org.mozilla.javascript.FunctionObject Maven / Gradle / Ivy
/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
// API class
package org.mozilla.javascript;
import java.lang.reflect.*;
import java.io.*;
public class FunctionObject extends BaseFunction
{
static final long serialVersionUID = -5332312783643935019L;
/**
* Create a JavaScript function object from a Java method.
*
* The member argument must be either a java.lang.reflect.Method
* or a java.lang.reflect.Constructor and must match one of two forms.
*
* The first form is a member with zero or more parameters
* of the following types: Object, String, boolean, Scriptable,
* int, or double. The Long type is not supported
* because the double representation of a long (which is the
* EMCA-mandated storage type for Numbers) may lose precision.
* If the member is a Method, the return value must be void or one
* of the types allowed for parameters.
*
* The runtime will perform appropriate conversions based
* upon the type of the parameter. A parameter type of
* Object specifies that no conversions are to be done. A parameter
* of type String will use Context.toString to convert arguments.
* Similarly, parameters of type double, boolean, and Scriptable
* will cause Context.toNumber, Context.toBoolean, and
* Context.toObject, respectively, to be called.
*
* If the method is not static, the Java 'this' value will
* correspond to the JavaScript 'this' value. Any attempt
* to call the function with a 'this' value that is not
* of the right Java type will result in an error.
*
* The second form is the variable arguments (or "varargs")
* form. If the FunctionObject will be used as a constructor,
* the member must have the following parameters
*
* (Context cx, Object[] args, Function ctorObj,
* boolean inNewExpr)
* and if it is a Method, be static and return an Object result.
*
* Otherwise, if the FunctionObject will not be used to define a
* constructor, the member must be a static Method with parameters
*
* (Context cx, Scriptable thisObj, Object[] args,
* Function funObj)
* and an Object result.
*
* When the function varargs form is called as part of a function call,
* the args parameter contains the
* arguments, with thisObj
* set to the JavaScript 'this' value. funObj
* is the function object for the invoked function.
*
* When the constructor varargs form is called or invoked while evaluating
* a new expression, args contains the
* arguments, ctorObj refers to this FunctionObject, and
* inNewExpr is true if and only if a new
* expression caused the call. This supports defining a function that
* has different behavior when called as a constructor than when
* invoked as a normal function call. (For example, the Boolean
* constructor, when called as a function,
* will convert to boolean rather than creating a new object.)
*
* @param name the name of the function
* @param methodOrConstructor a java.lang.reflect.Method or a java.lang.reflect.Constructor
* that defines the object
* @param scope enclosing scope of function
* @see org.mozilla.javascript.Scriptable
*/
public FunctionObject(String name, Member methodOrConstructor,
Scriptable scope)
{
if (methodOrConstructor instanceof Constructor) {
member = new MemberBox((Constructor) methodOrConstructor);
isStatic = true; // well, doesn't take a 'this'
} else {
member = new MemberBox((Method) methodOrConstructor);
isStatic = member.isStatic();
}
String methodName = member.getName();
this.functionName = name;
Class[] types = member.argTypes;
int arity = types.length;
if (arity == 4 && (types[1].isArray() || types[2].isArray())) {
// Either variable args or an error.
