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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// A StringPiece points to part or all of a string, Cord, double-quoted string
// literal, or other string-like object. A StringPiece does *not* own the
// string to which it points. A StringPiece is not null-terminated.
//
// You can use StringPiece as a function or method parameter. A StringPiece
// parameter can receive a double-quoted string literal argument, a "const
// char*" argument, a string argument, or a StringPiece argument with no data
// copying. Systematic use of StringPiece for arguments reduces data
// copies and strlen() calls.
//
// Prefer passing StringPieces by value:
// void MyFunction(StringPiece arg);
// If circumstances require, you may also pass by const reference:
// void MyFunction(const StringPiece& arg); // not preferred
// Both of these have the same lifetime semantics. Passing by value
// generates slightly smaller code. For more discussion, see the thread
// go/stringpiecebyvalue on c-users.
//
// StringPiece is also suitable for local variables if you know that
// the lifetime of the underlying object is longer than the lifetime
// of your StringPiece variable.
//
// Beware of binding a StringPiece to a temporary:
// StringPiece sp = obj.MethodReturningString(); // BAD: lifetime problem
//
// This code is okay:
// string str = obj.MethodReturningString(); // str owns its contents
// StringPiece sp(str); // GOOD, because str outlives sp
//
// StringPiece is sometimes a poor choice for a return value and usually a poor
// choice for a data member. If you do use a StringPiece this way, it is your
// responsibility to ensure that the object pointed to by the StringPiece
// outlives the StringPiece.
//
// A StringPiece may represent just part of a string; thus the name "Piece".
// For example, when splitting a string, vector<StringPiece> is a natural data
// type for the output. For another example, a Cord is a non-contiguous,
// potentially very long string-like object. The Cord class has an interface
// that iteratively provides StringPiece objects that point to the
// successive pieces of a Cord object.
//
// A StringPiece is not null-terminated. If you write code that scans a
// StringPiece, you must check its length before reading any characters.
// Common idioms that work on null-terminated strings do not work on
// StringPiece objects.
//
// There are several ways to create a null StringPiece:
// StringPiece()
// StringPiece(NULL)
// StringPiece(NULL, 0)
// For all of the above, sp.data() == NULL, sp.length() == 0,
// and sp.empty() == true. Also, if you create a StringPiece with
// a non-NULL pointer then sp.data() != NULL. Once created,
// sp.data() will stay either NULL or not-NULL, except if you call
// sp.clear() or sp.set().
//
// Thus, you can use StringPiece(NULL) to signal an out-of-band value
// that is different from other StringPiece values. This is similar
// to the way that const char* p1 = NULL; is different from
// const char* p2 = "";.
//
// There are many ways to create an empty StringPiece:
// StringPiece()
// StringPiece(NULL)
// StringPiece(NULL, 0)
// StringPiece("")
// StringPiece("", 0)
// StringPiece("abcdef", 0)
// StringPiece("abcdef"+6, 0)
// For all of the above, sp.length() will be 0 and sp.empty() will be true.
// For some empty StringPiece values, sp.data() will be NULL.
// For some empty StringPiece values, sp.data() will not be NULL.
//
// Be careful not to confuse: null StringPiece and empty StringPiece.
// The set of empty StringPieces properly includes the set of null StringPieces.
// That is, every null StringPiece is an empty StringPiece,
// but some non-null StringPieces are empty Stringpieces too.
//
// All empty StringPiece values compare equal to each other.
// Even a null StringPieces compares equal to a non-null empty StringPiece:
// StringPiece() == StringPiece("", 0)
// StringPiece(NULL) == StringPiece("abc", 0)
// StringPiece(NULL, 0) == StringPiece("abcdef"+6, 0)
//
// Look carefully at this example:
// StringPiece("") == NULL
// True or false? TRUE, because StringPiece::operator== converts
// the right-hand side from NULL to StringPiece(NULL),
// and then compares two zero-length spans of characters.
// However, we are working to make this example produce a compile error.
