/**
* Evaluate the Array expression 'loc' on the given object, o. e.g. in 'a[2]', <code>2</code> is
* 'loc' and <code>a</code> is 'o'.
*
* <p>If o or loc are null, null is returned. If o is a Map, o.get(loc) is returned. If o is a
* List, o.get(loc) is returned. loc must resolve to an int value. If o is an Array, o[loc] is
* returned. loc must resolve to an int value. Otherwise loc is treated as a bean property of o.
*
* @param o an object to be accessed using the array operator or '.' operator.
* @param loc the index of the object to be returned.
* @return the resulting value.
* @throws Exception on any error.
*/
public static Object evaluateExpr(Object o, Object loc) throws Exception {
/*
* following the JSTL EL rules
*/
if (o == null) {
return null;
}
if (loc == null) {
return null;
}
if (o instanceof Map) {
if (!((Map) o).containsKey(loc)) {
return null;
}
return ((Map) o).get(loc);
} else if (o instanceof List) {
int idx = Coercion.coerceInteger(loc).intValue();
try {
return ((List) o).get(idx);
} catch (IndexOutOfBoundsException iobe) {
return null;
}
} else if (o.getClass().isArray()) {
int idx = Coercion.coerceInteger(loc).intValue();
try {
return Array.get(o, idx);
} catch (ArrayIndexOutOfBoundsException aiobe) {
return null;
}
} else {
/*
* "Otherwise (a JavaBean object)..." huh? :)
*/
String s = loc.toString();
VelPropertyGet vg = Introspector.getUberspect().getPropertyGet(o, s, DUMMY);
if (vg != null) {
return vg.invoke(o);
}
}
throw new Exception("Unsupported object type for array [] accessor");
}
