Packages

  • package root
    Definition Classes
    root
  • package scala
    Definition Classes
    root
  • package util
    Definition Classes
    scala
  • package parsing
    Definition Classes
    util
  • package combinator
    Definition Classes
    parsing
  • trait Parsers extends AnyRef

    Parsers is a component that provides generic parser combinators.

    Parsers is a component that provides generic parser combinators.

    There are two abstract members that must be defined in order to produce parsers: the type Elem and scala.util.parsing.combinator.Parsers.Parser. There are helper methods that produce concrete Parser implementations -- see primitive parser below.

    A Parsers may define multiple Parser instances, which are combined to produced the desired parser.

    The type of the elements these parsers should parse must be defined by declaring Elem (each parser is polymorphic in the type of result it produces).

    There are two aspects to the result of a parser:

    1. success or failure
    2. the result.

    A scala.util.parsing.combinator.Parsers.Parser produces both kinds of information, by returning a scala.util.parsing.combinator.Parsers.ParseResult when its apply method is called on an input.

    The term parser combinator refers to the fact that these parsers are constructed from primitive parsers and composition operators, such as sequencing, alternation, optionality, repetition, lifting, and so on. For example, given p1 and p2 of type scala.util.parsing.combinator.Parsers.Parser:

    p1 ~ p2 // sequencing: must match p1 followed by p2
p1 | p2 // alternation: must match either p1 or p2, with preference given to p1
p1.?    // optionality: may match p1 or not
p1.*    // repetition: matches any number of repetitions of p1

    These combinators are provided as methods on scala.util.parsing.combinator.Parsers.Parser, or as methods taking one or more Parsers and returning a Parser provided in this class.

    A primitive parser is a parser that accepts or rejects a single piece of input, based on a certain criterion, such as whether the input...

    • is equal to some given object (see method accept),
    • satisfies a certain predicate (see method acceptIf),
    • is in the domain of a given partial function (see method acceptMatch)
    • or other conditions, by using one of the other methods available, or subclassing Parser

    Even more primitive parsers always produce the same result, irrespective of the input. See methods success, err and failure as examples.

    Definition Classes
    combinator
    See also

    scala.util.parsing.combinator.RegexParsers and other known subclasses for practical examples.

  • Elem
  • Error
  • Failure
  • NoSuccess
  • OnceParser
  • ParseResult
  • Parser
  • Success
  • ~

abstract class Parser[+T] extends (Input) => ParseResult[T]

The root class of parsers. Parsers are functions from the Input type to ParseResult.

Source
Parsers.scala
Linear Supertypes
(Input) => ParseResult[T], AnyRef, Any
Known Subclasses
PackratParser, OnceParser
Type Hierarchy
Ordering
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Inherited
  1. Parser
  2. Function1
  3. AnyRef
  4. Any
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Visibility
  1. Public
  2. Protected

Instance Constructors

  1. new Parser()

Abstract Value Members

  1. abstract def apply(in: Input): ParseResult[T]

    An unspecified method that defines the behaviour of this parser.

    An unspecified method that defines the behaviour of this parser.

    Definition Classes
    Parser → Function1

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. def *[U >: T](sep: => Parser[(U, U) => U]): Parser[U]

    Returns a parser that repeatedly parses what this parser parses, interleaved with the sep parser.

    Returns a parser that repeatedly parses what this parser parses, interleaved with the sep parser. The sep parser specifies how the results parsed by this parser should be combined.

    returns

    chainl1(this, sep)

  4. def *: Parser[List[T]]

    Returns a parser that repeatedly parses what this parser parses.

    Returns a parser that repeatedly parses what this parser parses.

    returns

    rep(this)

  5. def +: Parser[List[T]]

    Returns a parser that repeatedly (at least once) parses what this parser parses.

    Returns a parser that repeatedly (at least once) parses what this parser parses.

    returns

    rep1(this)

  6. def -[U](q: Parser[U]): Parser[T]

    A parser combinator for exceptions.

    A parser combinator for exceptions.

    p - q succeeds if p succeeds, and q fails on the same input given p.

    q

    a parser that will be executed before p (this parser). q will not consume the input.

    returns

    a Parser that returns the result of p (this parser) if it succeeds and q fails. If q succeeds, the parser will fail.

  7. def <~[U](q: => Parser[U]): Parser[T]

    A parser combinator for sequential composition which keeps only the left result.

    A parser combinator for sequential composition which keeps only the left result.

    p <~ q succeeds if p succeeds and q succeeds on the input left over by p.

    q

    a parser that will be executed after p (this parser) succeeds -- evaluated at most once, and only when necessary

    returns

    a Parser that -- on success -- returns the result of p.

