/*
* Copyright (c) Facebook, Inc. and its affiliates.
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// @author Mark Rabkin (mrabkin@fb.com)
// @author Andrei Alexandrescu (andrei.alexandrescu@fb.com)
#pragma once
#include <folly/Portability.h>
#include <folly/hash/SpookyHashV2.h>
#include <folly/lang/Exception.h>
#include <folly/portability/Constexpr.h>
#include <folly/portability/String.h>
#include <algorithm>
#include <array>
#include <cassert>
#include <climits>
#include <cstddef>
#include <cstring>
#include <iosfwd>
#include <iterator>
#include <stdexcept>
#include <string>
#include <type_traits>
#if FOLLY_HAS_STRING_VIEW
#include <string_view> // @manual
#endif
#include <folly/CpuId.h>
#include <folly/Likely.h>
#include <folly/Traits.h>
#include <folly/detail/RangeCommon.h>
#include <folly/detail/RangeSse42.h>
// Ignore shadowing warnings within this file, so includers can use -Wshadow.
FOLLY_PUSH_WARNING
FOLLY_GNU_DISABLE_WARNING("-Wshadow")
namespace folly {
/**
* Ubiquitous helper template for knowing what's a string.
*/
template <class T>
struct IsSomeString : std::false_type {};
template <typename Alloc>
struct IsSomeString<std::basic_string<char, std::char_traits<char>, Alloc>>
: std::true_type {};
template <class Iter>
class Range;
/**
* Finds the first occurrence of needle in haystack. The algorithm is on
* average faster than O(haystack.size() * needle.size()) but not as fast
* as Boyer-Moore. On the upside, it does not do any upfront
* preprocessing and does not allocate memory.
*/
template <
class Iter,
class Comp = std::equal_to<typename Range<Iter>::value_type>>
inline size_t
qfind(const Range<Iter>& haystack, const Range<Iter>& needle, Comp eq = Comp());
/**
* Finds the first occurrence of needle in haystack. The result is the
* offset reported to the beginning of haystack, or string::npos if
* needle wasn't found.
*/
template <class Iter>
size_t qfind(
const Range<Iter>& haystack,
const typename Range<Iter>::value_type& needle);
/**
* Finds the last occurrence of needle in haystack. The result is the
* offset reported to the beginning of haystack, or string::npos if
* needle wasn't found.
*/
template <class Iter>
size_t rfind(
const Range<Iter>& haystack,
const typename Range<Iter>::value_type& needle);
/**
* Finds the first occurrence of any element of needle in
* haystack. The algorithm is O(haystack.size() * needle.size()).
*/
template <class Iter>
inline size_t qfind_first_of(
const Range<Iter>& haystack,
const Range<Iter>& needle);
/**
* Small internal helper - returns the value just before an iterator.
*/
namespace detail {
/*
* Use IsCharPointer<T>::type to enable const char* or char*.
* Use IsCharPointer<T>::const_type to enable only const char*.
*/
template <class T>
struct IsCharPointer {};
template <>
struct IsCharPointer<char*> {
typedef int type;
};
template <>
struct IsCharPointer<const char*> {
typedef int const_type;
typedef int type;
};
} // namespace detail
/**
* Range abstraction keeping a pair of iterators. We couldn't use
* boost's similar range abstraction because we need an API identical
* with the former StringPiece class, which is used by a lot of other
* code. This abstraction does fulfill the needs of boost's
* range-oriented algorithms though.
*
* (Keep memory lifetime in mind when using this class, since it
* doesn't manage the data it refers to - just like an iterator
* wouldn't.)
*/
template <class Iter>
class Range {
private:
template <typename Alloc>
using string = std::basic_string<char, std::char_traits<char>, Alloc>;
public:
typedef std::size_t size_type;
typedef Iter iterator;
typedef Iter const_iterator;
typedef typename std::remove_reference<
typename std::iterator_traits<Iter>::reference>::type value_type;
using difference_type = typename std::iterator_traits<Iter>::difference_type;
typedef typename std::iterator_traits<Iter>::reference reference;
/**
* For MutableStringPiece and MutableByteRange we define StringPiece
* and ByteRange as const_range_type (for everything else its just
* identity). We do that to enable operations such as find with
* args which are const.
