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// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
part of template_binding;
* Template Bindings native features enables a wide-range of use cases,
* but (by design) don't attempt to implement a wide array of specialized
* behaviors.
* Enabling these features is a matter of implementing and registering a
* BindingDelegate. A binding delegate is an object which contains one or more
* delegation functions which implement specialized behavior. This object is
* registered via [TemplateBindExtension.bindingDelegate]:
* <template bind>
* {{ What!Ever('crazy')->thing^^^I+Want(data) }}
* </template>
* Dart:
* class MySyntax extends BindingDelegate {
* prepareBinding(path, name, node) {
* // The magic happens here!
* }
* }
* ...
* templateBind(query('template'))
* ..bindingDelegate = new MySyntax()
* ..model = new MyModel();
* See
* <>
* for more information about the binding delegate.
// TODO(jmesserly): need better api docs here. The link above seems out of date.
class BindingDelegate {
* Prepares a binding. This is called immediately after parsing a mustache
* token with `{{ path }}` in the context of the [node] and the property named
* [name]. This should return a function that will be passed the actual
* node and model, and either returns null or an object with a `value`
* property. This allows the syntax to reinterpret the model for each binding.
PrepareBindingFunction prepareBinding(String path, String name, Node node)
=> null;
* Returns a function that can optionally replace the model that will be
* passed to [TemplateBindExtension.createInstance]. This can be used to
* implement syntax such as `<template repeat="{{ item in items }}">` by
* ensuring that the returned model has the "item" name available.
PrepareInstanceModelFunction prepareInstanceModel(Element template) => null;
* Returns a function that will be called whenever the position of an item
* inside this template changes.
PrepareInstancePositionChangedFunction prepareInstancePositionChanged(
Element template) => null;
Expando<_InstanceBindingMap> _bindingMaps;
// TODO(jmesserly): if we have use this everywhere, we can avoid many
// delegate != null checks throughout the code, simplifying things.
// For now we just use it for _bindingMaps.
static final _DEFAULT = new BindingDelegate();
typedef PrepareBindingFunction(model, Node node, bool oneTime);
typedef PrepareInstanceModelFunction(model);
typedef PrepareInstancePositionChangedFunction(TemplateInstance instance,
int index);