gecko/js/src/jsvector.h

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sw=4 et tw=99 ft=cpp:
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla SpiderMonkey JavaScript 1.9 code, released
 * June 12, 2009.
 *
 * The Initial Developer of the Original Code is
 *   the Mozilla Corporation.
 *
 * Contributor(s):
 *   Luke Wagner <lw@mozilla.com>
 *   Nicholas Nethercote <nnethercote@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef jsvector_h_
#define jsvector_h_

#include "jstl.h"
#include "jsprvtd.h"

/* Silence dire "bugs in previous versions of MSVC have been fixed" warnings */
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable:4345)
#endif

namespace js {

/*
 * This template class provides a default implementation for vector operations
 * when the element type is not known to be a POD, as judged by IsPodType.
 */
template <class T, size_t N, class AP, bool IsPod>
struct VectorImpl
{
    /* Destroys constructed objects in the range [begin, end). */
    static inline void destroy(T *begin, T *end) {
        for (T *p = begin; p != end; ++p)
            p->~T();
    }

    /* Constructs objects in the uninitialized range [begin, end). */
    static inline void initialize(T *begin, T *end) {
        for (T *p = begin; p != end; ++p)
            new(p) T();
    }

    /*
     * Copy-constructs objects in the uninitialized range
     * [dst, dst+(srcend-srcbeg)) from the range [srcbeg, srcend).
     */
    template <class U>
    static inline void copyConstruct(T *dst, const U *srcbeg, const U *srcend) {
        for (const U *p = srcbeg; p != srcend; ++p, ++dst)
            new(dst) T(*p);
    }

    /*
     * Copy-constructs objects in the uninitialized range [dst, dst+n) from the
     * same object u.
     */
    template <class U>
    static inline void copyConstructN(T *dst, size_t n, const U &u) {
        for (T *end = dst + n; dst != end; ++dst)
            new(dst) T(u);
    }

    /*
     * Grows the given buffer to have capacity newcap, preserving the objects
     * constructed in the range [begin, end) and updating v. Assumes that (1)
     * newcap has not overflowed, and (2) multiplying newcap by sizeof(T) will
     * not overflow.
     */
    static inline bool growTo(Vector<T,N,AP> &v, size_t newcap) {
        JS_ASSERT(!v.usingInlineStorage());
        T *newbuf = reinterpret_cast<T *>(v.malloc(newcap * sizeof(T)));
        if (!newbuf)
            return false;
        for (T *dst = newbuf, *src = v.beginNoCheck(); src != v.endNoCheck(); ++dst, ++src)
            new(dst) T(*src);
        VectorImpl::destroy(v.beginNoCheck(), v.endNoCheck());
        v.free(v.mBegin);
        v.mBegin = newbuf;
        /* v.mLength is unchanged. */
        v.mCapacity = newcap;
        return true;
    }
};

/*
 * This partial template specialization provides a default implementation for
 * vector operations when the element type is known to be a POD, as judged by
 * IsPodType.
 */
template <class T, size_t N, class AP>
struct VectorImpl<T, N, AP, true>
{
    static inline void destroy(T *, T *) {}

    static inline void initialize(T *begin, T *end) {
        /*
         * You would think that memset would be a big win (or even break even)
         * when we know T is a POD. But currently it's not. This is probably
         * because |append| tends to be given small ranges and memset requires
         * a function call that doesn't get inlined.
         *
         * memset(begin, 0, sizeof(T) * (end-begin));
         */
        for (T *p = begin; p != end; ++p)
            new(p) T();
    }

    template <class U>
    static inline void copyConstruct(T *dst, const U *srcbeg, const U *srcend) {
        /*
         * See above memset comment. Also, notice that copyConstruct is
         * currently templated (T != U), so memcpy won't work without
         * requiring T == U.
         *
         * memcpy(dst, srcbeg, sizeof(T) * (srcend - srcbeg));
         */
        for (const U *p = srcbeg; p != srcend; ++p, ++dst)
            *dst = *p;
    }

    static inline void copyConstructN(T *dst, size_t n, const T &t) {
        for (T *p = dst, *end = dst + n; p != end; ++p)
            *p = t;
    }

    static inline bool growTo(Vector<T,N,AP> &v, size_t newcap) {
        JS_ASSERT(!v.usingInlineStorage());
        size_t bytes = sizeof(T) * newcap;
        T *newbuf = reinterpret_cast<T *>(v.realloc(v.mBegin, bytes));
        if (!newbuf)
            return false;
        v.mBegin = newbuf;
        /* v.mLength is unchanged. */
        v.mCapacity = newcap;
        return true;
    }
};

