combinator

object combinator

This module contains a huge number of pre-made combinators that are very useful for a variety of purposes.

In particular, it contains combinators for: performing a parser iteratively, collecting all the results; querying whether or not any input is left; optionally performing parsers; parsing delimited constructions; handling multiple possible alternatives or parsers to sequence; handling more complex conditional execution; and more.

Since: 2.2.0

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final def ##: Int
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final def asInstanceOf[T0]: T0
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def attemptChoice[A](ps: Parsley[A]*): Parsley[A]
This combinator tries to parse each of the parsers ps in order, until one of them succeeds.
This combinator tries to parse each of the parsers ps in order, until one of them succeeds.
Finds the first parser in ps which succeeds, returning its result. If none of the parsers succeed, then this combinator fails. This combinator will always try and parse each of the combinators until one succeeds, regardless of how they fail. The last argument will not be wrapped in attempt, as this is not necessary.
ps
the parsers to try, in order.
returns
a parser that tries to parse one of ps.
Example:
1. scala> import parsley.combinator.attemptChoice scala> import parsley.character.string scala> val p = attemptChoice(string("abc"), string("ab"), string("bc"), string("d")) scala> p.parse("abc") val res0 = Success("abc") scala> p.parse("ab") val res1 = Success("ab") scala> p.parse("bc") val res2 = Success("bc") scala> p.parse("x") val res3 = Failure(..)
Note
this combinator is not particularly efficient, because it may unnecessarily backtrack for each alternative.
See also
<|>
attempt
def between[A](open: Parsley[_], close: => Parsley[_], p: => Parsley[A]): Parsley[A]
This combinator parses open, followed by p, and then close.
This combinator parses open, followed by p, and then close.
First parse open, ignore its result, then parse, p, producing x. Finally, parse close, ignoring its result. If open, p, and close all succeeded, then return x. If any of them failed, this combinator fails.
open
the first parser to parse.
close
the last parser to parse.
p
the parser to parse between the other two.
returns
a parser that reads open, then p, then close and returns the result of p.
Example:
1. def braces[A](p: Parsley[A]) = between(char('{'), char('}'), p)
def choice[A](ps: Parsley[A]*): Parsley[A]
This combinator tries to parse each of the parsers ps in order, until one of them succeeds.
This combinator tries to parse each of the parsers ps in order, until one of them succeeds.
Finds the first parser in ps which succeeds, returning its result. If none of the parsers succeed, then this combinator fails. If a parser fails having consumed input, this combinator fails immediately.
ps
the parsers to try, in order.
returns
a parser that tries to parse one of ps.
Example:
1. scala> import parsley.combinator.choice scala> import parsley.character.string scala> val p = choice(string("abc"), string("ab"), string("bc"), string("d")) scala> p.parse("abc") val res0 = Success("abc") scala> p.parse("ab") val res1 = Failure(..) scala> p.parse("bc") val res2 = Success("bc") scala> p.parse("x") val res3 = Failure(..)
See also
<|>
def clone(): AnyRef
Attributes
protected[lang]
Definition Classes
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@throws(classOf[java.lang.CloneNotSupportedException]) @native()
def decide[A](p: Parsley[Option[A]], q: => Parsley[A]): Parsley[A]
This combinator parses q depending only if p returns a None.
This combinator parses q depending only if p returns a None.
First parses p. If p returned Some(x), then x is returned. Otherwise, if p returned None then q is parsed, producing y, and y is returned. If p or q fails, the combinator fails.
p
the first parser, which returns an Option to eliminate.
q
a parser to execute when p returns None, to provide a value of type A.
returns
a parser that either just parses p or both p and q in order to return an A.
Example:
1. decide(option(p), q) = p <|> q
def decide[A](p: Parsley[Option[A]]): Parsley[A]
This combinator can eliminate an Option from the result of the parser p.
This combinator can eliminate an Option from the result of the parser p.
First parse p, if it succeeds returning Some(x), then return x. However, if p fails, or returned None, then this combinator fails.
p
the parser to parse and extract the result from.
returns
a parser that tries to extract the result from p.
Example:
1. decide(option(p)) = p
def endBy[A](p: Parsley[A], sep: => Parsley[_]): Parsley[List[A]]
This combinator parses zero or more occurrences of p, separated and ended by sep.
