implement null aware ops, fixes #249

this also implements multitest support, which fixes #280

Fixes some other preexisting bugs:
* MetaLets did not simplify themselves correctly in some nested cases
* Library prefixed identifiers did not work as lvalues in opassign
* dsetindex/dput/[]= methods did not return a value
* checker did not correctly handle invalid constructor field initializers
* cascades did not correctly work with method invocations(?)
* postfix ++/-- did not correctly generate lvalues in some cases

The good news: because this reuses on our existing lvalue/metalet helpers, it managed to flush out a lot of bugs in other features that use them.

R=vsm@google.com

Review URL: https://codereview.chromium.org/1316723003 .

Author: John Messerly

pkg/dev_compiler/.gitignore

@@ -17,6 +17,7 @@ node_modules
 test/codegen/expect/dev_compiler/
 test/codegen/expect/language/
 test/codegen/expect/sunflower/dev_compiler/
+test/codegen/language/*_multi.dart
 
 # Created by ./tool/build_sdk.sh
 tool/generated_sdk/

pkg/dev_compiler/lib/runtime/_operations.js

@@ -62,6 +62,7 @@ dart_library.library('dart_runtime/_operations', null, /* Imports */[
     // TODO(vsm): Implement NSM and type checks.
     // See: https://github.com/dart-lang/dev_compiler/issues/170
     obj[field] = value;
+    return value;
   }
   exports.dput = dput;
 
@@ -168,7 +169,8 @@ dart_library.library('dart_runtime/_operations', null, /* Imports */[
   exports.dindex = dindex;
 
   function dsetindex(obj, index, value) {
-    return callMethod(obj, 'set', [index, value], '[]=');
+    callMethod(obj, 'set', [index, value], '[]=');
+    return value;
   }
   exports.dsetindex = dsetindex;
 
@@ -318,6 +320,23 @@ dart_library.library('dart_runtime/_operations', null, /* Imports */[
   }
   exports.stackTrace = stackTrace;
 
+  /**
+   * Implements a sequence of .? operations.
+   *
+   * Will call each successive callback, unless one returns null, which stops
+   * the sequence.
+   */
+  function nullSafe(obj /*, ...callbacks*/) {
+    let callbacks = slice.call(arguments, 1);
+    if (obj == null) return obj;
+    for (const callback of callbacks) {
+      obj = callback(obj);
+      if (obj == null) break;
+    }
+    return obj;
+  }
+  exports.nullSafe = nullSafe;
+
   let _value = Symbol('_value');
   /**
    * Looks up a sequence of [keys] in [map], recursively, and

pkg/dev_compiler/lib/runtime/dart/_interceptors.js

@@ -386,6 +386,7 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
         if (dart.notNull(index) >= dart.notNull(this[dartx.length]) || dart.notNull(index) < 0)
           dart.throw(new core.RangeError.value(index));
         this[index] = value;
+        return value;
       }
       [dartx.asMap]() {
         return new (_internal.IterableMixinWorkaround$(E))().asMapList(this);

pkg/dev_compiler/lib/runtime/dart/_internal.js

@@ -1655,6 +1655,7 @@ dart_library.library('dart/_internal', null, /* Imports */[
       set(index, value) {
         dart.as(value, E);
         dart.throw(new core.UnsupportedError("Cannot modify an unmodifiable list"));
+        return value;
       }
       set length(newLength) {
         dart.throw(new core.UnsupportedError("Cannot change the length of an unmodifiable list"));
@@ -1857,6 +1858,7 @@ dart_library.library('dart/_internal', null, /* Imports */[
       set(key, value) {
         dart.as(value, E);
         dart.throw(new core.UnsupportedError("Cannot modify an unmodifiable map"));
+        return value;
       }
       putIfAbsent(key, ifAbsent) {
         dart.as(ifAbsent, dart.functionType(E, []));

pkg/dev_compiler/lib/runtime/dart/_native_typed_data.js

@@ -232,6 +232,7 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       this[_storage].set(dart.notNull(index) * 4 + 1, value.y);
       this[_storage].set(dart.notNull(index) * 4 + 2, value.z);
       this[_storage].set(dart.notNull(index) * 4 + 3, value.w);
+      return value;
     }
     sublist(start, end) {
       if (end === void 0)
@@ -340,6 +341,7 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       this[_storage].set(dart.notNull(index) * 4 + 1, value.y);
       this[_storage].set(dart.notNull(index) * 4 + 2, value.z);
       this[_storage].set(dart.notNull(index) * 4 + 3, value.w);
+      return value;
     }
     sublist(start, end) {
       if (end === void 0)
@@ -442,6 +444,7 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       this[_checkIndex](index, this.length);
       this[_storage].set(dart.notNull(index) * 2 + 0, value.x);
       this[_storage].set(dart.notNull(index) * 2 + 1, value.y);
+      return value;
     }
     sublist(start, end) {
       if (end === void 0)
@@ -745,6 +748,7 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
     set(index, value) {
       this[_checkIndex](index, this.length);
       this[index] = value;
+      return value;
     }
     setRange(start, end, iterable, skipCount) {
       if (skipCount === void 0)
@@ -771,6 +775,7 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
     set(index, value) {
       this[_checkIndex](index, this.length);
       this[index] = value;
+      return value;
     }
     setRange(start, end, iterable, skipCount) {
       if (skipCount === void 0)

