Migrate: Replace BCEL with ASM completely!

- BCEL dependencies are removed

Thanks to Claude Code!

Author: kmizu

.claude/settings.local.json

@@ -0,0 +1,17 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(find:*)",
+      "Bash(java:*)",
+      "Bash(sbt clean:*)",
+      "Bash(rm:*)",
+      "Bash(sbt:*)",
+      "Bash(grep:*)",
+      "Bash(mv:*)",
+      "Bash(ls:*)",
+      "Bash(cat:*)",
+      "Bash(timeout 30 sbt 'testOnly *CountersSpec')"
+    ],
+    "deny": []
+  }
+}

CLAUDE.md

@@ -0,0 +1,49 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build Commands
+
+- **Build the project**: `sbt compile`
+- **Run tests**: `sbt test`  
+- **Run a single test**: `sbt 'testOnly *HelloWorldSpec'`
+- **Package JAR**: `sbt assembly` or `sbt packageBin`
+- **Create distribution**: `sbt dist` (creates a distribution zip in target/dist)
+- **Run a script**: `sbt 'runScript <script.on> [args]'`
+- **Clean**: `sbt clean`
+
+## High-Level Architecture
+
+The Onion compiler follows a pipeline architecture with distinct phases:
+
+1. **Parsing** (`Parsing.scala`) - Uses JavaCC-generated parser (`JJOnionParser.jj`) to create untyped AST
+2. **Rewriting** (`Rewriting.scala`) - Transforms and normalizes the AST
+3. **Type Checking** (`Typing.scala`) - Produces typed AST from untyped AST
+4. **Code Generation** (`TypedGenerating.scala`) - Generates JVM bytecode from typed AST
+   - Currently transitioning from BCEL to ASM for bytecode generation
+   - `AsmCodeGeneration.scala` contains the new ASM-based backend
+
+### Key Components
+
+- **Processor Pipeline**: Compiler phases extend `Processor[A,B]` trait and can be composed with `andThen`
+- **AST Types**: 
+  - Untyped AST in `AST.scala`
+  - Typed AST in `TypedAST.scala`
+- **Entry Points**:
+  - `onion.tools.CompilerFrontend` - Main compiler executable (`onionc`)
+  - `onion.tools.ScriptRunner` - Script execution (`onion`)
+  - `onion.tools.Shell` - Interactive shell/REPL
+- **Error Handling**: `SemanticError`, `CompileError`, and `SemanticErrorReporter` for compilation diagnostics
+
+### Testing
+
+Tests use ScalaTest and extend `AbstractShellSpec` for integration testing. Test files are in `src/test/scala/onion/compiler/tools/`.
+
+### Language Features
+
+Onion is a statically-typed, object-oriented language that compiles to JVM bytecode. Key features include:
+- Classes with public/private visibility modifiers
+- Static and instance methods
+- Type inference
+- First-class functions (Function0 through Function10 interfaces)
+- Module system with imports

README.md

@@ -6,14 +6,21 @@ compiles into JVM class files as in-memory or real files.
 Originally, Onion was written in Java.  It has been rewritten in Scala completely except Parser,
 using JavaCC.
 
+## Architecture
+
+The compiler parses source code into an untyped AST and then performs type
+checking to produce a **typed AST**.  The old intermediate representation (IRT)
+has been folded into this typed tree.  Code generation now runs on the typed
+AST via a thin compatibility layer using ASM.
+
 ## Tools
 
