Implement .getCallType

pkg/compiler/lib/src/kernel/element_map_impl.dart

Index: pkg/compiler/lib/src/kernel/element_map_impl.dart
diff --git a/pkg/compiler/lib/src/kernel/element_map_impl.dart b/pkg/compiler/lib/src/kernel/element_map_impl.dart
index 8437fe8f7ab200849ff3ea9817ce8b4567448e81..ce3e0a511430a76d55c2782c835149c203c8e6b3 100644
--- a/pkg/compiler/lib/src/kernel/element_map_impl.dart
+++ b/pkg/compiler/lib/src/kernel/element_map_impl.dart
@@ -459,6 +459,146 @@ abstract class KernelToElementMapBase extends KernelToElementMapBaseMixin {
         context.typeArguments, _getThisType(context.element).typeArguments);
   }
 
+  // TODO(johnniwinther): Remove this when call-type is provided by fasta.
+  void _ensureCallType(IndexedClass cls, ClassData data) {
+    if (!data.isCallTypeComputed) {
+      data.isCallTypeComputed = true;
+      MemberEntity callMethod = lookupClassMember(cls, Identifiers.call);
+      if (callMethod != null) {
+        if (callMethod.isFunction) {
+          data.callType = _getFunctionType(callMethod);
+        } else {
+          data.callType = const DynamicType();
+        }
+        return;
+      }
+
+      Set<FunctionType> inheritedCallTypes = new Set<FunctionType>();
+      bool inheritsInvalidCallMember = false;
+
+      void addCallType(InterfaceType supertype) {
+        if (supertype == null) return;
+        DartType type = _getCallType(supertype);
+        if (type == null) return;
+        if (type.isFunctionType) {
+          inheritedCallTypes.add(type);
+        } else {
+          inheritsInvalidCallMember = true;
+        }
+      }
+
+      addCallType(_getSuperType(cls));
+      _getInterfaces(cls).forEach(addCallType);
+
+      // Following §11.1.1 in the spec.
+      if (inheritsInvalidCallMember) {
+        // From §11.1.1 in the spec (continued):
+        //
+        // If some but not all of the m_i, 1 ≤ i ≤ k are getters none of the m_i
+        // are inherited, and a static warning is issued.
+        data.callType = const DynamicType();
+      } else if (inheritedCallTypes.isEmpty) {
+        return;
+      } else if (inheritedCallTypes.length == 1) {
+        data.callType = inheritedCallTypes.single;
+      } else {
+        // From §11.1.1 in the spec (continued):
+        //
+        // Otherwise, if the static types T_1, ... , T_k of the members
+        // m_1, ..., m_k are not identical, then there must be a member m_x such
+        // that T_x <: T_i, 1 ≤ x ≤ k for all i ∈ 1..k, or a static type warning
+        // occurs.
+        List<FunctionType> subtypesOfAllInherited = <FunctionType>[];
+        outer:
+        for (FunctionType a in inheritedCallTypes) {
+          for (FunctionType b in inheritedCallTypes) {
+            if (identical(a, b)) continue;
+            if (!types.isSubtype(a, b)) continue outer;
+          }
+          subtypesOfAllInherited.add(a);
+        }
+        if (subtypesOfAllInherited.length == 1) {
+          // From §11.1.1 in the spec (continued):
+          //
+          // The member that is inherited is m_x, if it exists.
+          data.callType = subtypesOfAllInherited.single;
+          return;
+        }
+
+        // From §11.1.1 in the spec (continued):
+        //
+        // Otherwise: let numberOfPositionals(f) denote the number of
+        // positional parameters of a function f, and let
+        // numberOfRequiredParams(f) denote the number of required parameters of
+        // a function f. Furthermore, let s denote the set of all named
+        // parameters of the m_1, . . . , m_k. Then let
+        //
+        //     h = max(numberOfPositionals(mi)),
+        //     r = min(numberOfRequiredParams(mi)), i ∈ 1..k.
+
+        // Then I has a method named n, with r required parameters of type
+        // dynamic, h positional parameters of type dynamic, named parameters s