//
// Suppose you want to write:
// bool TestWhat?(StringPiece sp) { return sp == NULL; } // BAD
// Do not do that. Write one of these instead:
// bool TestNull(StringPiece sp) { return sp.data() == NULL; }
// bool TestEmpty(StringPiece sp) { return sp.empty(); }
// The intent of TestWhat? is unclear. Did you mean TestNull or TestEmpty?
// Right now, TestWhat? behaves likes TestEmpty.
// We are working to make TestWhat? produce a compile error.
// TestNull is good to test for an out-of-band signal.
// TestEmpty is good to test for an empty StringPiece.
//
// Caveats (again):
// (1) The lifetime of the pointed-to string (or piece of a string)
// must be longer than the lifetime of the StringPiece.
// (2) There may or may not be a '\0' character after the end of
// StringPiece data.
// (3) A null StringPiece is empty.
// An empty StringPiece may or may not be a null StringPiece.
#ifndef GOOGLE_PROTOBUF_STUBS_STRINGPIECE_H_
#define GOOGLE_PROTOBUF_STUBS_STRINGPIECE_H_
#include <assert.h>
#include <stddef.h>
#include <string.h>
#include <iosfwd>
#include <limits>
#include <string>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/stubs/hash.h>
namespace google {
namespace protobuf {
// StringPiece has *two* size types.
// StringPiece::size_type
// is unsigned
// is 32 bits in LP32, 64 bits in LP64, 64 bits in LLP64
// no future changes intended
// stringpiece_ssize_type
// is signed
// is 32 bits in LP32, 64 bits in LP64, 64 bits in LLP64
// future changes intended: http://go/64BitStringPiece
//
typedef string::difference_type stringpiece_ssize_type;
// STRINGPIECE_CHECK_SIZE protects us from 32-bit overflows.
// TODO(mec): delete this after stringpiece_ssize_type goes 64 bit.
#if !defined(NDEBUG)
#define STRINGPIECE_CHECK_SIZE 1
#elif defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0
#define STRINGPIECE_CHECK_SIZE 1
#else
#define STRINGPIECE_CHECK_SIZE 0
#endif
class LIBPROTOBUF_EXPORT StringPiece {
private:
const char* ptr_;
stringpiece_ssize_type length_;
// Prevent overflow in debug mode or fortified mode.
// sizeof(stringpiece_ssize_type) may be smaller than sizeof(size_t).
static stringpiece_ssize_type CheckedSsizeTFromSizeT(size_t size) {
#if STRINGPIECE_CHECK_SIZE > 0
#ifdef max
#undef max
#endif
if (size > static_cast<size_t>(
std::numeric_limits<stringpiece_ssize_type>::max())) {
// Some people grep for this message in logs
// so take care if you ever change it.
LogFatalSizeTooBig(size, "size_t to int conversion");
}
#endif
return static_cast<stringpiece_ssize_type>(size);
}
// Out-of-line error path.
static void LogFatalSizeTooBig(size_t size, const char* details);
public:
// We provide non-explicit singleton constructors so users can pass
// in a "const char*" or a "string" wherever a "StringPiece" is
// expected.
//
// Style guide exception granted:
// http://goto/style-guide-exception-20978288
StringPiece() : ptr_(NULL), length_(0) {}
StringPiece(const char* str) // NOLINT(runtime/explicit)
: ptr_(str), length_(0) {
if (str != NULL) {
length_ = CheckedSsizeTFromSizeT(strlen(str));
}
}
template <class Allocator>
StringPiece( // NOLINT(runtime/explicit)
const std::basic_string<char, std::char_traits<char>, Allocator>& str)
: ptr_(str.data()), length_(0) {
length_ = CheckedSsizeTFromSizeT(str.size());
}
#if defined(HAS_GLOBAL_STRING)
template <class Allocator>
StringPiece( // NOLINT(runtime/explicit)
const basic_string<char, std::char_traits<char>, Allocator>& str)
: ptr_(str.data()), length_(0) {
length_ = CheckedSsizeTFromSizeT(str.size());
}
#endif
StringPiece(const char* offset, stringpiece_ssize_type len)
: ptr_(offset), length_(len) {
assert(len >= 0);
}
// Substring of another StringPiece.
