Revert "Move dart2js from sdk/lib/_internal/compiler to pkg/compiler"

pkg/compiler/lib/src/types/type_mask.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-part of types;
-
-/**
- * A type mask represents a set of contained classes, but the
- * operations on it are not guaranteed to be precise and they may
- * yield conservative answers that contain too many classes.
- */
-abstract class TypeMask {
-  factory TypeMask(ClassElement base,
-                   int kind,
-                   bool isNullable,
-                   ClassWorld classWorld) {
-    return new FlatTypeMask.normalized(
-        base, (kind << 1) | (isNullable ? 1 : 0), classWorld);
-  }
-
-  const factory TypeMask.empty() = FlatTypeMask.empty;
-
-  factory TypeMask.exact(ClassElement base, ClassWorld classWorld) {
-    assert(invariant(base, classWorld.isInstantiated(base),
-        message: "Cannot create extact type mask for uninstantiated class"));
-    return new FlatTypeMask.exact(base);
-  }
-
-  factory TypeMask.exactOrEmpty(ClassElement base, ClassWorld classWorld) {
-    if (classWorld.isInstantiated(base)) return new FlatTypeMask.exact(base);
-    return const TypeMask.empty();
-  }
-
-  factory TypeMask.subclass(ClassElement base, ClassWorld classWorld) {
-    if (classWorld.hasAnySubclass(base)) {
-      return new FlatTypeMask.subclass(base);
-    } else {
-      return new TypeMask.exactOrEmpty(base, classWorld);
-    }
-  }
-
-  factory TypeMask.subtype(ClassElement base, ClassWorld classWorld) {
-    if (classWorld.hasOnlySubclasses(base)) {
-      return new TypeMask.subclass(base, classWorld);
-    }
-    if (classWorld.hasAnySubtype(base)) {
-      return new FlatTypeMask.subtype(base);
-    } else {
-      return new TypeMask.exactOrEmpty(base, classWorld);
-    }
-  }
-
-  const factory TypeMask.nonNullEmpty() = FlatTypeMask.nonNullEmpty;
-
-  factory TypeMask.nonNullExact(ClassElement base, ClassWorld classWorld) {
-    assert(invariant(base, classWorld.isInstantiated(base),
-        message: "Cannot create extact type mask for uninstantiated class"));
-    return new FlatTypeMask.nonNullExact(base);
-  }
-
-  factory TypeMask.nonNullExactOrEmpty(ClassElement base,
-      ClassWorld classWorld) {
-    if (classWorld.isInstantiated(base)) {
-      return new FlatTypeMask.nonNullExact(base);
-    }
-    return const TypeMask.nonNullEmpty();
-  }
-
-  factory TypeMask.nonNullSubclass(ClassElement base, ClassWorld classWorld) {
-    if (classWorld.hasAnySubclass(base)) {
-      return new FlatTypeMask.nonNullSubclass(base);
-    } else {
-      return new TypeMask.nonNullExactOrEmpty(base, classWorld);
-    }
-  }
-
-  factory TypeMask.nonNullSubtype(ClassElement base, ClassWorld classWorld) {
-    if (classWorld.hasOnlySubclasses(base)) {
-      return new TypeMask.nonNullSubclass(base, classWorld);
-    }
-    if (classWorld.hasAnySubtype(base)) {
-      return new FlatTypeMask.nonNullSubtype(base);
-    } else {
-      return new TypeMask.nonNullExactOrEmpty(base, classWorld);
-    }
-  }
-
-  factory TypeMask.unionOf(Iterable<TypeMask> masks, ClassWorld classWorld) {
-    return UnionTypeMask.unionOf(masks, classWorld);
-  }
-
-  /**
-   * If [mask] is forwarding, returns the first non-forwarding [TypeMask] in
-   * [mask]'s forwarding chain.
-   */
-  static TypeMask nonForwardingMask(mask) {
-    while (mask.isForwarding) {
-      mask = mask.forwardTo;
-    }
-    return mask;
-  }
-
-  /**
-   * Asserts that this mask uses the smallest possible representation for
-   * its types. Currently, we normalize subtype and subclass to exact if no
-   * subtypes or subclasses are present and subtype to subclass if only
-   * subclasses exist. We also normalize exact to empty if the corresponding
-   * baseclass was never instantiated.
