Matchers

REL comes with some matchers built-in for commonly needed entities like dates. Matchers are RE expressions and corresponding extractors.

As the matchers collection will probably grow, they may come in a separate packaging one day (e.g. rel-contrib), but should keep their package and class names.

Dates

The dates matchers provide regexes and extractors for dates, both numeric (1/23/12, 2012-01-23) and alphanumeric (january 23rd, 2012), for English and French, partial (with at least a month or a year) or full.

Regexes

Extractors

Numerical dates may be ambiguous. For this reason, the date extractors will extract, for each match in the input string, a List[DateExtractor.Result]. Any additional disambiguation is left to client code.

DateExtractor.Result is a case class with three Option[Int]: y, m, d. A year may be on 2 or 4 digits, left for interpretation too. The toString method provides search-engine-friendly tokens: 1998-10-20 will yield Y1998 Y10 M10 D20 (note the doubling of the year in 2 digits form too).

The extractors to use are:

• matchers.DateExtractor for numeric (full or partial, English or French)
• matchers.en.FullDateExtractor for matchers.en.*_FULL
• matchers.en.DateExtractor for matchers.en.*
• matchers.fr.FullDateExtractor for matchers.fr.*_FULL
• matchers.fr.DateExtractor for matchers.fr.*

To extract dates from a String:

import fr.splayce.rel.matchers
import matchers.DateExtractor.NUMERIC
import matchers.fr.{FullDateExtractor => FrDateExtr}

NUMERIC("2012-12-31").next // List(Y2012 Y12 M12 D31)
FrDateExtr("31 janvier 2013").next // List(Y2013 Y13 M01 D31)

We can also reuse those extractor in other extractors to get Lists of DateExtractor.Result directly form a String, Regex.Match, MatchGroup… DateExtratorSpec contains several examples and use cases.

Utilities

The matchers package also provides a few utility functions to help build other matchers. The escaped and unescaped functions build a RE expression to match an escaped (resp. unescaped) sub-expression, i.e. preceded by an even (resp. odd) number of the escape string.