Bring in a gradle plugin

Many thanks to @renatoathaydes for
https://github.com/renatoathaydes/wasm-on-jvm which is the basis of the
code.  I've mangled it somewhat, any issues are obviously mine.

Author: andrewaylett

annotations/gradle.lockfile

@@ -20,20 +20,20 @@ org.jetbrains.intellij.deps:trove4j:1.0.20181211=kotlinCompilerClasspath,spotles
 org.jetbrains.kotlin:kotlin-compiler-embeddable:1.5.31=kotlinCompilerClasspath,spotless-1972456287
 org.jetbrains.kotlin:kotlin-daemon-embeddable:1.5.31=kotlinCompilerClasspath,spotless-1972456287
 org.jetbrains.kotlin:kotlin-reflect:1.5.31=kotlinCompilerClasspath,spotless-1972456287
-org.jetbrains.kotlin:kotlin-reflect:1.6.20=compileClasspath
+org.jetbrains.kotlin:kotlin-reflect:1.5.32=compileClasspath
 org.jetbrains.kotlin:kotlin-script-runtime:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,spotless-1972456287
 org.jetbrains.kotlin:kotlin-scripting-common:1.5.31=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-scripting-compiler-embeddable:1.5.31=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-scripting-compiler-impl-embeddable:1.5.31=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-scripting-jvm:1.5.31=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-stdlib-common:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,spotless-1972456287
-org.jetbrains.kotlin:kotlin-stdlib-common:1.6.20=compileClasspath
+org.jetbrains.kotlin:kotlin-stdlib-common:1.5.32=compileClasspath
 org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.5.0=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.5.31=spotless-1972456287
 org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.5.0=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.5.31=spotless-1972456287
 org.jetbrains.kotlin:kotlin-stdlib:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,spotless-1972456287
-org.jetbrains.kotlin:kotlin-stdlib:1.6.20=compileClasspath
+org.jetbrains.kotlin:kotlin-stdlib:1.5.32=compileClasspath
 org.jetbrains.kotlinx:kotlinx-coroutines-core-jvm:1.5.0=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.0=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlinx:kotlinx-serialization-core-jvm:1.1.0=spotless-1972456287

buildSrc/build.gradle.kts

@@ -26,7 +26,6 @@ dependencies {
 
 kotlin {
     jvmToolchain {
-        (this as JavaToolchainSpec).languageVersion.set(JavaLanguageVersion.of(11))
+        (this as JavaToolchainSpec).languageVersion.set(JavaLanguageVersion.of(8))
     }
-    target { JavaLanguageVersion.of(11) }
 }

buildSrc/src/main/kotlin/asmble.java-conventions.gradle.kts

@@ -20,7 +20,7 @@ dependencyLocking {
     lockAllConfigurations()
 }
 
-var kotlinRequire="1.6.+"
+var kotlinRequire="1.5.+"
 var junitJupiterRequire="5.+"
 
 dependencies {

cli/gradle.lockfile

@@ -20,20 +20,20 @@ org.jetbrains.intellij.deps:trove4j:1.0.20181211=kotlinCompilerClasspath,spotles
 org.jetbrains.kotlin:kotlin-compiler-embeddable:1.5.31=kotlinCompilerClasspath,spotless-1972456287
 org.jetbrains.kotlin:kotlin-daemon-embeddable:1.5.31=kotlinCompilerClasspath,spotless-1972456287
 org.jetbrains.kotlin:kotlin-reflect:1.5.31=kotlinCompilerClasspath,spotless-1972456287
-org.jetbrains.kotlin:kotlin-reflect:1.6.20=compileClasspath,runtimeClasspath
+org.jetbrains.kotlin:kotlin-reflect:1.5.32=compileClasspath,runtimeClasspath
 org.jetbrains.kotlin:kotlin-script-runtime:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,spotless-1972456287
 org.jetbrains.kotlin:kotlin-scripting-common:1.5.31=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-scripting-compiler-embeddable:1.5.31=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-scripting-compiler-impl-embeddable:1.5.31=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-scripting-jvm:1.5.31=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-stdlib-common:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,spotless-1972456287
-org.jetbrains.kotlin:kotlin-stdlib-common:1.6.20=compileClasspath,runtimeClasspath
+org.jetbrains.kotlin:kotlin-stdlib-common:1.5.32=compileClasspath,runtimeClasspath
 org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.5.0=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.5.31=spotless-1972456287
 org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.5.0=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.5.31=spotless-1972456287
 org.jetbrains.kotlin:kotlin-stdlib:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,spotless-1972456287
-org.jetbrains.kotlin:kotlin-stdlib:1.6.20=compileClasspath,runtimeClasspath
+org.jetbrains.kotlin:kotlin-stdlib:1.5.32=compileClasspath,runtimeClasspath
 org.jetbrains.kotlinx:kotlinx-coroutines-core-jvm:1.5.0=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.0=kotlinCompilerPluginClasspathMain
 org.jetbrains.kotlinx:kotlinx-serialization-core-jvm:1.1.0=spotless-1972456287

