javassist.expr.NewExpr Maven / Gradle / Ivy
/*
* Javassist, a Java-bytecode translator toolkit.
* Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. Alternatively, the contents of this file may be used under
* the terms of the GNU Lesser General Public License Version 2.1 or later,
* or the Apache License Version 2.0.
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*/
package javassist.expr;
import javassist.*;
import javassist.bytecode.*;
import javassist.compiler.*;
import javassist.compiler.ast.ASTList;
/**
* Object creation (new expression).
*/
public class NewExpr extends Expr {
String newTypeName;
int newPos;
/**
* Undocumented constructor. Do not use; internal-use only.
*/
protected NewExpr(int pos, CodeIterator i, CtClass declaring,
MethodInfo m, String type, int np) {
super(pos, i, declaring, m);
newTypeName = type;
newPos = np;
}
/*
* Not used
*
private int getNameAndType(ConstPool cp) {
int pos = currentPos;
int c = iterator.byteAt(pos);
int index = iterator.u16bitAt(pos + 1);
if (c == INVOKEINTERFACE)
return cp.getInterfaceMethodrefNameAndType(index);
else
return cp.getMethodrefNameAndType(index);
} */
/**
* Returns the method or constructor containing the new
* expression represented by this object.
*/
public CtBehavior where() { return super.where(); }
/**
* Returns the line number of the source line containing the
* new expression.
*
* @return -1 if this information is not available.
*/
public int getLineNumber() {
return super.getLineNumber();
}
/**
* Returns the source file containing the new expression.
*
* @return null if this information is not available.
*/
public String getFileName() {
return super.getFileName();
}
/**
* Returns the class of the created object.
*/
private CtClass getCtClass() throws NotFoundException {
return thisClass.getClassPool().get(newTypeName);
}
/**
* Returns the class name of the created object.
*/
public String getClassName() {
return newTypeName;
}
/**
* Get the signature of the constructor
*
* The signature is represented by a character string
* called method descriptor, which is defined in the JVM specification.
*
* @see javassist.CtBehavior#getSignature()
* @see javassist.bytecode.Descriptor
* @return the signature
*/
public String getSignature() {
ConstPool constPool = getConstPool();
int methodIndex = iterator.u16bitAt(currentPos + 1); // constructor
return constPool.getMethodrefType(methodIndex);
}
/**
* Returns the constructor called for creating the object.
*/
public CtConstructor getConstructor() throws NotFoundException {
ConstPool cp = getConstPool();
int index = iterator.u16bitAt(currentPos + 1);
String desc = cp.getMethodrefType(index);
return getCtClass().getConstructor(desc);
}
/**
* Returns the list of exceptions that the expression may throw.
* This list includes both the exceptions that the try-catch statements
* including the expression can catch and the exceptions that
* the throws declaration allows the method to throw.
*/
public CtClass[] mayThrow() {
return super.mayThrow();
}
/*
* Returns the parameter types of the constructor.
public CtClass[] getParameterTypes() throws NotFoundException {
ConstPool cp = getConstPool();
int index = iterator.u16bitAt(currentPos + 1);
String desc = cp.getMethodrefType(index);
return Descriptor.getParameterTypes(desc, thisClass.getClassPool());
}
*/
private int canReplace() throws CannotCompileException {
int op = iterator.byteAt(newPos + 3);
if (op == Opcode.DUP) // Typical single DUP or Javaflow DUP DUP2_X2 POP2
return ((iterator.byteAt(newPos + 4) == Opcode.DUP2_X2
&& iterator.byteAt(newPos + 5) == Opcode.POP2)) ? 6 : 4;
else if (op == Opcode.DUP_X1
&& iterator.byteAt(newPos + 4) == Opcode.SWAP)
return 5;
else
return 3; // for Eclipse. The generated code may include no DUP.
// throw new CannotCompileException(
// "sorry, cannot edit NEW followed by no DUP");
}
/**
* Replaces the new expression with the bytecode derived from
* the given source text.
*
* $0 is available but the value is null.
*
* @param statement a Java statement except try-catch.
*/
public void replace(String statement) throws CannotCompileException {
thisClass.getClassFile(); // to call checkModify().
final int bytecodeSize = 3;
int pos = newPos;
int newIndex = iterator.u16bitAt(pos + 1);
/* delete the preceding NEW and DUP (or DUP_X1, SWAP) instructions.
*/
int codeSize = canReplace();
int end = pos + codeSize;
for (int i = pos; i < end; ++i)
iterator.writeByte(NOP, i);
ConstPool constPool = getConstPool();
pos = currentPos;
int methodIndex = iterator.u16bitAt(pos + 1); // constructor
String signature = constPool.getMethodrefType(methodIndex);
Javac jc = new Javac(thisClass);
ClassPool cp = thisClass.getClassPool();
CodeAttribute ca = iterator.get();
try {
CtClass[] params = Descriptor.getParameterTypes(signature, cp);
CtClass newType = cp.get(newTypeName);
int paramVar = ca.getMaxLocals();
jc.recordParams(newTypeName, params,
true, paramVar, withinStatic());
int retVar = jc.recordReturnType(newType, true);
jc.recordProceed(new ProceedForNew(newType, newIndex,
methodIndex));
/* Is $_ included in the source code?
*/
checkResultValue(newType, statement);
Bytecode bytecode = jc.getBytecode();
storeStack(params, true, paramVar, bytecode);
jc.recordLocalVariables(ca, pos);
bytecode.addConstZero(newType);
bytecode.addStore(retVar, newType); // initialize $_
jc.compileStmnt(statement);
if (codeSize > 3) // if the original code includes DUP.
bytecode.addAload(retVar);
replace0(pos, bytecode, bytecodeSize);
}
catch (CompileError e) { throw new CannotCompileException(e); }
catch (NotFoundException e) { throw new CannotCompileException(e); }
catch (BadBytecode e) {
throw new CannotCompileException("broken method");
}
}
static class ProceedForNew implements ProceedHandler {
CtClass newType;
int newIndex, methodIndex;
ProceedForNew(CtClass nt, int ni, int mi) {
newType = nt;
newIndex = ni;
methodIndex = mi;
}
public void doit(JvstCodeGen gen, Bytecode bytecode, ASTList args)
throws CompileError
{
bytecode.addOpcode(NEW);
bytecode.addIndex(newIndex);
bytecode.addOpcode(DUP);
gen.atMethodCallCore(newType, MethodInfo.nameInit, args,
false, true, -1, null);
gen.setType(newType);
}
public void setReturnType(JvstTypeChecker c, ASTList args)
throws CompileError
{
c.atMethodCallCore(newType, MethodInfo.nameInit, args);
c.setType(newType);
}
}
}