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@kevinmeredith
Description
In the following Parser:
object Foo extends JavaTokenParsers {
def word(x: String) = s"\\b$x\\b".r
lazy val expr = aSentence | something
lazy val aSentence = noun ~ verb ~ obj
lazy val noun = word("noun")
lazy val verb = word("verb") | err("not a verb!")
lazy val obj = word("object")
lazy val something = word("FOO")
}
It will parse noun verb object.
scala> Foo.parseAll(Foo.expr, "noun verb object")
res1: Foo.ParseResult[java.io.Serializable] = [1.17] parsed: ((noun~verb)~object)
But, when entering a valid noun, but an invalid verb, why won't the err("not a verb!") return an Error with that particular error message?
scala> Foo.parseAll(Foo.expr, "noun vedsfasdf")
res2: Foo.ParseResult[java.io.Serializable] =
[1.6] failure: string matching regex `\bverb\b' expected but `v' found
noun vedsfasdf
^
credit: Thanks to Travis Brown for explaining the need for the word function here.
@dcsobral provides a thorough explanation here - http://stackoverflow.com/questions/25147833/using-err-in-a-child-parser as to why this behavior is occurring.
I don't completely understand his answer (re-reading it a few more times), but shouldn't err(... in my above example result in that particular Error?