 ### onionc
 
 #### Usage
 
-```
-    onionc [options] source files...
+```txt
+onionc [options] source files...
 ```
 
 ####  Available options:

bin/onion

@@ -1,21 +1,33 @@
 #!/bin/sh
 
-# This variable represents the directory in which Onion is installed.
-# ONION_HOME=
+# Use java from PATH if JAVA_HOME is not set
+if [ -z "$JAVA_HOME" ]; then
+    JAVA_CMD="java"
+else
+    JAVA_CMD="$JAVA_HOME/bin/java"
+fi
 
-# This variable represents the directory in which J2SE is installed. 
-# JAVA_HOME= 
+# Check if java is available
+if ! command -v "$JAVA_CMD" > /dev/null 2>&1; then
+    echo "Error: Java not found. Please install Java or set JAVA_HOME environment variable."
+    exit 1
+fi
 
-if [ $JAVA_HOME/ = / ]
-then
-  echo Please set the environment variable JAVA_HOME.
-  exit
+# Build classpath with all jars in lib directory
+CLASSPATH="$ONION_HOME/onion.jar"
+if [ -d "$ONION_HOME/lib" ]; then
+    for jar in "$ONION_HOME/lib"/*.jar; do
+        if [ -f "$jar" ]; then
+            CLASSPATH="$CLASSPATH:$jar"
+        fi
+    done
 fi
 
-if [ $ONION_HOME/ = / ]
-then
-  echo Please set the environment variable ONION_HOME.
-  exit
+# Add user classpath if set
+if [ -n "$CLASSPATH" ]; then
+    CLASSPATH="$CLASSPATH:$CLASSPATH"
 fi
+echo $CLASSPATH
 
-$JAVA_HOME/bin/java -classpath $CLASSPATH:$ONION_HOME/onion.jar:$ONION_HOME/onion-library.jar:$ONION_HOME/lib/bcel.jar onion.tools.ScriptRunner $@
+# Run the Onion script runner
+exec "$JAVA_CMD" -classpath "$CLASSPATH" onion.tools.ScriptRunner "$@"

bin/onion.bat

@@ -1,26 +1,35 @@
 @echo off
-
-rem This variable represents the directory in which Onion is installed.
-rem set ONION_HOME=
-
-rem This variable represents the directory in which J2SE is installed.
-rem set JAVA_HOME=$JAVA_HOME$ 
-
-if /i %ONION_HOME%/ == / goto NO_ONION_HOME
-
-if /i %JAVA_HOME%/ == / goto NO_JAVA_HOME
-
-goto START
-
-:NO_JAVA_HOME
-echo Please set the environment variable JAVA_HOME
-goto END
-
-:NO_ONION_HOME
-echo Please set the environment variable ONION_HOME
-goto END
-
-:START
-%JAVA_HOME%\bin\java -classpath %CLASSPATH%;%ONION_HOME%\onion.jar;%ONION_HOME%\lib\bcel.jar;%ONION_HOME%\onion-library.jar onion.tools.ScriptRunner %*
-
-:END
+setlocal enabledelayedexpansion
+
+rem Remove trailing backslash from ONION_HOME if present
+if "%ONION_HOME:~-1%"=="\" set "ONION_HOME=%ONION_HOME:~0,-1%"
+
+rem Use java from PATH if JAVA_HOME is not set
+if defined JAVA_HOME (
+    set "JAVA_CMD=%JAVA_HOME%\bin\java"
+) else (
+    set "JAVA_CMD=java"
+)
+
+rem Check if java is available
+"%JAVA_CMD%" -version >nul 2>&1
+if errorlevel 1 (
+    echo Error: Java not found. Please install Java or set JAVA_HOME environment variable.
+    exit /b 1
+)
+
+rem Build classpath with all jars in lib directory
+set "CP=%ONION_HOME%\onion.jar"
+if exist "%ONION_HOME%\lib" (
+    for %%F in ("%ONION_HOME%\lib\*.jar") do (
+        set "CP=!CP!;%%F"
+    )
+)
+
+rem Add user classpath if set
+if defined CLASSPATH (
+    set "CP=%CP%;%CLASSPATH%"
+)
+
+rem Run the Onion script runner
+"%JAVA_CMD%" -classpath "%CP%" onion.tools.ScriptRunner %*

bin/onionc

@@ -1,21 +1,17 @@
 #!/bin/sh
 
-# This variable represents the directory in which Onion is installed.
-# ONION_HOME=
-
-# This variable represents the directory in which J2SE is installed. 
-# JAVA_HOME= 
-
-if [ $JAVA_HOME/ = / ]
-then
-  echo Please set the environment variable JAVA_HOME.
