Packages

  • package root
    Definition Classes
    root
  • package parsley
    Definition Classes
    root
  • package expr

    This package contains various functionality relating to the parsing of expressions..

    This package contains various functionality relating to the parsing of expressions..

    This includes the "chain" combinators, which tackle the left-recursion problem and allow for the parsing and combining of operators with values. It also includes functionality for constructing larger precedence tables, which may even vary the type of each layer in the table, allowing for strongly-typed expression parsing.

    Definition Classes
    parsley
  • Atoms
  • Fixity
  • GOps
  • InfixL
  • InfixN
  • InfixR
  • Ops
  • Postfix
  • Prec
  • Prefix
  • SOps
  • chain
  • infix
  • mixed
  • precedence

object chain

This module contains the very useful chaining family of combinators, which are mostly used to parse operators and expressions of varying fixities. It is a more low-level API compared with precedence.

Source
chain.scala
Since

2.2.0

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  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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    @throws( ... ) @native()
  6. final def eq(arg0: AnyRef): Boolean
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  8. def finalize(): Unit
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    @throws( classOf[java.lang.Throwable] )
  9. final def getClass(): Class[_]
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  10. def hashCode(): Int
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  11. final def isInstanceOf[T0]: Boolean
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  12. def left[A](p: Parsley[A], op: ⇒ Parsley[(A, A) ⇒ A], x: A): Parsley[A]

    This combinator handles left-associative parsing, and application of, zero or more binary operators between zero or more values.

    This combinator handles left-associative parsing, and application of, zero or more binary operators between zero or more values.

    First parse p, then parse op followed by a p repeatedly. The results of the ps, x1 through xn, are combined with the results of the ops, f1 through fn-1, with left-associative application: fn-1(fn-2(..f1(x1, x2).., xn-1), xn). This application is then returned as the result of the combinator. If p or op fails having consumed input at any point, the whole combinator fails. If no p could be parsed, this combinator will return a default result x.

    p

    the value to be parsed.

    op

    the operator between each value.

    x

    the default value to return if no ps can be parsed.

    returns

    a parser that parses alternating p and op, ending in a p and applies their results left-associatively or returns x if no p was parsed.

    Example: 

    1. scala> import parsley.expr.chain
scala> import parsley.character.{digit, char}
scala> sealed trait Expr
scala> case class Add(x: Expr, y: Expr) extends Expr
scala> case class Num(x: Int) extends Expr
scala> val expr = chain.left(digit.map(d => Num(d.asDigit)), char('+') #> Add, Num(0))
scala> expr.parse("1+2+3+4")
val res0 = Success(Add(Add(Add(Num(1), Num(2)), Num(3)), Num(4)))
scala> expr.parse("")
val res1 = Success(Num(0))
    Since

    4.0.0

    See also

    infix.left for a version where the types can vary, ensuring that the associativity is enforced in a type-safe way.

  13. def left1[A](p: Parsley[A], op: ⇒ Parsley[(A, A) ⇒ A]): Parsley[A]

    This combinator handles left-associative parsing, and application of, zero or more binary operators between one or more values.

    This combinator handles left-associative parsing, and application of, zero or more binary operators between one or more values.

    First parse p, then parse op followed by a p repeatedly. The results of the ps, x1 through xn, are combined with the results of the ops, f1 through fn-1, with left-associative application: fn-1(fn-2(..f1(x1, x2).., xn-1), xn). This application is then returned as the result of the combinator. If p or op fails having consumed input at any point, the whole combinator fails.

    p

    the value to be parsed.

    op

    the operator between each value.

    returns

    a parser that parses alternating p and op, ending in a p and applies their results left-associatively.

    Example: 

    1. scala> import parsley.expr.chain
scala> import parsley.character.{digit, char}
scala> sealed trait Expr
scala> case class Add(x: Expr, y: Expr) extends Expr
scala> case class Num(x: Int) extends Expr
scala> val expr = chain.left1(digit.map(d => Num(d.asDigit)), char('+') #> Add)
scala> expr.parse("1+2+3+4")
val res0 = Success(Add(Add(Add(Num(1), Num(2)), Num(3)), Num(4)))
scala> expr.parse("")
val res1 = Failure(..)
    Since

    4.0.0

    See also

    infix.left1 for a version where the types can vary, ensuring that the associativity is enforced in a type-safe way.

  14. final def ne(arg0: AnyRef): Boolean
    Definition Classes
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  15. final def notify(): Unit
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    @native()
  16. final def notifyAll(): Unit
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  17. def postfix[A](p: Parsley[A], op: ⇒ Parsley[(A) ⇒ A]): Parsley[A]

    This combinator handles left-assocative parsing, and application of, zero or more postfix unary operators to a single value.

