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/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.dev.shell.rewrite;
import com.google.gwt.dev.shell.JavaScriptHost;
import com.google.gwt.dev.util.Name.InternalName;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.commons.GeneratorAdapter;
import org.objectweb.asm.commons.Method;
import java.lang.reflect.Modifier;
import java.util.Locale;
import java.util.Map;
/**
* Turns native method declarations into normal Java functions which perform the
* corresponding JSNI dispatch.
*/
public class RewriteJsniMethods extends ClassVisitor {
/**
* Fast way to look up boxing methods.
*/
private static class Boxing {
/**
* A matching list of boxed types for each primitive type.
*/
private static final Type[] BOXED_TYPES = new Type[] {
VOID_TYPE, BOOLEAN_TYPE, CHARACTER_TYPE, BYTE_TYPE, SHORT_TYPE,
INTEGER_TYPE, FLOAT_TYPE, LONG_TYPE, DOUBLE_TYPE,};
/**
* The list of primitive types.
*/
private static final Type[] PRIMITIVE_TYPES = new Type[] {
Type.VOID_TYPE, Type.BOOLEAN_TYPE, Type.CHAR_TYPE, Type.BYTE_TYPE,
Type.SHORT_TYPE, Type.INT_TYPE, Type.FLOAT_TYPE, Type.LONG_TYPE,
Type.DOUBLE_TYPE,};
/**
* A map of Type.sort() to valueOf Method. There are 11 possible results
* from Type.sort(), 0 through 10.
*/
private static final Method[] SORT_MAP = new Method[11];
static {
assert PRIMITIVE_TYPES.length == BOXED_TYPES.length;
for (int i = 0; i < PRIMITIVE_TYPES.length; ++i) {
Type primitive = PRIMITIVE_TYPES[i];
Type boxed = BOXED_TYPES[i];
if (boxed != null) {
SORT_MAP[i] = new Method("valueOf", boxed, new Type[] {primitive});
}
}
}
public static Method getBoxMethod(Type type) {
int sortType = type.getSort();
assert (sortType >= 0 && sortType < SORT_MAP.length) : "Unexpected JavaScriptHostInfo.get index - "
+ sortType;
return SORT_MAP[sortType];
}
}
/**
* Oracle for info regarding {@link JavaScriptHost}.
*/
private static class JavaScriptHostInfo {
/**
* The {@link JavaScriptHost} type.
*/
public static final Type TYPE = Type.getType(JavaScriptHost.class);
/**
* The parameter signature of {@link JavaScriptHost}'s invoke* methods, in
* classes.
*/
private static final Class[] INVOKE_NATIVE_PARAM_CLASSES = new Class[] {
String.class, Object.class, Class[].class, Object[].class,};
/**
* The parameter signature of {@link JavaScriptHost}'s invoke* methods, in
* types.
*/
private static final Type[] INVOKE_NATIVE_PARAM_TYPES;
/**
* A map of Type.sort() to JavaScriptHostInfo.
*/
private static final JavaScriptHostInfo[] SORT_MAP = new JavaScriptHostInfo[11];
static {
INVOKE_NATIVE_PARAM_TYPES = new Type[INVOKE_NATIVE_PARAM_CLASSES.length];
for (int i = 0; i < INVOKE_NATIVE_PARAM_TYPES.length; ++i) {
INVOKE_NATIVE_PARAM_TYPES[i] = Type.getType(INVOKE_NATIVE_PARAM_CLASSES[i]);
}
Class[] primitives = {
void.class, boolean.class, byte.class, char.class, short.class,
int.class, long.class, float.class, double.class};
for (Class c : primitives) {
Type type = Type.getType(c);
String typeName = type.getClassName();
String firstChar = typeName.substring(0, 1).toUpperCase(Locale.ROOT);
typeName = firstChar + typeName.substring(1);
SORT_MAP[type.getSort()] = new JavaScriptHostInfo(type, "invokeNative"
+ typeName);
}
JavaScriptHostInfo objectType = new JavaScriptHostInfo(
Type.getType(Object.class), "invokeNativeObject", true);
SORT_MAP[Type.ARRAY] = objectType;
SORT_MAP[Type.OBJECT] = objectType;
assert noNulls(SORT_MAP) : "Did not fully fill in JavaScriptHostInfo.SORT_MAP";
}
public static JavaScriptHostInfo get(int sortType) {
assert (sortType >= 0 && sortType < SORT_MAP.length) : "Unexpected JavaScriptHostInfo.get index - "
+ sortType;
return SORT_MAP[sortType];
}
/**
* Validate our model against the real JavaScriptHost class.