compiler/gradle.lockfile

@@ -23,22 +23,22 @@ org.jetbrains.intellij.deps:trove4j:1.0.20181211=kotlinCompilerClasspath,spotles
 org.jetbrains.kotlin:kotlin-compiler-embeddable:1.5.31=kotlinCompilerClasspath,spotless-1972456287
 org.jetbrains.kotlin:kotlin-daemon-embeddable:1.5.31=kotlinCompilerClasspath,spotless-1972456287
 org.jetbrains.kotlin:kotlin-reflect:1.5.31=kotlinCompilerClasspath,spotless-1972456287
-org.jetbrains.kotlin:kotlin-reflect:1.6.20=compileClasspath,testCompileClasspath,testRuntimeClasspath
+org.jetbrains.kotlin:kotlin-reflect:1.5.32=compileClasspath,testCompileClasspath,testRuntimeClasspath
 org.jetbrains.kotlin:kotlin-script-runtime:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest,spotless-1972456287
 org.jetbrains.kotlin:kotlin-scripting-common:1.5.31=kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest
 org.jetbrains.kotlin:kotlin-scripting-compiler-embeddable:1.5.31=kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest
 org.jetbrains.kotlin:kotlin-scripting-compiler-impl-embeddable:1.5.31=kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest
 org.jetbrains.kotlin:kotlin-scripting-jvm:1.5.31=kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest
 org.jetbrains.kotlin:kotlin-stdlib-common:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest,spotless-1972456287
-org.jetbrains.kotlin:kotlin-stdlib-common:1.6.20=compileClasspath,testCompileClasspath,testRuntimeClasspath
+org.jetbrains.kotlin:kotlin-stdlib-common:1.5.32=compileClasspath,testCompileClasspath,testRuntimeClasspath
 org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.5.0=kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest
 org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.5.31=spotless-1972456287
 org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.5.0=kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest
 org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.5.31=spotless-1972456287
 org.jetbrains.kotlin:kotlin-stdlib:1.5.31=kotlinCompilerClasspath,kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest,spotless-1972456287
-org.jetbrains.kotlin:kotlin-stdlib:1.6.20=compileClasspath,testCompileClasspath,testRuntimeClasspath
-org.jetbrains.kotlin:kotlin-test-junit:1.6.20=testCompileClasspath,testRuntimeClasspath
-org.jetbrains.kotlin:kotlin-test:1.6.20=testCompileClasspath,testRuntimeClasspath
+org.jetbrains.kotlin:kotlin-stdlib:1.5.32=compileClasspath,testCompileClasspath,testRuntimeClasspath
+org.jetbrains.kotlin:kotlin-test-junit:1.5.32=testCompileClasspath,testRuntimeClasspath
+org.jetbrains.kotlin:kotlin-test:1.5.32=testCompileClasspath,testRuntimeClasspath
 org.jetbrains.kotlinx:kotlinx-coroutines-core-jvm:1.5.0=kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest
 org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.0=kotlinCompilerPluginClasspathMain,kotlinCompilerPluginClasspathTest
 org.jetbrains.kotlinx:kotlinx-serialization-core-jvm:1.1.0=spotless-1972456287

compiler/src/test/kotlin/eu/aylett/asmble/TestBase.kt

@@ -2,7 +2,7 @@ package eu.aylett.asmble
 
 import eu.aylett.asmble.util.Logger
 
-abstract class TestBase : Logger by TestBase.logger {
+abstract class TestBase : Logger by logger {
     companion object {
         val logger = Logger.Print(Logger.Level.INFO)
     }

gradle-plugin/LICENSE

@@ -0,0 +1,18 @@
+Copyright 2019 Renato Athaydes
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
+following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