*/
typedef typename std::conditional<
std::is_same<Iter, char*>::value ||
std::is_same<Iter, unsigned char*>::value,
Range<const value_type*>,
Range<Iter>>::type const_range_type;
typedef std::char_traits<typename std::remove_const<value_type>::type>
traits_type;
static const size_type npos;
// Works for all iterators
constexpr Range() : b_(), e_() {}
constexpr Range(const Range&) = default;
constexpr Range(Range&&) = default;
public:
// Works for all iterators
constexpr Range(Iter start, Iter end) : b_(start), e_(end) {}
// Works only for random-access iterators
constexpr Range(Iter start, size_t size) : b_(start), e_(start + size) {}
/* implicit */ Range(std::nullptr_t) = delete;
constexpr /* implicit */ Range(Iter str)
: b_(str), e_(str + constexpr_strlen(str)) {
static_assert(
std::is_same<int, typename detail::IsCharPointer<Iter>::type>::value,
"This constructor is only available for character ranges");
}
template <
class Alloc,
class T = Iter,
typename detail::IsCharPointer<T>::const_type = 0>
/* implicit */ Range(const string<Alloc>& str)
: b_(str.data()), e_(b_ + str.size()) {}
template <
class Alloc,
class T = Iter,
typename detail::IsCharPointer<T>::const_type = 0>
Range(const string<Alloc>& str, typename string<Alloc>::size_type startFrom) {
if (UNLIKELY(startFrom > str.size())) {
throw_exception<std::out_of_range>("index out of range");
}
b_ = str.data() + startFrom;
e_ = str.data() + str.size();
}
template <
class Alloc,
class T = Iter,
typename detail::IsCharPointer<T>::const_type = 0>
Range(
const string<Alloc>& str,
typename string<Alloc>::size_type startFrom,
typename string<Alloc>::size_type size) {
if (UNLIKELY(startFrom > str.size())) {
throw_exception<std::out_of_range>("index out of range");
}
b_ = str.data() + startFrom;
if (str.size() - startFrom < size) {
e_ = str.data() + str.size();
} else {
e_ = b_ + size;
}
}
Range(const Range& other, size_type first, size_type length = npos)
: Range(other.subpiece(first, length)) {}
template <
class Container,
class = typename std::enable_if<
std::is_same<Iter, typename Container::const_pointer>::value>::type,
class = decltype(
Iter(std::declval<Container const&>().data()),
Iter(
std::declval<Container const&>().data() +
std::declval<Container const&>().size()))>
/* implicit */ constexpr Range(Container const& container)
: b_(container.data()), e_(b_ + container.size()) {}
template <
class Container,
class = typename std::enable_if<
std::is_same<Iter, typename Container::const_pointer>::value>::type,
class = decltype(
Iter(std::declval<Container const&>().data()),
Iter(
std::declval<Container const&>().data() +
std::declval<Container const&>().size()))>
Range(Container const& container, typename Container::size_type startFrom) {
auto const cdata = container.data();
auto const csize = container.size();
if (UNLIKELY(startFrom > csize)) {
throw_exception<std::out_of_range>("index out of range");
}
b_ = cdata + startFrom;
e_ = cdata + csize;
}
template <
class Container,
class = typename std::enable_if<
std::is_same<Iter, typename Container::const_pointer>::value>::type,
class = decltype(
Iter(std::declval<Container const&>().data()),
Iter(
std::declval<Container const&>().data() +
std::declval<Container const&>().size()))>
Range(
Container const& container,
typename Container::size_type startFrom,
typename Container::size_type size) {
auto const cdata = container.data();
auto const csize = container.size();
if (UNLIKELY(startFrom > csize)) {
throw_exception<std::out_of_range>("index out of range");
}
b_ = cdata + startFrom;
if (csize - startFrom < size) {
e_ = cdata + csize;
} else {
e_ = b_ + size;
}
}
// Allow implicit conversion from Range<const char*> (aka StringPiece) to
// Range<const unsigned char*> (aka ByteRange), as they're both frequently
// used to represent ranges of bytes. Allow explicit conversion in the other
// direction.
template <
class OtherIter,
typename std::enable_if<
(std::is_same<Iter, const unsigned char*>::value &&
(std::is_same<OtherIter, const char*>::value ||
std::is_same<OtherIter, char*>::value)),
int>::type = 0>
/* implicit */ Range(const Range<OtherIter>& other)
: b_(reinterpret_cast<const unsigned char*>(other.begin())),
e_(reinterpret_cast<const unsigned char*>(other.end())) {}
template <
class OtherIter,
typename std::enable_if<
(std::is_same<Iter, unsigned char*>::value &&
std::is_same<OtherIter, char*>::value),
int>::type = 0>
/* implicit */ Range(const Range<OtherIter>& other)
: b_(reinterpret_cast<unsigned char*>(other.begin())),
e_(reinterpret_cast<unsigned char*>(other.end())) {}
template <
class OtherIter,
typename std::enable_if<
(std::is_same<Iter, const char*>::value &&
(std::is_same<OtherIter, const unsigned char*>::value ||
std::is_same<OtherIter, unsigned char*>::value)),
int>::type = 0>
explicit Range(const Range<OtherIter>& other)
: b_(reinterpret_cast<const char*>(other.begin())),
e_(reinterpret_cast<const char*>(other.end())) {}
template <
class OtherIter,
typename std::enable_if<
(std::is_same<Iter, char*>::value &&
std::is_same<OtherIter, unsigned char*>::value),
int>::type = 0>
explicit Range(const Range<OtherIter>& other)
: b_(reinterpret_cast<char*>(other.begin())),
e_(reinterpret_cast<char*>(other.end())) {}
// Allow implicit conversion from Range<From> to Range<To> if From is
// implicitly convertible to To.
template <
class OtherIter,
typename std::enable_if<
(!std::is_same<Iter, OtherIter>::value &&
std::is_convertible<OtherIter, Iter>::value),
int>::type = 0>
constexpr /* implicit */ Range(const Range<OtherIter>& other)
: b_(other.begin()), e_(other.end()) {}
// Allow explicit conversion from Range<From> to Range<To> if From is
// explicitly convertible to To.
template <
class OtherIter,
typename std::enable_if<
(!std::is_same<Iter, OtherIter>::value &&
!std::is_convertible<OtherIter, Iter>::value &&
std::is_constructible<Iter, const OtherIter&>::value),
int>::type = 0>
constexpr explicit Range(const Range<OtherIter>& other)
: b_(other.begin()), e_(other.end()) {}
/**
* Allow explicit construction of Range() from a std::array of a
* convertible type.