*/
private static boolean matchesRealMethod(String methodName, Type returnType) {
try {
java.lang.reflect.Method method = JavaScriptHost.class.getDeclaredMethod(
methodName, INVOKE_NATIVE_PARAM_CLASSES);
assert (method.getModifiers() & Modifier.STATIC) != 0 : "Was expecting method '"
+ method + "' to be static";
Type realReturnType = Type.getType(method.getReturnType());
return realReturnType.getDescriptor().equals(returnType.getDescriptor());
} catch (SecurityException e) {
} catch (NoSuchMethodException e) {
}
return false;
}
private static boolean noNulls(Object[] array) {
for (Object element : array) {
if (element == null) {
return false;
}
}
return true;
}
private final Method method;
private final boolean requiresCast;
private JavaScriptHostInfo(Type returnType, String methodName) {
this(returnType, methodName, false);
}
private JavaScriptHostInfo(Type returnType, String methodName,
boolean requiresCast) {
this.requiresCast = requiresCast;
this.method = new Method(methodName, returnType,
INVOKE_NATIVE_PARAM_TYPES);
assert matchesRealMethod(methodName, returnType) : "JavaScriptHostInfo for '"
+ this + "' does not match real method";
}
public Method getMethod() {
return method;
}
public boolean requiresCast() {
return requiresCast;
}
@Override
public String toString() {
return method.toString();
}
}
/**
* Rewrites native Java methods to dispatch as JSNI.
*/
private class MyMethodAdapter extends GeneratorAdapter {
private String descriptor;
private boolean isStatic;
private String name;
public MyMethodAdapter(MethodVisitor mv, int access, String name,
String desc) {
super(Opcodes.ASM5, mv, access, name, desc);
this.descriptor = desc;
this.name = name;
isStatic = (access & Opcodes.ACC_STATIC) != 0;
}
/**
* Replacement for {@link GeneratorAdapter#box(Type)}, which always calls,
* for example, {@code new Boolean} instead of using
* {@link Boolean#valueOf(boolean)}.
*/
@Override
public void box(Type type) {
Method method = Boxing.getBoxMethod(type);
if (method != null) {
invokeStatic(method.getReturnType(), method);
}
}
/**
* Does all of the work necessary to do the dispatch to the appropriate
* variant of {@link JavaScriptHost#invokeNativeVoid
* JavaScriptHost.invokeNative*}. And example output:
*
*
* return JavaScriptHost.invokeNativeInt(
* "@com.google.gwt.sample.hello.client.Hello::echo(I)", null,
* new Class[] {int.class,}, new Object[] {x,});
*
*/
@Override
public void visitCode() {
super.visitCode();
/*
* If you modify the generated code, you must recompute the stack size in
* visitEnd().
*/
// First argument - JSNI signature
String jsniTarget = getJsniSignature(name, descriptor);
visitLdcInsn(jsniTarget);
// Stack is at 1
// Second argument - target; "null" if static, otherwise "this".
if (isStatic) {
visitInsn(Opcodes.ACONST_NULL);
} else {
loadThis();
}
// Stack is at 2
// Third argument - a Class[] describing the types of this method
loadClassArray();
// Stack is at 3; reaches 6 internally
// Fourth argument - all the arguments boxed into an Object[]
loadArgArray();
// Stack is at 4; reaches 7 or 8 internally (long/double takes 2)
// Invoke the matching JavaScriptHost.invokeNative* method
Type returnType = Type.getReturnType(descriptor);
JavaScriptHostInfo info = JavaScriptHostInfo.get(returnType.getSort());
invokeStatic(JavaScriptHostInfo.TYPE, info.getMethod());
// Stack is at 1
if (info.requiresCast()) {
checkCast(returnType);
}
returnValue();
// Stack is at 0
}
@Override
public void visitEnd() {
// Force code to be visited; required since this was a native method.
visitCode();
/*
* For speed, we don't ask ASM to COMPUTE_MAXS. We manually calculated a
* max depth of 8.
