feat($parse): add support for transparent evaluation of Promises

Parser now builds expressions that can detect promises and transparently
evaluate them to undefined or the promise value.

If promiseA is resolved with value 'A', then {{promiseA}} evals to 'A';
If promiseA is unresolved, then {{promiseA}} evals to undefined;

Following invocations are supported:

- {{promise}}
- {{promise.futureProp}}
- {{[promise][0]}}
- {{object.promise}}
- {{object[promise]}}
- {{array[promise]}}
- {{fn(promise)}}
- combinations of the above

1 files changed, 24 insertions, 5 deletions

diff --git a/src/service/parse.js b/src/service/parse.js
index 432929b5..3a6c4106 100644
--- a/src/service/parse.js
+++ b/src/service/parse.js
@@ -522,9 +522,21 @@ function parser(text, json, $filter){
     consume(']');
     return extend(
       function(self){
-        var o = obj(self);
-        var i = indexFn(self);
-        return (o) ? o[i] : undefined;
+        var o = obj(self),
+            i = indexFn(self),
+            v, p;
+
+        if (!o) return undefined;
+        v = o[i];
+        if (v && v.then) {
+          p = v;
+          if (!('$$v' in v)) {
+            p.$$v = undefined;
+            p.then(function(val) { p.$$v = val; });
+          }
+          v = v.$$v;
+        }
+        return v;
       }, {
         assign:function(self, value){
           return obj(self)[indexFn(self)] = value;
@@ -673,7 +685,7 @@ function getterFn(path) {
   var fn = getterFnCache[path];
   if (fn) return fn;
 
-  var code = 'var l, fn, t;\n';
+  var code = 'var l, fn, p;\n';
   forEach(path.split('.'), function(key) {
     key = (JS_KEYWORDS[key]) ? '["' + key + '"]' : '.' + key;
     code += 'if(!s) return s;\n' +
@@ -683,11 +695,18 @@ function getterFn(path) {
               ' fn=function(){ return l' + key + '.apply(l, arguments); };\n' +
               ' fn.$unboundFn=s;\n' +
               ' s=fn;\n' +
+            '} else if (s && s.then) {\n' +
+              ' if (!("$$v" in s)) {\n' +
+                ' p=s;\n' +
+                ' p.$$v = undefined;\n' +
+                ' p.then(function(v) {p.$$v=v;});\n' +
+                '}\n' +
+              ' s=s.$$v\n' +
             '}\n';
   });
   code += 'return s;';
   fn = Function('s', code);
-  fn["toString"] = function() { return code; };
+  fn.toString = function() { return code; };
 
   return getterFnCache[path] = fn;
 }