Improved support for Object.defineProperty

Issue angelozerr#377

Author: marijnh

defs/ecma5.json

@@ -29,7 +29,7 @@
       "!doc": "Creates a new object with the specified prototype object and properties."
     },
     "defineProperty": {
-      "!type": "fn(obj: ?, prop: string, desc: ?)",
+      "!type": "fn(obj: ?, prop: string, desc: ?) -> !custom:Object_defineProperty",
       "!url": "https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Object/defineProperty",
       "!doc": "Defines a new property directly on an object, or modifies an existing property on an object, and returns the object. If you want to see how to use the Object.defineProperty method with a binary-flags-like syntax, see this article."
     },

lib/def.js

@@ -449,6 +449,26 @@
     return result;
   });
 
+  var PropSpec = infer.constraint("target", {
+    addType: function(tp) {
+      if (!(tp instanceof infer.Obj)) return;
+      if (tp.hasProp("value"))
+        tp.getProp("value").propagate(this.target);
+      else if (tp.hasProp("get"))
+        tp.getProp("get").propagate(new infer.IsCallee(infer.ANull, [], null, this.target));
+    }
+  });
+
+  infer.registerFunction("Object_defineProperty", function(_self, args, argNodes) {
+    if (argNodes && argNodes.length >= 3 && argNodes[1].type == "Literal" &&
+        typeof argNodes[1].value == "string") {
+      var obj = args[0], connect = new infer.AVal;
+      obj.propagate(new infer.PropHasSubset(argNodes[1].value, connect, argNodes[1]));
+      args[2].propagate(new PropSpec(connect));
+    }
+    return infer.ANull;
+  });
+
   var IsBound = infer.constraint("self, args, target", {
     addType: function(tp) {
       if (!(tp instanceof infer.Fn)) return;

plugin/doc_comment.js

@@ -45,10 +45,21 @@
       ObjectExpression: function(node) {
         for (var i = 0; i < node.properties.length; ++i)
           attachComments(node.properties[i].key);
+      },
+      CallExpression: function(node) {
+        if (isDefinePropertyCall(node)) attachComments(node);
       }
     });
   }
 
+  function isDefinePropertyCall(node) {
+    return node.callee.type == "MemberExpression" &&
+      node.callee.object.name == "Object" &&
+      node.callee.property.name == "defineProperty" &&
+      node.arguments.length >= 3 &&
+      typeof node.arguments[1].value == "string";
+  }
+
   function postInfer(ast, scope) {
     jsdocParseTypedefs(ast.sourceFile.text, scope);
 
@@ -76,6 +87,15 @@
             interpretComments(prop, key.commentsBefore, scope,
                               node.objType.getProp(key.name));
         }
+      },
+      CallExpression: function(node, scope) {
+        if (node.commentsBefore && isDefinePropertyCall(node)) {
+          var type = infer.expressionType({node: node.arguments[0], state: scope}).getType();
+          if (type && type instanceof infer.Obj) {
+            var prop = type.props[node.arguments[1].value];
+            if (prop) interpretComments(node, node.commentsBefore, scope, prop);
+          }
+        }
       }
     }, infer.searchVisitor, scope);
   }
@@ -333,6 +353,7 @@
     } else if (node.type == "AssignmentExpression") {
       if (node.right.type == "FunctionExpression")
         fn = node.right.body.scope.fnType;
+    } else if (node.type == "CallExpression") {
     } else { // An object property
       if (node.value.type == "FunctionExpression") fn = node.value.body.scope.fnType;
     }

test/cases/defineProperty.js

@@ -0,0 +1,15 @@
+var o = {};
+
+// Docstring for prop1
+Object.defineProperty(o, "prop1", {
+  get: function() { return "hi"; }
+});
+
+Object.defineProperty(o, "prop2", {
+  value: 100
+});
+
+o.prop1; //: string
+o.prop2; //: number
+
+o.prop1; //doc: Docstring for prop1