*
* For instance, this allows constructing StringPiece from a
* std::array<char, N> or a std::array<const char, N>
*/
template <
class T,
size_t N,
typename = typename std::enable_if<
std::is_convertible<const T*, Iter>::value>::type>
constexpr explicit Range(const std::array<T, N>& array)
: b_{array.empty() ? nullptr : &array.at(0)},
e_{array.empty() ? nullptr : &array.at(0) + N} {}
template <
class T,
size_t N,
typename =
typename std::enable_if<std::is_convertible<T*, Iter>::value>::type>
constexpr explicit Range(std::array<T, N>& array)
: b_{array.empty() ? nullptr : &array.at(0)},
e_{array.empty() ? nullptr : &array.at(0) + N} {}
Range& operator=(const Range& rhs) & = default;
Range& operator=(Range&& rhs) & = default;
template <
class Alloc,
class T = Iter,
typename detail::IsCharPointer<T>::const_type = 0>
Range& operator=(string<Alloc>&& rhs) = delete;
void clear() {
b_ = Iter();
e_ = Iter();
}
void assign(Iter start, Iter end) {
b_ = start;
e_ = end;
}
void reset(Iter start, size_type size) {
b_ = start;
e_ = start + size;
}
// Works only for Range<const char*>
template <typename Alloc>
void reset(const string<Alloc>& str) {
reset(str.data(), str.size());
}
constexpr size_type size() const {
#if __clang__ || !__GNUC__ || __GNUC__ >= 7
assert(b_ <= e_);
#endif
return size_type(e_ - b_);
}
constexpr size_type walk_size() const {
return size_type(std::distance(b_, e_));
}
constexpr bool empty() const {
return b_ == e_;
}
constexpr Iter data() const {
return b_;
}
constexpr Iter start() const {
return b_;
}
constexpr Iter begin() const {
return b_;
}
constexpr Iter end() const {
return e_;
}
constexpr Iter cbegin() const {
return b_;
}
constexpr Iter cend() const {
return e_;
}
value_type& front() {
assert(b_ < e_);
return *b_;
}
value_type& back() {
assert(b_ < e_);
return *std::prev(e_);
}
const value_type& front() const {
assert(b_ < e_);
return *b_;
}
const value_type& back() const {
assert(b_ < e_);
return *std::prev(e_);
}
private:
// It would be nice to be able to implicit convert to any target type
// T for which either an (Iter, Iter) or (Iter, size_type) noexcept
// constructor was available, and explicitly convert to any target
// type for which those signatures were available but not noexcept.
// The problem is that this creates ambiguity when there is also a
// T constructor that takes a type U that is implicitly convertible
// from Range.
//
// To avoid ambiguity, we need to avoid having explicit operator T
// and implicit operator U coexist when T is constructible from U.
// U cannot be deduced when searching for operator T (and C++ won't
// perform an existential search for it), so we must limit the implicit
// target types to a finite set that we can enumerate.
//
// At the moment the set of implicit target types consists of just
// std::string_view (when it is available).
#if FOLLY_HAS_STRING_VIEW
struct NotStringView {};
template <typename ValueType>
struct StringViewType
: std::conditional<
std::is_pod<std::remove_const_t<ValueType>>::value,
std::basic_string_view<std::remove_const_t<ValueType>>,
NotStringView> {};
template <typename Target>
struct IsConstructibleViaStringView
: Conjunction<
std::is_constructible<
_t<StringViewType<value_type>>,
Iter const&,
size_type>,
std::is_constructible<Target, _t<StringViewType<value_type>>>> {};
#else
template <typename Target>
using IsConstructibleViaStringView = std::false_type;
#endif
public:
/// explicit operator conversion to any compatible type
///
/// A compatible type is one which is constructible with an iterator and a
/// size (preferred), or a pair of iterators (fallback), passed by const-ref.
///
/// Participates in overload resolution precisely when the target type is
/// compatible. This allows std::is_constructible compile-time checks to work.
template <
typename Tgt,
std::enable_if_t<
std::is_constructible<Tgt, Iter const&, size_type>::value &&
!IsConstructibleViaStringView<Tgt>::value,
int> = 0>
constexpr explicit operator Tgt() const noexcept(
std::is_nothrow_constructible<Tgt, Iter const&, size_type>::value) {
return Tgt(b_, walk_size());
}
template <
typename Tgt,
std::enable_if_t<
!std::is_constructible<Tgt, Iter const&, size_type>::value &&
std::is_constructible<Tgt, Iter const&, Iter const&>::value &&
!IsConstructibleViaStringView<Tgt>::value,
int> = 0>
constexpr explicit operator Tgt() const noexcept(
std::is_nothrow_constructible<Tgt, Iter const&, Iter const&>::value) {
return Tgt(b_, e_);
}
#if FOLLY_HAS_STRING_VIEW
/// implicit operator conversion to std::string_view
template <
typename Tgt,
typename ValueType = value_type,
std::enable_if_t<
StrictConjunction<
std::is_same<Tgt, _t<StringViewType<ValueType>>>,
std::is_constructible<
_t<StringViewType<ValueType>>,
Iter const&,
size_type>>::value,
int> = 0>
constexpr operator Tgt() const noexcept(
std::is_nothrow_constructible<Tgt, Iter const&, size_type>::value) {
return Tgt(b_, walk_size());
}
#endif
/// explicit non-operator conversion to any compatible type
///
/// A compatible type is one which is constructible with an iterator and a
/// size (preferred), or a pair of iterators (fallback), passed by const-ref.