/*
 * JS-friendly, STL-like container providing a short-lived, dynamic buffer.
 * Vector calls the constructors/destructors of all elements stored in
 * its internal buffer, so non-PODs may be safely used. Additionally,
 * Vector will store the first N elements in-place before resorting to
 * dynamic allocation.
 *
 * T requirements:
 *  - default and copy constructible, assignable, destructible
 *  - operations do not throw
 * N requirements:
 *  - any value, however, N is clamped to min/max values
 * AllocPolicy:
 *  - see "Allocation policies" in jstl.h (default ContextAllocPolicy)
 *
 * N.B: Vector is not reentrant: T member functions called during Vector member
 *      functions must not call back into the same object.
 */
template <class T, size_t N, class AllocPolicy>
class Vector : AllocPolicy
{
    /* utilities */

    static const bool sElemIsPod = tl::IsPodType<T>::result;
    typedef VectorImpl<T, N, AllocPolicy, sElemIsPod> Impl;
    friend struct VectorImpl<T, N, AllocPolicy, sElemIsPod>;

    bool calculateNewCapacity(size_t curLength, size_t lengthInc, size_t &newCap);
    bool growStorageBy(size_t lengthInc);
    bool growHeapStorageBy(size_t lengthInc);
    bool convertToHeapStorage(size_t lengthInc);

    template <bool InitNewElems> inline bool growByImpl(size_t inc);

    /* magic constants */

    static const int sMaxInlineBytes = 1024;

    /* compute constants */

    static const size_t sInlineCapacity =
        tl::Min<N, sMaxInlineBytes / sizeof(T)>::result;

    /* Calculate inline buffer size; avoid 0-sized array. */
    static const size_t sInlineBytes =
        tl::Max<1, sInlineCapacity * sizeof(T)>::result;

    /* member data */

    /*
     * Pointer to the buffer, be it inline or heap-allocated. Only [mBegin,
     * mBegin + mLength) hold valid constructed T objects. The range [mBegin +
     * mLength, mBegin + mCapacity) holds uninitialized memory.
     */
    T *mBegin;
    size_t mLength;     /* Number of elements in the Vector. */
    size_t mCapacity;   /* Max number of elements storable in the Vector without resizing. */

    AlignedStorage<sInlineBytes> storage;

#ifdef DEBUG
    friend class ReentrancyGuard;
    bool entered;
#endif

    Vector(const Vector &);
    Vector &operator=(const Vector &);

    /* private accessors */

    bool usingInlineStorage() const {
        return mBegin == (T *)storage.addr();
    }

    T *beginNoCheck() const {
        return mBegin;
    }

    T *endNoCheck() {
        return mBegin + mLength;
    }

    const T *endNoCheck() const {
        return mBegin + mLength;
    }

  public:
    Vector(AllocPolicy = AllocPolicy());
    ~Vector();

    /* accessors */

    enum { InlineLength = N };

    size_t length() const {
        return mLength;
    }

    bool empty() const {
        return mLength == 0;
    }

    size_t capacity() const {
        return mCapacity;
    }

    T *begin() const {
        JS_ASSERT(!entered);
        return mBegin;
    }

    T *end() {
        JS_ASSERT(!entered);
        return mBegin + mLength;
    }

    const T *end() const {
        JS_ASSERT(!entered);
        return mBegin + mLength;
    }

    T &operator[](size_t i) {
        JS_ASSERT(!entered && i < mLength);
        return begin()[i];
    }

    const T &operator[](size_t i) const {
        JS_ASSERT(!entered && i < mLength);
        return begin()[i];
    }

    T &back() {
        JS_ASSERT(!entered && !empty());
        return *(end() - 1);
    }

    const T &back() const {
        JS_ASSERT(!entered && !empty());
        return *(end() - 1);
    }

