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user:zeman:interset:how-to-write-a-driver [2007/10/01 13:53] zeman use tagset::common; |
user:zeman:interset:how-to-write-a-driver [2007/10/01 14:47] zeman \&decode |
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**Note:** This approach cannot encode situations where some combinations of feature values are plausible and some are not! For instance, if positions [2] and [3] in a tag encode gender and number, respectively, | **Note:** This approach cannot encode situations where some combinations of feature values are plausible and some are not! For instance, if positions [2] and [3] in a tag encode gender and number, respectively, | ||
+ | |||
+ | |||
+ | |||
+ | ===== Replacing feature values with defaults ===== | ||
+ | |||
+ | The encoder' | ||
+ | |||
+ | - A table of replacement values for each value, ordered by precedence. There is a default table in '' | ||
+ | - The list of all tags in the tag set (implemented by the '' | ||
+ | |||
+ | Building the list of permitted values is expensive (all tags must be decoded!) and you should do it only once when your driver initializes. In your '' | ||
+ | |||
+ | <code perl> | ||
+ | use tagset:: | ||
+ | BEGIN | ||
+ | { | ||
+ | # Store the hash reference in a global variable. | ||
+ | $permitvals = tagset:: | ||
+ | } | ||
+ | ... | ||
+ | $replacement = tagset:: | ||
+ | </ | ||
+ | |||
+ | If array is an allowed value, it can be matched only against an array where all elements match. (However, order of elements in array is not significant.) If array needs to be replaced, we first check whether a subarray is allowed. (Again, there should be ordering of value priorities.) If not, we look simultaneously for replacements of all elements. Only one replacement value is selected. | ||
===== Common problems ===== | ===== Common problems ===== |