I am trying out scala parser combinators with the following object:
object LogParser extends JavaTokenParsers with PackratParsers {
Some of the parsers are working. But the following one is getting tripped up:
def time = """([\d]{2}:[\d]{2}:[\d]{2}\.[\d]+)"""
Following is the input not working:
09:58:24.608891
On reaching that line we get:
[2.22] failure: `([\d]{2}:[\d]{2}:[\d]{2}\.[\d]+)' expected but `:' found
09:58:24.608891
Note: I did verify correct behavior of that regex within the scala repl on the same input pattern.
val r = """([\d]{2}):([\d]{2}):([\d]{2}\.[\d]+)""".r
val s = """09:58:24.608891"""
val r(t,t2,t3) = s
t: String = 09
t2: String = 58
t3: String = 24.608891
So.. AFA parser combinator: is there an issue with the ":" token itself - i.e. need to create my own custom Lexer and add ":" to lexical.delimiters?
Update an answer was provided to add ".r". I had already tried that- but in any case to be explicit: the following has the same behavior (does not work):
def time = """([\d]{2}:[\d]{2}:[\d]{2}.[\d]+)""".r
I think you're just missing an .r at the end here to actually have a Regex as opposed to a string literal.
def time = """([\d]{2}:[\d]{2}:[\d]{2}\.[\d]+)"""
it should be
def time = """([\d]{2}:[\d]{2}:[\d]{2}\.[\d]+)""".r
The first one expects the text to be exactly like the regex string literal (which obviously isn't present), the second one expects text that actually matches the regex. Both create a Parser[String], so it's not immediately obvious that something is missing.
- There's an implicit conversion from java.lang.String to Parser[String], so that string literals can be used as parser combinators.
- There's an implicit conversion from scala.util.matching.Regex to > Parser[String], so that regex expressions can be used as parser combinators.