+        // of type dynamic and return type dynamic.
+
+        // Multiple signatures with different types => create the synthesized
+        // version.
+        int minRequiredParameters;
+        int maxPositionalParameters;
+        Set<String> names = new Set<String>();
+        for (FunctionType type in inheritedCallTypes) {
+          type.namedParameters.forEach((String name) => names.add(name));
+          int requiredParameters = type.parameterTypes.length;
+          int optionalParameters = type.optionalParameterTypes.length;
+          int positionalParameters = requiredParameters + optionalParameters;
+          if (minRequiredParameters == null ||
+              minRequiredParameters > requiredParameters) {
+            minRequiredParameters = requiredParameters;
+          }
+          if (maxPositionalParameters == null ||
+              maxPositionalParameters < positionalParameters) {
+            maxPositionalParameters = positionalParameters;
+          }
+        }
+        int optionalParameters =
+            maxPositionalParameters - minRequiredParameters;
+        // TODO(johnniwinther): Support function types with both optional
+        // and named parameters?
+        if (optionalParameters == 0 || names.isEmpty) {
+          DartType dynamic = const DynamicType();
+          List<DartType> requiredParameterTypes =
+              new List.filled(minRequiredParameters, dynamic);
+          List<DartType> optionalParameterTypes =
+              new List.filled(optionalParameters, dynamic);
+          List<String> namedParameters = names.toList()
+            ..sort((a, b) => a.compareTo(b));
+          List<DartType> namedParameterTypes =
+              new List.filled(namedParameters.length, dynamic);
+          data.callType = new FunctionType(dynamic, requiredParameterTypes,
+              optionalParameterTypes, namedParameters, namedParameterTypes);
+        } else {
+          // The function type is not valid.
+          data.callType = const DynamicType();
+        }
+      }
+    }
+  }
+
+  /// Returns the type of the `call` method on 'type'.
+  ///
+  /// If [type] doesn't have a `call` member `null` is returned. If [type] has
+  /// an invalid `call` member (non-method or a synthesized method with both
+  /// optional and named parameters) a [DynamicType] is returned.
+  DartType _getCallType(InterfaceType type) {
+    IndexedClass cls = type.element;
+    assert(checkFamily(cls));
+    ClassData data = _classData[cls.classIndex];
+    _ensureCallType(cls, data);
+    if (data.callType != null) {
+      return _substByContext(data.callType, type);
+    }
+    return null;
+  }
+
   InterfaceType _getThisType(IndexedClass cls) {
     assert(checkFamily(cls));
     ClassData data = _classData[cls.classIndex];
@@ -1107,6 +1247,20 @@ class KernelToElementMapForImpactImpl extends KernelToElementMapBase
           name, memberContext, executableContext, functionType);
     });
   }
+
+  bool _implementsFunction(IndexedClass cls) {
+    assert(checkFamily(cls));
+    ClassData data = _classData[cls.classIndex];
+    OrderedTypeSet orderedTypeSet = data.orderedTypeSet;
+    InterfaceType supertype = orderedTypeSet.asInstanceOf(
+        commonElements.functionClass,
+        _getHierarchyDepth(commonElements.functionClass));
+    if (supertype != null) {
+      return true;
+    }
+    _ensureCallType(cls, data);
+    return data.callType is FunctionType;
+  }
 }
 
 class KernelElementEnvironment implements ElementEnvironment {
@@ -1537,8 +1691,7 @@ class KernelResolutionWorldBuilder extends KernelResolutionWorldBuilderBase {
 
   @override
   bool implementsFunction(ClassEntity cls) {
-    // TODO(redemption): Implement this.
-    return false;
+    return elementMap._implementsFunction(cls);
   }
 
   @override