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  • package root
    Definition Classes
    root
  • package org
    Definition Classes
    root
  • package benknoble
    Definition Classes
    org
  • package ebnf

    Provides classes for dealing with context-free grammars in EBNF form.

    Provides classes for dealing with context-free grammars in EBNF form.

    Provides a org.benknoble.ebnf.Grammar model, complete with scala DSL for creating complex grammars in code, and an org.benknoble.ebnf.EbnfParser to generate Grammars from a String.

    Overview

    The main class is org.benknoble.ebnf.Grammar:

    scala> val grammar = Grammar(
     |   new Production(
     |     Nonterminal('A),
     |     Alternation(Nonterminal('A),
     |     Sequence(Repetition(Terminal("abc")), Option(Terminal("def"))))))
grammar: org.benknoble.ebnf.Grammar = Grammar(List(Production(Nonterminal('A), Alternation(Nonterminal('A),Sequence(Repetition(Terminal(abc)),Option(Terminal(def)))))))

scala> val s = grammar.format
s: String = <A> ::= <A>|{'abc'}['def'] ;

    If you include org.benknoble.ebnf.ExprImplicits and take advantage of org.benknoble.ebnf.Expr syntax, it looks a lot cleaner:

    scala> val grammar = Grammar('A ::= 'A || Terminal("abc").* ~ "def".?)
grammar: org.benknoble.ebnf.Grammar = Grammar(List(Production(Nonterminal('A), Alternation(Nonterminal('A),Sequence(Repetition(Terminal(abc)),Option(Terminal(def)))))))

scala> val s = grammar.format
s: String = <A> ::= <A>|{'abc'}['def'] ;

    Finally, you can take advantage of org.benknoble.ebnf.EbnfParser:

    scala> val grammar = EbnfParser("<A> ::= <A>|{'abc'}['def'] ;")
grammar: Either[String,org.benknoble.ebnf.Grammar] = Right(Grammar(List(Production(Nonterminal('A), Alternation(Nonterminal('A),Sequence(Repetition(Terminal(abc)),Option(Terminal(def))))))))

scala> val msg = grammar.fold(s => s, g => g.format)
msg: String = <A> ::= <A>|{'abc'}['def'] ;
    Definition Classes
    benknoble
  • Alternation
  • EbnfParser
  • Expr
  • ExprImplicits
  • Grammar
  • Main
  • Nonterminal
  • Option
  • Production
  • Repetition
  • Sequence
  • Terminal
  • Word
  • ε

class Grammar extends AnyRef

A (context-free) grammar of productions

The preferred construction method is via the companion object's apply method, which is variadic.

A Grammar is represented by ;-delimited, newline-separated Productions:

scala> val g = new Grammar(Seq(new Production(Nonterminal('A), Alternation(Terminal("abc"), Option(Nonterminal('B)))))).format
g: String = <A> ::= 'abc'|[<B>] ;
See also

org.benknoble.ebnf.Production

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Instance Constructors

  1. new Grammar(_rules: Seq[Production])

    create a new Grammar

    create a new Grammar

    _rules

    the sequence of Productions

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  5. def clone(): AnyRef
    Attributes
    protected[java.lang]
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    @native() @throws( ... )
  6. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  7. def equals(that: Any): Boolean
    Definition Classes
    Grammar → AnyRef → Any
  8. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  9. def format: String

    Returns a formatted version of this

  10. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  11. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  12. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  13. def isWellFormed: Boolean

    true iff all non-terminals on the right side of a production are also on the left side of a production

  14. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  15. def nonterminals: Set[Nonterminal]

    A set of nonterminals present in the grammar

  16. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  17. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  18. val rules: Seq[Production]

    The rules of the Grammar

    The rules of the Grammar

    Any original rules with the same Nonterminal left-hand side are collapsed into alternations:

    scala> val g = Grammar('A ::= "abc", 'A ::= "def").format
g: String = <A> ::= 'abc'|'def' ;

    Rather than expose the original constructor parameter, we apply a grouping and then branchify the groups in order to create a "simplified" (but more manageable) grammar.

  19. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  20. def toString(): String
    Definition Classes
    Grammar → AnyRef → Any
  21. final def wait(): Unit
    Definition Classes
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    @throws( ... )
  22. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
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    @throws( ... )
  23. final def wait(arg0: Long): Unit
    Definition Classes
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