    This combinator handles left-assocative parsing, and application of, zero or more postfix unary operators to a single value.

    First parse a single p. Then, parse many repeated ops. The result of p, x, is applied to each of the results of the ops, f1 through fn, such that f1 is applied first and fn last: fn(fn-1(..f1(x)..)). This application is then returned as the result of the combinator. If p or op fails having consumed input at any point, the whole combinator fails.

    p

    the single value to be parsed.

    op

    the postfix operator to repeatedly parser after p.

    returns

    a parser that an initial p, then many ops, and applies all of the results left-associatively.

    Example: 

    1. scala> import parsley.expr.chain
scala> import parsley.character.{digit, string}
scala> sealed trait Expr
scala> case class Inc(x: Expr) extends Expr
scala> case class Dec(x: Expr) extends Expr
scala> case class Num(x: Int) extends Expr
scala> val expr = chain.postfix(digit.map(d => Num(d.asDigit)), string("++") #> Inc <|> string("--") #> Dec)
scala> expr.parse("1++----")
val res0 = Success(Dec(Dec(Inc(Num(1)))))
scala> expr.parse("1")
val res1 = Success(Num(1))
scala> expr.parse("")
val res2 = Failure(..)
    Since

    2.2.0

  18. def postfix1[A, B <: A](p: Parsley[A], op: ⇒ Parsley[(A) ⇒ B]): Parsley[B]

    This combinator handles left-assocative parsing, and application of, one or more postfix unary operators to a single value.

    This combinator handles left-assocative parsing, and application of, one or more postfix unary operators to a single value.

    First parse a single p. Then, parse at least one repeated ops. The result of p, x, is applied to each of the results of the ops, f1 through fn, such that f1 is applied first and fn last: fn(fn-1(..f1(x)..)). This application is then returned as the result of the combinator. If p or op fails having consumed input at any point, the whole combinator fails.

    p

    the single value to be parsed.

    op

    the postfix operator to repeatedly parser after p.

    returns

    a parser that an initial p, then some ops, and applies all of the results left-associatively.

    Example: 

    1. scala> import parsley.expr.chain
scala> import parsley.character.{digit, string}
scala> sealed trait Expr
scala> case class Inc(x: Expr) extends Expr
scala> case class Dec(x: Expr) extends Expr
scala> case class Num(x: Int) extends Expr
scala> val expr = chain.postfix1(digit.map(d => Num(d.asDigit)), string("++") #> Inc <|> string("--") #> Dec)
scala> expr.parse("1++----")
val res0 = Success(Dec(Dec(Inc(Num(1)))))
scala> expr.parse("1")
val res1 = Failure(..)
scala> expr.parse("")
val res2 = Failure(..)
    Since

    3.0.0

  19. def prefix[A](op: Parsley[(A) ⇒ A], p: Parsley[A]): Parsley[A]

    This combinator handles right-assocative parsing, and application of, zero or more prefix unary operators to a single value.

    This combinator handles right-assocative parsing, and application of, zero or more prefix unary operators to a single value.

    First parse many repeated ops. When there are no more ops left to parse, parse a single p. The result of p, x, is applied to each of the results of the ops, f1 through fn, such that fn is applied first and f1 last: f1(f2(..fn(x)..)). This application is then returned as the result of the combinator. If p or op fails having consumed input at any point, the whole combinator fails.

    op

    the prefix operator to repeatedly parse before p.

    p

    the single value to be parsed.

    returns

    a parser that parses many ops, and a final p, and applies all of the results right-associatively.

    Example: 

    1. scala> import parsley.expr.chain
scala> import parsley.character.{digit, char}
scala> sealed trait Expr
scala> case class Negate(x: Expr) extends Expr
scala> case class Id(x: Expr) extends Expr
scala> case class Num(x: Int) extends Expr
scala> val expr = chain.prefix(char('-') #> Negate <|> char('+') #> Id, digit.map(d => Num(d.asDigit)))
scala> expr.parse("--+1")
val res0 = Success(Negate(Negate(Id(Num(1)))))
scala> expr.parse("1")
val res1 = Success(Num(1))
scala> expr.parse("")
val res2 = Failure(..)
    Since

    2.2.0

  20. def prefix1[A, B <: A](op: Parsley[(A) ⇒ B], p: ⇒ Parsley[A]): Parsley[B]

    This combinator handles right-assocative parsing, and application of, one or more prefix unary operators to a single value.

    This combinator handles right-assocative parsing, and application of, one or more prefix unary operators to a single value.

