ELSupport.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.el.lang;
import java.beans.PropertyEditor;
import java.beans.PropertyEditorManager;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import javax.el.ELContext;
import javax.el.ELException;
import org.apache.el.util.MessageFactory;
/**
* A helper class that implements the EL Specification
*
* @author Jacob Hookom [jacob@hookom.net]
*/
public class ELSupport {
private static final Long ZERO = Long.valueOf(0L);
protected static final boolean COERCE_TO_ZERO;
static {
String coerceToZeroStr;
if (System.getSecurityManager() != null) {
coerceToZeroStr = AccessController.doPrivileged(
new PrivilegedAction<String>(){
@Override
public String run() {
return System.getProperty(
"org.apache.el.parser.COERCE_TO_ZERO", "false");
}
}
);
} else {
coerceToZeroStr = System.getProperty(
"org.apache.el.parser.COERCE_TO_ZERO", "false");
}
COERCE_TO_ZERO = Boolean.parseBoolean(coerceToZeroStr);
}
/**
* Compare two objects, after coercing to the same type if appropriate.
*
* If the objects are identical, or they are equal according to
* {@link #equals(ELContext, Object, Object)} then return 0.
*
* If either object is a BigDecimal, then coerce both to BigDecimal first.
* Similarly for Double(Float), BigInteger, and Long(Integer, Char, Short, Byte).
*
* Otherwise, check that the first object is an instance of Comparable, and compare
* against the second object. If that is null, return 1, otherwise
* return the result of comparing against the second object.
*
* Similarly, if the second object is Comparable, if the first is null, return -1,
* else return the result of comparing against the first object.
*
* A null object is considered as:
* <ul>
* <li>ZERO when compared with Numbers</li>
* <li>the empty string for String compares</li>
* <li>Otherwise null is considered to be lower than anything else.</li>
* </ul>
*
* @param ctx the context in which this comparison is taking place
* @param obj0 first object
* @param obj1 second object
* @return -1, 0, or 1 if this object is less than, equal to, or greater than val.
* @throws ELException if neither object is Comparable
* @throws ClassCastException if the objects are not mutually comparable
*/
public static final int compare(final ELContext ctx, final Object obj0, final Object obj1)
throws ELException {
if (obj0 == obj1 || equals(ctx, obj0, obj1)) {
return 0;
}
if (isBigDecimalOp(obj0, obj1)) {
BigDecimal bd0 = (BigDecimal) coerceToNumber(ctx, obj0, BigDecimal.class);
BigDecimal bd1 = (BigDecimal) coerceToNumber(ctx, obj1, BigDecimal.class);
return bd0.compareTo(bd1);
}
if (isDoubleOp(obj0, obj1)) {
Double d0 = (Double) coerceToNumber(ctx, obj0, Double.class);
Double d1 = (Double) coerceToNumber(ctx, obj1, Double.class);
return d0.compareTo(d1);
}
if (isBigIntegerOp(obj0, obj1)) {
BigInteger bi0 = (BigInteger) coerceToNumber(ctx, obj0, BigInteger.class);
BigInteger bi1 = (BigInteger) coerceToNumber(ctx, obj1, BigInteger.class);
return bi0.compareTo(bi1);
}
if (isLongOp(obj0, obj1)) {
Long l0 = (Long) coerceToNumber(ctx, obj0, Long.class);
Long l1 = (Long) coerceToNumber(ctx, obj1, Long.class);
return l0.compareTo(l1);
}
if (obj0 instanceof String || obj1 instanceof String) {
return coerceToString(ctx, obj0).compareTo(coerceToString(ctx, obj1));
}
if (obj0 instanceof Comparable<?>) {
@SuppressWarnings("unchecked") // checked above
final Comparable<Object> comparable = (Comparable<Object>) obj0;
return (obj1 != null) ? comparable.compareTo(obj1) : 1;
}
if (obj1 instanceof Comparable<?>) {
@SuppressWarnings("unchecked") // checked above
final Comparable<Object> comparable = (Comparable<Object>) obj1;
return (obj0 != null) ? -comparable.compareTo(obj0) : -1;
}
throw new ELException(MessageFactory.get("error.compare", obj0, obj1));
}
/**
* Compare two objects for equality, after coercing to the same type if appropriate.
*
* If the objects are identical (including both null) return true.
* If either object is null, return false.
* If either object is Boolean, coerce both to Boolean and check equality.
* Similarly for Enum, String, BigDecimal, Double(Float), Long(Integer, Short, Byte, Character)
* Otherwise default to using Object.equals().