This combinator parses zero or more occurrences of p, separated and ended by sep.
Behaves just like endBy1, except does not require an initial p and sep, returning the empty list instead.
p
the parser whose results are collected into a list.
sep
the delimiter that must be parsed between every p.
returns
a parser that parses p delimited by sep, returning the list of p's results.
Example:
1. scala> ... scala> val args = endBy(int, string(";\n")) scala> args.parse("7;\n3;\n2") val res0 = Failure(..) scala> args.parse("") val res1 = Success(Nil) scala> args.parse("1;\n") val res2 = Success(List(1)) scala> args.parse("1;\n2;\n") val res3 = Success(List(1, 2))
def endBy1[A](p: Parsley[A], sep: => Parsley[_]): Parsley[List[A]]
This combinator parses one or more occurrences of p, separated and ended by sep.
This combinator parses one or more occurrences of p, separated and ended by sep.
Parses p followed by sep one or more times. The results of the p's, x₁ through x_n, are returned as List(x₁, .., x_n). If p or sep fails having consumed input, the whole parser fails.
p
the parser whose results are collected into a list.
sep
the delimiter that must be parsed between every p.
returns
a parser that parses p delimited by sep, returning the list of p's results.
Example:
1. scala> ... scala> val args = endBy1(int, string(";\n")) scala> args.parse("7;\n3;\n2") val res0 = Failure(..) scala> args.parse("") val res1 = Failure(..) scala> args.parse("1;\n") val res2 = Success(List(1)) scala> args.parse("1;\n2;\n") val res3 = Success(List(1, 2))
val eof: Parsley[Unit]
This parser only succeeds at the end of the input.
This parser only succeeds at the end of the input.
Equivalent to notFollowedBy(item).
Example:
1. scala> import parsley.combinator.eof scala> eof.parse("a") val res0 = Failure(..) scala> eof.parse("") val res1 = Success(())
final def eq(arg0: AnyRef): Boolean
Definition Classes
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def equals(arg0: AnyRef): Boolean
Definition Classes
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def exactly[A](n: Int, p: Parsley[A]): Parsley[List[A]]
This combinator parses exactly n occurrences of p, returning these n results in a list.
This combinator parses exactly n occurrences of p, returning these n results in a list.
Parses p repeatedly up to n times. If p fails before n is reached, then this combinator fails. It is not required for p to fail after the n^th parse. The results produced by p, x₁ through x_n, are returned as List(x₁, .., x_n).
n
the number of times to repeat p.
p
the parser to repeat.
returns
a parser that parses p exactly n times, returning a list of the results.
Example:
1. scala> import parsley.character.item scala> import parsley.combinator.exactly scala> val p = exactly(3, item) scala> p.parse("ab") val res0 = Failure(..) scala> p.parse("abc") val res1 = Success(List('a', 'b', 'c')) scala> p.parse("abcd") val res2 = Success(List('a', 'b', 'c'))
Since
4.0.0
def finalize(): Unit
Attributes
protected[lang]
Definition Classes
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@throws(classOf[java.lang.Throwable])
final def getClass(): Class[_ <: AnyRef]
Definition Classes
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@native()
def hashCode(): Int
Definition Classes
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Annotations
@native()
def ifP[A](condP: Parsley[Boolean], thenP: => Parsley[A], elseP: => Parsley[A]): Parsley[A]
This combinator parses one of thenP or elseP depending on the result of parsing condP.
This combinator parses one of thenP or elseP depending on the result of parsing condP.
This is a lifted if-statement. First, parse condP: if it is successful and returns true, then parse thenP; else, if it returned false, parse elseP; or, if condP failed then fail. If either of thenP or elseP fail, then this combinator also fails.
Most useful in conjunction with Registers, as this allows for decisions to be made based on state.
condP
the parser that yields the condition value.
thenP
the parser to execute if the condition is true.
elseP
the parser to execute if the condition is false.
returns
a parser that conditionally parses thenP or elseP after condP.
Example:
1. ifP(pure(true), p, _) == p ifP(pure(false), _, p) == p
Since
4.0.0
final def isInstanceOf[T0]: Boolean
Definition Classes
Any
def many[A](p: Parsley[A]): Parsley[List[A]]
This combinator repeatedly parses a given parser zero or more times, collecting the results into a list.
This combinator repeatedly parses a given parser zero or more times, collecting the results into a list.
Parses a given parser, p, repeatedly until it fails. If p failed having consumed input, this combinator fails. Otherwise when p fails without consuming input, this combinator will return all of the results, x₁ through x_n (with n >= 0), in a list: List(x₁, .., x_n). If p was never successful, the empty list is returned.
