fix(kernel): Return object literals as references

packages/jsii-calc/lib/compliance.ts

@@ -887,3 +887,11 @@ export class AbstractClassReturner {
         }
     }
 }
+
+export interface MutableObjectLiteral {
+    value: string;
+}
+
+export class ClassWithMutableObjectLiteralProperty {
+    public mutableObject: MutableObjectLiteral = { value: 'default' };
+}

packages/jsii-calc/test/assembly.jsii

@@ -1018,6 +1018,23 @@
         }
       ]
     },
+    "jsii-calc.ClassWithMutableObjectLiteralProperty": {
+      "assembly": "jsii-calc",
+      "fqn": "jsii-calc.ClassWithMutableObjectLiteralProperty",
+      "initializer": {
+        "initializer": true
+      },
+      "kind": "class",
+      "name": "ClassWithMutableObjectLiteralProperty",
+      "properties": [
+        {
+          "name": "mutableObject",
+          "type": {
+            "fqn": "jsii-calc.MutableObjectLiteral"
+          }
+        }
+      ]
+    },
     "jsii-calc.DefaultedConstructorArgument": {
       "assembly": "jsii-calc",
       "fqn": "jsii-calc.DefaultedConstructorArgument",
@@ -1883,6 +1900,22 @@
         }
       ]
     },
+    "jsii-calc.MutableObjectLiteral": {
+      "assembly": "jsii-calc",
+      "datatype": true,
+      "fqn": "jsii-calc.MutableObjectLiteral",
+      "kind": "interface",
+      "name": "MutableObjectLiteral",
+      "properties": [
+        {
+          "abstract": true,
+          "name": "value",
+          "type": {
+            "primitive": "string"
+          }
+        }
+      ]
+    },
     "jsii-calc.Negate": {
       "assembly": "jsii-calc",
       "base": {
@@ -3230,5 +3263,5 @@
     }
   },
   "version": "0.7.6",
-  "fingerprint": "ecDtx3DHVZi7UjyCDhGncg4jbSRaD536bUyh6YzAxlY="
+  "fingerprint": "DFShLmIJQmPjTv5Dmz4JoBKqoCtAyifD1RpCuHo+sEc="
 }

packages/jsii-kernel/lib/kernel.ts

@@ -14,6 +14,7 @@ import { TOKEN_DATE, TOKEN_ENUM, TOKEN_REF } from './api';
  */
 const OBJID_PROP = '$__jsii__objid__$';
 const FQN_PROP = '$__jsii__fqn__$';
+const PROXIES_PROP = '$__jsii__proxies__$';
 
 /**
  * A special FQN that can be used to create empty javascript objects.
@@ -923,12 +924,17 @@ export class Kernel {
         // so the client receives a real object.
         if (typeof(v) === 'object' && targetType && spec.isNamedTypeReference(targetType)) {
             this._debug('coalescing to', targetType);
-            const newObjRef = this._create({ fqn: targetType.fqn });
-            const newObj = this._findObject(newObjRef);
-            for (const k of Object.keys(v)) {
-                newObj[k] = v[k];
-            }
-            return newObjRef;
+            const proxies = v[PROXIES_PROP] = v[PROXIES_PROP] || {};
+            if (proxies[targetType.fqn]) { return proxies[targetType.fqn]; }
+            const proxy = new Proxy(v, {
+                has(target: any, propertyKey: string) {
+                    return propertyKey in target || propertyKey === FQN_PROP;
+                },
+                get(target: any, propertyKey: string) {
+                    return propertyKey === FQN_PROP ? targetType.fqn : target[propertyKey];
+                }
+            });
+            return this._createObjref(proxy, targetType.fqn);
         }
 
         // date (https://stackoverflow.com/a/643827/737957)

packages/jsii-kernel/test/test.kernel.ts

@@ -873,6 +873,21 @@ defineTest('node.js standard library', async (test, sandbox) => {
         { result: "6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50" });
 });
 
