rewrite_and_compile(self.__text)
  32
  33         self.set_parent(parent)
  34
  35     def set_parent(self, parent):
  36         self.__parent = parent
  37
  38     def get_result_scope(self):
  39         return self.result_scope
  40
  41     def do_output(self, *args):
  42         if len(args) == 1:
  43             arg = args[0]
  44
  45             if args[0] == None:
  46                 return
  47             elif isinstance(args[0], CustomResult):
  48                 self.results.append(args[0])
  49             else:
  50                 self.results.append(repr(args[0]))
  51                 self.result_scope['_'] = args[0]
  52         else:
  53             self.results.append(repr(args))
  54             self.result_scope['_'] = args
  55
  56     def do_print(self, *args):
  57         self.results.append(" ".join(map(str, args)))
  58
  59     def execute(self):
  60         root_scope = self.__worksheet.global_scope
  61         if self.__parent:
  62             scope = copy.copy(self.__parent.result_scope)
  63         else:
  64             scope = copy.copy(root_scope)
  65
  66         self.results = []
  67         self.result_scope = scope
  68
  69         for mutation in self.__mutated:
  70             if isinstance(mutation, tuple):
  71                 variable, method = mutation
  72             else:
  73                 variable = mutation
  74
  75             try:
  76                 scope[variable] = copy.copy(scope[variable])
  77             except:
  78                 self.results.append(WarningResult("Variable '%s' apparently modified, but can't copy it" % variable))
  79
  80         root_scope['__reinteract_statement'] = self
  81         try:
  82             exec self.__compiled in scope, scope
  83         except:
  84             self.results = None
  85             self.result_scope = None
  86             type, value, traceback = sys.exc_info()
  87             raise ExecutionError(type, value, traceback)
  88         finally:
  89             root_scope['__reinteract_statement'] = None
  90
  91 if __name__=='__main__':
  92     def expect(actual,expected):
  93         if actual != expected:
  94             raise AssertionError("Got: '%s'; Expected: '%s'" % (actual, expected))
  95
  96     def expect_result(text, result):
  97         s = Statement(text)
  98         s.execute()
  99         expect(s.results[0], result)
 100
 101     # A bare expression should give the repr of the expression
 102     expect_result("'a'", repr('a'))
 103     expect_result("1,2", repr((1,2)))
 104
 105     # Print, on the other hand, gives the string form of the expression
 106     expect_result("print 'a'", 'a')
 107
 108     # Test that we copy a variable before mutating it (when we can detect
 109     # the mutation)
 110     s1 = Statement("b = [0]")
 111     s1.execute()
 112     s2 = Statement("b[0] = 1", parent=s1)
 113     s2.execute()
 114     s3 = Statement("b[0]", parent = s2)
 115     s3.execute()
 116     expect(s3.results[0], "1")
 117
 118     s2a = Statement("b[0]", parent=s1)
 119     s2a.execute()
 120     expect(s2a.results[0], "0")