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Puncher

A regex based string parser

Parsing strings can be done in a million ways, and often are. Even within the same project. This small utility is an attempt to unite behind one way of doing things. Regular expressions have been used since the dawn of days, and even if I have had my strong doubts about them, I must confess that they can be quite handy.

Puncher is configured with patterns containing named groups. Punchers can also be combined into a composite puncher, to break regex up into more manageable parts.

Get it from Maven Central
Maven Central

<dependency>
    <groupId>io.github.jebl01</groupId>
    <artifactId>puncher</artifactId>
    <version>0.3</version>
</dependency>

Usage

Say we have entities with composite keys like <id>:<version>. One way of parsing this is by splitting on : and expecting something like String[2] in return. An other way is to write some regexp code to accomplish the same.

By using Puncher you can do this without breaking a sweat;

final Puncher puncher = Puncher.forPattern("^(?<id>[^:]+):(?<version>[^:]+)$");
final Optional<String> idOpt = puncher.punch("123:4", "id").findFirst();

assertTrue(idOpt.isPresent());
idOpt.ifPresent(id -> assertEquals("123", id));

It becomes even more tricky if the key comes in different formats. Say for example that you have evolved your system to include a type in the key, like <type>:<id>:<version>.

The Puncher code to solve this looks like (using a composit puncher);

final Puncher puncher = Puncher.forPattern("^(?<id>[^:]+):(?<version>[^:]+)$")
        .or(Punchers.forPattern("^(?<type>[^:]+):(?<id>[^:]+):(?<version>[^:]+)$"));

final Optional<String> idOptShort = puncher.punch("123:4", "id").findFirst();
final Optional<String> idOptLong = puncher.punch("book:123:4", "id").findFirst();

assertTrue(idOptShort.isPresent());
idOptShort.ifPresent(id -> assertEquals("123", id));

assertTrue(idOptLong.isPresent());
idOptLong.ifPresent(id -> assertEquals("123", id));

Pattern flags

Puncher.forPattern comes with an overload accepting standard Pattern flags, e.g.:

forPattern("^Name: (?<name>\\w+)", Pattern.MULTILINE);

Composite punchers

There are two flavours of composite punchers, OrPuncher and AndPuncher. The first type will only yield matches from the first puncher providing one, while the second will return matches from both.

You can combine punchers in many ways to yield different results.

See PuncherTest for more examples!

And that's about it!