+// @see awslabs/jsii#248
+defineTest('object literals are returned by reference', async (test, sandbox) => {
+    const objref = sandbox.create({ fqn: 'jsii-calc.ClassWithMutableObjectLiteralProperty' });
+    const property = sandbox.get({ objref, property: 'mutableObject' }).value;
+
+    const newValue = 'Bazinga!1!';
+    sandbox.set({ objref: property, property: 'value', value: newValue });
+
+    test.equal(newValue,
+               sandbox.get({
+                   objref: sandbox.get({ objref, property: 'mutableObject' }).value,
+                   property: 'value'
+               }).value);
+});
+
 const testNames: { [name: string]: boolean } = { };
 
 async function createCalculatorSandbox(name: string) {

packages/jsii-pacmak/test/expected.jsii-calc/dotnet/Amazon.JSII.Tests.CalculatorPackageId/.jsii

@@ -1018,6 +1018,23 @@
         }
       ]
     },
+    "jsii-calc.ClassWithMutableObjectLiteralProperty": {
+      "assembly": "jsii-calc",
+      "fqn": "jsii-calc.ClassWithMutableObjectLiteralProperty",
+      "initializer": {
+        "initializer": true
+      },
+      "kind": "class",
+      "name": "ClassWithMutableObjectLiteralProperty",
+      "properties": [
+        {
+          "name": "mutableObject",
+          "type": {
+            "fqn": "jsii-calc.MutableObjectLiteral"
+          }
+        }
+      ]
+    },
     "jsii-calc.DefaultedConstructorArgument": {
       "assembly": "jsii-calc",
       "fqn": "jsii-calc.DefaultedConstructorArgument",
@@ -1883,6 +1900,22 @@
         }
       ]
     },
+    "jsii-calc.MutableObjectLiteral": {
+      "assembly": "jsii-calc",
+      "datatype": true,
+      "fqn": "jsii-calc.MutableObjectLiteral",
+      "kind": "interface",
+      "name": "MutableObjectLiteral",
+      "properties": [
+        {
+          "abstract": true,
+          "name": "value",
+          "type": {
+            "primitive": "string"
+          }
+        }
+      ]
+    },
     "jsii-calc.Negate": {
       "assembly": "jsii-calc",
       "base": {
@@ -3230,5 +3263,5 @@
     }
   },
   "version": "0.7.6",
-  "fingerprint": "ecDtx3DHVZi7UjyCDhGncg4jbSRaD536bUyh6YzAxlY="
+  "fingerprint": "DFShLmIJQmPjTv5Dmz4JoBKqoCtAyifD1RpCuHo+sEc="
 }

packages/jsii-pacmak/test/expected.jsii-calc/dotnet/Amazon.JSII.Tests.CalculatorPackageId/Amazon/JSII/Tests/CalculatorNamespace/ClassWithMutableObjectLiteralProperty.cs

@@ -0,0 +1,27 @@
+using Amazon.JSII.Runtime.Deputy;
+
+namespace Amazon.JSII.Tests.CalculatorNamespace
+{
+    [JsiiClass(typeof(ClassWithMutableObjectLiteralProperty), "jsii-calc.ClassWithMutableObjectLiteralProperty", "[]")]
+    public class ClassWithMutableObjectLiteralProperty : DeputyBase
+    {
+        public ClassWithMutableObjectLiteralProperty(): base(new DeputyProps(new object[]{}))
+        {
+        }
+
+        protected ClassWithMutableObjectLiteralProperty(ByRefValue reference): base(reference)
+        {
+        }
+
+        protected ClassWithMutableObjectLiteralProperty(DeputyProps props): base(props)
+        {
+        }
+
+        [JsiiProperty("mutableObject", "{\"fqn\":\"jsii-calc.MutableObjectLiteral\"}")]
+        public virtual IMutableObjectLiteral MutableObject
+        {
+            get => GetInstanceProperty<IMutableObjectLiteral>();
+            set => SetInstanceProperty(value);
+        }
+    }
+}

packages/jsii-pacmak/test/expected.jsii-calc/dotnet/Amazon.JSII.Tests.CalculatorPackageId/Amazon/JSII/Tests/CalculatorNamespace/IMutableObjectLiteral.cs

