javassist.expr.Cast 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.CannotCompileException;
import javassist.ClassPool;
import javassist.CtBehavior;
import javassist.CtClass;
import javassist.NotFoundException;
import javassist.bytecode.BadBytecode;
import javassist.bytecode.Bytecode;
import javassist.bytecode.CodeAttribute;
import javassist.bytecode.CodeIterator;
import javassist.bytecode.ConstPool;
import javassist.bytecode.MethodInfo;
import javassist.bytecode.Opcode;
import javassist.compiler.CompileError;
import javassist.compiler.Javac;
import javassist.compiler.JvstCodeGen;
import javassist.compiler.JvstTypeChecker;
import javassist.compiler.ProceedHandler;
import javassist.compiler.ast.ASTList;
/**
* Explicit type cast.
*/
public class Cast extends Expr {
/**
* Undocumented constructor. Do not use; internal-use only.
*/
protected Cast(int pos, CodeIterator i, CtClass declaring, MethodInfo m) {
super(pos, i, declaring, m);
}
/**
* Returns the method or constructor containing the type cast
* expression represented by this object.
*/
@Override
public CtBehavior where() { return super.where(); }
/**
* Returns the line number of the source line containing the
* type-cast expression.
*
* @return -1 if this information is not available.
*/
@Override
public int getLineNumber() {
return super.getLineNumber();
}
/**
* Returns the source file containing the type-cast expression.
*
* @return null if this information is not available.
*/
@Override
public String getFileName() {
return super.getFileName();
}
/**
* Returns the CtClass object representing
* the type specified by the cast.
*/
public CtClass getType() throws NotFoundException {
ConstPool cp = getConstPool();
int pos = currentPos;
int index = iterator.u16bitAt(pos + 1);
String name = cp.getClassInfo(index);
return thisClass.getClassPool().getCtClass(name);
}
/**
* 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.
*/
@Override
public CtClass[] mayThrow() {
return super.mayThrow();
}
/**
* Replaces the explicit cast operator 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.
*/
@Override
public void replace(String statement) throws CannotCompileException {
thisClass.getClassFile(); // to call checkModify().
@SuppressWarnings("unused")
ConstPool constPool = getConstPool();
int pos = currentPos;
int index = iterator.u16bitAt(pos + 1);
Javac jc = new Javac(thisClass);
ClassPool cp = thisClass.getClassPool();
CodeAttribute ca = iterator.get();
try {
CtClass[] params
= new CtClass[] { cp.get(javaLangObject) };
CtClass retType = getType();
int paramVar = ca.getMaxLocals();
jc.recordParams(javaLangObject, params, true, paramVar,
withinStatic());
int retVar = jc.recordReturnType(retType, true);
jc.recordProceed(new ProceedForCast(index, retType));
/* Is $_ included in the source code?
*/
checkResultValue(retType, statement);
Bytecode bytecode = jc.getBytecode();
storeStack(params, true, paramVar, bytecode);
jc.recordLocalVariables(ca, pos);
bytecode.addConstZero(retType);
bytecode.addStore(retVar, retType); // initialize $_
jc.compileStmnt(statement);
bytecode.addLoad(retVar, retType);
replace0(pos, bytecode, 3);
}
catch (CompileError e) { throw new CannotCompileException(e); }
catch (NotFoundException e) { throw new CannotCompileException(e); }
catch (BadBytecode e) {
throw new CannotCompileException("broken method");
}
}
/* $proceed(Object obj)
*/
static class ProceedForCast implements ProceedHandler {
int index;
CtClass retType;
ProceedForCast(int i, CtClass t) {
index = i;
retType = t;
}
@Override
public void doit(JvstCodeGen gen, Bytecode bytecode, ASTList args)
throws CompileError
{
if (gen.getMethodArgsLength(args) != 1)
throw new CompileError(Javac.proceedName
+ "() cannot take more than one parameter "
+ "for cast");
gen.atMethodArgs(args, new int[1], new int[1], new String[1]);
bytecode.addOpcode(Opcode.CHECKCAST);
bytecode.addIndex(index);
gen.setType(retType);
}
@Override
public void setReturnType(JvstTypeChecker c, ASTList args)
throws CompileError
{
c.atMethodArgs(args, new int[1], new int[1], new String[1]);
c.setType(retType);
}
}
}