tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
Log | Files | Refs | README | LICENSE

GCVector.h (12642B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
      2 * vim: set ts=8 sts=2 et sw=2 tw=80:
      3 * This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef js_GCVector_h
      8 #define js_GCVector_h
      9 
     10 #include "mozilla/Assertions.h"       // MOZ_ASSERT
     11 #include "mozilla/Attributes.h"       // MOZ_STACK_CLASS
     12 #include "mozilla/MemoryReporting.h"  // MallocSizeOf
     13 #include "mozilla/Span.h"
     14 #include "mozilla/Vector.h"
     15 
     16 #include <stddef.h>  // size_t
     17 #include <utility>   // forward, move
     18 
     19 #include "js/AllocPolicy.h"
     20 #include "js/GCPolicyAPI.h"
     21 #include "js/RootingAPI.h"
     22 
     23 class JSTracer;
     24 struct JSContext;
     25 
     26 namespace JS {
     27 
     28 // A GCVector is a Vector with an additional trace method that knows how
     29 // to visit all of the items stored in the Vector. For vectors that contain GC
     30 // things, this is usually more convenient than manually iterating and marking
     31 // the contents.
     32 //
     33 // Most types of GC pointers as keys and values can be traced with no extra
     34 // infrastructure. For structs and non-gc-pointer members, ensure that there is
     35 // a specialization of GCPolicy<T> with an appropriate trace method available
     36 // to handle the custom type. Generic helpers can be found in
     37 // js/public/TracingAPI.h.
     38 //
     39 // Note that although this Vector's trace will deal correctly with moved items,
     40 // it does not itself know when to barrier or trace items. To function properly
     41 // it must either be used with Rooted, or barriered and traced manually.
     42 template <typename T, size_t MinInlineCapacity = 0,
     43          typename AllocPolicy = js::TempAllocPolicy>
     44 class GCVector {
     45 protected:
     46  mozilla::Vector<T, MinInlineCapacity, AllocPolicy> vector;
     47 
     48 public:
     49  using ElementType = T;
     50  static constexpr size_t InlineLength = decltype(vector)::InlineLength;
     51 
     52  explicit GCVector(AllocPolicy alloc) : vector(std::move(alloc)) {}
     53  GCVector() : GCVector(AllocPolicy()) {}
     54 
     55  GCVector(GCVector&& vec) : vector(std::move(vec.vector)) {}
     56 
     57  GCVector& operator=(GCVector&& vec) {
     58    vector = std::move(vec.vector);
     59    return *this;
     60  }
     61 
     62  size_t length() const { return vector.length(); }
     63  bool empty() const { return vector.empty(); }
     64  size_t capacity() const { return vector.capacity(); }
     65 
     66  T* begin() { return vector.begin(); }
     67  const T* begin() const { return vector.begin(); }
     68 
     69  T* end() { return vector.end(); }
     70  const T* end() const { return vector.end(); }
     71 
     72  T& operator[](size_t i) { return vector[i]; }
     73  const T& operator[](size_t i) const { return vector[i]; }
     74 
     75  T& back() { return vector.back(); }
     76  const T& back() const { return vector.back(); }
     77 
     78  operator mozilla::Span<T>() { return vector; }
     79  operator mozilla::Span<const T>() const { return vector; }
     80 
     81  bool initCapacity(size_t cap) { return vector.initCapacity(cap); }
     82  [[nodiscard]] bool reserve(size_t req) { return vector.reserve(req); }
     83  void shrinkBy(size_t amount) { return vector.shrinkBy(amount); }
     84  void shrinkTo(size_t newLen) { return vector.shrinkTo(newLen); }
     85  [[nodiscard]] bool growBy(size_t amount) { return vector.growBy(amount); }
     86  [[nodiscard]] bool resize(size_t newLen) { return vector.resize(newLen); }
     87 
     88  void clear() { vector.clear(); }
     89  void clearAndFree() { vector.clearAndFree(); }
     90 
     91  template <typename U>
     92  bool append(U&& item) {
     93    return vector.append(std::forward<U>(item));
     94  }
     95 
     96  void erase(T* it) { vector.erase(it); }
     97  void erase(T* begin, T* end) { vector.erase(begin, end); }
     98  template <typename Pred>