///
/// Participates in overload resolution precisely when the target type is
/// compatible. This allows is_invocable compile-time checks to work.
///
/// Provided in addition to the explicit operator conversion to permit passing
/// additional arguments to the target type constructor. A canonical example
/// of an additional argument might be an allocator, where the target type is
/// some specialization of std::vector or std::basic_string in a context which
/// requires a non-default-constructed allocator.
template <typename Tgt, typename... Args>
constexpr std::enable_if_t<
std::is_constructible<Tgt, Iter const&, size_type>::value,
Tgt>
to(Args&&... args) const noexcept(
std::is_nothrow_constructible<Tgt, Iter const&, size_type, Args&&...>::
value) {
return Tgt(b_, walk_size(), static_cast<Args&&>(args)...);
}
template <typename Tgt, typename... Args>
constexpr std::enable_if_t<
!std::is_constructible<Tgt, Iter const&, size_type>::value &&
std::is_constructible<Tgt, Iter const&, Iter const&>::value,
Tgt>
to(Args&&... args) const noexcept(
std::is_nothrow_constructible<Tgt, Iter const&, Iter const&, Args&&...>::
value) {
return Tgt(b_, e_, static_cast<Args&&>(args)...);
}
// Works only for Range<const char*> and Range<char*>
std::string str() const {
return to<std::string>();
}
std::string toString() const {
return to<std::string>();
}
const_range_type castToConst() const {
return const_range_type(*this);
}
int compare(const const_range_type& o) const {
const size_type tsize = this->size();
const size_type osize = o.size();
const size_type msize = std::min(tsize, osize);
int r = traits_type::compare(data(), o.data(), msize);
if (r == 0 && tsize != osize) {
// We check the signed bit of the subtraction and bit shift it
// to produce either 0 or 2. The subtraction yields the
// comparison values of either -1 or 1.
r = (static_cast<int>((osize - tsize) >> (CHAR_BIT * sizeof(size_t) - 1))
<< 1) -
1;
}
return r;
}
value_type& operator[](size_t i) {
assert(i < size());
return b_[i];
}
const value_type& operator[](size_t i) const {
assert(i < size());
return b_[i];
}
value_type& at(size_t i) {
if (i >= size()) {
throw_exception<std::out_of_range>("index out of range");
}
return b_[i];
}
const value_type& at(size_t i) const {
if (i >= size()) {
throw_exception<std::out_of_range>("index out of range");
}
return b_[i];
}
// Do NOT use this function, which was left behind for backwards
// compatibility. Use SpookyHashV2 instead -- it is faster, and produces
// a 64-bit hash, which means dramatically fewer collisions in large maps.
// (The above advice does not apply if you are targeting a 32-bit system.)
//
// Works only for Range<const char*> and Range<char*>
//
//
// ** WANT TO GET RID OF THIS LINT? **
//
// A) Use a better hash function (*cough*folly::Hash*cough*), but
// only if you don't serialize data in a format that depends on
// this formula (ie the writer and reader assume this exact hash
// function is used).
//
// B) If you have to use this exact function then make your own hasher
// object and copy the body over (see thrift example: D3972362).
// https://github.com/facebook/fbthrift/commit/f8ed502e24ab4a32a9d5f266580
[[deprecated(
"Replace with folly::Hash if the hash is not serialized")]] uint32_t
hash() const {
// Taken from fbi/nstring.h:
// Quick and dirty bernstein hash...fine for short ascii strings
uint32_t hash = 5381;
for (size_t ix = 0; ix < size(); ix++) {
hash = ((hash << 5) + hash) + b_[ix];
}
return hash;
}
void advance(size_type n) {
if (UNLIKELY(n > size())) {
throw_exception<std::out_of_range>("index out of range");
}
b_ += n;
}
void subtract(size_type n) {
if (UNLIKELY(n > size())) {
throw_exception<std::out_of_range>("index out of range");
}
e_ -= n;
}
Range subpiece(size_type first, size_type length = npos) const {
if (UNLIKELY(first > size())) {
throw_exception<std::out_of_range>("index out of range");
}
return Range(b_ + first, std::min(length, size() - first));
}
// unchecked versions
void uncheckedAdvance(size_type n) {
assert(n <= size());
b_ += n;
}
void uncheckedSubtract(size_type n) {
assert(n <= size());
e_ -= n;
}
Range uncheckedSubpiece(size_type first, size_type length = npos) const {
assert(first <= size());
return Range(b_ + first, std::min(length, size() - first));
}
void pop_front() {
assert(b_ < e_);
++b_;
}
void pop_back() {
assert(b_ < e_);
--e_;
}
// string work-alike functions
size_type find(const_range_type str) const {
return qfind(castToConst(), str);
}
size_type find(const_range_type str, size_t pos) const {
if (pos > size()) {
return std::string::npos;
}
size_t ret = qfind(castToConst().subpiece(pos), str);
return ret == npos ? ret : ret + pos;
}
size_type find(Iter s, size_t pos, size_t n) const {
if (pos > size()) {
return std::string::npos;
}
auto forFinding = castToConst();
size_t ret = qfind(
pos ? forFinding.subpiece(pos) : forFinding, const_range_type(s, n));
return ret == npos ? ret : ret + pos;
}
// Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
size_type find(const Iter s) const {
return qfind(castToConst(), const_range_type(s));
}
// Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
size_type find(const Iter s, size_t pos) const {
if (pos > size()) {
return std::string::npos;
}
size_type ret = qfind(castToConst().subpiece(pos), const_range_type(s));
return ret == npos ? ret : ret + pos;
}
size_type find(value_type c) const {
return qfind(castToConst(), c);
}
size_type rfind(value_type c) const {
return folly::rfind(castToConst(), c);
}
size_type find(value_type c, size_t pos) const {
if (pos > size()) {
return std::string::npos;
}
size_type ret = qfind(castToConst().subpiece(pos), c);
return ret == npos ? ret : ret + pos;
}
size_type find_first_of(const_range_type needles) const {
return qfind_first_of(castToConst(), needles);
}
size_type find_first_of(const_range_type needles, size_t pos) const {
if (pos > size()) {
return std::string::npos;
}
size_type ret = qfind_first_of(castToConst().subpiece(pos), needles);
return ret == npos ? ret : ret + pos;
}
// Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
size_type find_first_of(Iter needles) const {
return find_first_of(const_range_type(needles));
}
// Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
size_type find_first_of(Iter needles, size_t pos) const {
return find_first_of(const_range_type(needles), pos);
}
size_type find_first_of(Iter needles, size_t pos, size_t n) const {
return find_first_of(const_range_type(needles, n), pos);
}
size_type find_first_of(value_type c) const {
return find(c);
}
size_type find_first_of(value_type c, size_t pos) const {
return find(c, pos);
}
/**
* Determine whether the range contains the given subrange or item.