    Note

    <~ has lower operator precedence than ~ or ~>.

  8. def <~![U](q: => Parser[U]): Parser[T]

    A parser combinator for non-back-tracking sequential composition which only keeps the left result.

    A parser combinator for non-back-tracking sequential composition which only keeps the left result.

    p <~! q succeeds if p succeeds and q succeeds on the input left over by p. In case of failure, no back-tracking is performed (in an earlier parser produced by the | combinator).

    q

    a parser that will be executed after p (this parser) succeeds -- evaluated at most once, and only when necessary

    returns

    a Parser that -- on success -- reutrns the result of p. The resulting parser fails if either p or q fails, this failure is fatal.

  9. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  10. def >>[U](fq: (T) => Parser[U]): Parser[U]

    Returns into(fq).

  11. def ?: Parser[Option[T]]

    Returns a parser that optionally parses what this parser parses.

    Returns a parser that optionally parses what this parser parses.

    returns

    opt(this)

  12. def ^?[U](f: PartialFunction[T, U]): Parser[U]

    A parser combinator for partial function application.

    A parser combinator for partial function application.

    p ^? f succeeds if p succeeds AND f is defined at the result of p; in that case, it returns f applied to the result of p.

    f

    a partial function that will be applied to this parser's result (see mapPartial in ParseResult).

    returns

    a parser that succeeds if the current parser succeeds and f is applicable to the result. If so, the result will be transformed by f.

  13. def ^?[U](f: PartialFunction[T, U], error: (T) => String): Parser[U]

    A parser combinator for partial function application.

    A parser combinator for partial function application.

    p ^? (f, error) succeeds if p succeeds AND f is defined at the result of p; in that case, it returns f applied to the result of p. If f is not applicable, error(the result of p) should explain why.

    f

    a partial function that will be applied to this parser's result (see mapPartial in ParseResult).

    error

    a function that takes the same argument as f and produces an error message to explain why f wasn't applicable

    returns

    a parser that succeeds if the current parser succeeds and f is applicable to the result. If so, the result will be transformed by f.

  14. def ^^[U](f: (T) => U): Parser[U]

    A parser combinator for function application.

    A parser combinator for function application.

    p ^^ f succeeds if p succeeds; it returns f applied to the result of p.

    f

    a function that will be applied to this parser's result (see map in ParseResult).

    returns

    a parser that has the same behaviour as the current parser, but whose result is transformed by f.

  15. def ^^^[U](v: => U): Parser[U]

    A parser combinator that changes a successful result into the specified value.

    A parser combinator that changes a successful result into the specified value.

    p ^^^ v succeeds if p succeeds; discards its result, and returns v instead.

    v

    The new result for the parser, evaluated at most once (if p succeeds), not evaluated at all if p fails.

    returns

    a parser that has the same behaviour as the current parser, but whose successful result is v

  16. def andThen[A](g: (ParseResult[T]) => A): (Input) => A
    Definition Classes
    Function1
    Annotations
    @unspecialized()
  17. def append[U >: T](p0: => Parser[U]): Parser[U]
  18. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  19. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native()
  20. def compose[A](g: (A) => Input): (A) => ParseResult[T]
    Definition Classes
    Function1
    Annotations
    @unspecialized()
  21. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  22. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  23. def filter(p: (T) => Boolean): Parser[T]
  24. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable])
  25. def flatMap[U](f: (T) => Parser[U]): Parser[U]
  26. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  27. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  28. def into[U](fq: (T) => Parser[U]): Parser[U]

    A parser combinator that parameterizes a subsequent parser with the result of this one.

    A parser combinator that parameterizes a subsequent parser with the result of this one.

    Use this combinator when a parser depends on the result of a previous parser. p should be a function that takes the result from the first parser and returns the second parser.

    p into fq (with fq typically {x => q}) first applies p, and then, if p successfully returned result r, applies fq(r) to the rest of the input.

    From: G. Hutton. Higher-order functions for parsing. J. Funct. Program., 2(3):323--343, 1992.

    fq

    a function that, given the result from this parser, returns the second parser to be applied

    returns

    a parser that succeeds if this parser succeeds (with result x) and if then fq(x) succeeds

    Example:

    1. def perlRE = "m" ~> (".".r into (separator => """[^%s]*""".format(separator).r <~ separator))
  29. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  30. def map[U](f: (T) => U): Parser[U]
  31. def named(n: String): Parser.this.type
  32. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  33. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  34. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  35. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  36. def toString(): String
    Definition Classes
    Parser → Function1 → AnyRef → Any
  37. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  38. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  39. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()
  40. def withErrorMessage(msg: String): Parser[T]

    Changes the error message produced by a parser.

