Javacc
Java version Yacc Lex, Lucene uses this to do query analysis. Official website https://javacc.dev.java.net/
IBM DW introduces javacc, parsing tree and xquery syntax http://www-900.ibm.com/developerWorks/cn/xml/x-javacc/part1/index.shtml Now you can define your own language! http://www-900.ibm.com/developerWorks/cn/dmdd/library/techarticles/dm-0401brereton/index.shtml
JavaWorld About the article Build Your Own Languages with javacc: http://www.javaworld.com/javaworld/jw 12-2000/jw-1229-cooltools-p2.html
JAVACC uses .jj file
A simple calculator Calculator.jj generates Parserjjdoc Calculator.jj Gene BNF using javacc calculator.jj
Options
{
LOOKAHEAD = 2;
}
Parser_Begin (Calculator)
Public Class Calculator
{
Public static void main (string args []) Throws Parsexception
{
Calculator Parser = New Calculator (System.in);
While (True)
{
Parser.ParseOnline ();
}
}
}
Parser_end (Calculator)
SKIP:
{
""
| "/ r"
| "/ t"
}
TOKEN:
{
) ("." ) )?> | | } Void ParseOnline (): { Double A; } { A = expr () {System.out.println (a); | | {System.exit (-1); } Double EXPR (): { Double A; Double B; } { a = term () ( " " b = expr () {a = b;} | "-" b = expr () {a - = b;} ) * {RETURN A;} } Double Term (): { Double A; Double B; } { a = unary () ( "*" b = term () {a * = b;} | "/" b = term () {a / = b;} ) * {RETURN A;} } Double unary (): { Double A; } { "-" A = Element () {return -a;} | a = Element () {Return A;} } Double Element (): { Token T; Double A; } { t = {Return Double.Parsedouble (t.toString ()); | "(" A = EXPR () ")" {Return A;}} From Xinyun: JAVACC
