kotlin-parsing-charset is a Kotlin Multiplatform library for representing sets of Char values as compact sorted ranges.

It is intended for parser, lexer, tokenizer, and automaton implementations that need fast character membership checks, set operations, and deterministic partitioning of the Char space.

repositories {
    mavenCentral()
}

dependencies {
    implementation("one.wabbit:kotlin-parsing-charset:1.3.0")
}

import one.wabbit.parsing.charset.CharSet

val identifierStart = CharSet.letter union CharSet.one('_')
val identifierPart = identifierStart union CharSet.digit

check('a' in identifierStart)
check('_' in identifierStart)
check('9' !in identifierStart)
check('9' in identifierPart)

CharSet stores sorted, non-overlapping ranges, so adjacent characters are compacted into a single range.

import one.wabbit.parsing.charset.CharSet

val lowercase = CharSet.range('a', 'z')
val vowels = CharSet.of("aeiou")
val consonants = lowercase difference vowels

check('b' in consonants)
check('a' !in consonants)
check((vowels union consonants) == lowercase)

The main operations are union, intersect, difference, invert, subset/superset predicates, and overlap classification.

CharSetTop represents a partition of the whole Char.MIN_VALUE..Char.MAX_VALUE space. It is useful when several character sets must be refined into disjoint basis ranges for parser or automaton construction.

import one.wabbit.parsing.charset.CharSet
import one.wabbit.parsing.charset.CharSetTop

val top = CharSetTop.trivial
    .refine(CharSet.digit)
    .refine(CharSet.letter)

check(top.size >= 3)

The library is small and stable in scope. It focuses on character-set algebra and partitioning; it does not parse regular expressions or build automata by itself.

• User guide
• API reference notes
• Troubleshooting
• Development

Generated API docs can be built locally with Dokka. See API reference notes for the command.

• CHANGELOG.md

This project is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0) for open source use.

For commercial use, contact Wabbit Consulting Corporation at wabbit@wabbit.one.

Before contributions can be merged, contributors need to agree to the repository CLA.