Lexical

abstract class Lexical extends Scanners with Tokens

This component complements the Scanners component with common operations for lexical parsers.

Refer to scala.util.parsing.combinator.lexical.StdLexical for a concrete implementation for a simple, Scala-like language.

Source: Lexical.scala

Linear Supertypes

Tokens, Scanners, Parsers, AnyRef, Any

Known Subclasses

StdLexical

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Lexical
Tokens
Scanners
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Instance Constructors

new Lexical()

Type Members

case class Error(msg: String, next: Input) extends NoSuccess with Product with Serializable
The fatal failure case of ParseResult: contains an error-message and the remaining input.
The fatal failure case of ParseResult: contains an error-message and the remaining input. No back-tracking is done when a parser returns an Error.
msg
An error message string describing the error.
next
The parser's unconsumed input at the point where the error occurred.
Definition Classes
Parsers
case class Failure(msg: String, next: Input) extends NoSuccess with Product with Serializable
The failure case of ParseResult: contains an error-message and the remaining input.
The failure case of ParseResult: contains an error-message and the remaining input. Parsing will back-track when a failure occurs.
msg
An error message string describing the failure.
next
The parser's unconsumed input at the point where the failure occurred.
Definition Classes
Parsers
sealed abstract class NoSuccess extends ParseResult[Nothing]
A common super-class for unsuccessful parse results.
A common super-class for unsuccessful parse results.
Definition Classes
Parsers
trait OnceParser[+T] extends Parser[T]
A parser whose ~ combinator disallows back-tracking.
A parser whose ~ combinator disallows back-tracking.
Definition Classes
Parsers
sealed abstract class ParseResult[+T] extends AnyRef
A base class for parser results.
A base class for parser results. A result is either successful or not (failure may be fatal, i.e., an Error, or not, i.e., a Failure). On success, provides a result of type T which consists of some result (and the rest of the input).
Definition Classes
Parsers
abstract class Parser[+T] extends (Input) => ParseResult[T]
The root class of parsers.
The root class of parsers. Parsers are functions from the Input type to ParseResult.
Definition Classes
Parsers
case class Success[+T](result: T, next: Input) extends ParseResult[T] with Product with Serializable
The success case of ParseResult: contains the result and the remaining input.
The success case of ParseResult: contains the result and the remaining input.
result
The parser's output
next
The parser's remaining input
Definition Classes
Parsers
case class ~[+a, +b](_1: a, _2: b) extends Product with Serializable
A wrapper over sequence of matches.
A wrapper over sequence of matches.
Given p1: Parser[A] and p2: Parser[B], a parser composed with p1 ~ p2 will have type Parser[~[A, B]]. The successful result of the parser can be extracted from this case class.
It also enables pattern matching, so something like this is possible:
```
def concat(p1: Parser[String], p2: Parser[String]): Parser[String] =
  p1 ~ p2 ^^ { case a ~ b => a + b }
```
Definition Classes
Parsers
type Elem = Char
the type of input elements the provided parsers consume (When consuming invidual characters, a parser is typically called a scanner, which produces tokens that are consumed by what is normally called a parser.
the type of input elements the provided parsers consume (When consuming invidual characters, a parser is typically called a scanner, which produces tokens that are consumed by what is normally called a parser. Nonetheless, the same principles apply, regardless of the input type.)
Definition Classes
Scanners → Parsers
type Input = Reader[Elem]
The parser input is an abstract reader of input elements, i.e.
The parser input is an abstract reader of input elements, i.e. the type of input the parsers in this component expect.
Definition Classes
Parsers
class Scanner extends Reader[Token]
Scanner is essentially¹ a parser that produces Tokens from a stream of characters.
Scanner is essentially¹ a parser that produces Tokens from a stream of characters. The tokens it produces are typically passed to parsers in TokenParsers.
Definition Classes
Scanners
Note
¹ Scanner is really a Reader of Tokens
case class ErrorToken(msg: String) extends Token with Product with Serializable
A class of error tokens.
A class of error tokens. Error tokens are used to communicate errors detected during lexical analysis
Definition Classes
Tokens
abstract class Token extends AnyRef
Objects of this type are produced by a lexical parser or scanner, and consumed by a parser.
Objects of this type are produced by a lexical parser or scanner, and consumed by a parser.
Definition Classes
Tokens
See also
scala.util.parsing.combinator.syntactical.TokenParsers