*
* @param ctx the context in which this equality test is taking place
* @param obj0 the first object
* @param obj1 the second object
* @return true if the objects are equal
* @throws ELException if one of the coercion fails
*/
public static final boolean equals(final ELContext ctx, final Object obj0, final Object obj1)
throws ELException {
if (obj0 == obj1) {
return true;
} else if (obj0 == null || obj1 == null) {
return false;
} else if (isBigDecimalOp(obj0, obj1)) {
BigDecimal bd0 = (BigDecimal) coerceToNumber(ctx, obj0, BigDecimal.class);
BigDecimal bd1 = (BigDecimal) coerceToNumber(ctx, obj1, BigDecimal.class);
return bd0.equals(bd1);
} else if (isDoubleOp(obj0, obj1)) {
Double d0 = (Double) coerceToNumber(ctx, obj0, Double.class);
Double d1 = (Double) coerceToNumber(ctx, obj1, Double.class);
return d0.equals(d1);
} else if (isBigIntegerOp(obj0, obj1)) {
BigInteger bi0 = (BigInteger) coerceToNumber(ctx, obj0, BigInteger.class);
BigInteger bi1 = (BigInteger) coerceToNumber(ctx, obj1, BigInteger.class);
return bi0.equals(bi1);
} else if (isLongOp(obj0, obj1)) {
Long l0 = (Long) coerceToNumber(ctx, obj0, Long.class);
Long l1 = (Long) coerceToNumber(ctx, obj1, Long.class);
return l0.equals(l1);
} else if (obj0 instanceof Boolean || obj1 instanceof Boolean) {
return coerceToBoolean(ctx, obj0, false).equals(coerceToBoolean(ctx, obj1, false));
} else if (obj0.getClass().isEnum()) {
return obj0.equals(coerceToEnum(ctx, obj1, obj0.getClass()));
} else if (obj1.getClass().isEnum()) {
return obj1.equals(coerceToEnum(ctx, obj0, obj1.getClass()));
} else if (obj0 instanceof String || obj1 instanceof String) {
int lexCompare = coerceToString(ctx, obj0).compareTo(coerceToString(ctx, obj1));
return (lexCompare == 0) ? true : false;
} else {
return obj0.equals(obj1);
}
}
// Going to have to have some casts /raw types somewhere so doing it here
// keeps them all in one place. There might be a neater / better solution
// but I couldn't find it
@SuppressWarnings("unchecked")
public static final Enum<?> coerceToEnum(final ELContext ctx, final Object obj,
@SuppressWarnings("rawtypes") Class type) {
if (ctx != null) {
boolean originalIsPropertyResolved = ctx.isPropertyResolved();
try {
Object result = ctx.getELResolver().convertToType(ctx, obj, type);
if (ctx.isPropertyResolved()) {
return (Enum<?>) result;
}
} finally {
ctx.setPropertyResolved(originalIsPropertyResolved);
}
}
if (obj == null || "".equals(obj)) {
return null;
}
if (type.isAssignableFrom(obj.getClass())) {
return (Enum<?>) obj;
}
if (!(obj instanceof String)) {
throw new ELException(MessageFactory.get("error.convert",
obj, obj.getClass(), type));
}
Enum<?> result;
try {
result = Enum.valueOf(type, (String) obj);
} catch (IllegalArgumentException iae) {
throw new ELException(MessageFactory.get("error.convert",
obj, obj.getClass(), type));
}
return result;
}
/**
* Convert an object to Boolean.
* Null and empty string are false.
* @param ctx the context in which this conversion is taking place
* @param obj the object to convert
* @param primitive is the target a primitive in which case coercion to null
* is not permitted
* @return the Boolean value of the object
* @throws ELException if object is not Boolean or String
*/
public static final Boolean coerceToBoolean(final ELContext ctx, final Object obj,
boolean primitive) throws ELException {
if (ctx != null) {
boolean originalIsPropertyResolved = ctx.isPropertyResolved();
try {
Object result = ctx.getELResolver().convertToType(ctx, obj, Boolean.class);
if (ctx.isPropertyResolved()) {
return (Boolean) result;
}
} finally {
ctx.setPropertyResolved(originalIsPropertyResolved);
}
}
if (!COERCE_TO_ZERO && !primitive) {
if (obj == null) {
return null;
}
}
if (obj == null || "".equals(obj)) {
return Boolean.FALSE;
}
if (obj instanceof Boolean) {
return (Boolean) obj;
}
if (obj instanceof String) {
return Boolean.valueOf((String) obj);
}
throw new ELException(MessageFactory.get("error.convert",
obj, obj.getClass(), Boolean.class));
}
private static Character coerceToCharacter(final ELContext ctx, final Object obj)
throws ELException {
if (ctx != null) {
boolean originalIsPropertyResolved = ctx.isPropertyResolved();
try {
Object result = ctx.getELResolver().convertToType(ctx, obj, Character.class);
if (ctx.isPropertyResolved()) {
return (Character) result;
}
} finally {