*
* Also, when tobyr tried getting ASM to compute the correct stack size,
* ASM seemed to compute the wrong value for reasons we don't understand.
*/
int maxStack = 8;
int maxLocals = 0; // Computed by GeneratorAdapter superclass.
super.visitMaxs(maxStack, maxLocals);
super.visitEnd();
}
private void loadClassArray() {
Type[] argTypes = Type.getArgumentTypes(descriptor);
push(argTypes.length);
newArray(CLASS_TYPE);
// Stack is at 3
for (int i = 0; i < argTypes.length; ++i) {
dup();
push(i);
push(argTypes[i]);
arrayStore(CLASS_TYPE);
}
}
}
private static final Type BOOLEAN_TYPE = Type.getObjectType("java/lang/Boolean");
private static final Type BYTE_TYPE = Type.getObjectType("java/lang/Byte");
private static final Type CHARACTER_TYPE = Type.getObjectType("java/lang/Character");
private static final Type CLASS_TYPE = Type.getObjectType("java/lang/Class");
private static final Type DOUBLE_TYPE = Type.getObjectType("java/lang/Double");
private static final Type FLOAT_TYPE = Type.getObjectType("java/lang/Float");
private static final Type INTEGER_TYPE = Type.getObjectType("java/lang/Integer");
private static final Type LONG_TYPE = Type.getObjectType("java/lang/Long");
private static final Type SHORT_TYPE = Type.getObjectType("java/lang/Short");
private static final Type VOID_TYPE = Type.getObjectType("java/lang/Void");
/**
* The internal name of the class we're operating on.
*/
private String classDesc;
private Map anonymousClassMap;
public RewriteJsniMethods(ClassVisitor v,
Map anonymousClassMap) {
super(Opcodes.ASM5, v);
this.anonymousClassMap = anonymousClassMap;
}
@Override
public void visit(final int version, final int access, final String name,
final String signature, final String superName, final String[] interfaces) {
this.classDesc = name;
super.visit(version, access, name, signature, superName, interfaces);
}
@Override
public MethodVisitor visitMethod(int access, String name, String desc,
String signature, String[] exceptions) {
boolean isNative = (access & Opcodes.ACC_NATIVE) != 0;
access &= ~Opcodes.ACC_NATIVE;
MethodVisitor mv = super.visitMethod(access, name, desc, signature,
exceptions);
if (isNative) {
mv = new MyMethodAdapter(mv, access, name, desc);
}
return mv;
}
/**
* Returns the JSNI signature describing the method.
*
* @param name the name of the method; for example {@code "echo"}
* @param descriptor the descriptor for the method; for example {@code "(I)I"}
* @return the JSNI signature for the method; for example, {@code
* "@com.google.gwt.sample.hello.client.Hello::echo(I)"}
*/
private String getJsniSignature(String name, String descriptor) {
int argsIndexBegin = descriptor.indexOf('(');
int argsIndexEnd = descriptor.indexOf(')');
assert argsIndexBegin != -1 && argsIndexEnd != -1
&& argsIndexBegin < argsIndexEnd : "Could not find the arguments in the descriptor, "
+ descriptor;
String argsDescriptor = descriptor.substring(argsIndexBegin,
argsIndexEnd + 1);
String classDescriptor = InternalName.toBinaryName(classDesc);
String newDescriptor = anonymousClassMap.get(classDesc);
if (newDescriptor != null) {
classDescriptor = InternalName.toBinaryName(newDescriptor);
}
// Always use binary names for JSNI method names
return "@" + classDescriptor + "::" + name + argsDescriptor;
}
}