if (types[1].isArray()) {
if (!isStatic ||
types[0] != ScriptRuntime.ContextClass ||
types[1].getComponentType() != ScriptRuntime.ObjectClass ||
types[2] != ScriptRuntime.FunctionClass ||
types[3] != Boolean.TYPE)
{
throw Context.reportRuntimeError1(
"msg.varargs.ctor", methodName);
}
parmsLength = VARARGS_CTOR;
} else {
if (!isStatic ||
types[0] != ScriptRuntime.ContextClass ||
types[1] != ScriptRuntime.ScriptableClass ||
types[2].getComponentType() != ScriptRuntime.ObjectClass ||
types[3] != ScriptRuntime.FunctionClass)
{
throw Context.reportRuntimeError1(
"msg.varargs.fun", methodName);
}
parmsLength = VARARGS_METHOD;
}
} else {
parmsLength = arity;
if (arity > 0) {
typeTags = new byte[arity];
for (int i = 0; i != arity; ++i) {
int tag = getTypeTag(types[i]);
if (tag == JAVA_UNSUPPORTED_TYPE) {
throw Context.reportRuntimeError2(
"msg.bad.parms", types[i].getName(), methodName);
}
typeTags[i] = (byte)tag;
}
}
}
if (member.isMethod()) {
Method method = member.method();
Class returnType = method.getReturnType();
if (returnType == Void.TYPE) {
hasVoidReturn = true;
} else {
returnTypeTag = getTypeTag(returnType);
}
} else {
Class ctorType = member.getDeclaringClass();
if (!ScriptRuntime.ScriptableClass.isAssignableFrom(ctorType)) {
throw Context.reportRuntimeError1(
"msg.bad.ctor.return", ctorType.getName());
}
}
ScriptRuntime.setFunctionProtoAndParent(this, scope);
}
/**
* @return One of JAVA_*_TYPE constants to indicate desired type
* or {@link #JAVA_UNSUPPORTED_TYPE} if the convertion is not
* possible
*/
public static int getTypeTag(Class type)
{
if (type == ScriptRuntime.StringClass)
return JAVA_STRING_TYPE;
if (type == ScriptRuntime.IntegerClass || type == Integer.TYPE)
return JAVA_INT_TYPE;
if (type == ScriptRuntime.BooleanClass || type == Boolean.TYPE)
return JAVA_BOOLEAN_TYPE;
if (type == ScriptRuntime.DoubleClass || type == Double.TYPE)
return JAVA_DOUBLE_TYPE;
if (ScriptRuntime.ScriptableClass.isAssignableFrom(type))
return JAVA_SCRIPTABLE_TYPE;
if (type == ScriptRuntime.ObjectClass)
return JAVA_OBJECT_TYPE;
// Note that the long type is not supported; see the javadoc for
// the constructor for this class
return JAVA_UNSUPPORTED_TYPE;
}
public static Object convertArg(Context cx, Scriptable scope,
Object arg, int typeTag)
{
switch (typeTag) {
case JAVA_STRING_TYPE:
if (arg instanceof String)
return arg;
return ScriptRuntime.toString(arg);
case JAVA_INT_TYPE:
if (arg instanceof Integer)
return arg;
return Integer.valueOf(ScriptRuntime.toInt32(arg));
case JAVA_BOOLEAN_TYPE:
if (arg instanceof Boolean)
return arg;
return ScriptRuntime.toBoolean(arg) ? Boolean.TRUE
: Boolean.FALSE;
case JAVA_DOUBLE_TYPE:
if (arg instanceof Double)
return arg;
return new Double(ScriptRuntime.toNumber(arg));
case JAVA_SCRIPTABLE_TYPE:
return ScriptRuntime.toObjectOrNull(cx, arg, scope);
case JAVA_OBJECT_TYPE:
return arg;
default:
throw new IllegalArgumentException();
}
}
/**
* Return the value defined by the method used to construct the object
* (number of parameters of the method, or 1 if the method is a "varargs"
* form).
*/
@Override
public int getArity() {
return parmsLength < 0 ? 1 : parmsLength;
}
/**
* Return the same value as {@link #getArity()}.
*/
@Override
public int getLength() {
return getArity();
}
@Override
public String getFunctionName()
{
return (functionName == null) ? "" : functionName;
}
/**
* Get Java method or constructor this function represent.
*/
public Member getMethodOrConstructor()
{
if (member.isMethod()) {
return member.method();
} else {
return member.ctor();
}
}
static Method findSingleMethod(Method[] methods, String name)
{
Method found = null;
for (int i = 0, N = methods.length; i != N; ++i) {
Method method = methods[i];
if (method != null && name.equals(method.getName())) {
if (found != null) {
throw Context.reportRuntimeError2(
"msg.no.overload", name,
method.getDeclaringClass().getName());
}
found = method;
}
}
return found;
}
/**
* Returns all public methods declared by the specified class. This excludes
* inherited methods.
