Module io.jenetics.ext

Package io.jenetics.ext.grammar

Class Bnf

java.lang.Object

io.jenetics.ext.grammar.Bnf

public final class Bnf
extends Object

This class contains methods for parsing and formatting context-free grammars in BNF format.

final Cfg<String> grammar = Bnf.parse(""" <expr> ::= <num> | <var> | '(' <expr> <op> <expr> ')' <op> ::= + | - | * | / <var> ::= x | y <num> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 """ );

Since:

7.1

Version:

7.1

Method Summary

Modifier and Type	Method	Description
static String	format(Cfg<?> grammar)	Formats the given CFG as BNF grammar string.
static Cfg<String>	parse(String grammar)	Parses the given BNF grammar string to a Cfg object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

parse

public static Cfg<String> parse(String grammar)

Parses the given BNF grammar string to a Cfg object. The following example show the grammar of a simple arithmetic expression.

<expr> ::= <num> | <var> | '(' <expr> <op> <expr> ')' <op> ::= + | - | * | / <var> ::= x | y <num> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

Parameters:

grammar - the BNF grammar string

Returns:

the parsed BNF object

Throws:

ParsingException - if the given grammar is invalid

NullPointerException - it the given grammar string is null

format

public static String format(Cfg<?> grammar)

Formats the given CFG as BNF grammar string.

Parameters:

grammar - the CFG to format as BNF

Returns:

the BNF formatted grammar string

Throws:

NullPointerException - if the give grammar is null