ctx.setPropertyResolved(originalIsPropertyResolved);
}
}
if (obj == null || "".equals(obj)) {
return Character.valueOf((char) 0);
}
if (obj instanceof String) {
return Character.valueOf(((String) obj).charAt(0));
}
if (ELArithmetic.isNumber(obj)) {
return Character.valueOf((char) ((Number) obj).shortValue());
}
Class<?> objType = obj.getClass();
if (obj instanceof Character) {
return (Character) obj;
}
throw new ELException(MessageFactory.get("error.convert",
obj, objType, Character.class));
}
protected static final Number coerceToNumber(final Number number,
final Class<?> type) throws ELException {
if (Long.TYPE == type || Long.class.equals(type)) {
return Long.valueOf(number.longValue());
}
if (Double.TYPE == type || Double.class.equals(type)) {
return Double.valueOf(number.doubleValue());
}
if (Integer.TYPE == type || Integer.class.equals(type)) {
return Integer.valueOf(number.intValue());
}
if (BigInteger.class.equals(type)) {
if (number instanceof BigDecimal) {
return ((BigDecimal) number).toBigInteger();
}
if (number instanceof BigInteger) {
return number;
}
return BigInteger.valueOf(number.longValue());
}
if (BigDecimal.class.equals(type)) {
if (number instanceof BigDecimal) {
return number;
}
if (number instanceof BigInteger) {
return new BigDecimal((BigInteger) number);
}
return new BigDecimal(number.doubleValue());
}
if (Byte.TYPE == type || Byte.class.equals(type)) {
return Byte.valueOf(number.byteValue());
}
if (Short.TYPE == type || Short.class.equals(type)) {
return Short.valueOf(number.shortValue());
}
if (Float.TYPE == type || Float.class.equals(type)) {
return Float.valueOf(number.floatValue());
}
if (Number.class.equals(type)) {
return number;
}
throw new ELException(MessageFactory.get("error.convert",
number, number.getClass(), type));
}
public static final Number coerceToNumber(final ELContext ctx, final Object obj,
final Class<?> type) throws ELException {
if (ctx != null) {
boolean originalIsPropertyResolved = ctx.isPropertyResolved();
try {
Object result = ctx.getELResolver().convertToType(ctx, obj, type);
if (ctx.isPropertyResolved()) {
return (Number) result;
}
} finally {
ctx.setPropertyResolved(originalIsPropertyResolved);
}
}
if (!COERCE_TO_ZERO) {
if (obj == null && !type.isPrimitive()) {
return null;
}
}
if (obj == null || "".equals(obj)) {
return coerceToNumber(ZERO, type);
}
if (obj instanceof String) {
return coerceToNumber((String) obj, type);
}
if (ELArithmetic.isNumber(obj)) {
return coerceToNumber((Number) obj, type);
}
if (obj instanceof Character) {
return coerceToNumber(Short.valueOf((short) ((Character) obj)
.charValue()), type);
}
throw new ELException(MessageFactory.get("error.convert",
obj, obj.getClass(), type));
}
protected static final Number coerceToNumber(final String val,
final Class<?> type) throws ELException {
if (Long.TYPE == type || Long.class.equals(type)) {
try {
return Long.valueOf(val);
} catch (NumberFormatException nfe) {
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
}
if (Integer.TYPE == type || Integer.class.equals(type)) {
try {
return Integer.valueOf(val);
} catch (NumberFormatException nfe) {
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
}
if (Double.TYPE == type || Double.class.equals(type)) {
try {
return Double.valueOf(val);
} catch (NumberFormatException nfe) {
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
}
if (BigInteger.class.equals(type)) {
try {
return new BigInteger(val);
} catch (NumberFormatException nfe) {
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
}
if (BigDecimal.class.equals(type)) {
try {
return new BigDecimal(val);
} catch (NumberFormatException nfe) {
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
}
if (Byte.TYPE == type || Byte.class.equals(type)) {
try {
return Byte.valueOf(val);
} catch (NumberFormatException nfe) {
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
}
if (Short.TYPE == type || Short.class.equals(type)) {
try {
return Short.valueOf(val);
} catch (NumberFormatException nfe) {
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
}
if (Float.TYPE == type || Float.class.equals(type)) {
try {
return Float.valueOf(val);
} catch (NumberFormatException nfe) {
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
}
throw new ELException(MessageFactory.get("error.convert",
val, String.class, type));
}
/**
* Coerce an object to a string.