     99  void eraseIf(Pred pred) {
    100    vector.eraseIf(pred);
    101  }
    102  template <typename U>
    103  void eraseIfEqual(const U& u) {
    104    vector.eraseIfEqual(u);
    105  }
    106 
    107  template <typename... Args>
    108  [[nodiscard]] bool emplaceBack(Args&&... args) {
    109    return vector.emplaceBack(std::forward<Args>(args)...);
    110  }
    111 
    112  template <typename... Args>
    113  void infallibleEmplaceBack(Args&&... args) {
    114    vector.infallibleEmplaceBack(std::forward<Args>(args)...);
    115  }
    116 
    117  template <typename U>
    118  void infallibleAppend(U&& aU) {
    119    return vector.infallibleAppend(std::forward<U>(aU));
    120  }
    121  void infallibleAppendN(const T& aT, size_t aN) {
    122    return vector.infallibleAppendN(aT, aN);
    123  }
    124  template <typename U>
    125  void infallibleAppend(const U* aBegin, const U* aEnd) {
    126    return vector.infallibleAppend(aBegin, aEnd);
    127  }
    128  template <typename U>
    129  void infallibleAppend(const U* aBegin, size_t aLength) {
    130    return vector.infallibleAppend(aBegin, aLength);
    131  }
    132 
    133  template <typename U>
    134  [[nodiscard]] bool appendAll(const U& aU) {
    135    return vector.append(aU.begin(), aU.end());
    136  }
    137  template <typename T2, size_t MinInlineCapacity2, typename AllocPolicy2>
    138  [[nodiscard]] bool appendAll(
    139      GCVector<T2, MinInlineCapacity2, AllocPolicy2>&& aU) {
    140    return vector.appendAll(std::move(aU.vector));
    141  }
    142 
    143  [[nodiscard]] bool appendN(const T& val, size_t count) {
    144    return vector.appendN(val, count);
    145  }
    146 
    147  template <typename U>
    148  [[nodiscard]] bool append(const U* aBegin, const U* aEnd) {
    149    return vector.append(aBegin, aEnd);
    150  }
    151  template <typename U>
    152  [[nodiscard]] bool append(const U* aBegin, size_t aLength) {
    153    return vector.append(aBegin, aLength);
    154  }
    155 
    156  void popBack() { return vector.popBack(); }
    157  T popCopy() { return vector.popCopy(); }
    158 
    159  void swap(GCVector& other) {
    160    // Note, this only will work for MinInlineCapacity of zero.
    161    // See Bug 1987683.
    162    vector.swap(other.vector);
    163  }
    164 
    165  size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
    166    return vector.sizeOfExcludingThis(mallocSizeOf);
    167  }
    168 
    169  size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
    170    return mallocSizeOf(this) + sizeOfExcludingThis(mallocSizeOf);
    171  }
    172 
    173  void trace(JSTracer* trc) {
    174    for (auto& elem : vector) {
    175      GCPolicy<T>::trace(trc, &elem, "vector element");
    176    }
    177  }
    178 
    179  bool traceWeak(JSTracer* trc) {
    180    mutableEraseIf(
    181        [trc](T& elem) { return !GCPolicy<T>::traceWeak(trc, &elem); });
    182    return !empty();
    183  }
    184 
    185  // Like eraseIf, but may mutate the contents of the vector. Iterates from
    186  // |startIndex| to the last element of the vector.
    187  template <typename Pred>
    188  void mutableEraseIf(Pred&& pred, size_t startIndex = 0) {
    189    MOZ_ASSERT(startIndex <= length());
    190 
    191    T* src = begin() + startIndex;
    192    T* dst = src;
    193    while (src != end()) {
    194      if (!pred(*src)) {
    195        if (src != dst) {
    196          *dst = std::move(*src);
    197        }
    198        dst++;
    199      }
    200      src++;
    201    }
    202 
    203    MOZ_ASSERT(dst <= end());
    204    shrinkBy(end() - dst);
    205  }
    206 };
    207 
    208 // AllocPolicy is optional. It has a default value declared in TypeDecls.h
    209 template <typename T, typename AllocPolicy>
    210 class MOZ_STACK_CLASS StackGCVector : public GCVector<T, 8, AllocPolicy> {
    211 public:
    212  using Base = GCVector<T, 8, AllocPolicy>;
    213 
    214  void trace(JSTracer* trc) {
    215    if constexpr (!GCPolicy<T>::mightBeInNursery()) {
    216      // Skip tracing of non-nursery types in minor GC.