@@ -0,0 +1,15 @@
+using Amazon.JSII.Runtime.Deputy;
+
+namespace Amazon.JSII.Tests.CalculatorNamespace
+{
+    [JsiiInterface(typeof(IMutableObjectLiteral), "jsii-calc.MutableObjectLiteral")]
+    public interface IMutableObjectLiteral
+    {
+        [JsiiProperty("value", "{\"primitive\":\"string\"}")]
+        string Value
+        {
+            get;
+            set;
+        }
+    }
+}

packages/jsii-pacmak/test/expected.jsii-calc/dotnet/Amazon.JSII.Tests.CalculatorPackageId/Amazon/JSII/Tests/CalculatorNamespace/MutableObjectLiteral.cs

@@ -0,0 +1,14 @@
+using Amazon.JSII.Runtime.Deputy;
+
+namespace Amazon.JSII.Tests.CalculatorNamespace
+{
+    public class MutableObjectLiteral : DeputyBase, IMutableObjectLiteral
+    {
+        [JsiiProperty("value", "{\"primitive\":\"string\"}", true)]
+        public string Value
+        {
+            get;
+            set;
+        }
+    }
+}

packages/jsii-pacmak/test/expected.jsii-calc/dotnet/Amazon.JSII.Tests.CalculatorPackageId/Amazon/JSII/Tests/CalculatorNamespace/MutableObjectLiteralProxy.cs

@@ -0,0 +1,19 @@
+using Amazon.JSII.Runtime.Deputy;
+
+namespace Amazon.JSII.Tests.CalculatorNamespace
+{
+    [JsiiTypeProxy(typeof(IMutableObjectLiteral), "jsii-calc.MutableObjectLiteral")]
+    internal sealed class MutableObjectLiteralProxy : DeputyBase, IMutableObjectLiteral
+    {
+        private MutableObjectLiteralProxy(ByRefValue reference): base(reference)
+        {
+        }
+
+        [JsiiProperty("value", "{\"primitive\":\"string\"}")]
+        public string Value
+        {
+            get => GetInstanceProperty<string>();
+            set => SetInstanceProperty(value);
+        }
+    }
+}

packages/jsii-pacmak/test/expected.jsii-calc/java/src/main/java/software/amazon/jsii/tests/calculator/$Module.java

@@ -29,6 +29,7 @@ protected Class<?> resolveClass(final String fqn) throws ClassNotFoundException
             case "jsii-calc.BinaryOperation": return software.amazon.jsii.tests.calculator.BinaryOperation.class;
             case "jsii-calc.Calculator": return software.amazon.jsii.tests.calculator.Calculator.class;
             case "jsii-calc.CalculatorProps": return software.amazon.jsii.tests.calculator.CalculatorProps.class;
+            case "jsii-calc.ClassWithMutableObjectLiteralProperty": return software.amazon.jsii.tests.calculator.ClassWithMutableObjectLiteralProperty.class;
             case "jsii-calc.DefaultedConstructorArgument": return software.amazon.jsii.tests.calculator.DefaultedConstructorArgument.class;
             case "jsii-calc.DerivedClassHasNoProperties.Base": return software.amazon.jsii.tests.calculator.DerivedClassHasNoProperties.Base.class;
             case "jsii-calc.DerivedClassHasNoProperties.Derived": return software.amazon.jsii.tests.calculator.DerivedClassHasNoProperties.Derived.class;
@@ -51,6 +52,7 @@ protected Class<?> resolveClass(final String fqn) throws ClassNotFoundException
             case "jsii-calc.JSObjectLiteralToNativeClass": return software.amazon.jsii.tests.calculator.JSObjectLiteralToNativeClass.class;
             case "jsii-calc.JavaReservedWords": return software.amazon.jsii.tests.calculator.JavaReservedWords.class;
             case "jsii-calc.Multiply": return software.amazon.jsii.tests.calculator.Multiply.class;
+            case "jsii-calc.MutableObjectLiteral": return software.amazon.jsii.tests.calculator.MutableObjectLiteral.class;
             case "jsii-calc.Negate": return software.amazon.jsii.tests.calculator.Negate.class;
             case "jsii-calc.NodeStandardLibrary": return software.amazon.jsii.tests.calculator.NodeStandardLibrary.class;
             case "jsii-calc.NumberGenerator": return software.amazon.jsii.tests.calculator.NumberGenerator.class;

packages/jsii-pacmak/test/expected.jsii-calc/java/src/main/java/software/amazon/jsii/tests/calculator/ClassWithMutableObjectLiteralProperty.java