    First parse at least one repeated ops. When there are no more ops left to parse, parse a single p. The result of p, x, is applied to each of the results of the ops, f1 through fn, such that fn is applied first and f1 last: f1(f2(..fn(x)..)). This application is then returned as the result of the combinator. If p or op fails having consumed input at any point, the whole combinator fails.

    op

    the prefix operator to repeatedly parse before p.

    p

    the single value to be parsed.

    returns

    a parser that parses some ops, and a final p, and applies all of the results right-associatively.

    Example: 

    1. scala> import parsley.expr.chain
scala> import parsley.character.{digit, char}
scala> sealed trait Expr
scala> case class Negate(x: Expr) extends Expr
scala> case class Id(x: Expr) extends Expr
scala> case class Num(x: Int) extends Expr
scala> val expr = chain.prefix1(char('-') #> Negate <|> char('+') #> Id, digit.map(d => Num(d.asDigit)))
scala> expr.parse("--+1")
val res0 = Success(Negate(Negate(Id(Num(1)))))
scala> expr.parse("1")
val res1 = Failure(..)
scala> expr.parse("")
val res2 = Failure(..)
    Since

    3.0.0

  21. def right[A](p: Parsley[A], op: ⇒ Parsley[(A, A) ⇒ A], x: A): Parsley[A]

    This combinator handles right-associative parsing, and application of, zero or more binary operators between zero or more values.

    This combinator handles right-associative parsing, and application of, zero or more binary operators between zero or more values.

    First parse p, then parse op followed by a p repeatedly. The results of the ps, x1 through xn, are combined with the results of the ops, f1 through fn-1, with right-associative application: f1(x1, f2(x2, ..fn-1(xn-1, xn)..)). This application is then returned as the result of the combinator. If p or op fails having consumed input at any point, the whole combinator fails. If no p could be parsed, this combinator will return a default result x.

    p

    the value to be parsed.

    op

    the operator between each value.

    x

    the default value to return if no ps can be parsed.

    returns

    a parser that parses alternating p and op, ending in a p and applies their results right-associatively or returns x if no p was parsed.

    Example: 

    1. scala> import parsley.expr.chain
scala> import parsley.character.{digit, char}
scala> sealed trait Expr
scala> case class Add(x: Expr, y: Expr) extends Expr
scala> case class Num(x: Int) extends Expr
scala> val expr = chain.right(digit.map(d => Num(d.asDigit)), char('+') #> Add, Num(0))
scala> expr.parse("1+2+3+4")
val res0 = Success(Add(Num(1), Add(Num(2), Add(Num(3), Num(4)))))
scala> expr.parse("")
val res1 = Success(Num(0))
    Since

    4.0.0

    See also

    infix.right for a version where the types can vary, ensuring that the associativity is enforced in a type-safe way.

  22. def right1[A](p: Parsley[A], op: ⇒ Parsley[(A, A) ⇒ A]): Parsley[A]

    This combinator handles right-associative parsing, and application of, zero or more binary operators between one or more values.

    This combinator handles right-associative parsing, and application of, zero or more binary operators between one or more values.

    First parse p, then parse op followed by a p repeatedly. The results of the ps, x1 through xn, are combined with the results of the ops, f1 through fn-1, with right-associative application: f1(x1, f2(x2, ..fn-1(xn-1, xn)..)). This application is then returned as the result of the combinator. If p or op fails having consumed input at any point, the whole combinator fails.

    p

    the value to be parsed.

    op

    the operator between each value.

    returns

    a parser that parses alternating p and op, ending in a p and applies their results right-associatively.

    Example: 

    1. scala> import parsley.expr.chain
scala> import parsley.character.{digit, char}
scala> sealed trait Expr
scala> case class Add(x: Expr, y: Expr) extends Expr
scala> case class Num(x: Int) extends Expr
scala> val expr = chain.right1(digit.map(d => Num(d.asDigit)), char('+') #> Add)
scala> expr.parse("1+2+3+4")
val res0 = Success(Add(Num(1), Add(Num(2), Add(Num(3), Num(4)))))
scala> expr.parse("")
val res1 = Failure(..)
    Since

    4.0.0

    See also

    infix.right1 for a version where the types can vary, ensuring that the associativity is enforced in a type-safe way.

  23. final def synchronized[T0](arg0: ⇒ T0): T0
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  24. def toString(): String
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  25. final def wait(): Unit
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Inherited from AnyRef

Inherited from Any

Binary Operator Chains

These chains allow for the chaining together of values and binary operators in either left- or right-associative application.

Unary Operator Chains

These chains allow for the chaining together and application of multiple prefix or postfix unary operators to a single value.

Ungrouped