[Sync] Move //sync to //components/sync.

sync/internal_api/public/base/enum_set.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SYNC_INTERNAL_API_PUBLIC_BASE_ENUM_SET_H_
-#define SYNC_INTERNAL_API_PUBLIC_BASE_ENUM_SET_H_
-
-#include <bitset>
-#include <cstddef>
-#include <string>
-
-#include "base/logging.h"
-
-namespace syncer {
-
-// Forward declarations needed for friend declarations.
-template <typename E, E MinEnumValue, E MaxEnumValue>
-class EnumSet;
-
-template <typename E, E Min, E Max>
-EnumSet<E, Min, Max> Union(EnumSet<E, Min, Max> set1,
-                           EnumSet<E, Min, Max> set2);
-
-template <typename E, E Min, E Max>
-EnumSet<E, Min, Max> Intersection(EnumSet<E, Min, Max> set1,
-                                  EnumSet<E, Min, Max> set2);
-
-template <typename E, E Min, E Max>
-EnumSet<E, Min, Max> Difference(EnumSet<E, Min, Max> set1,
-                                EnumSet<E, Min, Max> set2);
-
-// An EnumSet is a set that can hold enum values between a min and a
-// max value (inclusive of both).  It's essentially a wrapper around
-// std::bitset<> with stronger type enforcement, more descriptive
-// member function names, and an iterator interface.
-//
-// If you're working with enums with a small number of possible values
-// (say, fewer than 64), you can efficiently pass around an EnumSet
-// for that enum around by value.
-
-template <typename E, E MinEnumValue, E MaxEnumValue>
-class EnumSet {
- public:
-  typedef E EnumType;
-  static const E kMinValue = MinEnumValue;
-  static const E kMaxValue = MaxEnumValue;
-  static const size_t kValueCount = kMaxValue - kMinValue + 1;
-  static_assert(kMinValue < kMaxValue,
-                "min value must be less than max value");
-
- private:
-  // Declaration needed by Iterator.
-  typedef std::bitset<kValueCount> EnumBitSet;
-
- public:
-  // Iterator is a forward-only read-only iterator for EnumSet.  Its
-  // interface is deliberately distinct from an STL iterator as its
-  // semantics are substantially different.
-  //
-  // Example usage:
-  //
-  // for (EnumSet<...>::Iterator it = enums.First(); it.Good(); it.Inc()) {
-  //   Process(it.Get());
-  // }
-  //
-  // The iterator must not be outlived by the set.  In particular, the
-  // following is an error:
-  //
-  // EnumSet<...> SomeFn() { ... }
-  //
-  // /* ERROR */
-  // for (EnumSet<...>::Iterator it = SomeFun().First(); ...
-  //
-  // Also, there are no guarantees as to what will happen if you
-  // modify an EnumSet while traversing it with an iterator.
-  class Iterator {
-   public:
-    // A default-constructed iterator can't do anything except check
-    // Good().  You need to call First() on an EnumSet to get a usable
-    // iterator.
-    Iterator() : enums_(NULL), i_(kValueCount) {}
-    ~Iterator() {}
-
-    // Copy constructor and assignment welcome.
-
-    // Returns true iff the iterator points to an EnumSet and it
-    // hasn't yet traversed the EnumSet entirely.
-    bool Good() const {
-      return enums_ && i_ < kValueCount && enums_->test(i_);
-    }
-
-    // Returns the value the iterator currently points to.  Good()
-    // must hold.
-    E Get() const {
-      CHECK(Good());
-      return FromIndex(i_);
-    }
-
-    // Moves the iterator to the next value in the EnumSet.  Good()
-    // must hold.  Takes linear time.
-    void Inc() {
-      CHECK(Good());
-      i_ = FindNext(i_ + 1);
-    }
-
-   private:
-    friend Iterator EnumSet::First() const;
-
-    explicit Iterator(const EnumBitSet& enums)
-        : enums_(&enums), i_(FindNext(0)) {}
-
-    size_t FindNext(size_t i) {
-      while ((i < kValueCount) && !enums_->test(i)) {
-        ++i;
-      }
-      return i;
-    }
-
-    const EnumBitSet* enums_;
-    size_t i_;
-  };
-
-  // You can construct an EnumSet with 0, 1, 2, or 3 initial values.
-
-  EnumSet() {}
-
-  explicit EnumSet(E value) {
-    Put(value);
-  }
-
-  EnumSet(E value1, E value2) {
-    Put(value1);
-    Put(value2);
-  }
-
-  EnumSet(E value1, E value2, E value3) {
-    Put(value1);
-    Put(value2);
-    Put(value3);
-  }
-
-  // Returns an EnumSet with all possible values.
-  static EnumSet All() {
-    EnumBitSet enums;
-    enums.set();
-    return EnumSet(enums);
-  }
-
-  ~EnumSet() {}
-
-  // Copy constructor and assignment welcome.