p
the parser to execute multiple times.
returns
a parser that parses p until it fails, returning the list of all the successful results.
Example:
1. scala> import parsley.character.string scala> import parsley.combinator.many scala> val p = many(string("ab")) scala> p.parse("") val res0 = Success(Nil) scala> p.parse("ab") val res1 = Success(List("ab")) scala> p.parse("abababab") val res2 = Success(List("ab", "ab", "ab", "ab")) scala> p.parse("aba") val res3 = Failure(..)
Since
2.2.0
def manyN[A](n: Int, p: Parsley[A]): Parsley[List[A]]
This combinator repeatedly parses a given parser n or more times, collecting the results into a list.
This combinator repeatedly parses a given parser n or more times, collecting the results into a list.
Parses a given parser, p, repeatedly until it fails. If p failed having consumed input, this combinator fails. Otherwise when p fails without consuming input, this combinator will return all of the results, x₁ through x_m (with m >= n), in a list: List(x₁, .., x_m). If p was not successful at least n times, this combinator fails.
n
the minimum number of ps required.
p
the parser to execute multiple times.
returns
a parser that parses p until it fails, returning the list of all the successful results.
Example:
1. scala> import parsley.character.string scala> import parsley.combinator.manyN scala> val p = manyN(2, string("ab")) scala> p.parse("") val res0 = Failure(..) scala> p.parse("ab") val res1 = Failure(..) scala> p.parse("abababab") val res2 = Success(List("ab", "ab", "ab", "ab")) scala> p.parse("aba") val res3 = Failure(..)
Note
many(p) == many(0, p) and some(p) == many(1, p).
def manyUntil[A](p: Parsley[A], end: Parsley[_]): Parsley[List[A]]
This combinator repeatedly parses a given parser zero or more times, until the end parser succeeds, collecting the results into a list.
This combinator repeatedly parses a given parser zero or more times, until the end parser succeeds, collecting the results into a list.
First tries to parse end, if it fails without consuming input, then parses p, which must succeed. This repeats until end succeeds. When end does succeed, this combinator will return all of the results generated by p, x₁ through x_n (with n >= 0), in a list: List(x₁, .., x_n). If end could be parsed immediately, the empty list is returned.
p
the parser to execute multiple times.
end
the parser that stops the parsing of p.
returns
a parser that parses p until end succeeds, returning the list of all the successful results.
Example:
1. This can be useful for scanning comments:
  scala> import parsley.character.{string, item, endOfLine} scala> import parsley.combinator.many scala> val comment = string("//") *> manyUntil(item, endOfLine) scala> p.parse("//hello world") val res0 = Failure(..) scala> p.parse("//hello world\n") val res1 = Success(List('h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd')) scala> p.parse("//\n") val res2 = Success(Nil)
val more: Parsley[Unit]
This parser only succeeds if there is still more input.
This parser only succeeds if there is still more input.
Equivalent to lookAhead(item).void.
Example:
1. scala> import parsley.combinator.more scala> more.parse("") val res0 = Failure(..) scala> more.parse("a") val res1 = Success(())
final def ne(arg0: AnyRef): Boolean
Definition Classes
AnyRef
final def notify(): Unit
Definition Classes
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Annotations
@native()
final def notifyAll(): Unit
Definition Classes
AnyRef
Annotations
@native()
def option[A](p: Parsley[A]): Parsley[Option[A]]
This combinator tries to parse p, wrapping its result in a Some if it succeeds, or returns None if it fails.
This combinator tries to parse p, wrapping its result in a Some if it succeeds, or returns None if it fails.
Tries to parse p. If p succeeded, producing x, then Some(x) is returned. Otherwise, if p failed without consuming input, then None is returned instead.
p
the parser to try to parse.
returns
a parser that tries to parse p, but can still succeed with None if that was not possible.
Example:
1. scala> import parsley.combinator.option scala> import parsley.character.string scala> val p = option(string("abc")) scala> p.parse("") val res0 = Success(None) scala> p.parse("abc") val res1 = Success(Some("abc")) scala> p.parse("ab") val res2 = Failure(..)
def optional(p: Parsley[_]): Parsley[Unit]
This combinator will parse p if possible, otherwise will do nothing.
This combinator will parse p if possible, otherwise will do nothing.
Tries to parse p. If p succeeds, or fails without consuming input then this combinator is successful. Otherwise, if p failed having consumed input, this combinator fails.
p
the parser to try to parse.
returns