// pos must be non-negative and <= x.length().
StringPiece(StringPiece x, stringpiece_ssize_type pos);
// Substring of another StringPiece.
// pos must be non-negative and <= x.length().
// len must be non-negative and will be pinned to at most x.length() - pos.
StringPiece(StringPiece x,
stringpiece_ssize_type pos,
stringpiece_ssize_type len);
// data() may return a pointer to a buffer with embedded NULs, and the
// returned buffer may or may not be null terminated. Therefore it is
// typically a mistake to pass data() to a routine that expects a NUL
// terminated string.
const char* data() const { return ptr_; }
stringpiece_ssize_type size() const { return length_; }
stringpiece_ssize_type length() const { return length_; }
bool empty() const { return length_ == 0; }
void clear() {
ptr_ = NULL;
length_ = 0;
}
void set(const char* data, stringpiece_ssize_type len) {
assert(len >= 0);
ptr_ = data;
length_ = len;
}
void set(const char* str) {
ptr_ = str;
if (str != NULL)
length_ = CheckedSsizeTFromSizeT(strlen(str));
else
length_ = 0;
}
void set(const void* data, stringpiece_ssize_type len) {
ptr_ = reinterpret_cast<const char*>(data);
length_ = len;
}
char operator[](stringpiece_ssize_type i) const {
assert(0 <= i);
assert(i < length_);
return ptr_[i];
}
void remove_prefix(stringpiece_ssize_type n) {
assert(length_ >= n);
ptr_ += n;
length_ -= n;
}
void remove_suffix(stringpiece_ssize_type n) {
assert(length_ >= n);
length_ -= n;
}
// returns {-1, 0, 1}
int compare(StringPiece x) const {
const stringpiece_ssize_type min_size =
length_ < x.length_ ? length_ : x.length_;
int r = memcmp(ptr_, x.ptr_, min_size);
if (r < 0) return -1;
if (r > 0) return 1;
if (length_ < x.length_) return -1;
if (length_ > x.length_) return 1;
return 0;
}
string as_string() const {
return ToString();
}
// We also define ToString() here, since many other string-like
// interfaces name the routine that converts to a C++ string
// "ToString", and it's confusing to have the method that does that
// for a StringPiece be called "as_string()". We also leave the
// "as_string()" method defined here for existing code.
string ToString() const {
if (ptr_ == NULL) return string();
return string(data(), size());
}
operator string() const {
return ToString();
}
void CopyToString(string* target) const;
void AppendToString(string* target) const;
bool starts_with(StringPiece x) const {
return (length_ >= x.length_) && (memcmp(ptr_, x.ptr_, x.length_) == 0);
}
bool ends_with(StringPiece x) const {
return ((length_ >= x.length_) &&
(memcmp(ptr_ + (length_-x.length_), x.ptr_, x.length_) == 0));
}
// Checks whether StringPiece starts with x and if so advances the beginning
// of it to past the match. It's basically a shortcut for starts_with
// followed by remove_prefix.
bool Consume(StringPiece x);
// Like above but for the end of the string.
