236 lines
7 KiB
C++
236 lines
7 KiB
C++
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_RUNTIME_BASE_STRINGPIECE_H_
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#define ART_RUNTIME_BASE_STRINGPIECE_H_
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#include <string.h>
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#include <string>
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namespace art {
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// A string-like object that points to a sized piece of memory.
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//
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// Functions or methods may use const StringPiece& parameters to accept either
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// a "const char*" or a "string" value that will be implicitly converted to
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// a StringPiece. The implicit conversion means that it is often appropriate
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// to include this .h file in other files rather than forward-declaring
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// StringPiece as would be appropriate for most other Google classes.
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class StringPiece {
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public:
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// standard STL container boilerplate
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typedef char value_type;
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typedef const char* pointer;
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typedef const char& reference;
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typedef const char& const_reference;
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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static constexpr size_type npos = size_type(-1);
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typedef const char* const_iterator;
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typedef const char* iterator;
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typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
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typedef std::reverse_iterator<iterator> reverse_iterator;
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// We provide non-explicit singleton constructors so users can pass
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// in a "const char*" or a "string" wherever a "StringPiece" is
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// expected.
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StringPiece() : ptr_(nullptr), length_(0) { }
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StringPiece(const char* str) // NOLINT implicit constructor desired
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: ptr_(str), length_((str == nullptr) ? 0 : strlen(str)) { }
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StringPiece(const std::string& str) // NOLINT implicit constructor desired
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: ptr_(str.data()), length_(str.size()) { }
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StringPiece(const char* offset, size_t len) : ptr_(offset), length_(len) { }
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// data() may return a pointer to a buffer with embedded NULs, and the
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// returned buffer may or may not be null terminated. Therefore it is
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// typically a mistake to pass data() to a routine that expects a NUL
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// terminated string.
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const char* data() const { return ptr_; }
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size_type size() const { return length_; }
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size_type length() const { return length_; }
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bool empty() const { return length_ == 0; }
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void clear() {
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ptr_ = nullptr;
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length_ = 0;
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}
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void set(const char* data_in, size_type len) {
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ptr_ = data_in;
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length_ = len;
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}
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void set(const char* str) {
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ptr_ = str;
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if (str != nullptr) {
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length_ = strlen(str);
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} else {
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length_ = 0;
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}
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}
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void set(const void* data_in, size_type len) {
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ptr_ = reinterpret_cast<const char*>(data_in);
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length_ = len;
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}
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#if defined(NDEBUG)
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char operator[](size_type i) const {
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return ptr_[i];
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}
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#else
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char operator[](size_type i) const;
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#endif
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void remove_prefix(size_type n) {
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ptr_ += n;
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length_ -= n;
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}
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void remove_suffix(size_type n) {
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length_ -= n;
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}
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int compare(const StringPiece& x) const;
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std::string as_string() const {
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return std::string(data(), size());
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}
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// We also define ToString() here, since many other string-like
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// interfaces name the routine that converts to a C++ string
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// "ToString", and it's confusing to have the method that does that
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// for a StringPiece be called "as_string()". We also leave the
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// "as_string()" method defined here for existing code.
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std::string ToString() const {
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return std::string(data(), size());
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}
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void CopyToString(std::string* target) const;
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void AppendToString(std::string* target) const;
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// Does "this" start with "x"
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bool starts_with(const StringPiece& x) const {
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return ((length_ >= x.length_) &&
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(memcmp(ptr_, x.ptr_, x.length_) == 0));
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}
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// Does "this" end with "x"
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bool ends_with(const StringPiece& x) const {
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return ((length_ >= x.length_) &&
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(memcmp(ptr_ + (length_-x.length_), x.ptr_, x.length_) == 0));
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}
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iterator begin() const { return ptr_; }
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iterator end() const { return ptr_ + length_; }
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const_reverse_iterator rbegin() const {
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return const_reverse_iterator(ptr_ + length_);
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}
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const_reverse_iterator rend() const {
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return const_reverse_iterator(ptr_);
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}
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size_type copy(char* buf, size_type n, size_type pos = 0) const;
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size_type find(const StringPiece& s, size_type pos = 0) const;
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size_type find(char c, size_type pos = 0) const;
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size_type rfind(const StringPiece& s, size_type pos = npos) const;
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size_type rfind(char c, size_type pos = npos) const;
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StringPiece substr(size_type pos, size_type n = npos) const;
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int Compare(const StringPiece& rhs) const {
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const int r = memcmp(data(), rhs.data(), std::min(size(), rhs.size()));
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if (r != 0) {
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return r;
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}
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if (size() < rhs.size()) {
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return -1;
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} else if (size() > rhs.size()) {
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return 1;
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}
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return 0;
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}
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private:
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// Pointer to char data, not necessarily zero terminated.
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const char* ptr_;
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// Length of data.
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size_type length_;
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};
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// This large function is defined inline so that in a fairly common case where
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// one of the arguments is a literal, the compiler can elide a lot of the
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// following comparisons.
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inline bool operator==(const StringPiece& x, const StringPiece& y) {
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StringPiece::size_type len = x.size();
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if (len != y.size()) {
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return false;
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}
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const char* p1 = x.data();
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const char* p2 = y.data();
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if (p1 == p2) {
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return true;
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}
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if (len == 0) {
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return true;
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}
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// Test last byte in case strings share large common prefix
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if (p1[len-1] != p2[len-1]) return false;
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if (len == 1) return true;
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// At this point we can, but don't have to, ignore the last byte. We use
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// this observation to fold the odd-length case into the even-length case.
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len &= ~1;
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return memcmp(p1, p2, len) == 0;
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}
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inline bool operator==(const StringPiece& x, const char* y) {
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if (y == nullptr) {
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return x.size() == 0;
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} else {
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return strncmp(x.data(), y, x.size()) == 0 && y[x.size()] == '\0';
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}
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}
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inline bool operator!=(const StringPiece& x, const StringPiece& y) {
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return !(x == y);
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}
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inline bool operator!=(const StringPiece& x, const char* y) {
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return !(x == y);
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}
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inline bool operator<(const StringPiece& x, const StringPiece& y) {
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return x.Compare(y) < 0;
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}
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inline bool operator>(const StringPiece& x, const StringPiece& y) {
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return y < x;
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}
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inline bool operator<=(const StringPiece& x, const StringPiece& y) {
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return !(x > y);
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}
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inline bool operator>=(const StringPiece& x, const StringPiece& y) {
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return !(x < y);
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}
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extern std::ostream& operator<<(std::ostream& o, const StringPiece& piece);
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} // namespace art
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#endif // ART_RUNTIME_BASE_STRINGPIECE_H_
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