*
* Note: Call find() directly if the index is needed.
*/
bool contains(const const_range_type& other) const {
return find(other) != std::string::npos;
}
bool contains(const value_type& other) const {
return find(other) != std::string::npos;
}
void swap(Range& rhs) {
std::swap(b_, rhs.b_);
std::swap(e_, rhs.e_);
}
/**
* Does this Range start with another range?
*/
bool startsWith(const const_range_type& other) const {
return size() >= other.size() &&
castToConst().subpiece(0, other.size()) == other;
}
bool startsWith(value_type c) const {
return !empty() && front() == c;
}
template <class Comp>
bool startsWith(const const_range_type& other, Comp&& eq) const {
if (size() < other.size()) {
return false;
}
auto const trunc = subpiece(0, other.size());
return std::equal(
trunc.begin(), trunc.end(), other.begin(), std::forward<Comp>(eq));
}
/**
* Does this Range end with another range?
*/
bool endsWith(const const_range_type& other) const {
return size() >= other.size() &&
castToConst().subpiece(size() - other.size()) == other;
}
bool endsWith(value_type c) const {
return !empty() && back() == c;
}
template <class Comp>
bool endsWith(const const_range_type& other, Comp&& eq) const {
if (size() < other.size()) {
return false;
}
auto const trunc = subpiece(size() - other.size());
return std::equal(
trunc.begin(), trunc.end(), other.begin(), std::forward<Comp>(eq));
}
template <class Comp>
bool equals(const const_range_type& other, Comp&& eq) const {
return size() == other.size() &&
std::equal(begin(), end(), other.begin(), std::forward<Comp>(eq));
}
/**
* Remove the items in [b, e), as long as this subrange is at the beginning
* or end of the Range.
*
* Required for boost::algorithm::trim()
*/
void erase(Iter b, Iter e) {
if (b == b_) {
b_ = e;
} else if (e == e_) {
e_ = b;
} else {
throw_exception<std::out_of_range>("index out of range");
}
}
/**
* Remove the given prefix and return true if the range starts with the given
* prefix; return false otherwise.
*/
bool removePrefix(const const_range_type& prefix) {
return startsWith(prefix) && (b_ += prefix.size(), true);
}
bool removePrefix(value_type prefix) {
return startsWith(prefix) && (++b_, true);
}
/**
* Remove the given suffix and return true if the range ends with the given
* suffix; return false otherwise.
*/
bool removeSuffix(const const_range_type& suffix) {
return endsWith(suffix) && (e_ -= suffix.size(), true);
}
bool removeSuffix(value_type suffix) {
return endsWith(suffix) && (--e_, true);
}
/**
* Replaces the content of the range, starting at position 'pos', with
* contents of 'replacement'. Entire 'replacement' must fit into the
* range. Returns false if 'replacements' does not fit. Example use:
*
* char in[] = "buffer";
* auto msp = MutablesStringPiece(input);
* EXPECT_TRUE(msp.replaceAt(2, "tt"));
* EXPECT_EQ(msp, "butter");
*
* // not enough space
* EXPECT_FALSE(msp.replace(msp.size() - 1, "rr"));
* EXPECT_EQ(msp, "butter"); // unchanged
*/
bool replaceAt(size_t pos, const_range_type replacement) {
if (size() < pos + replacement.size()) {
return false;
}
std::copy(replacement.begin(), replacement.end(), begin() + pos);
return true;
}
/**
* Replaces all occurences of 'source' with 'dest'. Returns number
* of replacements made. Source and dest have to have the same
* length. Throws if the lengths are different. If 'source' is a
* pattern that is overlapping with itself, we perform sequential
* replacement: "aaaaaaa".replaceAll("aa", "ba") --> "bababaa"
*
* Example use:
*
* char in[] = "buffer";
* auto msp = MutablesStringPiece(input);
* EXPECT_EQ(msp.replaceAll("ff","tt"), 1);
* EXPECT_EQ(msp, "butter");
*/
size_t replaceAll(const_range_type source, const_range_type dest) {
if (source.size() != dest.size()) {
throw_exception<std::invalid_argument>(
"replacement must have the same size as source");
}
if (dest.empty()) {
return 0;
}
size_t pos = 0;
size_t num_replaced = 0;
size_type found = std::string::npos;
while ((found = find(source, pos)) != std::string::npos) {
replaceAt(found, dest);
pos += source.size();
++num_replaced;
}
return num_replaced;
}
/**
* Splits this `Range` `[b, e)` in the position `i` dictated by the next
* occurence of `delimiter`.