a parser that tries to parse p.
Example:
1. scala> import parsley.combinator.optional scala> import parsley.character.string scala> val p = optional(string("abc")) scala> p.parse("") val res0 = Success(()) scala> p.parse("abc") val res1 = Success(()) scala> p.parse("ab") val res2 = Failure(..)
Note
equivalent to optionalAs(p, ()).
def optionalAs[A](p: Parsley[_], x: A): Parsley[A]
This combinator will parse p if possible, otherwise will do nothing.
This combinator will parse p if possible, otherwise will do nothing.
Tries to parse p. If p succeeds, or fails without consuming input then this combinator is successful and returns x. Otherwise, if p failed having consumed input, this combinator fails.
p
the parser to try to parse.
x
the value to return regardless of how p performs.
returns
a parser that tries to parse p, returning x regardless of success or failure.
Example:
1. scala> import parsley.combinator.optionalAs scala> import parsley.character.string scala> val p = optionalAs(string("abc"), 7) scala> p.parse("") val res0 = Success(7) scala> p.parse("abc") val res1 = Success(7) scala> p.parse("ab") val res2 = Failure(..)
def sepBy[A](p: Parsley[A], sep: => Parsley[_]): Parsley[List[A]]
This combinator parses zero or more occurrences of p, separated by sep.
This combinator parses zero or more occurrences of p, separated by sep.
Behaves just like sepBy1, except does not require an initial p, returning the empty list instead.
p
the parser whose results are collected into a list.
sep
the delimiter that must be parsed between every p.
returns
a parser that parses p delimited by sep, returning the list of p's results.
Example:
1. scala> ... scala> val args = sepBy(int, string(", ")) scala> args.parse("7, 3, 2") val res0 = Success(List(7, 3, 2)) scala> args.parse("") val res1 = Success(Nil) scala> args.parse("1") val res2 = Success(List(1)) scala> args.parse("1, 2, ") val res3 = Failure(..) // no trailing comma allowed
def sepBy1[A](p: Parsley[A], sep: => Parsley[_]): Parsley[List[A]]
This combinator parses one or more occurrences of p, separated by sep.
This combinator parses one or more occurrences of p, separated by sep.
First parses a p. Then parses sep followed by p until there are no more seps. The results of the p's, x₁ through x_n, are returned as List(x₁, .., x_n). If p or sep fails having consumed input, the whole parser fails. Requires at least one p to have been parsed.
p
the parser whose results are collected into a list.
sep
the delimiter that must be parsed between every p.
returns
a parser that parses p delimited by sep, returning the list of p's results.
Example:
1. scala> ... scala> val args = sepBy1(int, string(", ")) scala> args.parse("7, 3, 2") val res0 = Success(List(7, 3, 2)) scala> args.parse("") val res1 = Failure(..) scala> args.parse("1") val res2 = Success(List(1)) scala> args.parse("1, 2, ") val res3 = Failure(..) // no trailing comma allowed
def sepEndBy[A](p: Parsley[A], sep: => Parsley[_]): Parsley[List[A]]
This combinator parses zero or more occurrences of p, separated and optionally ended by sep.
This combinator parses zero or more occurrences of p, separated and optionally ended by sep.
Behaves just like sepEndBy1, except does not require an initial p, returning the empty list instead.
p
the parser whose results are collected into a list.
sep
the delimiter that must be parsed between every p.
returns
a parser that parses p delimited by sep, returning the list of p's results.
Example:
1. scala> ... scala> val args = sepEndBy(int, string(";\n")) scala> args.parse("7;\n3;\n2") val res0 = Success(List(7, 3, 2)) scala> args.parse("") val res1 = Success(Nil) scala> args.parse("1") val res2 = Success(List(1)) scala> args.parse("1;\n2;\n") val res3 = Success(List(1, 2))
def sepEndBy1[A](p: Parsley[A], sep: => Parsley[_]): Parsley[List[A]]
This combinator parses one or more occurrences of p, separated and optionally ended by sep.
This combinator parses one or more occurrences of p, separated and optionally ended by sep.
First parses a p. Then parses sep followed by p until there are no more: if a final sep exists, this is parsed. The results of the p's, x₁ through x_n, are returned as List(x₁, .., x_n). If p or sep fails having consumed input, the whole parser fails. Requires at least one p to have been parsed.
p
the parser whose results are collected into a list.
sep
the delimiter that must be parsed between every p.
returns
a parser that parses p delimited by sep, returning the list of p's results.
Example:
1. scala> ... scala> val args = sepEndBy1(int, string(";\n")) scala> args.parse("7;\n3;\n2") val res0 = Success(List(7, 3, 2)) scala> args.parse("") val res1 = Failure(..) scala> args.parse("1") val res2 = Success(List(1)) scala> args.parse("1;\n2;\n") val res3 = Success(List(1, 2))