    217      if (trc->isTenuringTracer()) {
    218 #ifdef DEBUG
    219        for (auto& elem : this->vector) {
    220          MOZ_ASSERT(GCPolicy<T>::isTenured(elem));
    221        }
    222 #endif
    223        return;
    224      }
    225    }
    226 
    227    Base::trace(trc);
    228  }
    229 
    230 private:
    231  // Inherit constructor from GCVector.
    232  using Base::Base;
    233 };
    234 
    235 }  // namespace JS
    236 
    237 namespace js {
    238 
    239 template <typename Wrapper, typename T, size_t Capacity, typename AllocPolicy>
    240 class WrappedPtrOperations<JS::GCVector<T, Capacity, AllocPolicy>, Wrapper> {
    241  using Vec = JS::GCVector<T, Capacity, AllocPolicy>;
    242  const Vec& vec() const { return static_cast<const Wrapper*>(this)->get(); }
    243 
    244 public:
    245  const AllocPolicy& allocPolicy() const { return vec().allocPolicy(); }
    246  size_t length() const { return vec().length(); }
    247  bool empty() const { return vec().empty(); }
    248  size_t capacity() const { return vec().capacity(); }
    249  const T* begin() const { return vec().begin(); }
    250  const T* end() const { return vec().end(); }
    251  const T& back() const { return vec().back(); }
    252 
    253  JS::Handle<T> operator[](size_t aIndex) const {
    254    return JS::Handle<T>::fromMarkedLocation(&vec().operator[](aIndex));
    255  }
    256 };
    257 
    258 template <typename Wrapper, typename T, size_t Capacity, typename AllocPolicy>
    259 class MutableWrappedPtrOperations<JS::GCVector<T, Capacity, AllocPolicy>,
    260                                  Wrapper>
    261    : public WrappedPtrOperations<JS::GCVector<T, Capacity, AllocPolicy>,
    262                                  Wrapper> {
    263  using Vec = JS::GCVector<T, Capacity, AllocPolicy>;
    264  const Vec& vec() const { return static_cast<const Wrapper*>(this)->get(); }
    265  Vec& vec() { return static_cast<Wrapper*>(this)->get(); }
    266 
    267 public:
    268  const AllocPolicy& allocPolicy() const { return vec().allocPolicy(); }
    269  AllocPolicy& allocPolicy() { return vec().allocPolicy(); }
    270  const T* begin() const { return vec().begin(); }
    271  T* begin() { return vec().begin(); }
    272  const T* end() const { return vec().end(); }
    273  T* end() { return vec().end(); }
    274  const T& back() const { return vec().back(); }
    275  T& back() { return vec().back(); }
    276 
    277  JS::Handle<T> operator[](size_t aIndex) const {
    278    return JS::Handle<T>::fromMarkedLocation(&vec().operator[](aIndex));
    279  }
    280  JS::MutableHandle<T> operator[](size_t aIndex) {
    281    return JS::MutableHandle<T>::fromMarkedLocation(&vec().operator[](aIndex));
    282  }
    283 
    284  [[nodiscard]] bool initCapacity(size_t aRequest) {
    285    return vec().initCapacity(aRequest);
    286  }
    287  [[nodiscard]] bool reserve(size_t aRequest) {
    288    return vec().reserve(aRequest);
    289  }
    290  void shrinkBy(size_t aIncr) { vec().shrinkBy(aIncr); }
    291  [[nodiscard]] bool growBy(size_t aIncr) { return vec().growBy(aIncr); }
    292  [[nodiscard]] bool resize(size_t aNewLength) {
    293    return vec().resize(aNewLength);
    294  }
    295  void clear() { vec().clear(); }
    296  void clearAndFree() { vec().clearAndFree(); }
    297  template <typename U>
    298  [[nodiscard]] bool append(U&& aU) {
