| /*** |
| * ASM examples: examples showing how ASM can be used |
| * This example is adapted from the example that you can find in examples/compile |
| * and use invokedynamic to implement all operations. |
| * |
| * Copyright (c) 2000-2011 INRIA, France Telecom |
| * All rights reserved. |
| * |
| * 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. |
| * 3. Neither the name of the copyright holders nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * 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 OWNER 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. |
| */ |
| |
| import static org.objectweb.asm.Opcodes.ACC_PUBLIC; |
| import static org.objectweb.asm.Opcodes.ACC_STATIC; |
| import static org.objectweb.asm.Opcodes.ALOAD; |
| import static org.objectweb.asm.Opcodes.ARETURN; |
| import static org.objectweb.asm.Opcodes.DUP; |
| import static org.objectweb.asm.Opcodes.H_INVOKESTATIC; |
| import static org.objectweb.asm.Opcodes.IFEQ; |
| import static org.objectweb.asm.Opcodes.IFNE; |
| import static org.objectweb.asm.Opcodes.POP; |
| import static org.objectweb.asm.Opcodes.V1_7; |
| |
| import java.io.FileOutputStream; |
| import java.lang.reflect.Method; |
| |
| import org.objectweb.asm.ClassWriter; |
| import org.objectweb.asm.Handle; |
| import org.objectweb.asm.Label; |
| import org.objectweb.asm.MethodVisitor; |
| |
| /** |
| * @author Remi Forax |
| * @author Eric Bruneton |
| */ |
| public class IndyCompile extends ClassLoader { |
| |
| public static void main(final String[] args) throws Throwable { |
| // creates the expression tree corresponding to |
| // exp(i) = i > 3 && 6 > i |
| Exp exp = new And(new GT(new Var(0), new Cst(3)), new GT(new Cst(6), |
| new Var(0))); |
| |
| // compiles this expression into a generic static method in a class |
| IndyCompile main = new IndyCompile(); |
| byte[] b = exp.compile("Example"); |
| FileOutputStream fos = new FileOutputStream("Example.class"); |
| fos.write(b); |
| fos.close(); |
| Class<?> expClass = main.defineClass("Example", b, 0, b.length); |
| Method expMethod = expClass.getDeclaredMethods()[0]; |
| |
| // ... and use it to evaluate exp(0) to exp(9) |
| for (int i = 0; i < 10; ++i) { |
| boolean val = (Boolean) expMethod.invoke(null, i); |
| System.out.println(i + " > 3 && " + i + " < 6 = " + val); |
| } |
| |
| // ... more fun, test with strings !!! |
| for (int i = 0; i < 10; ++i) { |
| boolean val = (Boolean) expMethod.invoke(null, Integer.toString(i)); |
| System.out.println("\"" + i + "\" > 3 && 6 > \"" + i + "\" = " |
| + val); |
| } |
| } |
| |
| /** |
| * An abstract expression. |
| */ |
| static abstract class Exp { |
| |
| static final Handle CST = getHandle("cst", "Ljava/lang/Object;"); |
| |
| static final Handle UNARY = getHandle("unary", ""); |
| |
| static final Handle BINARY = getHandle("binary", ""); |
| |
| /** |
| * Returns the maximum variable index used in this expression. |
| * |
| * @return the maximum variable index used in this expression, or -1 if |
| * no variable is used. |
| */ |
| int getMaxVarIndex() { |
| return -1; |
| } |
| |
| /* |
| * Returns the byte code of a class corresponding to this expression. |
| */ |
| byte[] compile(final String name) { |
| // class header |
| ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES); |
| cw.visit(V1_7, ACC_PUBLIC, name, null, "java/lang/Object", null); |
| |
| // eval method type |
| StringBuilder desc = new StringBuilder("("); |
| for (int i = 0; i <= getMaxVarIndex(); ++i) { |
| desc.append("Ljava/lang/Object;"); |
| } |
| desc.append(")Ljava/lang/Object;"); |
| |
| // eval method |
| MethodVisitor mv = cw.visitMethod(ACC_PUBLIC | ACC_STATIC, "eval", |
| desc.toString(), null, null); |
| compile(mv); |
| mv.visitInsn(ARETURN); |
| // max stack and max locals automatically computed |
| mv.visitMaxs(0, 0); |
| mv.visitEnd(); |
| |
| return cw.toByteArray(); |
| } |
| |
| /* |
| * Compile this expression. This method must append to the given code |
| * writer the byte code that evaluates and pushes on the stack the value |
| * of this expression. |
| */ |
| abstract void compile(MethodVisitor mv); |
| |
| private static Handle getHandle(final String name, final String optArgs) { |
| return new Handle( |
| H_INVOKESTATIC, |
| "RT", |
| name, |
| "(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;" |
| + optArgs + ")Ljava/lang/invoke/CallSite;"); |
| } |
| } |
| |
| /** |
| * A constant expression. |
| */ |
| static class Cst extends Exp { |
| |
| private final Object value; |
| |
| Cst(final Object value) { |