*
* Returns a new `Range` `[b, i)` and adjusts this range to start right after
* the delimiter's position. This range will be empty if the delimiter is not
* found. If called on an empty `Range`, both this and the returned `Range`
* will be empty.
*
* Example:
*
* folly::StringPiece s("sample string for split_next");
* auto p = s.split_step(' ');
*
* // prints "string for split_next"
* cout << s << endl;
*
* // prints "sample"
* cout << p << endl;
*
* Example 2:
*
* void tokenize(StringPiece s, char delimiter) {
* while (!s.empty()) {
* cout << s.split_step(delimiter);
* }
* }
*
* @author: Marcelo Juchem <marcelo@fb.com>
*/
Range split_step(value_type delimiter) {
auto i = std::find(b_, e_, delimiter);
Range result(b_, i);
b_ = i == e_ ? e_ : std::next(i);
return result;
}
Range split_step(Range delimiter) {
auto i = find(delimiter);
Range result(b_, i == std::string::npos ? size() : i);
b_ = result.end() == e_
? e_
: std::next(
result.end(),
typename std::iterator_traits<Iter>::difference_type(
delimiter.size()));
return result;
}
/**
* Convenience method that calls `split_step()` and passes the result to a
* functor, returning whatever the functor does. Any additional arguments
* `args` passed to this function are perfectly forwarded to the functor.
*
* Say you have a functor with this signature:
*
* Foo fn(Range r) { }
*
* `split_step()`'s return type will be `Foo`. It works just like:
*
* auto result = fn(myRange.split_step(' '));
*
* A functor returning `void` is also supported.
*
* Example:
*
* void do_some_parsing(folly::StringPiece s) {
* auto version = s.split_step(' ', [&](folly::StringPiece x) {
* if (x.empty()) {
* throw std::invalid_argument("empty string");
* }
* return std::strtoull(x.begin(), x.end(), 16);
* });
*
* // ...
* }
*
* struct Foo {
* void parse(folly::StringPiece s) {
* s.split_step(' ', parse_field, bar, 10);
* s.split_step('\t', parse_field, baz, 20);
*
* auto const kludge = [](folly::StringPiece x, int &out, int def) {
* if (x == "null") {
* out = 0;
* } else {
* parse_field(x, out, def);
* }
* };
*
* s.split_step('\t', kludge, gaz);
* s.split_step(' ', kludge, foo);
* }
*
* private:
* int bar;
* int baz;
* int gaz;
* int foo;
*
* static parse_field(folly::StringPiece s, int &out, int def) {
* try {
* out = folly::to<int>(s);
* } catch (std::exception const &) {
* value = def;
* }
* }
* };
*
* @author: Marcelo Juchem <marcelo@fb.com>
*/
template <typename TProcess, typename... Args>
auto split_step(value_type delimiter, TProcess&& process, Args&&... args)
-> decltype(process(std::declval<Range>(), std::forward<Args>(args)...)) {
return process(split_step(delimiter), std::forward<Args>(args)...);
}
template <typename TProcess, typename... Args>
auto split_step(Range delimiter, TProcess&& process, Args&&... args)
-> decltype(process(std::declval<Range>(), std::forward<Args>(args)...)) {
return process(split_step(delimiter), std::forward<Args>(args)...);
}
private:
Iter b_, e_;
};
template <class Iter>
const typename Range<Iter>::size_type Range<Iter>::npos = std::string::npos;
template <class Iter>
void swap(Range<Iter>& lhs, Range<Iter>& rhs) {
lhs.swap(rhs);
}
/**
* Create a range from two iterators, with type deduction.
*/
template <class Iter>
constexpr Range<Iter> range(Iter first, Iter last) {
return Range<Iter>(first, last);
}
/*
* Creates a range to reference the contents of a contiguous-storage container.
