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212
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1
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2
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3
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4 class Token:
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5 pass
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6
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7 # Base functions:
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8 class Pbase:
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9 def __init__(self):
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10 self.pa = None
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11 def parse(self, txt):
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12 r = self.do(txt)
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13 if r:
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14 match, rest = r
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15 # Apply action:
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16 if self.ParseAction:
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17 match = self.ParseAction(match)
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18 return match, rest
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19 else:
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20 # TODO: fail in some way
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21 pass
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22 def getParseAction(self):
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23 return self.pa
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24 def setParseAction(self, pa):
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25 self.pa = pa
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26
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27 ParseAction = property(getParseAction, setParseAction)
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28
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29 # basic elements:
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30
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31 class Literal(Pbase):
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32 def __init__(self, s):
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33 super().__init__()
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34 self.pat = s
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35 def do(self, txt):
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36 if txt.startswith(self.pat):
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37 return self.pat, txt[len(self.pat):]
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38
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39 class Or(Pbase):
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40 def __init__(self, options):
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41 super().__init__()
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42 self.options = options
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43 def do(self, txt):
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44 for option in self.options:
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45 r = option.parse(txt)
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46 if r:
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47 return r
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48
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49 class And:
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50 def __init__(self, options):
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51 self.options = options
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52
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53 class Sequence(Pbase):
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54 def __init__(self, seq):
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55 super().__init__()
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56 self.seq = seq
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57 def do(self, txt):
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58 results = []
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59 for thung in self.seq:
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60 r = thung.parse(txt)
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61 if r:
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62 res, txt = r
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63 results.append(res)
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64 else:
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65 return
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66 return results, txt
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67
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68 class Optional(Pbase):
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69 def __init__(self, thung):
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70 super().__init__()
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71 self.thung = thung
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72 def do(self, txt):
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73 r = self.thung.do(txt)
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74 if r:
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75 return r
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76 return (0, txt)
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77
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78 # Contraptions of basic blocks:
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79
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80 def OneOrMore():
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81 def __init__(self, thingy):
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82 pass
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83
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