Re: Additional normalization test cases

From: Elliotte Rusty Harold (
Date: Sun Mar 27 2005 - 08:36:02 CST

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    Michael (michka) Kaplan wrote:

    > What was the bug you fixed? It might be easier to figure out a good way to
    > add test cases by knowing what the implementation was doing....

    The specific bug involved an off-by-one error indexing into the string
    in the composition step. Specifically, I was assuming the index into the
    source string could also serve as an index into the result string, and
    that turned out not to be the case. The result was that it recomposed
    into ĄL. I could successfully normalize the single characters Ľ or Ą. It
    was the combination of the two in succession that triggered the bug.

    What was really surprising was that I could pass all the Unicode
    supplied tests and still miss this. This may be because of the naivete
    of my algorithm, which is much less sophisticated than the standard
    Unicode implementation. In particular, it does not (yet) notice that the
    string ĄĽ is already in NFC which many implementations might do, and
    thus never check something like this in the first place.

    Elliotte Rusty Harold
    XML in a Nutshell 3rd Edition Just Published!

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