Arithmetic evaluation: Difference between revisions
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m (→Icon and Unicon: header simplification) |
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Left _ -> error "Did not parse"</lang> |
Left _ -> error "Did not parse"</lang> |
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== |
=={{header|Icon}} and {{header|Unicon}}== |
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A compact recursive descent parser using Hanson's device. This program |
A compact recursive descent parser using Hanson's device. This program |
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* handles left and right associativity and different precedences |
* handles left and right associativity and different precedences |
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* Notice that the code looks remarkably like a typical grammar, rather than being an opaque cryptic solution |
* Notice that the code looks remarkably like a typical grammar, rather than being an opaque cryptic solution |
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* Does not rely on any library to silently solve 1/2 the problem; in fact, this code would probably suit being put into a library almost verbatim |
* Does not rely on any library to silently solve 1/2 the problem; in fact, this code would probably suit being put into a library almost verbatim |
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==={{header|Icon}}=== |
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<lang Icon>procedure main() #: simple arithmetical parser / evaluator |
<lang Icon>procedure main() #: simple arithmetical parser / evaluator |
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write("Usage: Input expression = Abstract Syntax Tree = Value, ^Z to end.") |
write("Usage: Input expression = Abstract Syntax Tree = Value, ^Z to end.") |
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