DynamisExpression

MVEL3 expression language transpiler — compiles MVEL expressions into Java bytecode via transpilation to Java source, in-memory javac compilation, and bytecode execution.

Modules

Module	Description	GroupId	Version
javaparser-mvel-main	Fork of JavaParser with ~28 MVEL3/DRL-specific AST node types	org.mvel.javaparser	3.25.5-mvel3-SNAPSHOT
mvel-main	MVEL3 transpiler — parses, transpiles, compiles, and executes MVEL expressions	org.mvel	3.0.0-SNAPSHOT
mvel-benchmarks	JMH benchmark suite for MVEL3 expression evaluation	org.mvel	3.0.0-SNAPSHOT

Prerequisites

• JDK 17 (required — tests fail on JDK 21)
• Maven 3.8.7+

Build

Build all modules from the project root:

mvn clean install

The Maven reactor resolves build order automatically based on declared dependencies (javaparser-mvel-main builds first, then mvel-main, then mvel-benchmarks).

Build individual modules

# javaparser-mvel fork only
cd javaparser-mvel-main && ./mvnw clean install

# MVEL3 transpiler only (requires javaparser-mvel installed)
cd mvel-main && mvn clean install

# Benchmarks only (requires mvel3 installed)
cd mvel-benchmarks && mvn clean package

Run tests

# All tests from root
mvn test

# Single test class
cd mvel-main && mvn test -Dtest=MVELTranspilerTest

# Single test method
cd mvel-main && mvn test -Dtest=MVELTranspilerTest#testAssignmentIncrement

# javaparser-mvel tests including slow tests
cd javaparser-mvel-main && ./mvnw -B --errors clean test --activate-profiles AlsoSlowTests

Run benchmarks

cd mvel-benchmarks
mvn clean package
java -jar target/benchmarks.jar        # Run all benchmarks
java -jar target/benchmarks.jar -l     # List available benchmarks

Architecture

The MVEL3 transpilation pipeline:

MVEL source
  -> ANTLR4 parse tree
    -> JavaParser AST (with MVEL nodes)
      -> Rewrite to pure Java AST
        -> Java source
          -> javac in-memory
            -> Bytecode execution

Four stages:

1. Parse — ANTLR4 grammar produces a parse tree from MVEL expressions
2. Transpile — MVELTranspiler converts the parse tree into a JavaParser AST; MVELToJavaRewriter applies MVEL-specific rewrites (null-safe access, coercion, operator overloading)
3. Generate — CompilationUnitGenerator wraps the transpiled AST into a Java CompilationUnit implementing Evaluator<C, W, O>
4. Compile & Load — KieMemoryCompiler compiles generated Java via javac; ClassManager manages bytecode

See mvel-main/README.md for detailed API usage and examples.