*/
// Use pointers for types with '.data()' member
template <class Collection>
constexpr auto range(Collection& v) -> Range<decltype(v.data())> {
return Range<decltype(v.data())>(v.data(), v.data() + v.size());
}
template <class Collection>
constexpr auto range(Collection const& v) -> Range<decltype(v.data())> {
return Range<decltype(v.data())>(v.data(), v.data() + v.size());
}
template <class Collection>
constexpr auto crange(Collection const& v) -> Range<decltype(v.data())> {
return Range<decltype(v.data())>(v.data(), v.data() + v.size());
}
template <class T, size_t n>
constexpr Range<T*> range(T (&array)[n]) {
return Range<T*>(array, array + n);
}
template <class T, size_t n>
constexpr Range<T const*> range(T const (&array)[n]) {
return Range<T const*>(array, array + n);
}
template <class T, size_t n>
constexpr Range<T const*> crange(T const (&array)[n]) {
return Range<T const*>(array, array + n);
}
template <class T, size_t n>
constexpr Range<T*> range(std::array<T, n>& array) {
return Range<T*>{array};
}
template <class T, size_t n>
constexpr Range<T const*> range(std::array<T, n> const& array) {
return Range<T const*>{array};
}
template <class T, size_t n>
constexpr Range<T const*> crange(std::array<T, n> const& array) {
return Range<T const*>{array};
}
typedef Range<const char*> StringPiece;
typedef Range<char*> MutableStringPiece;
typedef Range<const unsigned char*> ByteRange;
typedef Range<unsigned char*> MutableByteRange;
template <class C>
std::basic_ostream<C>& operator<<(
std::basic_ostream<C>& os,
Range<C const*> piece) {
using StreamSize = decltype(os.width());
os.write(piece.start(), static_cast<StreamSize>(piece.size()));
return os;
}
template <class C>
std::basic_ostream<C>& operator<<(std::basic_ostream<C>& os, Range<C*> piece) {
using StreamSize = decltype(os.width());
os.write(piece.start(), static_cast<StreamSize>(piece.size()));
return os;
}
/**
* Templated comparison operators
*/
template <class Iter>
inline bool operator==(const Range<Iter>& lhs, const Range<Iter>& rhs) {
return lhs.size() == rhs.size() && lhs.compare(rhs) == 0;
}
template <class Iter>
inline bool operator!=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
return !(operator==(lhs, rhs));
}
template <class Iter>
inline bool operator<(const Range<Iter>& lhs, const Range<Iter>& rhs) {
return lhs.compare(rhs) < 0;
}
template <class Iter>
inline bool operator<=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
return lhs.compare(rhs) <= 0;
}
template <class Iter>
inline bool operator>(const Range<Iter>& lhs, const Range<Iter>& rhs) {
return lhs.compare(rhs) > 0;
}
template <class Iter>
inline bool operator>=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
return lhs.compare(rhs) >= 0;
}
/**
* Specializations of comparison operators for StringPiece
*/
namespace detail {
template <class A, class B>
struct ComparableAsStringPiece {
enum {
value = (std::is_convertible<A, StringPiece>::value &&
std::is_same<B, StringPiece>::value) ||
(std::is_convertible<B, StringPiece>::value &&
std::is_same<A, StringPiece>::value)
};
};
} // namespace detail
/**
* operator== through conversion for Range<const char*>
*/
template <class T, class U>
std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator==(
const T& lhs,
const U& rhs) {
return StringPiece(lhs) == StringPiece(rhs);
}
/**
* operator!= through conversion for Range<const char*>
*/
template <class T, class U>
std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator!=(
const T& lhs,
const U& rhs) {
return StringPiece(lhs) != StringPiece(rhs);
}
/**
* operator< through conversion for Range<const char*>
*/
template <class T, class U>
std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator<(
const T& lhs,
const U& rhs) {
return StringPiece(lhs) < StringPiece(rhs);
}
/**
* operator> through conversion for Range<const char*>
*/
template <class T, class U>
std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator>(
const T& lhs,
const U& rhs) {
return StringPiece(lhs) > StringPiece(rhs);
}
/**
* operator< through conversion for Range<const char*>
*/
template <class T, class U>
std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator<=(
const T& lhs,
const U& rhs) {
return StringPiece(lhs) <= StringPiece(rhs);
}
/**
* operator> through conversion for Range<const char*>
*/
template <class T, class U>
std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator>=(
const T& lhs,
const U& rhs) {
return StringPiece(lhs) >= StringPiece(rhs);
}
/**
* Finds substrings faster than brute force by borrowing from Boyer-Moore
*/
template <class Iter, class Comp>
size_t qfind(const Range<Iter>& haystack, const Range<Iter>& needle, Comp eq) {
// Don't use std::search, use a Boyer-Moore-like trick by comparing
// the last characters first
auto const nsize = needle.size();
if (haystack.size() < nsize) {
return std::string::npos;
}
if (!nsize) {
return 0;
}
auto const nsize_1 = nsize - 1;
auto const lastNeedle = needle[nsize_1];
// Boyer-Moore skip value for the last char in the needle. Zero is
// not a valid value; skip will be computed the first time it's
// needed.
std::string::size_type skip = 0;
auto i = haystack.begin();
auto iEnd = haystack.end() - nsize_1;
while (i < iEnd) {
// Boyer-Moore: match the last element in the needle
while (!eq(i[nsize_1], lastNeedle)) {
if (++i == iEnd) {
// not found
return std::string::npos;
}
}
// Here we know that the last char matches
// Continue in pedestrian mode
for (size_t j = 0;;) {
assert(j < nsize);
if (!eq(i[j], needle[j])) {
// Not found, we can skip
// Compute the skip value lazily
if (skip == 0) {
skip = 1;
while (skip <= nsize_1 && !eq(needle[nsize_1 - skip], lastNeedle)) {
++skip;
}
}
i += skip;
break;
}
// Check if done searching
if (++j == nsize) {
// Yay
return size_t(i - haystack.begin());
}
}
}
return std::string::npos;
}
namespace detail {
inline size_t qfind_first_byte_of(
const StringPiece haystack,
const StringPiece needles) {
static auto const qfind_first_byte_of_fn = folly::CpuId().sse42()
? qfind_first_byte_of_sse42
: qfind_first_byte_of_nosse;
return qfind_first_byte_of_fn(haystack, needles);
}
} // namespace detail
template <class Iter, class Comp>
size_t qfind_first_of(
const Range<Iter>& haystack,
const Range<Iter>& needles,
Comp eq) {
auto ret = std::find_first_of(
haystack.begin(), haystack.end(), needles.begin(), needles.end(), eq);
return ret == haystack.end() ? std::string::npos : ret - haystack.begin();
}
struct AsciiCaseSensitive {
bool operator()(char lhs, char rhs) const {
return lhs == rhs;
}
};
/**
* Check if two ascii characters are case insensitive equal.