    /* mutators */

    /* If reserve(length() + N) succeeds, the N next appends are guaranteed to succeed. */
    bool reserve(size_t capacity);

    /* Destroy elements in the range [begin() + incr, end()). */
    void shrinkBy(size_t incr);

    /* Grow the vector by incr elements. */
    bool growBy(size_t incr);

    /* Call shrinkBy or growBy based on whether newSize > length(). */
    bool resize(size_t newLength);

    /* Leave new elements as uninitialized memory. */
    bool growByUninitialized(size_t incr);
    bool resizeUninitialized(size_t newLength);

    void clear();

    bool append(const T &t);
    bool appendN(const T &t, size_t n);
    template <class U> bool append(const U *begin, const U *end);
    template <class U> bool append(const U *begin, size_t length);
    template <class U, size_t O, class BP> bool append(const Vector<U,O,BP> &other);

    void popBack();

    /*
     * Transfers ownership of the internal buffer used by Vector to the caller.
     * After this call, the Vector is empty. Since the returned buffer may need
     * to be allocated (if the elements are currently stored in-place), the
     * call can fail, returning NULL.
     *
     * N.B. Although a T*, only the range [0, length()) is constructed.
     */
    T *extractRawBuffer();

    /*
     * Transfer ownership of an array of objects into the Vector.
     * N.B. This call assumes that there are no uninitialized elements in the
     *      passed array.
     */
    void replaceRawBuffer(T *p, size_t length);

    /*
     * Places |val| at position |p|, shifting existing elements
     * from |p| onward one position higher.
     */
    bool insert(T *p, const T &val);

    /*
     * Removes the element |t|, which must fall in the bounds [begin, end),
     * shifting existing elements from |t + 1| onward one position lower.
     */
    void erase(T *t);
};

/* Helper functions */

/*
 * This helper function is specialized for appending the characters of a string
 * literal to a vector. This could not be done generically since one must take
 * care not to append the terminating '\0'.
 */
template <class T, size_t N, class AP, size_t ArrayLength>
JS_ALWAYS_INLINE bool
js_AppendLiteral(Vector<T,N,AP> &v, const char (&array)[ArrayLength])
{
    return v.append(array, array + ArrayLength - 1);
}

/* This does the re-entrancy check plus several other sanity checks. */
#define REENTRANCY_GUARD_ET_AL \
    ReentrancyGuard g(*this); \
    JS_ASSERT_IF(usingInlineStorage(), mCapacity == sInlineCapacity); \
    JS_ASSERT(mLength <= mCapacity)

/* Vector Implementation */

template <class T, size_t N, class AllocPolicy>
JS_ALWAYS_INLINE
Vector<T,N,AllocPolicy>::Vector(AllocPolicy ap)
  : AllocPolicy(ap), mBegin((T *)storage.addr()), mLength(0),
    mCapacity(sInlineCapacity)
#ifdef DEBUG
  , entered(false)
#endif
{}

template <class T, size_t N, class AP>
JS_ALWAYS_INLINE
Vector<T,N,AP>::~Vector()
{
    REENTRANCY_GUARD_ET_AL;
    Impl::destroy(beginNoCheck(), endNoCheck());
    if (!usingInlineStorage())
        this->free(beginNoCheck());
}

/*
 * Calculate a new capacity that is at least lengthInc greater than
 * curLength and check for overflow.
 */
template <class T, size_t N, class AP>
STATIC_POSTCONDITION(!return || newCap >= curLength + lengthInc)
inline bool
Vector<T,N,AP>::calculateNewCapacity(size_t curLength, size_t lengthInc,
                                     size_t &newCap)
{
    size_t newMinCap = curLength + lengthInc;

    /*
     * Check for overflow in the above addition, below CEILING_LOG2, and later
     * multiplication by sizeof(T).
     */
    if (newMinCap < curLength ||
        newMinCap & tl::MulOverflowMask<2 * sizeof(T)>::result) {
        this->reportAllocOverflow();
        return false;
    }

    /* Round up to next power of 2. */
    newCap = RoundUpPow2(newMinCap);

    /*
     * Do not allow a buffer large enough that the expression ((char *)end() -
     * (char *)begin()) overflows ptrdiff_t. See Bug 510319.
     */
    if (newCap & tl::UnsafeRangeSizeMask<T>::result) {
        this->reportAllocOverflow();
        return false;
    }
    return true;
}