-  exit
+# Use java from PATH if JAVA_HOME is not set
+if [ -z "$JAVA_HOME" ]; then
+    JAVA_CMD="java"
+else
+    JAVA_CMD="$JAVA_HOME/bin/java"
 fi
 
-if [ $ONION_HOME/ = / ]
-then
-  echo Please set the environment variable ONION_HOME.
-  exit
+# Check if java is available
+if ! command -v "$JAVA_CMD" > /dev/null 2>&1; then
+    echo "Error: Java not found. Please install Java or set JAVA_HOME environment variable."
+    exit 1
 fi
 
-$JAVA_HOME/bin/java -jar $ONION_HOME/onion.jar $@
+# Run the Onion compiler
+exec "$JAVA_CMD" -jar "$ONION_HOME/onion.jar" "$@"

bin/onionc.bat

@@ -1,26 +1,21 @@
 @echo off
 
-rem This variable represents the directory in which Onion is installed.
-rem set ONION_HOME=
-
-rem This variable represents the directory in which J2SE is installed.
-rem set JAVA_HOME=$JAVA_HOME$ 
-
-if /i %ONION_HOME%/ == / goto NO_ONION_HOME
-
-if /i %JAVA_HOME%/ == / goto NO_JAVA_HOME
-
-goto START
-
-:NO_JAVA_HOME
-echo Please set the environment variable JAVA_HOME
-goto END
-
-:NO_ONION_HOME
-echo Please set the environment variable ONION_HOME
-goto END
-
-:START
-%JAVA_HOME%\bin\java -jar %ONION_HOME%\onion.jar %*
-
-:END
+rem Remove trailing backslash from ONION_HOME if present
+if "%ONION_HOME:~-1%"=="\" set "ONION_HOME=%ONION_HOME:~0,-1%"
+
+rem Use java from PATH if JAVA_HOME is not set
+if defined JAVA_HOME (
+    set "JAVA_CMD=%JAVA_HOME%\bin\java"
+) else (
+    set "JAVA_CMD=java"
+)
+
+rem Check if java is available
+"%JAVA_CMD%" -version >nul 2>&1
+if errorlevel 1 (
+    echo Error: Java not found. Please install Java or set JAVA_HOME environment variable.
+    exit /b 1
+)
+
+rem Run the Onion compiler
+"%JAVA_CMD%" -jar "%ONION_HOME%\onion.jar" %*

build.sbt

@@ -78,10 +78,12 @@ lazy val onionSettings = Seq(
     (Seq((Compile / javaSource).value) ++ Seq((Compile / scalaSource).value) ++ Seq((Compile / sourceManaged).value))
   },
   scalacOptions ++= Seq("-encoding", "utf8", "-unchecked", "-deprecation", "-feature", "-language:implicitConversions", "-language:existentials"),
-  javacOptions ++= Seq("-sourcepath", "src.lib", "-Xlint:unchecked", "-source", "21"),
+  javacOptions ++= Seq("-sourcepath", "src.lib", "-Xlint:unchecked", "-source", "17"),
   libraryDependencies ++= Seq(
-    "org.apache.bcel" % "bcel" % "6.0",
-    "org.ow2.asm" % "asm" % "5.0.2",
+    "org.ow2.asm" % "asm" % "9.8",
+    "org.ow2.asm" % "asm-commons" % "9.8",
+    "org.ow2.asm" % "asm-tree" % "9.8",
+    "org.ow2.asm" % "asm-util" % "9.8",
     "net.java.dev.javacc" % "javacc" % "5.0",
     "junit" % "junit" % "4.7" % "test",
     "org.scalatest" %% "scalatest" % "3.2.19" % "test"
@@ -120,7 +122,13 @@ lazy val onionSettings = Seq(
     target.value / "dist"
   },
   mainClass := Some("onion.tools.CompilerFrontend"),
-  assembly / assemblyJarName := "onion.jar"
+  assembly / assemblyJarName := "onion.jar",
+  assembly / assemblyMergeStrategy := {
+    case "module-info.class" => MergeStrategy.discard
+    case x =>
+      val oldStrategy = (assembly / assemblyMergeStrategy).value
+      oldStrategy(x)
+  }
 )
 
-fork in run := true
+fork in run := true

src/main/resources/META-INF/Manifest.mf

@@ -1,2 +1,2 @@
 Main-Class: onion.tools.CompilerFrontend
-Class-Path: lib/bcel.jar lib/scala-compiler.jar lib/scala-library.jar lib/onion-library.jar
+Class-Path: lib/scala-compiler.jar lib/scala-library.jar lib/onion-library.jar