Scala Language Parser Combinators Basic Example
Example
import scala.util.parsing.combinator._
class SimpleParser extends RegexParsers {
// Define a grammar rule, turn it into a regex, and apply it the input.
def word: Parser[String] = """[A-Z][a-z]+""".r ^^ { _.toString }
}
object SimpleParser extends SimpleParser {
val parseAlice = parse(word, "Alice went to Alamo Square.")
val parseBarb = parse(word, "barb went Upside Down.")
}
//Successfully finds a match
println(SimpleParser.parseAlice)
//Fails to find a match
println(SimpleParser.parseBarb)
The output will be as follows:
[1.6] parsed: Alice
res0: Unit = ()
[1.1] failure: string matching regex `[A-Z][a-z]+' expected but `b' found
barb went Upside Down.
^
[1.6] in the Alice example indicates that the start of the match is at position 1, and the fist character remaining to match starts at position 6.