bool ConsumeFromEnd(StringPiece x);
// standard STL container boilerplate
typedef char value_type;
typedef const char* pointer;
typedef const char& reference;
typedef const char& const_reference;
typedef size_t size_type;
typedef ptrdiff_t difference_type;
static const size_type npos;
typedef const char* const_iterator;
typedef const char* iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
typedef std::reverse_iterator<iterator> reverse_iterator;
iterator begin() const { return ptr_; }
iterator end() const { return ptr_ + length_; }
const_reverse_iterator rbegin() const {
return const_reverse_iterator(ptr_ + length_);
}
const_reverse_iterator rend() const {
return const_reverse_iterator(ptr_);
}
stringpiece_ssize_type max_size() const { return length_; }
stringpiece_ssize_type capacity() const { return length_; }
// cpplint.py emits a false positive [build/include_what_you_use]
stringpiece_ssize_type copy(char* buf, size_type n, size_type pos = 0) const; // NOLINT
bool contains(StringPiece s) const;
stringpiece_ssize_type find(StringPiece s, size_type pos = 0) const;
stringpiece_ssize_type find(char c, size_type pos = 0) const;
stringpiece_ssize_type rfind(StringPiece s, size_type pos = npos) const;
stringpiece_ssize_type rfind(char c, size_type pos = npos) const;
stringpiece_ssize_type find_first_of(StringPiece s, size_type pos = 0) const;
stringpiece_ssize_type find_first_of(char c, size_type pos = 0) const {
return find(c, pos);
}
stringpiece_ssize_type find_first_not_of(StringPiece s,
size_type pos = 0) const;
stringpiece_ssize_type find_first_not_of(char c, size_type pos = 0) const;
stringpiece_ssize_type find_last_of(StringPiece s,
size_type pos = npos) const;
stringpiece_ssize_type find_last_of(char c, size_type pos = npos) const {
return rfind(c, pos);
}
stringpiece_ssize_type find_last_not_of(StringPiece s,
size_type pos = npos) const;
stringpiece_ssize_type find_last_not_of(char c, size_type pos = npos) const;
StringPiece substr(size_type pos, size_type n = npos) const;
};
// This large function is defined inline so that in a fairly common case where
// one of the arguments is a literal, the compiler can elide a lot of the
// following comparisons.
inline bool operator==(StringPiece x, StringPiece y) {
stringpiece_ssize_type len = x.size();
if (len != y.size()) {
return false;
}
return x.data() == y.data() || len <= 0 ||
memcmp(x.data(), y.data(), len) == 0;
}
inline bool operator!=(StringPiece x, StringPiece y) {
return !(x == y);
}
inline bool operator<(StringPiece x, StringPiece y) {
const stringpiece_ssize_type min_size =
x.size() < y.size() ? x.size() : y.size();
const int r = memcmp(x.data(), y.data(), min_size);
return (r < 0) || (r == 0 && x.size() < y.size());
}
inline bool operator>(StringPiece x, StringPiece y) {
return y < x;
}
inline bool operator<=(StringPiece x, StringPiece y) {
return !(x > y);
}
inline bool operator>=(StringPiece x, StringPiece y) {
return !(x < y);
}
// allow StringPiece to be logged
extern std::ostream& operator<<(std::ostream& o, StringPiece piece);
namespace internal {
// StringPiece is not a POD and can not be used in an union (pre C++11). We
// need a POD version of it.
struct StringPiecePod {
// Create from a StringPiece.
static StringPiecePod CreateFromStringPiece(StringPiece str) {
StringPiecePod pod;
pod.data_ = str.data();
pod.size_ = str.size();
return pod;
}
// Cast to StringPiece.
operator StringPiece() const { return StringPiece(data_, size_); }
bool operator==(const char* value) const {
return StringPiece(data_, size_) == StringPiece(value);
}
char operator[](stringpiece_ssize_type i) const {
assert(0 <= i);
assert(i < size_);
return data_[i];
}
const char* data() const { return data_; }
stringpiece_ssize_type size() const {
return size_;
}
std::string ToString() const { return std::string(data_, size_); }
private:
const char* data_;
stringpiece_ssize_type size_;
};
} // namespace internal
} // namespace protobuf
} // namespace google
GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_START
template<> struct hash<StringPiece> {
size_t operator()(const StringPiece& s) const {
size_t result = 0;
for (const char *str = s.data(), *end = str + s.size(); str < end; str++) {
result = 5 * result + *str;
}
return result;
}
};
GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_END
#endif // STRINGS_STRINGPIECE_H_