Abstract Value Members

abstract def token: Parser[Token]
A parser that produces a token (from a stream of characters).
A parser that produces a token (from a stream of characters).
Definition Classes
Scanners
abstract def whitespace: Parser[Any]
A parser for white-space -- its result will be discarded.
A parser for white-space -- its result will be discarded.
Definition Classes
Scanners

Concrete Value Members

object NoSuccess
An extractor so case NoSuccess(msg, next) can be used in matches.
An extractor so case NoSuccess(msg, next) can be used in matches.
Note: On Scala 2.13, using this extractor leads to an exhaustivity warning:
```
def m(r: ParseResult[Int]) = r match {
  case Success(i) => ...
  case NoSuccess(msg, _) => ... // "warning: match may not be exhaustive"
```
To eliminate this warning, use the irrefutable NoSuccess.I extractor. Due to binary compatibility, NoSuccess itself cannot be changed.
Definition Classes
Parsers
final def !=(arg0: Any): Boolean
Definition Classes
AnyRef → Any
final def ##: Int
Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean
Definition Classes
AnyRef → Any
def OnceParser[T](f: (Input) => ParseResult[T]): Parser[T] with OnceParser[T]
Definition Classes
Parsers
def Parser[T](f: (Input) => ParseResult[T]): Parser[T]
Definition Classes
Parsers
def accept[U](expected: String, f: PartialFunction[Elem, U]): Parser[U]
The parser that matches an element in the domain of the partial function f.
The parser that matches an element in the domain of the partial function f.
If f is defined on the first element in the input, f is applied to it to produce this parser's result.
Example: The parser accept("name", {case Identifier(n) => Name(n)}) accepts an Identifier(n) and returns a Name(n)
expected
a description of the kind of element this parser expects (for error messages)
f
a partial function that determines when this parser is successful and what its output is
returns
A parser that succeeds if f is applicable to the first element of the input, applying f to it to produce the result.
Definition Classes
Parsers
def accept[ES](es: ES)(implicit f: (ES) => List[Elem]): Parser[List[Elem]]
A parser that matches only the given list of element es.
A parser that matches only the given list of element es.
accept(es) succeeds if the input subsequently provides the elements in the list es.
es
the list of expected elements
returns
a Parser that recognizes a specified list of elements
Definition Classes
Parsers
implicit def accept(e: Elem): Parser[Elem]
A parser that matches only the given element e.
A parser that matches only the given element e.
The method is implicit so that elements can automatically be lifted to their parsers. For example, when parsing Tokens, Identifier("new") (which is a Token) can be used directly, instead of first creating a Parser using accept(Identifier("new")).
e
the Elem that must be the next piece of input for the returned parser to succeed
returns
a tParser that succeeds if e is the next available input.
Definition Classes
Parsers
def acceptIf(p: (Elem) => Boolean)(err: (Elem) => String): Parser[Elem]
A parser matching input elements that satisfy a given predicate.
A parser matching input elements that satisfy a given predicate.
acceptIf(p)(el => "Unexpected "+el) succeeds if the input starts with an element e for which p(e) is true.
p
A predicate that determines which elements match.
err
A function from the received element into an error message.
returns
A parser for elements satisfying p(e).
Definition Classes
Parsers
def acceptMatch[U](expected: String, f: PartialFunction[Elem, U]): Parser[U]
The parser that matches an element in the domain of the partial function f.
The parser that matches an element in the domain of the partial function f.
If f is defined on the first element in the input, f is applied to it to produce this parser's result.
Example: The parser acceptMatch("name", {case Identifier(n) => Name(n)}) accepts an Identifier(n) and returns a Name(n)
expected
a description of the kind of element this parser expects (for error messages)
f
a partial function that determines when this parser is successful and what its output is
returns
A parser that succeeds if f is applicable to the first element of the input, applying f to it to produce the result.
Definition Classes
Parsers
def acceptSeq[ES](es: ES)(implicit f: (ES) => Iterable[Elem]): Parser[List[Elem]]
A parser that matches only the given scala.collection.Iterable collection of elements es.
A parser that matches only the given scala.collection.Iterable collection of elements es.
acceptSeq(es) succeeds if the input subsequently provides the elements in the iterable es.
