Kudzu

A monadic (I think...) recursive-descent parser combinator written in Kotlin

Kudzu is a recursive-descent parser written in Kotlin, inspired by Parsec, with the goal of immutability, simplicity, testability, and multiplatform usability. It's designed to be a simple starting place for writing smaller parsers to evaluate relatively simple grammars for other Copper-Leaf libraries, but flexible enough to be used for larger languages.

Notable features:

• Multiplatform targets: JVM, Android, JS Legacy, JS IR, iOS
• No separate lexer/parser. You really just don't need it, so Kudzu omits it
• Parser combinator structure means every piece of your grammar is a complete parser, and thus smaller parsing units can be tested in isolation, but the combination of them creates the full language
• Everything in Kudzu is immutable, and thus fully thread-safe
• Built on top of DeepRecursiveFunction to provide readable stacktraces and prevent StackOverflowErrors
• No complicated DSL or arcane combinator operators required, just normal, readable Kotlin classes. You don't need a Ph.D. in computational linguistics or functional programming to understand a Kudzu parser
• Many useful combinators provided out of the box
  • Boolean, Int, Double literals
  • String and Character literals, with standard escaped characters (i.e. \n) and Unicode sequences (i.e. \u00A2)
  • Identifiers
  • Choice, repetition, optional higher-kinded parsers
• Parses input to an Abstract Syntax Tree (AST) and provides facilities for simplifying and/or introspecting the AST
• Line- and column-number source tracking
• Generic expression parser with all the fixin's
  • Customizable operator precedence
  • Operators with prefix, postfix, and infix with both left- and right-recursive associativity
  • Parentheses
  • Simplify deeply-nested expressions AST to simpler representation

Supported Platforms/Features

| Platform | |----------| | Android | | JVM | | iOS | | JS | | WasmJS |

Installation

repositories {
    mavenCentral()
}

// for plain JVM or Android projects
dependencies {
    implementation("io.github.copper-leaf:kudzu-core:{{gradle.version}}")
}

// for multiplatform projects
kotlin {
    sourceSets {
        val commonMain by getting {
            dependencies {
                implementation("io.github.copper-leaf:kudzu-core:{{gradle.version}}")
            }
        }
    }
}

Documentation

See the website for detailed documentation and usage instructions.

License

Kudzu is licensed under the BSD 3-Clause License, see LICENSE.md.

References

• Parsec
• JParsec