/*
 * This function will grow the current heap capacity to have capacity
 * (mLength + lengthInc) and fail on OOM or integer overflow.
 */
template <class T, size_t N, class AP>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::growHeapStorageBy(size_t lengthInc)
{
    JS_ASSERT(!usingInlineStorage());
    size_t newCap;
    return calculateNewCapacity(mLength, lengthInc, newCap) &&
           Impl::growTo(*this, newCap);
}

/*
 * This function will create a new heap buffer with capacity (mLength +
 * lengthInc()), move all elements in the inline buffer to this new buffer,
 * and fail on OOM or integer overflow.
 */
template <class T, size_t N, class AP>
inline bool
Vector<T,N,AP>::convertToHeapStorage(size_t lengthInc)
{
    JS_ASSERT(usingInlineStorage());
    size_t newCap;
    if (!calculateNewCapacity(mLength, lengthInc, newCap))
        return false;

    /* Allocate buffer. */
    T *newBuf = reinterpret_cast<T *>(this->malloc(newCap * sizeof(T)));
    if (!newBuf)
        return false;

    /* Copy inline elements into heap buffer. */
    Impl::copyConstruct(newBuf, beginNoCheck(), endNoCheck());
    Impl::destroy(beginNoCheck(), endNoCheck());

    /* Switch in heap buffer. */
    mBegin = newBuf;
    /* mLength is unchanged. */
    mCapacity = newCap;
    return true;
}

template <class T, size_t N, class AP>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::growStorageBy(size_t incr)
{
    JS_ASSERT(mLength + incr > mCapacity);
    return usingInlineStorage()
         ? convertToHeapStorage(incr)
         : growHeapStorageBy(incr);
}

template <class T, size_t N, class AP>
inline bool
Vector<T,N,AP>::reserve(size_t request)
{
    REENTRANCY_GUARD_ET_AL;
    if (request > mCapacity)
        return growStorageBy(request - mLength);
    return true;
}

template <class T, size_t N, class AP>
inline void
Vector<T,N,AP>::shrinkBy(size_t incr)
{
    REENTRANCY_GUARD_ET_AL;
    JS_ASSERT(incr <= mLength);
    Impl::destroy(endNoCheck() - incr, endNoCheck());
    mLength -= incr;
}

template <class T, size_t N, class AP>
template <bool InitNewElems>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::growByImpl(size_t incr)
{
    REENTRANCY_GUARD_ET_AL;
    if (incr > mCapacity - mLength && !growStorageBy(incr))
        return false;

    JS_ASSERT(mLength + incr <= mCapacity);
    T *newend = endNoCheck() + incr;
    if (InitNewElems)
        Impl::initialize(endNoCheck(), newend);
    mLength += incr;
    return true;
}

template <class T, size_t N, class AP>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::growBy(size_t incr)
{
    return growByImpl<true>(incr);
}

template <class T, size_t N, class AP>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::growByUninitialized(size_t incr)
{
    return growByImpl<false>(incr);
}

template <class T, size_t N, class AP>
STATIC_POSTCONDITION(!return || ubound(this->begin()) >= newLength)
inline bool
Vector<T,N,AP>::resize(size_t newLength)
{
    size_t curLength = mLength;
    if (newLength > curLength)
        return growBy(newLength - curLength);
    shrinkBy(curLength - newLength);
    return true;
}

template <class T, size_t N, class AP>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::resizeUninitialized(size_t newLength)
{
    size_t curLength = mLength;
    if (newLength > curLength)
        return growByUninitialized(newLength - curLength);
    shrinkBy(curLength - newLength);
    return true;
}

template <class T, size_t N, class AP>
inline void
Vector<T,N,AP>::clear()
{
    REENTRANCY_GUARD_ET_AL;
    Impl::destroy(beginNoCheck(), endNoCheck());
    mLength = 0;
}

template <class T, size_t N, class AP>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::append(const T &t)
{
    REENTRANCY_GUARD_ET_AL;
    if (mLength == mCapacity && !growStorageBy(1))
        return false;