es
the list of expected elements
returns
a Parser that recognizes a specified list of elements
Definition Classes
Parsers
final def asInstanceOf[T0]: T0
Definition Classes
Any
def chainl1[T, U](first: => Parser[T], p: => Parser[U], q: => Parser[(T, U) => T]): Parser[T]
A parser generator that, roughly, generalises the rep1sep generator so that q, which parses the separator, produces a left-associative function that combines the elements it separates.
A parser generator that, roughly, generalises the rep1sep generator so that q, which parses the separator, produces a left-associative function that combines the elements it separates.
first
a parser that parses the first element
p
a parser that parses the subsequent elements
q
a parser that parses the token(s) separating the elements, yielding a left-associative function that combines two elements into one
Definition Classes
Parsers
def chainl1[T](p: => Parser[T], q: => Parser[(T, T) => T]): Parser[T]
A parser generator that, roughly, generalises the rep1sep generator so that q, which parses the separator, produces a left-associative function that combines the elements it separates.
A parser generator that, roughly, generalises the rep1sep generator so that q, which parses the separator, produces a left-associative function that combines the elements it separates.
From: J. Fokker. Functional parsers. In J. Jeuring and E. Meijer, editors, Advanced Functional Programming, volume 925 of Lecture Notes in Computer Science, pages 1--23. Springer, 1995.
p
a parser that parses the elements
q
a parser that parses the token(s) separating the elements, yielding a left-associative function that combines two elements into one
Definition Classes
Parsers
def chainr1[T, U](p: => Parser[T], q: => Parser[(T, U) => U], combine: (T, U) => U, first: U): Parser[U]
A parser generator that generalises the rep1sep generator so that q, which parses the separator, produces a right-associative function that combines the elements it separates.
A parser generator that generalises the rep1sep generator so that q, which parses the separator, produces a right-associative function that combines the elements it separates. Additionally, the right-most (last) element and the left-most combining function have to be supplied.
rep1sep(p: Parser[T], q) corresponds to chainr1(p, q ^^ cons, cons, Nil) (where val cons = (x: T, y: List[T]) => x :: y)
p
a parser that parses the elements
q
a parser that parses the token(s) separating the elements, yielding a right-associative function that combines two elements into one
combine
the "last" (left-most) combination function to be applied
first
the "first" (right-most) element to be combined
Definition Classes
Parsers
def chrExcept(cs: Char*): Parser[Elem]
A character-parser that matches any character except the ones given in cs (and returns it).
def clone(): AnyRef
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
def commit[T](p: => Parser[T]): Parser[T]
Wrap a parser so that its failures become errors (the | combinator will give up as soon as it encounters an error, on failure it simply tries the next alternative).
Wrap a parser so that its failures become errors (the | combinator will give up as soon as it encounters an error, on failure it simply tries the next alternative).
Definition Classes
Parsers
def digit: Parser[Elem]
A character-parser that matches a digit (and returns it).
def elem(e: Elem): Parser[Elem]
A parser that matches only the given element e.
A parser that matches only the given element e.
elem(e) succeeds if the input starts with an element e.
e
the Elem that must be the next piece of input for the returned parser to succeed
returns
a Parser that succeeds if e is the next available input (and returns it).
Definition Classes
Parsers
def elem(kind: String, p: (Elem) => Boolean): Parser[Elem]
A parser matching input elements that satisfy a given predicate.
A parser matching input elements that satisfy a given predicate.
elem(kind, p) succeeds if the input starts with an element e for which p(e) is true.
kind
The element kind, used for error messages
p
A predicate that determines which elements match.
Definition Classes
Parsers
final def eq(arg0: AnyRef): Boolean
Definition Classes
AnyRef
def equals(arg0: AnyRef): Boolean
Definition Classes
AnyRef → Any
def err(msg: String): Parser[Nothing]
A parser that results in an error.
A parser that results in an error.
msg
The error message describing the failure.
returns
A parser that always fails with the specified error message.
Definition Classes
Parsers
def errorToken(msg: String): Token