-   */
-  static bool assertIsNormalized(TypeMask mask, ClassWorld classWorld) {
-    String reason = getNotNormalizedReason(mask, classWorld);
-    return invariant(NO_LOCATION_SPANNABLE, reason == null,
-        message: () => '$mask is not normalized: $reason');
-  }
-
-  static String getNotNormalizedReason(TypeMask mask, ClassWorld classWorld) {
-    mask = nonForwardingMask(mask);
-    if (mask is FlatTypeMask) {
-      if (mask.isEmpty) return null;
-      if (mask.isExact) {
-        if (!classWorld.isInstantiated(mask.base)) {
-          return 'Exact ${mask.base} is not instantiated.';
-        }
-        return null;
-      }
-      if (mask.isSubclass) {
-        if (!classWorld.hasAnySubclass(mask.base)) {
-          return 'Subclass ${mask.base} does not have any subclasses.';
-        }
-        return null;
-      }
-      assert(mask.isSubtype);
-      if (!classWorld.hasAnySubtype(mask.base)) {
-        return 'Subtype ${mask.base} does not have any subclasses.';
-      }
-      if (classWorld.hasOnlySubclasses(mask.base)) {
-        return 'Subtype ${mask.base} only has subclasses.';
-      }
-      return null;
-    } else if (mask is UnionTypeMask) {
-      for (TypeMask submask in mask.disjointMasks) {
-        String submaskReason = getNotNormalizedReason(submask, classWorld);
-        if (submaskReason != null) {
-          return 'Submask $submask in $mask: $submaskReason.';
-        }
-      }
-      return null;
-    }
-    return 'Unknown type mask $mask.';
-  }
-
-  /**
-   * Returns a nullable variant of [this] type mask.
-   */
-  TypeMask nullable();
-
-  /**
-   * Returns a non-nullable variant of [this] type mask.
-   */
-  TypeMask nonNullable();
-
-  bool get isEmpty;
-  bool get isNullable;
-  bool get isExact;
-
-  /// Returns true if this mask is a union type.
-  bool get isUnion;
-
-  /// Returns `true` if this mask is a [ContainerTypeMask].
-  bool get isContainer;
-
-  /// Returns `true` if this mask is a [MapTypeMask].
-  bool get isMap;
-
-  /// Returns `true` if this mask is a [MapTypeMask] in dictionary mode, i.e.,
-  /// all keys are known string values and we have specific type information for
-  /// corresponding values.
-  bool get isDictionary;
-
-  /// Returns `true` if this mask is wrapping another mask for the purpose of
-  /// tracing.
-  bool get isForwarding;
-
-  /// Returns `true` if this mask holds encodes an exact value within a type.
-  bool get isValue;
-
-  bool containsOnlyInt(ClassWorld classWorld);
-  bool containsOnlyDouble(ClassWorld classWorld);
-  bool containsOnlyNum(ClassWorld classWorld);
-  bool containsOnlyBool(ClassWorld classWorld);
-  bool containsOnlyString(ClassWorld classWorld);
-  bool containsOnly(ClassElement element);
-
-  /**
-   * Compares two [TypeMask] objects for structural equality.
-   *
-   * Note: This may differ from semantic equality in the set containment sense.
-   *   Use [containsMask] and [isInMask] for that, instead.
-   */
-  bool operator==(other);
-
-  /**
-   * Returns `true` if [other] is a supertype of this mask, i.e., if
-   * this mask is in [other].
-   */
-  bool isInMask(TypeMask other, ClassWorld classWorld);
-
-  /**
-   * Returns `true` if [other] is a subtype of this mask, i.e., if
-   * this mask contains [other].
-   */
-  bool containsMask(TypeMask other, ClassWorld classWorld);
-
-  /**
-   * Returns whether this type mask is an instance of [cls].
-   */
-  bool satisfies(ClassElement cls, ClassWorld classWorld);
-
-  /**
-   * Returns whether or not this type mask contains the given type.
-   */
-  bool contains(ClassElement type, ClassWorld classWorld);
-
-  /**
-   * Returns whether or not this type mask contains all types.
-   */
-  bool containsAll(ClassWorld classWorld);
-
-  /**
-   * Returns the [ClassElement] if this type represents a single class,
-   * otherwise returns `null`.  This method is conservative.
-   */
-  ClassElement singleClass(ClassWorld classWorld);
-
-  /**
-   * Returns a type mask representing the union of [this] and [other].
-   */
-  TypeMask union(TypeMask other, ClassWorld classWorld);
-
-  /**
-   * Returns a type mask representing the intersection of [this] and [other].
-   */
-  TypeMask intersection(TypeMask other, ClassWorld classWorld);
-
-  /**
-   * Returns whether this [TypeMask] applied to [selector] can hit a
-   * [noSuchMethod].
-   */
-  bool needsNoSuchMethodHandling(Selector selector, ClassWorld classWorld);
-
-  /**
-   * Returns whether [element] is a potential target when being
-   * invoked on this type mask. [selector] is used to ensure library
-   * privacy is taken into account.
-   */
-  bool canHit(Element element, Selector selector, ClassWorld classWorld);
-
-  /**
-   * Returns the [element] that is known to always be hit at runtime
-   * on this mask. Returns null if there is none.
-   */
-  // TODO(johnniwinther): Move this method to [World].
-  Element locateSingleElement(Selector selector, Compiler compiler);
-}