*
* @param clazz the class from which to pull public declared methods
* @return the public methods declared in the specified class
* @see Class#getDeclaredMethods()
*/
static Method[] getMethodList(Class clazz) {
Method[] methods = null;
try {
// getDeclaredMethods may be rejected by the security manager
// but getMethods is more expensive
if (!sawSecurityException)
methods = clazz.getDeclaredMethods();
} catch (SecurityException e) {
// If we get an exception once, give up on getDeclaredMethods
sawSecurityException = true;
}
if (methods == null) {
methods = clazz.getMethods();
}
int count = 0;
for (int i=0; i < methods.length; i++) {
if (sawSecurityException
? methods[i].getDeclaringClass() != clazz
: !Modifier.isPublic(methods[i].getModifiers()))
{
methods[i] = null;
} else {
count++;
}
}
Method[] result = new Method[count];
int j=0;
for (int i=0; i < methods.length; i++) {
if (methods[i] != null)
result[j++] = methods[i];
}
return result;
}
/**
* Define this function as a JavaScript constructor.
*
* Sets up the "prototype" and "constructor" properties. Also
* calls setParent and setPrototype with appropriate values.
* Then adds the function object as a property of the given scope, using
* prototype.getClassName()
* as the name of the property.
*
* @param scope the scope in which to define the constructor (typically
* the global object)
* @param prototype the prototype object
* @see org.mozilla.javascript.Scriptable#setParentScope
* @see org.mozilla.javascript.Scriptable#setPrototype
* @see org.mozilla.javascript.Scriptable#getClassName
*/
public void addAsConstructor(Scriptable scope, Scriptable prototype)
{
initAsConstructor(scope, prototype);
defineProperty(scope, prototype.getClassName(),
this, ScriptableObject.DONTENUM);
}
void initAsConstructor(Scriptable scope, Scriptable prototype)
{
ScriptRuntime.setFunctionProtoAndParent(this, scope);
setImmunePrototypeProperty(prototype);
prototype.setParentScope(this);
defineProperty(prototype, "constructor", this,
ScriptableObject.DONTENUM |
ScriptableObject.PERMANENT |
ScriptableObject.READONLY);
setParentScope(scope);
}
/**
* @deprecated Use {@link #getTypeTag(Class)}
* and {@link #convertArg(Context, Scriptable, Object, int)}
* for type conversion.
*/
@Deprecated
public static Object convertArg(Context cx, Scriptable scope,
Object arg, Class desired)
{
int tag = getTypeTag(desired);
if (tag == JAVA_UNSUPPORTED_TYPE) {
throw Context.reportRuntimeError1
("msg.cant.convert", desired.getName());
}
return convertArg(cx, scope, arg, tag);
}
/**
* Performs conversions on argument types if needed and
* invokes the underlying Java method or constructor.
*
* Implements Function.call.
*
* @see org.mozilla.javascript.Function#call(
* Context, Scriptable, Scriptable, Object[])
*/
@Override
public Object call(Context cx, Scriptable scope, Scriptable thisObj,
Object[] args)
{
Object result;
boolean checkMethodResult = false;
int argsLength = args.length;
for (int i = 0; i < argsLength; i++) {
// flatten cons-strings before passing them as arguments
if (args[i] instanceof ConsString) {
args[i] = args[i].toString();
}
}
if (parmsLength < 0) {
if (parmsLength == VARARGS_METHOD) {
Object[] invokeArgs = { cx, thisObj, args, this };
result = member.invoke(null, invokeArgs);
checkMethodResult = true;
} else {
boolean inNewExpr = (thisObj == null);
Boolean b = inNewExpr ? Boolean.TRUE : Boolean.FALSE;
Object[] invokeArgs = { cx, args, this, b };
result = (member.isCtor())
? member.newInstance(invokeArgs)
: member.invoke(null, invokeArgs);
}
} else {
if (!isStatic) {
Class clazz = member.getDeclaringClass();
if (!clazz.isInstance(thisObj)) {
boolean compatible = false;
if (thisObj == scope) {
Scriptable parentScope = getParentScope();
if (scope != parentScope) {
// Call with dynamic scope for standalone function,
// use parentScope as thisObj
compatible = clazz.isInstance(parentScope);
if (compatible) {
thisObj = parentScope;
}
}
}
if (!compatible) {
// Couldn't find an object to call this on.