This token is produced by a scanner Scanner when scanning failed.
This token is produced by a scanner Scanner when scanning failed.
Definition Classes
Tokens
def failure(msg: String): Parser[Nothing]
A parser that always fails.
A parser that always fails.
msg
The error message describing the failure.
returns
A parser that always fails with the specified error message.
Definition Classes
Parsers
def finalize(): Unit
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
final def getClass(): Class[_ <: AnyRef]
Definition Classes
AnyRef → Any
Annotations
@native()
def guard[T](p: => Parser[T]): Parser[T]
A parser generator for guard expressions.
A parser generator for guard expressions. The resulting parser will fail or succeed just like the one given as parameter but it will not consume any input.
p
a Parser that is to be applied to the input
returns
A parser that returns success if and only if p succeeds but never consumes any input
Definition Classes
Parsers
def hashCode(): Int
Definition Classes
AnyRef → Any
Annotations
@native()
final def isInstanceOf[T0]: Boolean
Definition Classes
Any
def letter: Parser[Elem]
A character-parser that matches a letter (and returns it).
def log[T](p: => Parser[T])(name: String): Parser[T]
A helper method that turns a Parser into one that will print debugging information to stdout before and after being applied.
A helper method that turns a Parser into one that will print debugging information to stdout before and after being applied.
Definition Classes
Parsers
def mkList[T]: (~[T, List[T]]) => collection.immutable.List[T]
Given a concatenation with a repetition (list), move the concatenated element into the list
Given a concatenation with a repetition (list), move the concatenated element into the list
Definition Classes
Parsers
final def ne(arg0: AnyRef): Boolean
Definition Classes
AnyRef
def not[T](p: => Parser[T]): Parser[Unit]
Wrap a parser so that its failures and errors become success and vice versa -- it never consumes any input.
Wrap a parser so that its failures and errors become success and vice versa -- it never consumes any input.
Definition Classes
Parsers
final def notify(): Unit
Definition Classes
AnyRef
Annotations
@native()
final def notifyAll(): Unit
Definition Classes
AnyRef
Annotations
@native()
def opt[T](p: => Parser[T]): Parser[Option[T]]
A parser generator for optional sub-phrases.
A parser generator for optional sub-phrases.
opt(p) is a parser that returns Some(x) if p returns x and None if p fails.
p
A Parser that is tried on the input
returns
a Parser that always succeeds: either with the result provided by p or with the empty result
Definition Classes
Parsers
def phrase[T](p: Parser[T]): Parser[T]
A parser generator delimiting whole phrases (i.e.
A parser generator delimiting whole phrases (i.e. programs).
phrase(p) succeeds if p succeeds and no input is left over after p.
p
the parser that must consume all input for the resulting parser to succeed.
returns
a parser that has the same result as p, but that only succeeds if p consumed all the input.
Definition Classes
Parsers
def positioned[T <: Positional](p: => Parser[T]): Parser[T]
positioned decorates a parser's result with the start position of the input it consumed.
positioned decorates a parser's result with the start position of the input it consumed.
p
a Parser whose result conforms to Positional.
returns
A parser that has the same behaviour as p, but which marks its result with the start position of the input it consumed, if it didn't already have a position.
Definition Classes
Parsers
def rep[T](p: => Parser[T]): Parser[List[T]]
A parser generator for repetitions.
A parser generator for repetitions.
rep(p) repeatedly uses p to parse the input until p fails (the result is a List of the consecutive results of p).
p
a Parser that is to be applied successively to the input
returns
A parser that returns a list of results produced by repeatedly applying p to the input.
Definition Classes
Parsers
def rep1[T](first: => Parser[T], p0: => Parser[T]): Parser[List[T]]
A parser generator for non-empty repetitions.
A parser generator for non-empty repetitions.
rep1(f, p) first uses f (which must succeed) and then repeatedly uses p to parse the input until p fails (the result is a List of the consecutive results of f and p)
first
a Parser that parses the first piece of input
p0
a Parser that is to be applied successively to the rest of the input (if any) -- evaluated at most once, and only when necessary
returns
A parser that returns a list of results produced by first applying f and then repeatedly p to the input (it only succeeds if f matches).
