Packages

  • package root

    This is the documentation for Parsley.

    This is the documentation for Parsley.

    Package structure

    The parsley package contains the Parsley class, as well as the Result, Success, and Failure types. In addition to these, it also contains the following packages and "modules" (a module is defined as being an object which mocks a package):

    • parsley.Parsley contains the bulk of the core "function-style" combinators.
    • parsley.combinator contains many helpful combinators that simplify some common parser patterns.
    • parsley.character contains the combinators needed to read characters and strings, as well as combinators to match specific sub-sets of characters.
    • parsley.debug contains debugging combinators, helpful for identifying faults in parsers.
    • parsley.extension contains syntactic sugar combinators exposed as implicit classes.
    • parsley.io contains extension methods to run parsers with input sourced from IO sources.
    • parsley.expr contains the following sub modules:
      • parsley.expr.chain contains combinators used in expression parsing
      • parsley.expr.precedence is a builder for expression parsers built on a precedence table.
      • parsley.expr.infix contains combinators used in expression parsing, but with more permissive types than their equivalents in chain.
      • parsley.expr.mixed contains combinators that can be used for expression parsing, but where different fixities may be mixed on the same level: this is rare in practice.
    • parsley.implicits contains several implicits to add syntactic sugar to the combinators. These are sub-categorised into the following sub modules:
      • parsley.implicits.character contains implicits to allow you to use character and string literals as parsers.
      • parsley.implicits.combinator contains implicits related to combinators, such as the ability to make any parser into a Parsley[Unit] automatically.
      • parsley.implicits.lift enables postfix application of the lift combinator onto a function (or value).
      • parsley.implicits.zipped enables boths a reversed form of lift where the function appears on the right and is applied on a tuple (useful when type inference has failed) as well as a .zipped method for building tuples out of several combinators.
    • parsley.errors contains modules to deal with error messages, their refinement and generation.
    • parsley.lift contains functions which lift functions that work on regular types to those which now combine the results of parsers returning those same types. these are ubiquitous.
    • parsley.ap contains functions which allow for the application of a parser returning a function to several parsers returning each of the argument types.
    • parsley.registers contains combinators that interact with the context-sensitive functionality in the form of registers.
    • parsley.token contains the Lexer class that provides a host of helpful lexing combinators when provided with the description of a language.
    • parsley.position contains parsers for extracting position information.
    • parsley.genericbridges contains some basic implementations of the Parser Bridge pattern (see Design Patterns for Parser Combinators in Scala, or the parsley wiki): these can be used before more specialised generic bridge traits can be constructed.
    Definition Classes
    root
  • package parsley
    Definition Classes
    root
  • object Parsley

    This object contains the core "function-style" combinators: all parsers will likely require something from within!

    This object contains the core "function-style" combinators: all parsers will likely require something from within!

    In particular, it contains combinators for: controlling how input is consumed; injecting values into the parser, or failing; extracting position information from the parser; conditional execution of parsers; and more.

    Definition Classes
    parsley
  • LazyParsley
c

parsley.Parsley

LazyParsley

implicit final class LazyParsley[A] extends AnyRef

This class enables the prefix ~ combinator, which allows a parser in an otherwise strict position to be made lazy.

Source
Parsley.scala
Since

4.0.0

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Instance Constructors

  1. new LazyParsley(p: => Parsley[A])

    This constructor should not be called manually, it is designed to be used via Scala's implicit resolution.

    This constructor should not be called manually, it is designed to be used via Scala's implicit resolution.

    p

    the parser that ~ is enabled on.

Value Members

  1. final def !=(arg0: Any): Boolean
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  2. final def ##: Int
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  3. final def ==(arg0: Any): Boolean
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  4. final def asInstanceOf[T0]: T0
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  5. def clone(): AnyRef
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  6. final def eq(arg0: AnyRef): Boolean
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  7. def equals(arg0: AnyRef): Boolean
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  8. def finalize(): Unit
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  9. final def getClass(): Class[_ <: AnyRef]
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  10. def hashCode(): Int
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  11. final def isInstanceOf[T0]: Boolean
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  12. final def ne(arg0: AnyRef): Boolean
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  13. final def notify(): Unit
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  14. final def notifyAll(): Unit
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  15. final def synchronized[T0](arg0: => T0): T0
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  16. def toString(): String
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  17. def unary_~: Parsley[A]

    This combinator makes a parser lazy.

    This combinator makes a parser lazy.

    There are some combinators that are, due to Scala limitations, strict in all their parameters. Usually, a combinator is strict in its "first position", which is to say the first part of the combinator to be executed; and lazy in all other "positions". The rationale behind this is that recursion appearing in a "first position" will result in infinite recursion at parse-time, it is left-recursive after all, and so it makes little sense to waste efficiency and complicate the API to support laziness there. Since method receivers are strict and only arguments can be lazy under regular conditions, this works well.

    However, for combinators that are always strict, this poses a problem: a recursion point inside one of these strict fields will cause an infinite loop at runtime! This can be fixed by ensuring that this becomes part of a lazy argument. This is a solution described by the skip combinator, for instance: p *> skip(q, .., r) will ensure that the skip is in a lazy position in *> meaning that even if any of q to r must be lazy, they can go in the strict positions of skip because the p *> provides the required laziness. However, if this isn't possible (for instance, with the zipped combinators), then how can this problem be solved?

    This is the job of the ~ combinator: very simply it wraps up a parser in a lazy box, so that even if the box is forced by a strict position, the parser will remain lazy. This means it serves as an adequate solution to this problem.

    returns

    the parser p, but guaranteed to be lazy.

    Example:

    1. // this works fine, even though all of `zipped`'s parsers are strict
lazy val expr = (attempt(term) <* '+', ~expr).zipped(_ + _) <|> term
// in this case, however, the following would fix the problem more elegantly:
lazy val expr = (attempt(term), '+' *> expr).zipped(_ + _) <|> term
  18. final def wait(): Unit
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  19. final def wait(arg0: Long, arg1: Int): Unit
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  20. final def wait(arg0: Long): Unit
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