kwatch / benry-java

Utility libraries for Java

benry.java

Useful tools for java.

$License: MIT License $

Package: benry.rexp

Useful wrapper over java.util.regex package.

Matching

import static benry.rexp.Rexp.rexp;
import benry.rexp.Matched;

public class Example {
    public static void main(String args[]) {

        // once
        Matched m = rexp("^(\\d+)-(\\d+)-(\\d+)$").match("2000-12-31");
        if (m != null) {
            System.out.println(m.get(0));  //=> 2000-12-31
            System.out.println(m.get(1));  //=> 2000
            System.out.println(m.get(2));  //=> 12
            System.out.println(m.get(3));  //=> 31
            //
            System.out.println(m.size());  //=> 3
            //
            System.out.println(m.start(1));  //=> 0
            System.out.println(m.start(2));  //=> 5
            System.out.println(m.start(3));  //=> 8
            System.out.println(m.end(1));    //=> 4
            System.out.println(m.end(2));    //=> 7
            System.out.println(m.end(3));    //=> 10
        }

        // all
        for (Matched m2: rexp("(\\d+)").matchAll("2000-12-31")) {
            System.out.println(m2.get(1));  //=> 2000
                                            //=> 12
                                            //=> 31
        }

    }
}

Replacing

import benry.rexp.Matched;
import benry.rexp.Replacer;

public class Example {
    public static void main(String args[]) {

        // replaces all
        String result;
        result = rexp("\\d+").gsub("2000-12-31", "X");
        System.out.println(result);      //=> X-X-X
        result = rexp("(\\d+)").gsub("2000-12-31", "<$1>");
        System.out.println(result);      //=> <2000>-<12>-<31>

        // replaces first
        result = rexp("\\d+").sub("2000-12-31", "X");
        System.out.println(result);      //=> X-12-31
        result = rexp("(\\d+)").sub("2000-12-31", "<$1>");
        System.out.println(result);      //=> <2000>-12-31

        // replaces with callback
        result = rexp("(\\d+)").gsub("2000-12-31", new Replacer() {
            public String replace(Matched m) {
                int intval = Integer.parseInt(m.get(1));
                return Integer.toString(intval + 1);
            }
        });
        System.out.println(result);      //=> 2001-13-32
        result = rexp("(\\d+)").sub("2000-12-31", new Replacer() {
            public String replace(Matched m) {
                int intval = Integer.parseInt(m.get(1));
                return Integer.toString(intval + 1);
            }
        });
        System.out.println(result);      //=> 2001-12-31

    }
}

Splitting

import static benry.rexp.Rexp.rexp;
import benry.rexp.Matched;

public class Example {
    public static void main(String args[]) {

        String[] items = rexp("\\s+").split("Haruhi  Mikuru   Yuki");
        System.out.println(items.length);  //=> 3
        for (String item: items) {
            System.out.println(item);    //=> Haruhi
                                         //=> Mikuru
                                         //=> Yuki
        }

    }
}

Pattern Options

import static benry.rexp.Rexp.rexp;
import benry.rexp.Matched;

public class Example {
    public static void main(String args[]) {

        // case-sensitive and insensitive matching
        Matched m1 = rexp("[a-z]+").match("SOS");
        System.out.println(m1);         //=> null
        Matched m2 = rexp("[a-z]+", "i").match("SOS");
        System.out.println(m2.get(0));  //=> SOS

    }
}

For example, "ims" means Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL.

• "i" : Pattern.CASE_INSENSITIVE
• "m" : Pattern.MULTILINE
• "s" : Pattern.DOTALL
• "x" : Pattern.COMMENTS
• "u" : Pattern.UNICODE_EQ
• "d" : Pattern.UNIX_LINES
• "E" : Pattern.CANON_EQ
• "L" : Pattern.LITERAL

Avoid Backslash-Hell

rexp() convers backquote into backslash in order to avoid backslash-hell.

import static benry.rexp.Rexp.rexp;
import benry.rexp.Matched;

public class Example {
    public static void main(String args[]) {

        // use backquote ("`") instead of backslash ("\\")
        Matched m1 = rexp("^(`d`d)/(`d`d)$").match("12/31");
        System.out.println(m1.get(1));    //=> 12
        System.out.println(m1.get(2));    //=> 31

        // use double-backqotes ('``') to represent single-backquote ('`')
        Matched m2 = rexp("^``$").match("`");
        System.out.println(m2.get(0));    //=> `

        // use arbitrary character instead of backslash
        Matched m3 = rexp("^(%d%d)/(%d%d)$", '%').match("12/31");
        System.out.println(m3.get(1));    //=> 12
        System.out.println(m3.get(2));    //=> 31

        // disable backquote
        Matched m4 = rexp("^(`d`d)/(`d`d)$", '\0').match("12/31");
        System.out.println(m4);           //=> null

    }
}

Caching Compiled Pattern

rexp() caches compiled pattern object into memory.

// pattern is compiled only once, because rexp() caches
// compiled pattern object into memory.
for (String filename: filenames) {
    if (rexp("\\.(jpg|png|gif)$").match(filename) != null) {
        System.out.println(filename + ": image file");
    }
}

If there is no need to cache pattern into memory, use new Rexp() instead of rexp().

import benry.rexp.Rexp;
class Example {
    // use new Rexp because there is no need to cache pattern
    static Rexp SUFFIX_REXP = new Rexp("\\.(jpg|png|gif)$");
}