Avoid direct references to sexpr in statements

This allows us to avoid creating unnecessary AST nodes and avoids things like isHelper.

Side effect of these changes is that @data functions can now have data parameters passed to them.

spec/ast.js

@@ -26,7 +26,7 @@ describe('ast', function() {
     it('should store args', function() {
       var id = {isSimple: true},
           hash = {},
-          mustache = new handlebarsEnv.AST.MustacheStatement({}, true, {}, LOCATION_INFO);
+          mustache = new handlebarsEnv.AST.MustacheStatement({}, null, null, true, {}, LOCATION_INFO);
       equals(mustache.type, 'MustacheStatement');
       equals(mustache.escaped, true);
       testLocationInfoStorage(mustache);
@@ -40,10 +40,10 @@ describe('ast', function() {
     });
 
     it('stores location info', function(){
-      var sexprNode = new handlebarsEnv.AST.SubExpression([{ original: 'foo'}], null);
-      var mustacheNode = new handlebarsEnv.AST.MustacheStatement(sexprNode, false, {});
+      var mustacheNode = new handlebarsEnv.AST.MustacheStatement([{ original: 'foo'}], null, null, false, {});
       var block = new handlebarsEnv.AST.BlockStatement(
             mustacheNode,
+            null, null,
             {body: []},
             {body: []},
             {},
@@ -104,7 +104,7 @@ describe('ast', function() {
 
   describe('PartialStatement', function(){
     it('stores location info', function(){
-      var pn = new handlebarsEnv.AST.PartialStatement('so_partial', {}, LOCATION_INFO);
+      var pn = new handlebarsEnv.AST.PartialStatement('so_partial', [], {}, {}, LOCATION_INFO);
       testLocationInfoStorage(pn);
     });
   });
@@ -200,7 +200,7 @@ describe('ast', function() {
             block = ast.body[0];
 
         equals(block.program.body[0].value, '');
-        equals(block.program.body[1].sexpr.path.original, 'foo');
+        equals(block.program.body[1].path.original, 'foo');
         equals(block.program.body[2].value, '\n');
       });
       it('marks nested block mustaches as standalone', function() {

spec/data.js

@@ -93,6 +93,17 @@ describe('data', function() {
     }, Error);
   });
 
+  it('data can be functions', function() {
+    var template = CompilerContext.compile('{{@hello}}');
+    var result = template({}, { data: { hello: function() { return 'hello'; } } });
+    equals('hello', result);
+  });
+  it('data can be functions with params', function() {
+    var template = CompilerContext.compile('{{@hello "hello"}}');
+    var result = template({}, { data: { hello: function(arg) { return arg; } } });
+    equals('hello', result);
+  });
+
   it("data is inherited downstream", function() {
     var template = CompilerContext.compile("{{#let foo=1 bar=2}}{{#let foo=bar.baz}}{{@bar}}{{@foo}}{{/let}}{{@foo}}{{/let}}", { data: true });
     var helpers = {

spec/visitor.js

@@ -24,11 +24,10 @@ describe('Visitor', function() {
     visitor.BooleanLiteral = function(bool) {
       equal(bool.value, true);
 
-      equal(this.parents.length, 4);
+      equal(this.parents.length, 3);
       equal(this.parents[0].type, 'SubExpression');
-      equal(this.parents[1].type, 'SubExpression');
-      equal(this.parents[2].type, 'BlockStatement');
-      equal(this.parents[3].type, 'Program');
+      equal(this.parents[1].type, 'BlockStatement');
+      equal(this.parents[2].type, 'Program');
     };
     visitor.PathExpression = function(id) {
       equal(/(foo\.)?bar$/.test(id.original), true);
@@ -84,26 +83,26 @@ describe('Visitor', function() {
           var visitor = new Handlebars.Visitor();
 
           visitor.mutating = true;
-          visitor.SubExpression = function() {
+          visitor.PathExpression = function() {
             return false;
           };
 
           var ast = Handlebars.parse('{{foo 42}}');
           visitor.accept(ast);
-        }, Handlebars.Exception, 'MustacheStatement requires sexpr');
+        }, Handlebars.Exception, 'MustacheStatement requires path');
       });
       it('should throw when returning non-node responses', function() {
         shouldThrow(function() {
           var visitor = new Handlebars.Visitor();
 
           visitor.mutating = true;
-          visitor.SubExpression = function() {
+          visitor.PathExpression = function() {
             return {};
           };
 
           var ast = Handlebars.parse('{{foo 42}}');
           visitor.accept(ast);
-        }, Handlebars.Exception, 'Unexpected node type "undefined" found when accepting sexpr on MustacheStatement');
+        }, Handlebars.Exception, 'Unexpected node type "undefined" found when accepting path on MustacheStatement');
       });
     });
     describe('arrays', function() {