@@ -0,0 +1,21 @@
+package software.amazon.jsii.tests.calculator;
+
+@javax.annotation.Generated(value = "jsii-pacmak")
+@software.amazon.jsii.Jsii(module = software.amazon.jsii.tests.calculator.$Module.class, fqn = "jsii-calc.ClassWithMutableObjectLiteralProperty")
+public class ClassWithMutableObjectLiteralProperty extends software.amazon.jsii.JsiiObject {
+    protected ClassWithMutableObjectLiteralProperty(final software.amazon.jsii.JsiiObject.InitializationMode mode) {
+        super(mode);
+    }
+    public ClassWithMutableObjectLiteralProperty() {
+        super(software.amazon.jsii.JsiiObject.InitializationMode.Jsii);
+        software.amazon.jsii.JsiiEngine.getInstance().createNewObject(this);
+    }
+
+    public software.amazon.jsii.tests.calculator.MutableObjectLiteral getMutableObject() {
+        return this.jsiiGet("mutableObject", software.amazon.jsii.tests.calculator.MutableObjectLiteral.class);
+    }
+
+    public void setMutableObject(final software.amazon.jsii.tests.calculator.MutableObjectLiteral value) {
+        this.jsiiSet("mutableObject", java.util.Objects.requireNonNull(value, "mutableObject is required"));
+    }
+}

packages/jsii-pacmak/test/expected.jsii-calc/java/src/main/java/software/amazon/jsii/tests/calculator/MutableObjectLiteral.java

@@ -0,0 +1,72 @@
+package software.amazon.jsii.tests.calculator;
+
+@javax.annotation.Generated(value = "jsii-pacmak")
+public interface MutableObjectLiteral extends software.amazon.jsii.JsiiSerializable {
+    java.lang.String getValue();
+    void setValue(final java.lang.String value);
+
+    /**
+     * @return a {@link Builder} of {@link MutableObjectLiteral}
+     */
+    static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * A builder for {@link MutableObjectLiteral}
+     */
+    final class Builder {
+        private java.lang.String _value;
+
+        /**
+         * Sets the value of Value
+         * @param value the value to be set
+         * @return {@code this}
+         */
+        public Builder withValue(final java.lang.String value) {
+            this._value = java.util.Objects.requireNonNull(value, "value is required");
+            return this;
+        }
+
+        /**
+         * Builds the configured instance.
+         * @return a new instance of {@link MutableObjectLiteral}
+         * @throws NullPointerException if any required attribute was not provided
+         */
+        public MutableObjectLiteral build() {
+            return new MutableObjectLiteral() {
+                private java.lang.String $value = java.util.Objects.requireNonNull(_value, "value is required");
+
+                @Override
+                public java.lang.String getValue() {
+                    return this.$value;
+                }
+
+                @Override
+                public void setValue(final java.lang.String value) {
+                    this.$value = java.util.Objects.requireNonNull(value, "value is required");
+                }
+
+            };
+        }
+    }
+
+    /**
+     * A proxy class which represents a concrete javascript instance of this type.
+     */
+    final static class Jsii$Proxy extends software.amazon.jsii.JsiiObject implements software.amazon.jsii.tests.calculator.MutableObjectLiteral {
+        protected Jsii$Proxy(final software.amazon.jsii.JsiiObject.InitializationMode mode) {
+            super(mode);
+        }
+
+        @Override
+        public java.lang.String getValue() {
+            return this.jsiiGet("value", java.lang.String.class);
+        }
+
+        @Override
+        public void setValue(final java.lang.String value) {
+            this.jsiiSet("value", java.util.Objects.requireNonNull(value, "value is required"));
+        }
+    }
+}