-
-  // Set operations.  Put, Retain, and Remove are basically
-  // self-mutating versions of Union, Intersection, and Difference
-  // (defined below).
-
-  // Adds the given value (which must be in range) to our set.
-  void Put(E value) {
-    enums_.set(ToIndex(value));
-  }
-
-  // Adds all values in the given set to our set.
-  void PutAll(EnumSet other) {
-    enums_ |= other.enums_;
-  }
-
-  // There's no real need for a Retain(E) member function.
-
-  // Removes all values not in the given set from our set.
-  void RetainAll(EnumSet other) {
-    enums_ &= other.enums_;
-  }
-
-  // If the given value is in range, removes it from our set.
-  void Remove(E value) {
-    if (InRange(value)) {
-      enums_.reset(ToIndex(value));
-    }
-  }
-
-  // Removes all values in the given set from our set.
-  void RemoveAll(EnumSet other) {
-    enums_ &= ~other.enums_;
-  }
-
-  // Removes all values from our set.
-  void Clear() {
-    enums_.reset();
-  }
-
-  // Returns true iff the given value is in range and a member of our set.
-  bool Has(E value) const {
-    return InRange(value) && enums_.test(ToIndex(value));
-  }
-
-  // Returns true iff the given set is a subset of our set.
-  bool HasAll(EnumSet other) const {
-    return (enums_ & other.enums_) == other.enums_;
-  }
-
-  // Returns true iff our set is empty.
-  bool Empty() const {
-    return !enums_.any();
-  }
-
-  // Returns how many values our set has.
-  size_t Size() const {
-    return enums_.count();
-  }
-
-  // Returns an iterator pointing to the first element (if any).
-  Iterator First() const {
-    return Iterator(enums_);
-  }
-
-  // Returns true iff our set and the given set contain exactly the same values.
-  bool operator==(const EnumSet& other) const { return enums_ == other.enums_; }
-
-  // Returns true iff our set and the given set do not contain exactly the same
-  // values.
-  bool operator!=(const EnumSet& other) const { return enums_ != other.enums_; }
-
- private:
-  friend EnumSet Union<E, MinEnumValue, MaxEnumValue>(
-      EnumSet set1, EnumSet set2);
-  friend EnumSet Intersection<E, MinEnumValue, MaxEnumValue>(
-      EnumSet set1, EnumSet set2);
-  friend EnumSet Difference<E, MinEnumValue, MaxEnumValue>(
-      EnumSet set1, EnumSet set2);
-
-  explicit EnumSet(EnumBitSet enums) : enums_(enums) {}
-
-  static bool InRange(E value) {
-    return (value >= MinEnumValue) && (value <= MaxEnumValue);
-  }
-
-  // Converts a value to/from an index into |enums_|.
-
-  static size_t ToIndex(E value) {
-    DCHECK_GE(value, MinEnumValue);
-    DCHECK_LE(value, MaxEnumValue);
-    return value - MinEnumValue;
-  }
-
-  static E FromIndex(size_t i) {
-    DCHECK_LT(i, kValueCount);
-    return static_cast<E>(MinEnumValue + i);
-  }
-
-  EnumBitSet enums_;
-};
-
-template <typename E, E MinEnumValue, E MaxEnumValue>
-const E EnumSet<E, MinEnumValue, MaxEnumValue>::kMinValue;
-
-template <typename E, E MinEnumValue, E MaxEnumValue>
-const E EnumSet<E, MinEnumValue, MaxEnumValue>::kMaxValue;
-
-template <typename E, E MinEnumValue, E MaxEnumValue>
-const size_t EnumSet<E, MinEnumValue, MaxEnumValue>::kValueCount;
-
-// The usual set operations.
-
-template <typename E, E Min, E Max>
-EnumSet<E, Min, Max> Union(EnumSet<E, Min, Max> set1,
-                           EnumSet<E, Min, Max> set2) {
-  return EnumSet<E, Min, Max>(set1.enums_ | set2.enums_);
-}
-
-template <typename E, E Min, E Max>
-EnumSet<E, Min, Max> Intersection(EnumSet<E, Min, Max> set1,
-                                  EnumSet<E, Min, Max> set2) {
-  return EnumSet<E, Min, Max>(set1.enums_ & set2.enums_);
-}
-
-template <typename E, E Min, E Max>
-EnumSet<E, Min, Max> Difference(EnumSet<E, Min, Max> set1,
-                                EnumSet<E, Min, Max> set2) {
-  return EnumSet<E, Min, Max>(set1.enums_ & ~set2.enums_);
-}
-
-}  // namespace syncer
-
-#endif  // SYNC_INTERNAL_API_PUBLIC_BASE_ENUM_SET_H_