* @param ctx the context in which this conversion is taking place
* @param obj the object to convert
* @return the String value of the object
*/
public static final String coerceToString(final ELContext ctx, final Object obj) {
if (ctx != null) {
boolean originalIsPropertyResolved = ctx.isPropertyResolved();
try {
Object result = ctx.getELResolver().convertToType(ctx, obj, String.class);
if (ctx.isPropertyResolved()) {
return (String) result;
}
} finally {
ctx.setPropertyResolved(originalIsPropertyResolved);
}
}
if (obj == null) {
return "";
} else if (obj instanceof String) {
return (String) obj;
} else if (obj instanceof Enum<?>) {
return ((Enum<?>) obj).name();
} else {
return obj.toString();
}
}
public static final Object coerceToType(final ELContext ctx, final Object obj,
final Class<?> type) throws ELException {
if (ctx != null) {
boolean originalIsPropertyResolved = ctx.isPropertyResolved();
try {
Object result = ctx.getELResolver().convertToType(ctx, obj, type);
if (ctx.isPropertyResolved()) {
return result;
}
} finally {
ctx.setPropertyResolved(originalIsPropertyResolved);
}
}
if (type == null || Object.class.equals(type) ||
(obj != null && type.isAssignableFrom(obj.getClass()))) {
return obj;
}
if (!COERCE_TO_ZERO) {
if (obj == null && !type.isPrimitive() &&
!String.class.isAssignableFrom(type)) {
return null;
}
}
if (String.class.equals(type)) {
return coerceToString(ctx, obj);
}
if (ELArithmetic.isNumberType(type)) {
return coerceToNumber(ctx, obj, type);
}
if (Character.class.equals(type) || Character.TYPE == type) {
return coerceToCharacter(ctx, obj);
}
if (Boolean.class.equals(type) || Boolean.TYPE == type) {
return coerceToBoolean(ctx, obj, Boolean.TYPE == type);
}
if (type.isEnum()) {
return coerceToEnum(ctx, obj, type);
}
// new to spec
if (obj == null) {
return null;
}
if (obj instanceof String) {
String str = (String) obj;
PropertyEditor editor = PropertyEditorManager.findEditor(type);
if (editor == null) {
if (str.isEmpty()) {
return null;
}
throw new ELException(MessageFactory.get("error.convert", obj,
obj.getClass(), type));
} else {
try {
editor.setAsText(str);
return editor.getValue();
} catch (RuntimeException e) {
if (str.isEmpty()) {
return null;
}
throw new ELException(MessageFactory.get("error.convert",
obj, obj.getClass(), type), e);
}
}
}
// Handle special case because the syntax for the empty set is the same
// for an empty map. The parser will always parse {} as an empty set.
if (obj instanceof Set && type == Map.class &&
((Set<?>) obj).isEmpty()) {
return Collections.EMPTY_MAP;
}
// Handle arrays
if (type.isArray() && obj.getClass().isArray()) {
return coerceToArray(ctx, obj, type);
}
throw new ELException(MessageFactory.get("error.convert",
obj, obj.getClass(), type));
}
private static Object coerceToArray(final ELContext ctx, final Object obj,
final Class<?> type) {
// Note: Nested arrays will result in nested calls to this method.
// Note: Calling method has checked the obj is an array.
int size = Array.getLength(obj);
// Cast the input object to an array (calling method has checked it is
// an array)
// Get the target type for the array elements
Class<?> componentType = type.getComponentType();
// Create a new array of the correct type
Object result = Array.newInstance(componentType, size);
// Coerce each element in turn.
for (int i = 0; i < size; i++) {
Array.set(result, i, coerceToType(ctx, Array.get(obj, i), componentType));
}
return result;
}
public static final boolean isBigDecimalOp(final Object obj0,
final Object obj1) {
return (obj0 instanceof BigDecimal || obj1 instanceof BigDecimal);
}
public static final boolean isBigIntegerOp(final Object obj0,
final Object obj1) {
return (obj0 instanceof BigInteger || obj1 instanceof BigInteger);
}
public static final boolean isDoubleOp(final Object obj0, final Object obj1) {
return (obj0 instanceof Double
|| obj1 instanceof Double
|| obj0 instanceof Float
|| obj1 instanceof Float);
}
public static final boolean isLongOp(final Object obj0, final Object obj1) {
return (obj0 instanceof Long
|| obj1 instanceof Long
|| obj0 instanceof Integer
|| obj1 instanceof Integer
|| obj0 instanceof Character
|| obj1 instanceof Character
|| obj0 instanceof Short
|| obj1 instanceof Short
|| obj0 instanceof Byte
|| obj1 instanceof Byte);
}
public static final boolean isStringFloat(final String str) {
int len = str.length();
if (len > 1) {
for (int i = 0; i < len; i++) {
switch (str.charAt(i)) {
case 'E':
return true;
case 'e':
return true;
case '.':
return true;
}
}
}
return false;
}
/**
*
*/
public ELSupport() {
super();
}
}