* The difference between the lower/upper case characters are the 6-th bit.
* We also check they are alpha chars, in case of xor = 32.
*/
struct AsciiCaseInsensitive {
bool operator()(char lhs, char rhs) const {
char k = lhs ^ rhs;
if (k == 0) {
return true;
}
if (k != 32) {
return false;
}
k = lhs | rhs;
return (k >= 'a' && k <= 'z');
}
};
template <class Iter>
size_t qfind(
const Range<Iter>& haystack,
const typename Range<Iter>::value_type& needle) {
auto pos = std::find(haystack.begin(), haystack.end(), needle);
return pos == haystack.end() ? std::string::npos : pos - haystack.data();
}
template <class Iter>
size_t rfind(
const Range<Iter>& haystack,
const typename Range<Iter>::value_type& needle) {
for (auto i = haystack.size(); i-- > 0;) {
if (haystack[i] == needle) {
return i;
}
}
return std::string::npos;
}
// specialization for StringPiece
template <>
inline size_t qfind(const Range<const char*>& haystack, const char& needle) {
// memchr expects a not-null pointer, early return if the range is empty.
if (haystack.empty()) {
return std::string::npos;
}
auto pos = static_cast<const char*>(
::memchr(haystack.data(), needle, haystack.size()));
return pos == nullptr ? std::string::npos : pos - haystack.data();
}
template <>
inline size_t rfind(const Range<const char*>& haystack, const char& needle) {
// memchr expects a not-null pointer, early return if the range is empty.
if (haystack.empty()) {
return std::string::npos;
}
auto pos = static_cast<const char*>(
::memrchr(haystack.data(), needle, haystack.size()));
return pos == nullptr ? std::string::npos : pos - haystack.data();
}
// specialization for ByteRange
template <>
inline size_t qfind(
const Range<const unsigned char*>& haystack,
const unsigned char& needle) {
// memchr expects a not-null pointer, early return if the range is empty.
if (haystack.empty()) {
return std::string::npos;
}
auto pos = static_cast<const unsigned char*>(
::memchr(haystack.data(), needle, haystack.size()));
return pos == nullptr ? std::string::npos : pos - haystack.data();
}
template <>
inline size_t rfind(
const Range<const unsigned char*>& haystack,
const unsigned char& needle) {
// memchr expects a not-null pointer, early return if the range is empty.
if (haystack.empty()) {
return std::string::npos;
}
auto pos = static_cast<const unsigned char*>(
::memrchr(haystack.data(), needle, haystack.size()));
return pos == nullptr ? std::string::npos : pos - haystack.data();
}
template <class Iter>
size_t qfind_first_of(const Range<Iter>& haystack, const Range<Iter>& needles) {
return qfind_first_of(haystack, needles, AsciiCaseSensitive());
}
// specialization for StringPiece
template <>
inline size_t qfind_first_of(
const Range<const char*>& haystack,
const Range<const char*>& needles) {
return detail::qfind_first_byte_of(haystack, needles);
}
// specialization for ByteRange
template <>
inline size_t qfind_first_of(
const Range<const unsigned char*>& haystack,
const Range<const unsigned char*>& needles) {
return detail::qfind_first_byte_of(
StringPiece(haystack), StringPiece(needles));
}
template <class Key, class Enable>
struct hasher;
template <class T>
struct hasher<
folly::Range<T*>,
std::enable_if_t<std::is_integral<T>::value, void>> {
using folly_is_avalanching = std::true_type;
size_t operator()(folly::Range<T*> r) const {
// std::is_integral<T> is too restrictive, but is sufficient to
// guarantee we can just hash all of the underlying bytes to get a
// suitable hash of T. Something like absl::is_uniquely_represented<T>
// would be better. std::is_pod is not enough, because POD types
// can contain pointers and padding. Also, floating point numbers
// may be == without being bit-identical.
return hash::SpookyHashV2::Hash64(r.begin(), r.size() * sizeof(T), 0);
}
};
/**
* _sp is a user-defined literal suffix to make an appropriate Range
* specialization from a literal string.
*
* Modeled after C++17's `sv` suffix.
*/
inline namespace literals {
inline namespace string_piece_literals {
constexpr Range<char const*> operator"" _sp(
char const* str,
size_t len) noexcept {
return Range<char const*>(str, len);
}
constexpr Range<char16_t const*> operator"" _sp(
char16_t const* str,
size_t len) noexcept {
return Range<char16_t const*>(str, len);
}
constexpr Range<char32_t const*> operator"" _sp(
char32_t const* str,
size_t len) noexcept {
return Range<char32_t const*>(str, len);
}
constexpr Range<wchar_t const*> operator"" _sp(
wchar_t const* str,
size_t len) noexcept {
return Range<wchar_t const*>(str, len);
}
} // namespace string_piece_literals
} // namespace literals
} // namespace folly
FOLLY_POP_WARNING
FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(folly::Range)