* This object enhances WOContext so that it properly sets up and tears down * the Rhino JavaScript context for the current thread. Its important that * awake() and sleep() are properly called for the transaction, but this is * ensured in WOApplication. *
* The JavaScript Context object is available using the 'jsContext' method * though I recommend accessing the 'jsContext' value via KVC so that it works * with arbitary custom classes. */ public class JSContext extends WOContext { // TBD: could we avoid this by adding listeners to WOContext? Would be nice, // we could use arbitary Context classes. protected static final Log jslog = LogFactory.getLog("JSBridge"); protected Context jsContext; protected Scriptable jsScope; protected JSKeyValueCodingScope jsSharedScope; public JSContext(WOApplication _app, WORequest _rq) { super(_app, _rq); } /* accessors */ public Scriptable jsScope() { if (this.jsScope == null) { jslog.warn("JSContext: no JS scope was predefined: " + this); this.jsScope = new ImporterTopLevel(this.jsContext(), false /* sealed */); } return this.jsScope; } public void setJsScope(Scriptable _scope) { if (this.jsScope == _scope) return; if (this.jsScope != null) jslog.warn("attempt to override jsScope of context: " + this); this.jsScope = _scope; } public JSKeyValueCodingScope jsSharedScope() { return this.jsSharedScope; } public void setJsSharedScope(JSKeyValueCodingScope _scope) { if (this.jsSharedScope == _scope) return; if (this.jsSharedScope != null) jslog.warn("attempt to override jsSharedScope of context: " + this); this.jsSharedScope = _scope; } /* notifications */ @Override public void sleep() { /* ensure that the JS Context is terminated */ try { super.sleep(); } finally { this.jsScope = null; this.jsSharedScope = null; this.jsContext = null; } } /* accessors */ /** * Method returns the Rhino JavaScript Context object. Instead of calling this * method directly its recommended to access the value using KVC, eg:
* Context jscx = (Context)this.context().valueForKey("jsContext");
* Its more verbose but it works with arbitary objects able to provide a
* Rhino Context.
*
* @return the Rhino JavaScript Context of the thread
*/
public Context jsContext() {
if (this.jsContext == null)
this.jsContext = Context.getCurrentContext();
return this.jsContext;
}
/* override KVC */
@Override
public void takeValueForKey(Object _value, String _key) {
// DUP: WOSession
// in theory we could move this to a KVC hander, no? One which is triggered
// based on the class (JSExtraVarClass => JSExtraVarKVCHandler) or something
// like that
// check whether extra vars contain the key and whether its a JS callable
if (this.extraAttributes != null) {
Object v;
/* first check for a setter */
String n = "set" + UString.capitalizedString(_key);
v = this.extraAttributes != null ? this.extraAttributes.get(n) : null;
if (v == null || v == Scriptable.NOT_FOUND) {
// TBD: better ways to deal with this? We need to check the script scope
// for the setter function (actually only that? we also support
// setters in instance scope, which is rather useless)
Scriptable proto = this.jsSharedScope().scope;
v = proto != null ? proto.get(n, this.jsScope()) : null;
}
if (v instanceof Callable) {
Scriptable scope = this.jsScope();
Object args[] = new Object[] { Context.javaToJS(_value, scope) };
((Callable)v).call(this.jsContext(),
scope /* scope */,
scope /* this */,
args);
return;
}
/* If there is no setter, check for a variable. But ensure that we do not
* override the getter!
*/
v = this.extraAttributes.get(_key);
// Note: no need to check our script scope, it is readonly
if (v != null && v != Scriptable.NOT_FOUND) {
if (jslog != null && jslog.isDebugEnabled()) {
jslog.debug("JSContext.setValForKey " + _key + " to " + _value+
" (" + (_value != null ? _value.getClass() : "[null]") + ")");
}
if (v instanceof Callable) {
/* its a getter function, do not overwrite the slot */
// TBD: should we just return and do nothing? Might be better in
// bindings
throw new NSException("attempt to write readonly slot via KVC");
}
this.extraAttributes.put(_key, _value);
return;
}
}
super.takeValueForKey(_value, _key);
}
@Override
public Object valueForKey(final String _key) {
// DUP: WOSession
// check whether extra vars contain the key and whether its a JS callable
if (_key != null) {
//System.err.println("GET KEY: " + _key);
Object v = this.extraAttributes != null
? this.extraAttributes.get(_key) : null;
if (v == null) { // Note: we intentionally do not check NOT_FOUND
/* check our 'prototype' scope (this is where the scriptfile lives) */
v = this.jsSharedScope.valueForKeyInScope(_key, jsScope());
if (v != null)
return v;
}
//System.err.println(" GOT JS VALUE: " + v);
if (v != null && v != Scriptable.NOT_FOUND) {
if (jslog != null && jslog.isDebugEnabled()) {
jslog.debug("JSContext.valForKey('" + _key + "') => " +
v + " (" + (v!= null?v.getClass():"[null]") + ")");
}
/* check whether the value is a getter */
if (v instanceof Callable) {
Scriptable scope = this.jsScope();
// TBD: we could pass in various args
v = ((Callable)v).call(this.jsContext(),
scope /* scope (where to lookup variables) */,
scope /* this */,
JSUtil.emptyArgs);
}
if (v instanceof Undefined)
v = null; /* we do not expose JavaScript Undefined values */
else
v = Context.jsToJava(v, Object.class);
//System.err.println(" GOT VALUE: " + v);
return v;
}
}
return super.valueForKey(_key);
}
/* description */
@Override
public void appendAttributesToDescription(StringBuilder _d) {
super.appendAttributesToDescription(_d);
_d.append(this.jsContext != null ? " ctx" : " no-ctx");
}
}