def sequence[A](ps: Parsley[A]*): Parsley[List[A]]
This combinator will parse each of ps in order, collecting the results.
This combinator will parse each of ps in order, collecting the results.
Given the parsers ps, consisting of p₁ through p_n, parses each in order. If they all succeed, producing the results x₁ through x_n, then List(x₁, .., x_n) is returned. If any of the parsers fail, then the whole combinator fails.
ps
parsers to be sequenced.
returns
a parser that parses each of ps, returning the results in a list
Example:
1. scala> import parsley.combinator.sequence scala> import parsley.character.{char, item} scala> val p = sequence(char('a'), item, char('c')) scala> p.parse("abc") val res0 = Success(List('a', 'b', 'c')) scala> p.parse("ab") val res1 = Failure(..)
Since
4.0.0
Note
be aware that all of the arguments to this combinator are in strict positions.
See also
<::>
def skip(p: Parsley[_], ps: Parsley[_]*): Parsley[Unit]
This combinator will parse each of ps in order, discarding the results.
This combinator will parse each of ps in order, discarding the results.
Given the parsers ps, consisting of p₁ through p_n, parses each in order. If they all succeed, this combinator succeeds. If any of the parsers fail, then the whole combinator fails.
p
first parser to be sequenced
ps
parsers to be sequenced.
returns
a parser that parses each of ps, returning ().
Example:
1. scala> import parsley.combinator.skip scala> import parsley.character.{char, item} scala> val p = skip(char('a'), item, char('c')) scala> p.parse("abc") val res0 = Success(()) scala> p.parse("ab") val res1 = Failure(..)
Note
be aware that all of the arguments to this combinator are in strict positions.
See also
*>
def skipMany(p: Parsley[_]): Parsley[Unit]
This combinator repeatedly parses a given parser zero or more times, ignoring the results.
This combinator repeatedly parses a given parser zero or more times, ignoring the results.
Parses a given parser, p, repeatedly until it fails. If p failed having consumed input, this combinator fails. Otherwise when p fails without consuming input, this combinator will succeed.
p
the parser to execute multiple times.
returns
a parser that parses p until it fails, returning unit.
Example:
1. scala> import parsley.character.string scala> import parsley.combinator.skipMany scala> val p = skipMany(string("ab")) scala> p.parse("") val res0 = Success(()) scala> p.parse("ab") val res1 = Success(()) scala> p.parse("abababab") val res2 = Success(()) scala> p.parse("aba") val res3 = Failure(..)
Since
2.2.0
def skipManyN(n: Int, p: Parsley[_]): Parsley[Unit]
This combinator repeatedly parses a given parser n or more times, ignoring the results.
This combinator repeatedly parses a given parser n or more times, ignoring the results.
Parses a given parser, p, repeatedly until it fails. If p failed having consumed input, this combinator fails. Otherwise when p fails without consuming input, this combinator will succeed. The parser p must succeed at least n times.
p
the parser to execute multiple times.
returns
a parser that parses p until it fails, returning unit.
Example:
1. scala> import parsley.character.string scala> import parsley.combinator.skipManyN scala> val p = skipManyN(2, string("ab")) scala> p.parse("") val res0 = Failure(..) scala> p.parse("ab") val res1 = Failure(..) scala> p.parse("abababab") val res2 = Success(()) scala> p.parse("aba") val res3 = Failure(..)
def skipSome(p: Parsley[_]): Parsley[Unit]
This combinator repeatedly parses a given parser one or more times, ignoring the results.
This combinator repeatedly parses a given parser one or more times, ignoring the results.
Parses a given parser, p, repeatedly until it fails. If p failed having consumed input, this combinator fails. Otherwise when p fails without consuming input, this combinator will succeed. The parser p must succeed at least once.
p
the parser to execute multiple times.
returns
a parser that parses p until it fails, returning unit.
Example:
1. scala> import parsley.character.string scala> import parsley.combinator.skipSome scala> val p = skipSome(string("ab")) scala> p.parse("") val res0 = Failure(..) scala> p.parse("ab") val res1 = Success(()) scala> p.parse("abababab") val res2 = Success(()) scala> p.parse("aba") val res3 = Failure(..)
def some[A](p: Parsley[A]): Parsley[List[A]]
This combinator repeatedly parses a given parser one or more times, collecting the results into a list.
This combinator repeatedly parses a given parser one or more times, collecting the results into a list.
Parses a given parser, p, repeatedly until it fails. If p failed having consumed input, this combinator fails. Otherwise when p fails without consuming input, this combinator will return all of the results, x₁ through x_n (with n >= 1), in a list: List(x₁, .., x_n). If p was not successful at least one time, this combinator fails.