    Changes the error message produced by a parser.

    This doesn't change the behavior of a parser on neither success nor failure, just on error. The semantics are slightly different than those obtained by doing | error(msg), in that the message produced by this method will always replace the message produced, which is not guaranteed by that idiom.

    For example, parser p below will always produce the designated error message, while q will not produce it if sign is parsed but number is not.

    def p = sign.? ~ number withErrorMessage  "Number expected!"
def q = sign.? ~ number | error("Number expected!")
    msg

    The message that will replace the default error message.

    returns

    A parser with the same properties and different error message.

  41. def withFailureMessage(msg: String): Parser[T]

    Changes the failure message produced by a parser.

    Changes the failure message produced by a parser.

    This doesn't change the behavior of a parser on neither success nor error, just on failure. The semantics are slightly different than those obtained by doing | failure(msg), in that the message produced by this method will always replace the message produced, which is not guaranteed by that idiom.

    For example, parser p below will always produce the designated failure message, while q will not produce it if sign is parsed but number is not.

    def p = sign.? ~ number withFailureMessage  "Number expected!"
def q = sign.? ~ number | failure("Number expected!")
    msg

    The message that will replace the default failure message.

    returns

    A parser with the same properties and different failure message.

  42. def withFilter(p: (T) => Boolean): Parser[T]
  43. def |[U >: T](q: => Parser[U]): Parser[U]

    A parser combinator for alternative composition.

    A parser combinator for alternative composition.

    p | q succeeds if p succeeds or q succeeds. Note that q is only tried if ps failure is non-fatal (i.e., back-tracking is allowed).

    q

    a parser that will be executed if p (this parser) fails (and allows back-tracking)

    returns

    a Parser that returns the result of the first parser to succeed (out of p and q) The resulting parser succeeds if (and only if)

    • p succeeds, or
    • if p fails allowing back-tracking and q succeeds.
  44. def |||[U >: T](q0: => Parser[U]): Parser[U]

    A parser combinator for alternative with longest match composition.

    A parser combinator for alternative with longest match composition.

    p ||| q succeeds if p succeeds or q succeeds. If p and q both succeed, the parser that consumed the most characters accepts.

    q0

    a parser that accepts if p consumes less characters. -- evaluated at most once, and only when necessary

    returns

    a Parser that returns the result of the parser consuming the most characters (out of p and q).

  45. def ~[U](q: => Parser[U]): Parser[~[T, U]]

    A parser combinator for sequential composition.

    A parser combinator for sequential composition.

    p ~ q succeeds if p succeeds and q succeeds on the input left over by p.

    q

    a parser that will be executed after p (this parser) succeeds -- evaluated at most once, and only when necessary.

    returns

    a Parser that -- on success -- returns a ~ (like a Pair, but easier to pattern match on) that contains the result of p and that of q. The resulting parser fails if either p or q fails.

  46. def ~![U](p: => Parser[U]): Parser[~[T, U]]

    A parser combinator for non-back-tracking sequential composition.

    A parser combinator for non-back-tracking sequential composition.

    p ~! q succeeds if p succeeds and q succeeds on the input left over by p. In case of failure, no back-tracking is performed (in an earlier parser produced by the | combinator).

    p

    a parser that will be executed after p (this parser) succeeds

    returns

    a Parser that -- on success -- returns a ~ (like a Pair, but easier to pattern match on) that contains the result of p and that of q. The resulting parser fails if either p or q fails, this failure is fatal.

  47. def ~>[U](q: => Parser[U]): Parser[U]

    A parser combinator for sequential composition which keeps only the right result.

    A parser combinator for sequential composition which keeps only the right result.

    p ~> q succeeds if p succeeds and q succeeds on the input left over by p.

    q

    a parser that will be executed after p (this parser) succeeds -- evaluated at most once, and only when necessary.

    returns

    a Parser that -- on success -- returns the result of q.

  48. def ~>![U](q: => Parser[U]): Parser[U]

    A parser combinator for non-back-tracking sequential composition which only keeps the right result.

    A parser combinator for non-back-tracking sequential composition which only keeps the right result.

    p ~>! q succeeds if p succeeds and q succeeds on the input left over by p. In case of failure, no back-tracking is performed (in an earlier parser produced by the | combinator).

    q

    a parser that will be executed after p (this parser) succeeds -- evaluated at most once, and only when necessary

    returns

    a Parser that -- on success -- reutrns the result of q. The resulting parser fails if either p or q fails, this failure is fatal.

Inherited from (Input) => ParseResult[T]

Inherited from AnyRef

Inherited from Any

Ungrouped