java library to parse regular expressions into a syntax tree

Question

I'd like a library that can take the string representation of a regexp and convert that into a syntax tree for easy programmatic manipulation. Something that would transform:

(\s?)bla[a-z]

into something like:

PARENTHESIS
  CHAR:SPACE
    WILD
WORD:bla
CHAR:a-z

Jose Muanis · Accepted Answer · 2012-01-02 03:50:32Z

2

Looks like what you're looking for is a syntax parser, right?

I would give a look on antlr (http://www.antlr.org/), you can create grammars and it will generate a syntax tree which you can walk, translate etc.

answered Jan 2, 2012 at 3:50

Jose Muanis

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7 Comments

jp. Over a year ago

I am looking for a syntax parser FOR regular expressions, not WITH regular expression. I modified the question to make it more clear.

Dave Newton Over a year ago

And there are some regex grammars available.

Dave Newton Over a year ago

@jp Nobody said "with", it has some regex grammars.

jp. Over a year ago

@DaveNewton Yes I could do a with a regex grammar that I can pass to javacc or antlr. But it's hard to search for it as search results are all about using regex in antlr or javacc...

Dave Newton Over a year ago

@jp There's a page with all the antlr grammars--maybe look there.

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fge · Accepted Answer · 2012-01-02 18:16:22Z

0

Parboiled looks like a good choice for what you want to make.

It allows easy writing of grammars, way more easily than antlr or javacc.

Sample:

Rule Digit()
{
    return CharRange('0', '9');
}

Rule Integer()
{
    return OneOrMore(Digit());
}

Rule WhiteSpace()
{
    return ZeroOrMore(AnyOf(" \t"));
}

Rule NToMQuantifier()
{
    return Sequence(
        '{',
        WhiteSpace(),
        Integer(),
        Optional(
            WhiteSpace(),
            Integer()
        ),
        '}'
    );
}

Rule OtherQuantifiers()
{
    return Sequence(AnyOf("+?*"), Optional(AnyOf("+?")));
}

Rule Quantifier()
{
    return FirstOf(OtherQuantifiers(), NToMQuantifier());
}

answered Jan 2, 2012 at 18:16

fge

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