    299    return vec().append(std::forward<U>(aU));
    300  }
    301  template <typename... Args>
    302  [[nodiscard]] bool emplaceBack(Args&&... aArgs) {
    303    return vec().emplaceBack(std::forward<Args>(aArgs)...);
    304  }
    305  template <typename... Args>
    306  void infallibleEmplaceBack(Args&&... args) {
    307    vec().infallibleEmplaceBack(std::forward<Args>(args)...);
    308  }
    309  template <typename U>
    310  [[nodiscard]] bool appendAll(U&& aU) {
    311    return vec().appendAll(aU);
    312  }
    313  [[nodiscard]] bool appendN(const T& aT, size_t aN) {
    314    return vec().appendN(aT, aN);
    315  }
    316  template <typename U>
    317  [[nodiscard]] bool append(const U* aBegin, const U* aEnd) {
    318    return vec().append(aBegin, aEnd);
    319  }
    320  template <typename U>
    321  [[nodiscard]] bool append(const U* aBegin, size_t aLength) {
    322    return vec().append(aBegin, aLength);
    323  }
    324  template <typename U>
    325  void infallibleAppend(U&& aU) {
    326    vec().infallibleAppend(std::forward<U>(aU));
    327  }
    328  void infallibleAppendN(const T& aT, size_t aN) {
    329    vec().infallibleAppendN(aT, aN);
    330  }
    331  template <typename U>
    332  void infallibleAppend(const U* aBegin, const U* aEnd) {
    333    vec().infallibleAppend(aBegin, aEnd);
    334  }
    335  template <typename U>
    336  void infallibleAppend(const U* aBegin, size_t aLength) {
    337    vec().infallibleAppend(aBegin, aLength);
    338  }
    339  void popBack() { vec().popBack(); }
    340  T popCopy() { return vec().popCopy(); }
    341  void erase(T* aT) { vec().erase(aT); }
    342  void erase(T* aBegin, T* aEnd) { vec().erase(aBegin, aEnd); }
    343  template <typename Pred>
    344  void eraseIf(Pred pred) {
    345    vec().eraseIf(pred);
    346  }
    347  template <typename U>
    348  void eraseIfEqual(const U& u) {
    349    vec().eraseIfEqual(u);
    350  }
    351 };
    352 
    353 template <typename Wrapper, typename T, typename AllocPolicy>
    354 class WrappedPtrOperations<JS::StackGCVector<T, AllocPolicy>, Wrapper>
    355    : public WrappedPtrOperations<
    356          typename JS::StackGCVector<T, AllocPolicy>::Base, Wrapper> {};
    357 
    358 template <typename Wrapper, typename T, typename AllocPolicy>
    359 class MutableWrappedPtrOperations<JS::StackGCVector<T, AllocPolicy>, Wrapper>
    360    : public MutableWrappedPtrOperations<
    361          typename JS::StackGCVector<T, AllocPolicy>::Base, Wrapper> {};
    362 
    363 }  // namespace js
    364 
    365 namespace JS {
    366 
    367 // An automatically rooted GCVector for stack use.
    368 template <typename T>
    369 class RootedVector : public Rooted<StackGCVector<T>> {
    370  using Vec = StackGCVector<T>;
    371  using Base = Rooted<Vec>;
    372 
    373 public:
    374  explicit RootedVector(JSContext* cx) : Base(cx, Vec(cx)) {}
    375 };
    376 
    377 // For use in rust code, an analog to RootedVector that doesn't require
    378 // instances to be destroyed in LIFO order.
    379 template <typename T>
    380 class PersistentRootedVector : public PersistentRooted<StackGCVector<T>> {
    381  using Vec = StackGCVector<T>;
    382  using Base = PersistentRooted<Vec>;
    383 
    384 public:
    385  explicit PersistentRootedVector(JSContext* cx) : Base(cx, Vec(cx)) {}
    386 };
    387 
    388 }  // namespace JS
    389 
    390 #endif  // js_GCVector_h