gradle-plugin/README.md

@@ -0,0 +1,56 @@
+# WASM-on-JVM Gradle Plugin
+
+This is a [Gradle Plugin](https://docs.gradle.org/current/userguide/plugins.html) that lets Java developers
+use [Web Assembly](https://webassembly.org/) (WASM) in their project with minimal friction,
+whether it's WASM text files [written by hand](https://blog.scottlogic.com/2018/04/26/webassembly-by-hand.html),
+or binaries compiled with [WASM compilers](https://github.com/appcypher/awesome-wasm-langs).
+
+Compilation from WASM to JVM bytecode is performed by the [cretz/asmble](https://github.com/cretz/asmble) project.
+
+## How to use
+
+Apply this plugin to your Gradle project:
+
+```groovy
+plugins {
+    id 'com.athaydes.wasm'
+}
+```
+
+Add `.wasm` (binary) or `wast` (text) WASM files to the `src/main/wasm` directory.
+
+Compile them with `gradle compileWasm`.
+
+Use the generated classes in your Java code.
+
+Compile everything and run it!
+
+## Configuration
+
+Optionally, you can configure how the WASM Plugin behaves:
+
+```groovy
+wasm {
+    // where to find wasm files
+    // (this value is the default, so omit if you don't want to change it)
+    sourceDir = file('src/main/wasm')
+
+    // this is used as the top-level package name for this project.
+    packageName = 'org.mypkg'
+
+    // mappings between WASM file names and desired Java class names.
+    // By default, WASM files are compiled into Java classes with the same name as the files,
+    // without their extension.
+    classNameByFile = [
+            'add.wasm': 'WasmAdder'
+    ]
+}
+```
+
+## Examples
+
+See the [hello-world](examples/hello-world) example to get started real quick!
+
+And the [C-to-WASM-to-JVM](examples/configured-c-to-wasm) example for more advanced usage, such as
+compiling C files to WASM, then using them from Java or other JVM languages, and running it with a single,
+fat jar.

gradle-plugin/build.gradle.kts

@@ -0,0 +1,19 @@
+plugins {
+    id("asmble.java-conventions")
+    `java-gradle-plugin`
+    id("asmble.publish-conventions")
+}
+
+dependencies {
+    implementation(project(":compiler"))
+    testImplementation(project(":annotations"))
+}
+
+gradlePlugin {
+    plugins {
+        create("asmbleGradlePlugin") {
+            id = "eu.aylett.asmble.gradle-plugin"
+            implementationClass = "com.athaydes.wasm.WasmGradlePlugin"
+        }
+    }
+}

gradle-plugin/examples/configured-c-to-wasm/README.md

@@ -0,0 +1,63 @@
+# Compile C to WASM to JVM bytecode Example
+
+This example illustrates two things:
+
+* how to compile C code to WASM via Gradle.
+* how to configure the build to customize package name and class names,
+  regardless of the WASM file name and location.
+
+See the [build.gradle](build.gradle) file for details.
+
+## Requirements
+
+This example requires that you have [LLVM](http://llvm.org/) installed as it will compile C code to WASM using
+the `clang` command.
+
+## Compiling
+
+The `compileC` Gradle task invokes the LLVM compiler to compile C files in
+[src/main/c](src/main/c) to WASM binaries.
+
+The WASM files are saved at `build/compiled-wasm`.
+
+After that, the `compileWasm` task, added by this plugin, compiles the WASM files to Java class
+files, putting them in the standard location `build/classes/wasm/main`.
+
+This directory is automatically added to the `implementation` dependencies of the Gradle project when
+this plugin is applied to it, so the classes are "visible" to Java (and other JVM languages) source code.
+
+To compile everything, run:
+
+```bash
+gradle compileJava
+```
+
+The `compileWasm` task is run automatically.
+
+## Running
+
+To run the `Main` class, which uses compiled C code, the easiest way is to create a fat jar first:
+
+```bash
+gradle fatJar
+```
+
+Then, simply run it with:
+
+```bash
+java -jar build/libs/wasm-example-1.0-SNAPSHOT.jar 2 3
+```
+
+Which should print `5` (showing that the C code is adding `2` and `3` as expected).
+
+<hr/>
+
+Notice that because this example does not have any external dependencies, using the jar produced by the `jar`
+task would still work as well, so a fat jar is not necessary.
+
+You can even run it by simply specifying where the class files are (as in the [hello-world](../hello-world) example)
+and giving the qualified name of the main class:
+
+```bash
+java -cp build/classes/java/main:build/classes/wasm/main com.athaydes.wasm.c.Main 2 3
+```