throw ScriptRuntime.typeError1("msg.incompat.call",
functionName);
}
}
}
Object[] invokeArgs;
if (parmsLength == argsLength) {
// Do not allocate new argument array if java arguments are
// the same as the original js ones.
invokeArgs = args;
for (int i = 0; i != parmsLength; ++i) {
Object arg = args[i];
Object converted = convertArg(cx, scope, arg, typeTags[i]);
if (arg != converted) {
if (invokeArgs == args) {
invokeArgs = args.clone();
}
invokeArgs[i] = converted;
}
}
} else if (parmsLength == 0) {
invokeArgs = ScriptRuntime.emptyArgs;
} else {
invokeArgs = new Object[parmsLength];
for (int i = 0; i != parmsLength; ++i) {
Object arg = (i < argsLength)
? args[i]
: Undefined.instance;
invokeArgs[i] = convertArg(cx, scope, arg, typeTags[i]);
}
}
if (member.isMethod()) {
result = member.invoke(thisObj, invokeArgs);
checkMethodResult = true;
} else {
result = member.newInstance(invokeArgs);
}
}
if (checkMethodResult) {
if (hasVoidReturn) {
result = Undefined.instance;
} else if (returnTypeTag == JAVA_UNSUPPORTED_TYPE) {
result = cx.getWrapFactory().wrap(cx, scope, result, null);
}
// XXX: the code assumes that if returnTypeTag == JAVA_OBJECT_TYPE
// then the Java method did a proper job of converting the
// result to JS primitive or Scriptable to avoid
// potentially costly Context.javaToJS call.
}
return result;
}
/**
* Return new {@link Scriptable} instance using the default
* constructor for the class of the underlying Java method.
* Return null to indicate that the call method should be used to create
* new objects.
*/
@Override
public Scriptable createObject(Context cx, Scriptable scope) {
if (member.isCtor() || parmsLength == VARARGS_CTOR) {
return null;
}
Scriptable result;
try {
result = (Scriptable) member.getDeclaringClass().newInstance();
} catch (Exception ex) {
throw Context.throwAsScriptRuntimeEx(ex);
}
result.setPrototype(getClassPrototype());
result.setParentScope(getParentScope());
return result;
}
boolean isVarArgsMethod() {
return parmsLength == VARARGS_METHOD;
}
boolean isVarArgsConstructor() {
return parmsLength == VARARGS_CTOR;
}
private void readObject(ObjectInputStream in)
throws IOException, ClassNotFoundException
{
in.defaultReadObject();
if (parmsLength > 0) {
Class[] types = member.argTypes;
typeTags = new byte[parmsLength];
for (int i = 0; i != parmsLength; ++i) {
typeTags[i] = (byte)getTypeTag(types[i]);
}
}
if (member.isMethod()) {
Method method = member.method();
Class returnType = method.getReturnType();
if (returnType == Void.TYPE) {
hasVoidReturn = true;
} else {
returnTypeTag = getTypeTag(returnType);
}
}
}
private static final short VARARGS_METHOD = -1;
private static final short VARARGS_CTOR = -2;
private static boolean sawSecurityException;
public static final int JAVA_UNSUPPORTED_TYPE = 0;
public static final int JAVA_STRING_TYPE = 1;
public static final int JAVA_INT_TYPE = 2;
public static final int JAVA_BOOLEAN_TYPE = 3;
public static final int JAVA_DOUBLE_TYPE = 4;
public static final int JAVA_SCRIPTABLE_TYPE = 5;
public static final int JAVA_OBJECT_TYPE = 6;
MemberBox member;
private String functionName;
private transient byte[] typeTags;
private int parmsLength;
private transient boolean hasVoidReturn;
private transient int returnTypeTag;
private boolean isStatic;
}