Apply grammar rules to token replacement values #49
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Added support for the “grammaticalization” system in osrm-text-instructions. The Russian grammar file is now converted into a plist and used to inflect road names according to the cases specified in the instructions.
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| for rule in rules { | ||
| let regularExpression = try! NSRegularExpression(pattern: rule[0], options: regularExpressionOptions) | ||
| grammaticalReplacement = regularExpression.stringByReplacingMatches(in: grammaticalReplacement, options: [], range: NSRange(location: 0, length: grammaticalReplacement.characters.count), withTemplate: rule[1]) |
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Does this method replace all matches not the first only (JS RegExp g flag is always on)? I hope this will not cause problems but this should be documented in OSRMTI Grammar feature description.
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Yes, the NSRegularExpression.stringByReplacingMatches(in:options:range:withTemplate:) method always replaces all matches. Replacing just one occurrence would be a more manual affair, either finding the first matching substring and replacing it, or enumerating the matches but stopping the enumeration after the first iteration.
I was thinking that the presence of ^ in each of the regular expression patterns would avoid issues where a rule unexpected matches multiple times, but that would be a brittle assumption unless we remove the ^ anchors from the JSON file and add them to the patterns at runtime.
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Yes, adding ^ at runtime is bad idea. So we just need to warn developers in Grammar description about implicitly turned on g flag in Swift and perhaps add some tests for this
Upgraded to osrm-text-instructions v0.9.0. The only substantive change is that Russian grammar rules are now applied to a token replacement value before modification by the client and insertion into the overall instruction string.
The sole unit test for this feature doesn’t run by default: it only runs when the environment is in Russian, since that’s the only language for which grammar rules have been supplied so far.
Fixes #48.
/cc @bsudekum @frederoni @yuryleb