Definition Classes
Parsers
def rep1[T](p: => Parser[T]): Parser[List[T]]
A parser generator for non-empty repetitions.
A parser generator for non-empty repetitions.
rep1(p) repeatedly uses p to parse the input until p fails -- p must succeed at least once (the result is a List of the consecutive results of p)
p
a Parser that is to be applied successively to the input
returns
A parser that returns a list of results produced by repeatedly applying p to the input (and that only succeeds if p matches at least once).
Definition Classes
Parsers
def rep1sep[T](p: => Parser[T], q: => Parser[Any]): Parser[List[T]]
A parser generator for non-empty repetitions.
A parser generator for non-empty repetitions.
rep1sep(p, q) repeatedly applies p interleaved with q to parse the input, until p fails. The parser p must succeed at least once.
p
a Parser that is to be applied successively to the input
q
a Parser that parses the elements that separate the elements parsed by p (interleaved with q)
returns
A parser that returns a list of results produced by repeatedly applying p to the input (and that only succeeds if p matches at least once). The results of p are collected in a list. The results of q are discarded.
Definition Classes
Parsers
def repN[T](num: Int, p: => Parser[T]): Parser[List[T]]
A parser generator for a specified number of repetitions.
A parser generator for a specified number of repetitions.
repN(n, p) uses p exactly n time to parse the input (the result is a List of the n consecutive results of p).
num
the exact number of times p must succeed
p
a Parser that is to be applied successively to the input
returns
A parser that returns a list of results produced by repeatedly applying p to the input (and that only succeeds if p matches exactly n times).
Definition Classes
Parsers
def repNM[T](n: Int, m: Int, p: Parser[T], sep: Parser[Any] = success(())): Parser[List[T]]
A parser generator for a specified range of repetitions interleaved by a separator.
A parser generator for a specified range of repetitions interleaved by a separator.
repNM(n, m, p, s) uses p at least n times and up to m times, interleaved with separator s, to parse the input (the result is a List of at least n consecutive results of p and up to m results).
n
minimum number of repetitions
m
maximum number of repetitions
p
a Parser that is to be applied successively to the input
sep
a Parser that interleaves with p
returns
A parser that returns a list of results produced by repeatedly applying p interleaved with sep to the input. The list has a size between n and up to m (and that only succeeds if p matches at least n times).
Definition Classes
Parsers
def repsep[T](p: => Parser[T], q: => Parser[Any]): Parser[List[T]]
A parser generator for interleaved repetitions.
A parser generator for interleaved repetitions.
repsep(p, q) repeatedly uses p interleaved with q to parse the input, until p fails. (The result is a List of the results of p.)
Example: repsep(term, ",") parses a comma-separated list of term's, yielding a list of these terms.
p
a Parser that is to be applied successively to the input
q
a Parser that parses the elements that separate the elements parsed by p
returns
A parser that returns a list of results produced by repeatedly applying p (interleaved with q) to the input. The results of p are collected in a list. The results of q are discarded.
Definition Classes
Parsers
def success[T](v: T): Parser[T]
A parser that always succeeds.
A parser that always succeeds.
v
The result for the parser
returns
A parser that always succeeds, with the given result v
Definition Classes
Parsers
final def synchronized[T0](arg0: => T0): T0
Definition Classes
AnyRef
def toString(): String
Definition Classes
AnyRef → Any
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 whitespaceChar: Parser[Elem]
A character-parser that matches a white-space character (and returns it).
case object EOF extends Token with Product with Serializable
A class for end-of-file tokens
A class for end-of-file tokens
Definition Classes
Tokens

Packages

Lexical

abstract class Lexical extends Scanners with Tokens

Instance Constructors

Type Members

Abstract Value Members

Concrete Value Members

Inherited from Tokens

Inherited from Scanners

Inherited from Parsers

Inherited from AnyRef

Inherited from Any

Ungrouped

Packages

Lexical

abstract class Lexical extends Scanners with Tokens

Instance Constructors

Type Members

Abstract Value Members

Concrete Value Members

Inherited from Tokens

Inherited from Scanners

Inherited from Parsers

Inherited from AnyRef

Inherited from Any

Ungrouped

Lexical