A Kotlin multiplatform library providing limited Unicode Character Database functionality.

Note: This project serves as a temporary solution until KT-23251 Extend Unicode support in Kotlin common and KT-24908 CodePoint inline class are implemented in the Kotlin standard library.

Kodepoint provides Unicode character property access across multiple platforms:

• JVM: Uses Java's Character class
• All other targets: Pure Kotlin implementations with generated Unicode lookup tables

Add the following dependency to your project:

dependencies {
    implementation("me.zolotov.kodepoint:kodepoint:$version")
}

import me.zolotov.kodepoint.*

// Create a Codepoint
val codepoint = Codepoint(0x1F600) // 😀

val isLetter = codepoint.isLetter()
val upperCase = codepoint.toUpperCase()

// String conversion
val string = codepoint.asString()

// Work with CharSequence
val text = "Hello 👋 World"
text.forEachCodepoint { cp ->
    println("U+${cp.codepoint.toString(16).uppercase()}: ${cp.asString()}")
}

// Append to StringBuilder
val sb = StringBuilder()
sb.appendCodePoint(Codepoint(0x1F44D)) // 👍

For detailed technical documentation on data storage, lookup tables, and platform-specific implementations, see ARCHITECTURE.md.

Core library providing Unicode character functionality through @JvmInline value class Codepoint.

• Unicode property API (case conversion, character classification, script detection)
• Platform-specific implementations with fallbacks
• Surrogate pair handling for supplementary Unicode characters
• Extensions for CharSequence and Appendable

Contains generated Unicode property lookup tables.

• Unicode database processing and lookup tables
• Used by lib for non-JVM platforms

Contains UnicodeScript enum accessible from both unicode and lib modules.

• Unicode script definitions generated from Unicode Character Database
• Shared across all platform-specific implementations

Note: Only JVM and WasmJS targets are actively tested. Other targets compile and should work correctly, but have not been thoroughly validated.

This library aims to provide consistent Unicode behavior across all platforms. On non-JVM platforms, it uses generated Unicode Character Database lookup tables. The implementation is validated against JVM's java.lang.Character methods.

The following functions produce identical results to JVM's Character class for all 1,114,112 Unicode codepoints:

• isLetter(), isDigit(), isLetterOrDigit()
• isUpperCase(), isLowerCase()
• toLowerCase(), toUpperCase()
• isSpaceChar()
• isIdeographic()
• isIdentifierIgnorable()
• isISOControl()
• isJavaIdentifierStart(), isJavaIdentifierPart() - generated directly from JVM's Character class during build

Some functions have intentional differences from JVM behavior to maintain Unicode standard compliance:

This library uses Unicode's White_Space property, which differs from Java's Character.isWhitespace():

Java excludes non-breaking spaces from isWhitespace() and includes control characters that Unicode does not classify as whitespace.

JVM includes U+2E2F (VERTICAL TILDA) for backward compatibility, but this character is not in Unicode's ID_Start or ID_Continue properties. This library follows the Unicode standard.

# Build all modules
./gradlew build

# Run tests
./gradlew allTests

# Full benchmarks (5 warmups, 5 iterations)
./gradlew :benchmarks:benchmark

# Quick benchmarks (2 warmups, 3 iterations)
./gradlew :benchmarks:quickBenchmark

CodepointsBenchmark – Measures performance across different character sets:

• ASCII characters (fast-path optimization)
• Latin Extended (U+0100-024F)
• Greek (U+0370-03FF)
• CJK ideographs (U+4E00-4E7F)
• Mixed workloads (80/20, 50/50, 20/80 ASCII/Unicode ratios)

JvmComparisonBenchmark – Direct comparison with java.lang.Character:

• isLetter, isDigit, toLowerCase, toUpperCase
• isWhitespace, isJavaIdentifierStart, isJavaIdentifierPart

Results are written to benchmarks/build/reports/benchmarks/.