gradle-plugin/examples/configured-c-to-wasm/build.gradle

@@ -0,0 +1,71 @@
+buildscript {
+    repositories {
+        maven {
+            url "https://plugins.gradle.org/m2/"
+        }
+        flatDir { dir '../../wasm-gradle-plugin/build/libs' }
+    }
+    dependencies {
+        classpath "gradle.plugin.com.athaydes.wasm:wasm-gradle-plugin:1.0"
+
+//        classpath name: "wasm-gradle-plugin-1.0-SNAPSHOT"
+//        classpath 'com.github.cretz.asmble:asmble-compiler:0.3.0'
+    }
+}
+
+apply plugin: "java"
+apply plugin: "com.athaydes.wasm"
+
+group 'com.athaydes.wasm'
+version '1.0-SNAPSHOT'
+
+repositories {
+    jcenter()
+}
+
+final wasmDir = file( "$buildDir/compiled-wasm" )
+
+wasm {
+    // where to find wasm files
+    sourceDir = wasmDir
+
+    // this is used as the top-level package name for this project.
+    packageName = 'com.athaydes.wasm.c'
+
+    // By default, class names are the same as the file names, so for `add.wasm` we would end up with
+    // a class named `add`, which is not very good Java-style.
+    // If the file name had a dash, as in `add-int`, then we wouldn't even be able to use it from Java source code!
+    // But renaming all your wasm files would be a bummer, so this plugin allows you to provide a mapping between
+    // file names and class names, as shown below.
+    // The resulting class is called (packageName + '.' + name), so in this case, the class will be called
+    // com.athaydes.wasm.c.Adder
+    classNameByFile = [
+            'add.wasm': 'Adder'
+    ]
+}
+
+task compileC( description: 'Compiles C sources into WASM binaries' ) {
+    inputs.dir( 'src/main/c' )
+    outputs.dir( wasmDir )
+    compileWasm.dependsOn( 'compileC' )
+
+    doFirst { wasmDir.mkdirs() }
+
+    doLast {
+        exec {
+            // See https://dassur.ma/things/c-to-webassembly/ for details about this
+            commandLine 'clang', '--target=wasm32', '-nostdlib',
+                    '-Wl,--no-entry', '-Wl,--export-all', '-o', "$wasmDir/add.wasm",
+                    'src/main/c/add.c'
+        }
+    }
+}
+
+task fatJar( type: Jar, description: 'Creates a fat, runnable jar for this app' ) {
+    manifest {
+        attributes 'Main-Class': 'com.athaydes.wasm.c.Main'
+    }
+    archiveBaseName = 'wasm-example'
+    from { configurations.runtime.collect { it.isDirectory() ? it : zipTree( it ) } }
+    with jar
+}

gradle-plugin/examples/configured-c-to-wasm/index.html

@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+
+<script type="module">
+  async function init() {
+    const { instance } = await WebAssembly.instantiateStreaming(
+      fetch("build/compiled-wasm/add.wasm")
+    );
+    console.log(instance.exports.add(4, 1));
+  }
+  init();
+</script>

gradle-plugin/examples/configured-c-to-wasm/src/main/c/add.c

@@ -0,0 +1,4 @@
+// Filename: add.c
+int add(int a, int b) {
+  return a + b;
+}

gradle-plugin/examples/configured-c-to-wasm/src/main/java/com/athaydes/wasm/c/Main.java

@@ -0,0 +1,13 @@
+package com.athaydes.wasm.c;
+
+public class Main {
+    public static void main( String[] args ) {
+        if ( args.length != 2 ) {
+            throw new RuntimeException( "Please provide two integer values to be added." );
+        }
+        int a = Integer.parseInt( args[ 0 ] );
+        int b = Integer.parseInt( args[ 1 ] );
+
+        System.out.println( new Adder( 131072 ).add( a, b ) );
+    }
+}

gradle-plugin/examples/hello-world/README.md

@@ -0,0 +1,22 @@
+# Hello World Example
+
+Simplest possible example using the Gradle WASM plugin.
+
+There are only 2 source files:
+
+* [src/main/java/Hello.java](src/main/java/Hello.java)
+* [src/main/wasm/HelloWasm.wast](src/main/wasm/HelloWasm.wast)
+
+To compile, run:
+
+```bash
+gradle compileJava
+```
+
+The `compileWasm` task is run automatically.
+
+To run the `Hello` class, which uses the WASM-derived `HelloWasm` class, run:
+
+```bash
+java -cp build/classes/java/main:build/classes/wasm/main Hello
+```