Class BytecodeExecutor

java.lang.Object

org.ek9lang.compiler.backend.jvm.BytecodeExecutor

public final class BytecodeExecutor
extends Object

Executes generated EK9 bytecode within the current JVM. This avoids spawning external JVM processes for each execution, significantly improving performance.

The executor uses a URLClassLoader to load generated .class files from the compilation output directory. The ek9-lang runtime classes are loaded from the classpath (parent-first delegation).

Output capture is achieved using thread-local PrintStreams. Each thread captures its own stdout and stderr independently, enabling parallel-safe execution. EK9 programs use Stdout/Stderr which write to System.out/System.err, but we redirect both to thread-local delegating streams.

Used by REPL, bytecode tests, and the EK9 test runner.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final record	BytecodeExecutor.ExecutionResult	Result of executing a generated EK9 program.

Method Summary

Modifier and Type	Method	Description
static String	execute(Path bytecodeDir, String programClassName, String... args)	Executes a generated EK9 program and returns its captured stdout output.
static BytecodeExecutor.ExecutionResult	executeWithFixtures(Path bytecodeDir, String programClassName, String[] args, Map<String,String> envVars, String stdinContent)	Executes a generated EK9 program with full test isolation fixtures.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

execute

public static String execute(Path bytecodeDir,
 String programClassName,
 String... args)
                      throws Exception

Executes a generated EK9 program and returns its captured stdout output.

This is the backward-compatible method for REPL and simple bytecode tests. No env var overrides, no stdin fixtures, no stderr capture returned.

Parameters:

bytecodeDir - Directory containing generated .class files

programClassName - Fully qualified class name (e.g., "bytecode.test.MyProgram")

args - String arguments to pass to _main() method

Returns:

The captured stdout output from the program

Throws:

Exception - if execution fails

executeWithFixtures

public static BytecodeExecutor.ExecutionResult executeWithFixtures(Path bytecodeDir,
 String programClassName,
 String[] args,
 Map<String,String> envVars,
 String stdinContent)

Executes a generated EK9 program with full test isolation fixtures.

Provides per-thread isolation for all four I/O channels:

• stdout - captured via thread-local PrintStream
• stderr - captured via thread-local PrintStream
• env vars - thread-local override via EnvVars._setThreadEnv()
• stdin - thread-local override via Stdin._setThreadInput()

Parameters:

bytecodeDir - Directory containing generated .class files

programClassName - Fully qualified class name

args - String arguments to pass to _main() method

envVars - Thread-local env var overrides (null = no override)

stdinContent - Content to provide as stdin (null = no override)

Returns:

Execution result with captured stdout, stderr, exit code, and duration