Make scanner switching lexically scoped, because when it's dynamically scoped... that way lies madness.
Cat's Eye Technologies
10 years ago
| 715 | 715 |
+ dog cat
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| 716 | 716 |
= ok
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| 717 | 717 |
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| 718 | |
Note that we don't actually save the old scanner and restore it after the
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| 719 | |
`with`. If we did, well, it would be more messy than it is currently, it
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| 720 | |
seems. Restore it yourself if you need to!
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718 |
Note that the scanner in force is lexically contained in the `with`. Outside
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719 |
of the `with`, scanning returns to whatever scanner was in force before the
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720 |
`with`.
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| 721 | 721 |
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| 722 | 722 |
| main = ("c" & "a" & "t" & " ") with raw & "dog".
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| 723 | |
+ cat dog
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| 724 | |
? expected 'dog' found 'd'
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| 725 | |
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| 726 | |
| main = ("c" & "a" & "t" & " ") with raw & "d" & "o" & "g".
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| 727 | |
+ cat dog
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| 728 | |
= g
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| 729 | |
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| 730 | |
| main = ("c" & "a" & "t" & " ") with raw & "dog" with tamsin.
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| 731 | 723 |
+ cat dog
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| 732 | 724 |
= dog
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| 733 | 725 |
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| 524 | 524 |
new_scanner_class = RawScanner
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| 525 | 525 |
else:
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| 526 | 526 |
raise ValueError("No such scanner '%s'" % scanner_name)
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527 |
old_scanner_class = self.scanner.__class__
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| 527 | 528 |
self.scanner = self.scanner.switch(new_scanner_class)
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| 528 | 529 |
result = self.interpret(sub)
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530 |
self.scanner = self.scanner.switch(old_scanner_class)
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| 529 | 531 |
return result
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| 530 | 532 |
elif ast[0] == 'WHILE':
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| 531 | 533 |
result = Term('nil')
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