pkg/dev_compiler/lib/runtime/dart/async.js

@@ -863,8 +863,8 @@ dart_library.library('dart/async', null, /* Imports */[
   let _cancelFuture = Symbol('_cancelFuture');
   let _pending = Symbol('_pending');
   let _setPendingEvents = Symbol('_setPendingEvents');
-  let _extractPending = Symbol('_extractPending');
   let _isCanceled = Symbol('_isCanceled');
+  let _extractPending = Symbol('_extractPending');
   let _isPaused = Symbol('_isPaused');
   let _isInputPaused = Symbol('_isInputPaused');
   let _inCallback = Symbol('_inCallback');
@@ -884,8 +884,8 @@ dart_library.library('dart/async', null, /* Imports */[
   let _sendData = Symbol('_sendData');
   let _addPending = Symbol('_addPending');
   let _sendError = Symbol('_sendError');
-  let _close = Symbol('_close');
   let _sendDone = Symbol('_sendDone');
+  let _close = Symbol('_close');
   let _checkState = Symbol('_checkState');
   let _BufferingStreamSubscription$ = dart.generic(function(T) {
     class _BufferingStreamSubscription extends core.Object {

pkg/dev_compiler/lib/runtime/dart/collection.js

@@ -2290,6 +2290,7 @@ dart_library.library('dart/collection', null, /* Imports */[
         dart.as(key, K);
         dart.as(value, V);
         dart.throw(new core.UnsupportedError("Cannot modify unmodifiable map"));
+        return value;
       }
       addAll(other) {
         dart.as(other, core.Map$(K, V));
@@ -2414,6 +2415,7 @@ dart_library.library('dart/collection', null, /* Imports */[
         dart.as(key, K);
         dart.as(value, V);
         this[_map].set(key, value);
+        return value;
       }
       addAll(other) {
         dart.as(other, core.Map$(K, V));
@@ -3324,8 +3326,8 @@ dart_library.library('dart/collection', null, /* Imports */[
   let _root = Symbol('_root');
   let _count = Symbol('_count');
   let _splayCount = Symbol('_splayCount');
-  let _splay = Symbol('_splay');
   let _compare = Symbol('_compare');
+  let _splay = Symbol('_splay');
   let _splayMin = Symbol('_splayMin');
   let _splayMax = Symbol('_splayMax');
   let _addNewRoot = Symbol('_addNewRoot');
@@ -3561,17 +3563,20 @@ dart_library.library('dart/collection', null, /* Imports */[
         return null;
       }
       set(key, value) {
-        dart.as(key, K);
-        dart.as(value, V);
-        if (key == null)
-          dart.throw(new core.ArgumentError(key));
-        let comp = this[_splay](key);
-        if (comp == 0) {
-          let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
-          mapRoot.value = value;
-          return;
-        }
-        this[_addNewRoot](new (_SplayTreeMapNode$(K, dart.dynamic))(key, value), comp);
+        ((() => {
+          dart.as(key, K);
+          dart.as(value, V);
+          if (key == null)
+            dart.throw(new core.ArgumentError(key));
+          let comp = this[_splay](key);
+          if (comp == 0) {
+            let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
+            mapRoot.value = value;
+            return;
+          }
+          this[_addNewRoot](new (_SplayTreeMapNode$(K, dart.dynamic))(key, value), comp);
+        }).bind(this))();
+        return value;
       }
       putIfAbsent(key, ifAbsent) {
         dart.as(key, K);
@@ -4227,6 +4232,7 @@ dart_library.library('dart/collection', null, /* Imports */[
         } else {
           this[_set](key, value);
         }
+        return value;
       }
       [_set](key, value) {
         dart.as(key, K);
@@ -4489,6 +4495,7 @@ dart_library.library('dart/collection', null, /* Imports */[
         dart.as(key, K);
         dart.as(value, V);
         super[_set](key, value);
+        return value;
       }
       containsKey(key) {
         if (!dart.notNull(this[_validKey](key)))
@@ -4718,6 +4725,7 @@ dart_library.library('dart/collection', null, /* Imports */[
         } else {
           this[_set](key, value);
         }
+        return value;
       }
       [_set](key, value) {
         dart.as(key, K);
@@ -4970,6 +4978,7 @@ dart_library.library('dart/collection', null, /* Imports */[
         dart.as(key, K);
         dart.as(value, V);
         super[_set](key, value);
+        return value;
       }
       containsKey(key) {
         if (!dart.notNull(this[_validKey](key)))

pkg/dev_compiler/lib/runtime/dart/convert.js

@@ -2665,6 +2665,7 @@ dart_library.library('dart/convert', null, /* Imports */[
       } else {
         this[_upgrade]().set(key, value);
       }
+      return value;
     }
     addAll(other) {
       other.forEach(dart.fn(((key, value) => {

pkg/dev_compiler/lib/runtime/dart/core.js

@@ -1179,6 +1179,7 @@ dart_library.library('dart/core', null, /* Imports */[
           _js_helper.Primitives.setProperty(object, Expando$()._EXPANDO_PROPERTY_NAME, values);
         }
         _js_helper.Primitives.setProperty(values, this[_getKey](), value);
+        return value;
       }
       [_getKey]() {
         let key = dart.as(_js_helper.Primitives.getProperty(this, Expando$()._KEY_PROPERTY_NAME), String);

pkg/dev_compiler/lib/runtime/dart/js.js

@@ -75,6 +75,7 @@ dart_library.library('dart/js', null, /* Imports */[
         dart.throw(new core.ArgumentError("property is not a String or num"));
       }
       this[_jsObject][property] = _convertToJS(value);
+      return value;
     }
     get hashCode() {
       return 0;
@@ -212,6 +213,7 @@ dart_library.library('dart/js', null, /* Imports */[
           this[_checkIndex](index);
         }
         super.set(index, value);
+        return value;
       }
       get length() {
         let len = this[_jsObject].length;