    JS_ASSERT(mLength < mCapacity);
    new(endNoCheck()) T(t);
    ++mLength;
    return true;
}

template <class T, size_t N, class AP>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::appendN(const T &t, size_t needed)
{
    REENTRANCY_GUARD_ET_AL;
    if (mLength + needed > mCapacity && !growStorageBy(needed))
        return false;

    JS_ASSERT(mLength + needed <= mCapacity);
    Impl::copyConstructN(endNoCheck(), needed, t);
    mLength += needed;
    return true;
}

template <class T, size_t N, class AP>
inline bool
Vector<T,N,AP>::insert(T *p, const T &val)
{
    JS_ASSERT(begin() <= p && p <= end());
    size_t pos = p - begin();
    JS_ASSERT(pos <= mLength);
    size_t oldLength = mLength;
    if (pos == oldLength)
        return append(val);
    {
        T oldBack = back();
        if (!append(oldBack)) /* Dup the last element. */
            return false;
    }
    for (size_t i = oldLength; i > pos; --i)
        (*this)[i] = (*this)[i - 1];
    (*this)[pos] = val;
    return true;
}

template<typename T, size_t N, class AP>
inline void
Vector<T,N,AP>::erase(T *it)
{
    JS_ASSERT(begin() <= it && it < end());
    while (it + 1 != end()) {
        *it = *(it + 1);
        ++it;
    }
    popBack();
}

template <class T, size_t N, class AP>
template <class U>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::append(const U *insBegin, const U *insEnd)
{
    REENTRANCY_GUARD_ET_AL;
    size_t needed = PointerRangeSize(insBegin, insEnd);
    if (mLength + needed > mCapacity && !growStorageBy(needed))
        return false;

    JS_ASSERT(mLength + needed <= mCapacity);
    Impl::copyConstruct(endNoCheck(), insBegin, insEnd);
    mLength += needed;
    return true;
}

template <class T, size_t N, class AP>
template <class U, size_t O, class BP>
inline bool
Vector<T,N,AP>::append(const Vector<U,O,BP> &other)
{
    return append(other.begin(), other.end());
}

template <class T, size_t N, class AP>
template <class U>
JS_ALWAYS_INLINE bool
Vector<T,N,AP>::append(const U *insBegin, size_t length)
{
    return this->append(insBegin, insBegin + length);
}

template <class T, size_t N, class AP>
JS_ALWAYS_INLINE void
Vector<T,N,AP>::popBack()
{
    REENTRANCY_GUARD_ET_AL;
    JS_ASSERT(!empty());
    --mLength;
    endNoCheck()->~T();
}

template <class T, size_t N, class AP>
inline T *
Vector<T,N,AP>::extractRawBuffer()
{
    T *ret;
    if (usingInlineStorage()) {
        ret = reinterpret_cast<T *>(this->malloc(mLength * sizeof(T)));
        if (!ret)
            return NULL;
        Impl::copyConstruct(ret, beginNoCheck(), endNoCheck());
        Impl::destroy(beginNoCheck(), endNoCheck());
        /* mBegin, mCapacity are unchanged. */
        mLength = 0;
    } else {
        ret = mBegin;
        mBegin = (T *)storage.addr();
        mLength = 0;
        mCapacity = sInlineCapacity;
    }
    return ret;
}

template <class T, size_t N, class AP>
inline void
Vector<T,N,AP>::replaceRawBuffer(T *p, size_t length)
{
    REENTRANCY_GUARD_ET_AL;

    /* Destroy what we have. */
    Impl::destroy(beginNoCheck(), endNoCheck());
    if (!usingInlineStorage())
        this->free(beginNoCheck());

    /* Take in the new buffer. */
    if (length <= sInlineCapacity) {
        /*
         * We convert to inline storage if possible, even though p might
         * otherwise be acceptable.  Maybe this behaviour should be
         * specifiable with an argument to this function.
         */
        mBegin = (T *)storage.addr();
        mLength = length;
        mCapacity = sInlineCapacity;
        Impl::copyConstruct(mBegin, p, p + length);
        Impl::destroy(p, p + length);
        this->free(p);
    } else {
        mBegin = p;
        mLength = length;
        mCapacity = length;
    }
}

}  /* namespace js */

#ifdef _MSC_VER
#pragma warning(pop)
#endif

#endif /* jsvector_h_ */