DAWG stands for a Directed Acyclic Word Graph, a data structure for storing a list of words and querying if the set contains a given word:
val dawg = Dawg.generate(listOf("directed", "acyclic", "word", "graph"))
assertThat("word" in dawg).isTrue()
assertThat("dawg" in dawg).isFalse()Sounds like a pretty limited functionality and you might be wondering why would you want to use a Dawg instead of a regular Set<String>. The answer is the memory footprint. Dawg encodes the Polish dictionary for word games – almost 3M words weighing 40Mb – in 1.5Mb binary file and allows blazing fast query method with no false positives or false negatives.
The API also exposes methods to encode the Dawg into binary format and decode it back. The library uses okio under the hood, and that dependency is also exposed in the encoding/decoding APIs:
val encodedDawg = Buffer().apply { dawg.encode(this) }
val decodedDawg = Dawg.decode(encodedDawg)If you're curious about how it all works under the hood, check out the blog post I wrote a couple eons ago.
No need to expose the JCommander dependency for the lib users.
Using 32 bits per node is actually quite wasteful. For example for TWL06 DAWG only 24 bits could be used per node: 2 for flags, 5 for letters (for 26 unique values) and 17 for child index (120223 nodes). For that particular example it would reduce the size of encoded DAWG by 25%. For Polish dictionary it would be 15% reduction.
None so far, but when I get my act together and push it to some Maven repo, you'll be able to do this:
dependencies {
compile 'org.chalup:dawg:x.y.z'
}<dependency>
<groupId>org.chalup</groupId>
<artifactId>dawg</artifactId>
<version>x.y.z</version>
</dependency>Copyright (C) 2019 Jerzy Chalupski
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