@module {function} can-view-scope
@parent can-views
@collection can-infrastructure
@inherits can-construct
@test can/view/scope/test.html
@group can-view-scope.prototype prototype
@group can-view-scope.types types
@package ../package.json

@description Create a lookup node for [can-mustache.key keys].

@signature `new Scope(context, [parent], [meta] )`

@release 2.0.1


@param {*} context A value that represents the
current context. This is often an object or observable and is the first
place a `key` is looked up.

@param {can-view-scope} [parent] The parent scope. If a `key` value
is not found in the current scope, it will then look in the parent
scope.

@param {can-view-scope/Meta} [meta] A configuration object that
can specify special behavior of the context.

@return {can-view-scope} Returns a scope instance.

@body

## Use

A [can-view-scope] represents a lookup context and parent contexts
that can be used to look up a [can-stache.key key] value.

If no parent scope is provided, only the scope’s context will be
explored for values.  For example:

```js
const data = { name: { first: "Justin" } };
const scope = new Scope( data );

scope.get( "name.first" ); //-> "Justin"
scope.get( "length" );     //-> undefined
```

However, if a `parent` scope is provided, key values can be
found in the parent’s context by prefixing the key with `"../"`.
[can-view-scope::find find] can also be used to search in the parent’s context
after the initial context is explored. For example:

```
var list = [{name: "Justin"}, {name: "Brian"}];
var justin = list[0];

var listScope = new Scope(list);
var curScope = new Scope(justin, listScope);

// use `get` to find a value in an explicit context
curScope.get("name") //-> "Justin"
curScope.get("../length") //-> 2

// use `find` to search for a value in any context
curScope.find("name") //-> "Justin"
curScope.find("../length") //-> 2
```

Use [can-view-scope::add add] to easily create a new scope from a parent scope like:

```js
const list = [ { name: "Justin" }, { name: "Brian" } ];
const justin = list[ 0 ];

const curScope = new Scope( list ).add( justin );

curScope.find( "name" ); //-> "Justin"
curScope.find( "length" ); //-> 2
```