Recursively merge properties.

When merging inputs and defaults in order to construct the set of inputs
for a call to `Create`, we must recursively merge each property value:
the provided defaults may contain nested values that must be present in
the merged result.

examples/dynamic-provider/recursive-merge/Pulumi.yaml

@@ -0,0 +1,4 @@
+name: recursive-merge
+description: A test for recursive merging of defaults.
+runtime: nodejs
+

examples/dynamic-provider/recursive-merge/index.ts

@@ -0,0 +1,29 @@
+// Copyright 2016-2017, Pulumi Corporation.  All rights reserved.
+
+import * as pulumi from "pulumi";
+import * as dynamic from "pulumi/dynamic";
+
+class TestProvider implements dynamic.ResourceProvider {
+    diff = (id: pulumi.ID, olds: any, news: any) => Promise.resolve(new dynamic.DiffResult([], []));
+    delete = (id: pulumi.ID, props: any) => Promise.resolve();
+    update = (id: string, olds: any, news: any) => Promise.resolve(new dynamic.UpdateResult({}));
+
+	check = (inputs: any) => Promise.resolve(new dynamic.CheckResult({prop: {def: true}, arr: [{def: true}], arr1: [], arr2: [{def:true}]}, []));
+
+    create = async (inputs: any) => {
+		if (!inputs.prop.def || !inputs.arr[0].def || !inputs.arr1[0].def || !inputs.arr2[0].def) {
+			throw new Error("expected defaults to be recursively merged");
+		}
+		return new dynamic.CreateResult("0", {ok: true});
+	}
+}
+
+class TestResource extends dynamic.Resource {
+	public readonly ok: pulumi.Computed<Boolean>;
+
+	constructor(name: string) {
+		super(new TestProvider(), name, {prop: {unused: ""}, arr: [{unused: ""}], arr1: [{def: true}], arr2: []}, undefined);
+	}
+}
+
+export const ok = new TestResource("test").ok;

examples/dynamic-provider/recursive-merge/package.json

@@ -0,0 +1,11 @@
+{
+    "name": "minimal",
+    "main": "bin/index.js",
+    "typings": "bin/index.d.ts",
+    "scripts": {
+        "build": "tsc"
+    },
+    "devDependencies": {
+        "typescript": "^2.5.3"
+    }
+}

examples/dynamic-provider/recursive-merge/tsconfig.json

@@ -0,0 +1,22 @@
+{
+    "compilerOptions": {
+        "outDir": "bin",
+        "target": "es6",
+        "module": "commonjs",
+        "moduleResolution": "node",
+        "declaration": true,
+        "sourceMap": true,
+        "stripInternal": true,
+        "experimentalDecorators": true,
+        "pretty": true,
+        "noFallthroughCasesInSwitch": true,
+        "noImplicitAny": true,
+        "noImplicitReturns": true,
+        "forceConsistentCasingInFileNames": true,
+        "strictNullChecks": true
+    },
+    "files": [
+        "index.ts"
+    ]
+}
+

examples/dynamic-provider/recursive-merge/yarn.lock

@@ -0,0 +1,7 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+typescript@^2.5.3:
+  version "2.6.2"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.6.2.tgz#3c5b6fd7f6de0914269027f03c0946758f7673a4"

pkg/resource/properties.go

@@ -141,6 +141,9 @@ func (m PropertyMap) Merge(other PropertyMap) PropertyMap {
 	new := m.Copy()
 	for k, v := range other {
 		if !v.IsNull() {
+			if mv, ok := m[k]; ok {
+				v = mv.Merge(v)
+			}
 			new[k] = v
 		}
 	}
@@ -454,6 +457,42 @@ func (v PropertyValue) MapRepl(replk func(string) (string, bool),
 	return v.ObjectValue().MapRepl(replk, replv)
 }
 
+// Merge simply merges the value of other into v. Merging proceeds as follows:
+// - If other is null, v is returned.
+// - If v and other are both arrays, the corresponding elements are recurively merged. Any unmerged elements in v or other are then
+//   appended to the result.
+// - If v and other are both maps, the corresponding key-value pairs are recursively merged.
+// - Otherwise, other is returned.
+func (v PropertyValue) Merge(other PropertyValue) PropertyValue {
+	switch {
+	case other.IsNull():
+		return v
+	case v.IsArray() && other.IsArray():
+		left, right, merged := v.ArrayValue(), other.ArrayValue(), []PropertyValue{}
+		for len(left) > 0 && len(right) > 0 {
+			merged = append(merged, left[0], right[0])
+			left, right = left[1:], right[1:]
+		}
+		switch {
+		case len(left) > 0:
+			contract.Assert(len(right) == 0)
+			for ; len(left) > 0; left = left[1:] {
+				merged = append(merged, left[0])
+			}
+		case len(right) > 0:
+			contract.Assert(len(left) == 0)
+			for ; len(right) > 0; right = right[1:] {
+				merged = append(merged, right[0])
+			}
+		}
+		return NewArrayProperty(merged)
+	case v.IsObject() && other.IsObject():
+		return NewObjectProperty(v.ObjectValue().Merge(other.ObjectValue()))
+	default:
+		return other
+	}
+}
+
 // String implements the fmt.Stringer interface to add slightly more information to the output.
 func (v PropertyValue) String() string {
 	if v.IsComputed() || v.IsOutput() {