| this.value = value; |
| } |
| |
| @Override |
| void compile(final MethodVisitor mv) { |
| if (value instanceof String) { |
| mv.visitLdcInsn(value); |
| return; |
| } |
| |
| // instead of pushing the constant and then box it, we use |
| // invokedynamic with the constant as bootstrap argument. The |
| // boxing will be performed by the VM when calling the bootstrap |
| // method |
| mv.visitInvokeDynamicInsn("cst", "()Ljava/lang/Object;", CST, value); |
| } |
| } |
| |
| /** |
| * A variable reference expression. |
| */ |
| static class Var extends Exp { |
| |
| final int index; |
| |
| Var(final int index) { |
| this.index = index; |
| } |
| |
| @Override |
| int getMaxVarIndex() { |
| return index; |
| } |
| |
| @Override |
| void compile(final MethodVisitor mv) { |
| // pushes the 'index' local variable onto the stack |
| mv.visitVarInsn(ALOAD, index); |
| } |
| } |
| |
| /** |
| * An abstract binary expression. |
| */ |
| static abstract class BinaryExp extends Exp { |
| |
| final Exp e1; |
| |
| final Exp e2; |
| |
| @Override |
| int getMaxVarIndex() { |
| return Math.max(e1.getMaxVarIndex(), e2.getMaxVarIndex()); |
| } |
| |
| BinaryExp(final Exp e1, final Exp e2) { |
| this.e1 = e1; |
| this.e2 = e2; |
| } |
| } |
| |
| /** |
| * An addition expression. |
| */ |
| static class Add extends BinaryExp { |
| |
| Add(final Exp e1, final Exp e2) { |
| super(e1, e2); |
| } |
| |
| @Override |
| void compile(final MethodVisitor mv) { |
| // compiles e1, e2, and adds an instruction to add the two values |
| e1.compile(mv); |
| e2.compile(mv); |
| mv.visitInvokeDynamicInsn("add", |
| "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;", |
| BINARY); |
| } |
| } |
| |
| /** |
| * A multiplication expression. |
| */ |
| static class Mul extends BinaryExp { |
| |
| Mul(final Exp e1, final Exp e2) { |
| super(e1, e2); |
| } |
| |
| @Override |
| void compile(final MethodVisitor mv) { |
| // compiles e1, e2, and adds an instruction to multiply the two |
| // values |
| e1.compile(mv); |
| e2.compile(mv); |
| mv.visitInvokeDynamicInsn("mul", |
| "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;", |
| BINARY); |
| } |
| } |
| |
| /** |
| * A "greater than" expression. |
| */ |
| static class GT extends BinaryExp { |
| |
| GT(final Exp e1, final Exp e2) { |
| super(e1, e2); |
| } |
| |
| @Override |
| void compile(final MethodVisitor mv) { |
| // compiles e1, e2, and adds the instructions to compare the two |
| // values |
| e1.compile(mv); |
| e2.compile(mv); |
| mv.visitInvokeDynamicInsn("gt", |
| "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;", |
| BINARY); |
| } |
| } |
| |
| /** |
| * A logical "and" expression. |
| */ |
| static class And extends BinaryExp { |
| |
| And(final Exp e1, final Exp e2) { |
| super(e1, e2); |
| } |
| |
| @Override |
| void compile(final MethodVisitor mv) { |
| // compiles e1 |
| e1.compile(mv); |
| // tests if e1 is false |
| mv.visitInsn(DUP); |
| // convert to a boolean |
| mv.visitInvokeDynamicInsn("asBoolean", "(Ljava/lang/Object;)Z", |
| UNARY); |
| |
| Label end = new Label(); |
| mv.visitJumpInsn(IFEQ, end); |
| // case where e1 is true : e1 && e2 is equal to e2 |
| mv.visitInsn(POP); |
| e2.compile(mv); |
| |
| // if e1 is false, e1 && e2 is equal to e1: |
| // we jump directly to this label, without evaluating e2 |
| mv.visitLabel(end); |
| } |
| } |
| |
| /** |
| * A logical "or" expression. |
| */ |
| static class Or extends BinaryExp { |
| |
| Or(final Exp e1, final Exp e2) { |
| super(e1, e2); |
| } |
| |
| @Override |
| void compile(final MethodVisitor mv) { |
| // compiles e1 |
| e1.compile(mv); |
| // tests if e1 is true |
| mv.visitInsn(DUP); |
| // convert to a boolean |
| mv.visitInvokeDynamicInsn("asBoolean", "(Ljava/lang/Object;)Z", |
| UNARY); |
| Label end = new Label(); |
| mv.visitJumpInsn(IFNE, end); |
| // case where e1 is false : e1 || e2 is equal to e2 |
| mv.visitInsn(POP); |
| e2.compile(mv); |
| // if e1 is true, e1 || e2 is equal to e1: |
| // we jump directly to this label, without evaluating e2 |
| mv.visitLabel(end); |
| } |
| } |
| |
| /** |
| * A logical "not" expression. |
| */ |
| static class Not extends Exp { |
| |
| private final Exp e; |
| |
| Not(final Exp e) { |
| this.e = e; |
| } |
| |
| @Override |
| int getMaxVarIndex() { |
| return e.getMaxVarIndex(); |
| } |
| |
| @Override |
| void compile(final MethodVisitor mv) { |
| // compiles e, and applies 'not' |
| e.compile(mv); |
| mv.visitInvokeDynamicInsn("not", |
| "(Ljava/lang/Object;)Ljava/lang/Object;", UNARY); |
| } |
| } |
| } |