p
the parser to execute multiple times.
returns
a parser that parses p until it fails, returning the list of all the successful results.
Example:
1. scala> import parsley.character.string scala> import parsley.combinator.some scala> val p = some(string("ab")) scala> p.parse("") val res0 = Failure(..) scala> p.parse("ab") val res1 = Success(List("ab")) scala> p.parse("abababab") val res2 = Success(List("ab", "ab", "ab", "ab")) scala> p.parse("aba") val res3 = Failure(..)
def someUntil[A](p: Parsley[A], end: Parsley[_]): Parsley[List[A]]
This combinator repeatedly parses a given parser one or more times, until the end parser succeeds, collecting the results into a list.
This combinator repeatedly parses a given parser one or more times, until the end parser succeeds, collecting the results into a list.
First ensures that trying to parse end fails, then tries to parse p. If it succeed then it will repeatedly: try to parse end, if it fails without consuming input, then parses p, which must succeed. When end does succeed, this combinator will return all of the results generated by p, x₁ through x_n (with n >= 1), in a list: List(x₁, .., x_n). The parser p must succeed at least once before end succeeds.
p
the parser to execute multiple times.
end
the parser that stops the parsing of p.
returns
a parser that parses p until end succeeds, returning the list of all the successful results.
Example:
1. This can be useful for scanning comments:
  scala> import parsley.character.{string, item, endOfLine} scala> import parsley.combinator.many scala> val comment = string("//") *> someUntil(item, endOfLine) scala> p.parse("//hello world") val res0 = Failure(..) scala> p.parse("//hello world\n") val res1 = Success(List('h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd')) scala> p.parse("//\n") val res2 = Failure(..) scala> p.parse("//a\n") val res3 = Success(List('a'))
final def synchronized[T0](arg0: => T0): T0
Definition Classes
AnyRef
def toString(): String
Definition Classes
AnyRef → Any
def traverse[A, B](f: (A) => Parsley[B], xs: A*): Parsley[List[B]]
This combinator will parse each of the parsers generated by applying f to xs, in order, collecting the results.
This combinator will parse each of the parsers generated by applying f to xs, in order, collecting the results.
Given the values xs, consisting of x₁ through x_n, first creates the parses f(x₁) through f(x_n) and then called sequence on them.
f
the function used to generate parsers for each values
xs
the values to turn into parsers and sequence.
returns
a parser that sequences the parsers generated from applying f to each of xs.
Example:
1. // this is an OK implementation for `string`, which is common in Haskell. def string(str: String) = { traverse(char, str: _*).map(_.mkString) }
Since
4.0.0
Note
be aware that all of the arguments to this combinator are in strict positions.
See also
sequence
final def wait(): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long, arg1: Int): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()
def when(condP: Parsley[Boolean], thenP: => Parsley[Unit]): Parsley[Unit]
This combinator conditionally parses thenP depending on the result of parsing condP.
This combinator conditionally parses thenP depending on the result of parsing condP.
This is a lifted if-statement. First, parse condP: if it is successful and returns true, then parse thenP; else, if it returned false do nothing; or, if condP failed then fail. If thenP fails, then this combinator also fails.
Most useful in conjunction with Registers, as this allows for decisions to be made based on state.
condP
the parser that yields the condition value.
thenP
the parser to execute if the condition is true.
returns
a parser that conditionally parses thenP or elseP after condP.
Example:
1. when(pure(true), p) == p when(pure(false), _) == unit
def whileP(p: Parsley[Boolean]): Parsley[Unit]
This combinator repeatedly parses p so long as it returns true.
This combinator repeatedly parses p so long as it returns true.
This is a lifted while-loop. First, parse p: if it is successful and returns true, then repeat; else if it returned false stop; or, if it failed then this combinator fails.
Most useful in conjunction with Registers, as this allows for decisions to be made based on state. In particular, this can be used to define the forP combinator.
p
the parser to repeatedly parse.
returns
a parser that continues to parse p until it returns false.
Example:
1. def forP[A](init: Parsley[A], cond: =>Parsley[A => Boolean], step: =>Parsley[A => A])(body: =>Parsley[_]): Parsley[Unit] = { val reg = Reg.make[A] lazy val _cond = reg.gets(cond) lazy val _step = reg.modify(step) reg.put(init) *> when(_cond, whileP(body *> _step *> _cond)) }

