/**
* Creates a child context.
*
* @param parent The parent context. Required.
* @param model The target value. Resolved as '.' or 'this' inside templates. Required.
* @return A child context.
*/
private static Context child(final Context parent, final Object model) {
notNull(parent, "A parent context is required.");
Context child = new Context(model);
child.extendedContext = new Context(new HashMap<String, Object>());
child.parent = parent;
child.data = parent.data;
return child;
}
/**
* Creates a root context.
*
* @param model The target value. Resolved as '.' or 'this' inside templates. Required.
* @return A root context.
*/
private static Context root(final Object model) {
Context root = new Context(model);
root.extendedContext = new Context(new HashMap<String, Object>());
root.parent = null;
root.data = new HashMap<String, Object>();
root.data.put(PARTIALS, new HashMap<String, Template>());
root.data.put(INVOCATION_STACK, new LinkedList<TemplateSource>());
return root;
}
/**
* Lookup the given key inside the context stack.
*
* <ul>
* <li>Objects and hashes should be pushed onto the context stack.
* <li>All elements on the context stack should be accessible.
* <li>Multiple sections per template should be permitted.
* <li>Failed context lookups should be considered falsey.
* <li>Dotted names should be valid for Section tags.
* <li>Dotted names that cannot be resolved should be considered falsey.
* <li>Dotted Names - Context Precedence: Dotted names should be resolved against former
* resolutions.
* </ul>
*
* @param key The object key.
* @return The value associated to the given key or <code>null</code> if no value is found.
*/
public Object get(final String key) {
// '.' or 'this'
if (MUSTACHE_THIS.equals(key) || THIS.equals(key)) {
return model;
}
// '..'
if (key.equals(PARENT)) {
return parent == null ? null : parent.model;
}
// '../'
if (key.startsWith(PARENT_ATTR)) {
return parent == null ? null : parent.get(key.substring(PARENT_ATTR.length()));
}
String[] path = toPath(key);
Object value = get(path);
if (value == null) {
// No luck, check the extended context.
value = get(extendedContext, key);
// No luck, check the data context.
if (value == null && data != null) {
String dataKey = key.charAt(0) == '@' ? key.substring(1) : key;
// simple data keys will be resolved immediately, complex keys need to go down and using a
// new context.
value = data.get(dataKey);
if (value == null && path.length > 1) {
// for complex keys, a new data context need to be created per invocation,
// bc data might changes per execution.
Context dataContext =
Context.newBuilder(data).resolver(MapValueResolver.INSTANCE).build();
// don't extend the lookup further.
dataContext.data = null;
value = dataContext.get(dataKey);
// destroy it!
dataContext.destroy();
}
}
// No luck, but before checking at the parent scope we need to check for
// the 'this' qualifier. If present, no look up will be done.
if (value == null && !path[0].equals(THIS)) {
value = get(parent, key);
}
}
return value == NULL ? null : value;
}