/*
* Copyright (C) 2009 The Project Lombok Authors.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package lombok.patcher;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import lombok.Getter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
/**
* Method rewriting support class.
*
* MethodLogistics tracks the return type as well as all parameter types, and can tell you exactly where a given parameter
* exists in the local method space. This tracking is non-trivial, as doubles and longs take up 2 spaces, both on the stack
* and in the local method space.
*/
public class MethodLogistics {
private final int staticOffset;
@Getter
private final int returnOpcode;
private final int returnSize;
private final List<Integer> loadOpcodes;
private final List<Integer> paramSizes;
private final List<Integer> paramIndices;
/**
* Creates a new logistics support class given a method descriptor and the access flags.
*
* These can be copied verbatim from what ASM gives you.
*
* @see org.objectweb.asm.ClassVisitor#visitMethod(int, String, String, String, String[])
*/
public MethodLogistics(int accessFlags, String descriptor) {
this.staticOffset = ((accessFlags & Opcodes.ACC_STATIC) != 0) ? 0 : 1;
List<String> specs = MethodTarget.decomposeFullDesc(descriptor);
Iterator<String> it = specs.iterator();
String returnSpec = it.next();
returnSize = sizeOf(returnSpec);
returnOpcode = returnOpcodeFor(returnSpec);
int index = staticOffset;
List<Integer> paramSizes = new ArrayList<Integer>();
List<Integer> paramIndices = new ArrayList<Integer>();
List<Integer> loadOpcodes = new ArrayList<Integer>();
while (it.hasNext()) {
String spec = it.next();
int size = sizeOf(spec);
paramSizes.add(size);
paramIndices.add(index);
loadOpcodes.add(loadOpcodeFor(spec));
index += size;
}
this.paramSizes = Collections.unmodifiableList(paramSizes);
this.paramIndices = Collections.unmodifiableList(paramIndices);
this.loadOpcodes = Collections.unmodifiableList(loadOpcodes);
}
/**
* @return {@code true} if the method is static.
*/
public boolean isStatic() {
return staticOffset == 0;
}
public int getParamCount() {
return this.paramSizes.size();
}
/**
* Writes the opcode to load the i-th parameter to the supplied {@code MethodVisitor}.
*
* @param index 0-based index into the method parameter (the index-th parameter will be loaded).
* @param mv The opcode will be generated in this MethodVisitor object.
*/
public void generateLoadOpcodeForParam(int index, MethodVisitor mv) {
mv.visitVarInsn(loadOpcodes.get(index), paramIndices.get(index));
}
/**
* Writes the opcode to load 'this', or, for static methods, 'null'.
*
* @param mv The opcode will be generated in this MethodVisitor object.
*/
public void generateLoadOpcodeForThis(MethodVisitor mv) {
if (isStatic()) mv.visitInsn(Opcodes.ACONST_NULL);
else mv.visitVarInsn(Opcodes.ALOAD, 0);
}
/**
* Writes the opcode to return from this method.
* Writes the appropriate opcode for this method's return type, so RETURN, ARETURN, IRETURN, LRETURN, FRETURN, or DRETURN.
*
* @param mv The opcode will be generated in this MethodVisitor object.
*/
public void generateReturnOpcode(MethodVisitor mv) {
mv.visitInsn(returnOpcode);
}
/**
* Generates either POP or POP2 depending on the size of the return type - if a value of the return type is on the stack,
* it'll be removed exactly by the generated POP.
*
* @param mv The opcode will be generated in this MethodVisitor object.
*/
public void generatePopForReturn(MethodVisitor mv) {
mv.visitInsn(returnSize == 2 ? Opcodes.POP2 : Opcodes.POP);
}
/**
* Generates either DUP or DUP2 depending on the size of the return type - if a value of the return type is on the stack,
* it'll be duplicated exactly by the generated POP.
*
* @param mv The opcode will be generated in this MethodVisitor object.
*/
public void generateDupForReturn(MethodVisitor mv) {
mv.visitInsn(returnSize == 2 ? Opcodes.DUP2 : Opcodes.DUP);
}
/**
* Generates an instruction to duplicate an object on the stack. The object is of the stated type, in JVM typespec, so
* {@code I} refers to an integer, and {@code Ljava/lang/Object;} would refer to an object.
*
* @param type A type spec in JVM format.
* @param mv This visitor will be given the call to visit DUP2, DUP, or nothing dependent on the type name.
*/
public static void generateDupForType(String type, MethodVisitor mv) {
switch (sizeOf(type)) {
default:
case 1:
mv.visitInsn(Opcodes.DUP);
break;
case 2:
mv.visitInsn(Opcodes.DUP2);
break;
case 0:
//Do nothing
break;
}
}
private static int loadOpcodeFor(String spec) {
switch (spec.charAt(0)) {
case 'D':
return Opcodes.DLOAD;
case 'J':
return Opcodes.LLOAD;
case 'F':
return Opcodes.FLOAD;
case 'I':
case 'S':
case 'B':
case 'Z':
return Opcodes.ILOAD;
case 'V':
throw new IllegalArgumentException("There's no load opcode for 'void'");
case 'L':
case '[':
return Opcodes.ALOAD;
}
throw new IllegalStateException("Uhoh - bug - unrecognized JVM type: " + spec);
}
private static int returnOpcodeFor(String returnSpec) {
switch (returnSpec.charAt(0)) {
case 'D':
return Opcodes.DRETURN;
case 'J':
return Opcodes.LRETURN;
case 'F':
return Opcodes.FRETURN;
case 'I':
case 'S':
case 'B':
case 'Z':
return Opcodes.IRETURN;
case 'V':
return Opcodes.RETURN;
case 'L':
case '[':
return Opcodes.ARETURN;
}
throw new IllegalStateException("Uhoh - bug - unrecognized JVM type: " + returnSpec);
}
private static int sizeOf(String spec) {
switch (spec.charAt(0)) {
case 'D':
case 'J':
return 2;
case 'V':
return 0;
default:
return 1;
}
}
}