Inherited from AnyRef

Inherited from Any

Iterative Combinators

These combinators all execute a given parser an unbounded number of times, until either it fails, or another parser succeeds, depending on the combinator. Depending on the combinator, all of the results produced by the repeated execution of the parser may be returned in a List. These are almost essential for any practical parsing task.

Input Query Combinators

These combinators do not consume input, but they allow for querying of the input stream - specifically checking whether or not there is more input that can be consumed or not. In particular, most parsers should be making use of eof to ensure that the parser consumes all the input available at the end of the parse.

Optional Parsing Combinators

These combinators allow for the possible parsing of some parser. If the parser succeeds, that is ok so long as it did not consume input. Be aware that the result of the success may be replaced with these combinators, with the exception of option, which still preserves the result.

Separated Values Combinators

These combinators are concerned with delimited parsing, where one parser is repeated but delimited by another one. In each of these cases p is the parser of interest and sep is the delimeter. These combinators mainly differ in either the number of ps they require, or exactly where the delimeters are allowed (only between, always trailing, or either). In all cases, they return the list of results generated by the repeated parses of p.

Multiple Branching/Sequencing Combinators

These combinators allow for testing or sequencing a large number of parsers in one go. Be careful, however, these are variadic combinators and are necessarily (for compatibility with Scala 2) not lazy. In such a case where laziness is desired without resorting to the other lazier combinators, there is a neat trick: unroll the first iteration of the combinator, and use the corresponding regular combinator to do that (i.e. <::> or *>): since these will have a lazy right-hand side, the remaining variadic arguments will be kept lazily suspended until later. Alternatively, it is possible to use the prefix ~ combinator to make any individual arguments lazy as required, for example skip(p, ~q, r).

Conditional Combinators

These combinators allow for the conditional extraction of a result, or the execution of a parser based on another. They are morally related to branch and select but are less fundamental.

Packages

Package structure

combinator

object combinator

Value Members

Inherited from AnyRef

Inherited from Any

Iterative Combinators

Input Query Combinators

Optional Parsing Combinators

Separated Values Combinators

Multiple Branching/Sequencing Combinators

Conditional Combinators

Miscellaneous

Ungrouped

Packages

Package structure

combinator

object combinator

Value Members

Inherited from AnyRef

Inherited from Any

Iterative Combinators

Input Query Combinators

Optional Parsing Combinators

Separated Values Combinators

Multiple Branching/Sequencing Combinators

Conditional Combinators

Miscellaneous

Ungrouped

combinator