blob: e8cc2c3b238eb54503a199badbb941be4824c891 [file] [log] [blame]
/*
* Copyright (C) 2010 The Android Open Source Project
*
* 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.
*/
#ifndef ART_LIBARTBASE_BASE_STRINGPIECE_H_
#define ART_LIBARTBASE_BASE_STRINGPIECE_H_
#include <string.h>
#include <string>
#include <android-base/logging.h>
namespace art {
// A string-like object that points to a sized piece of memory.
//
// Functions or methods may use const StringPiece& parameters to accept either
// a "const char*" or a "string" value that will be implicitly converted to
// a StringPiece. The implicit conversion means that it is often appropriate
// to include this .h file in other files rather than forward-declaring
// StringPiece as would be appropriate for most other Google classes.
class StringPiece {
public:
// 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 constexpr size_type npos = size_type(-1);
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;
// We provide non-explicit singleton constructors so users can pass
// in a "const char*" or a "string" wherever a "StringPiece" is
// expected.
StringPiece() : ptr_(nullptr), length_(0) { }
StringPiece(const char* str) // NOLINT implicit constructor desired
: ptr_(str), length_((str == nullptr) ? 0 : strlen(str)) { }
StringPiece(const std::string& str) // NOLINT implicit constructor desired
: ptr_(str.data()), length_(str.size()) { }
StringPiece(const char* offset, size_t len) : ptr_(offset), length_(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_; }
size_type size() const { return length_; }
size_type length() const { return length_; }
bool empty() const { return length_ == 0; }
void clear() {
ptr_ = nullptr;
length_ = 0;
}
void set(const char* data_in, size_type len) {
ptr_ = data_in;
length_ = len;
}
void set(const char* str) {
ptr_ = str;
if (str != nullptr) {
length_ = strlen(str);
} else {
length_ = 0;
}
}
void set(const void* data_in, size_type len) {
ptr_ = reinterpret_cast<const char*>(data_in);
length_ = len;
}
char operator[](size_type i) const {
DCHECK_LT(i, length_);
return ptr_[i];
}
void remove_prefix(size_type n) {
ptr_ += n;
length_ -= n;
}
void remove_suffix(size_type n) {
length_ -= n;
}
int compare(const StringPiece& x) const {
int r = memcmp(ptr_, x.ptr_, std::min(length_, x.length_));
if (r == 0) {
if (length_ < x.length_) r = -1;
else if (length_ > x.length_) r = +1;
}
return r;
}
std::string as_string() const {
return std::string(data(), size());
}
// 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.
std::string ToString() const {
return std::string(data(), size());
}
void CopyToString(std::string* target) const {
target->assign(ptr_, length_);
}
void AppendToString(std::string* target) const;
// Does "this" start with "x"
bool starts_with(const StringPiece& x) const {
return ((length_ >= x.length_) &&
(memcmp(ptr_, x.ptr_, x.length_) == 0));
}
// Does "this" end with "x"
bool ends_with(const StringPiece& x) const {
return ((length_ >= x.length_) &&
(memcmp(ptr_ + (length_-x.length_), x.ptr_, x.length_) == 0));
}
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_);
}
size_type copy(char* buf, size_type n, size_type pos = 0) const {
size_type ret = std::min(length_ - pos, n);
memcpy(buf, ptr_ + pos, ret);
return ret;
}
size_type find(const StringPiece& s, size_type pos = 0) const {
if (length_ == 0 || pos > static_cast<size_type>(length_)) {
return npos;
}
const char* result = std::search(ptr_ + pos, ptr_ + length_, s.ptr_, s.ptr_ + s.length_);
const size_type xpos = result - ptr_;
return xpos + s.length_ <= length_ ? xpos : npos;
}
size_type find(char c, size_type pos = 0) const {
if (length_ == 0 || pos >= length_) {
return npos;
}
const char* result = std::find(ptr_ + pos, ptr_ + length_, c);
return result != ptr_ + length_ ? result - ptr_ : npos;
}
size_type rfind(const StringPiece& s, size_type pos = npos) const {
if (length_ < s.length_) return npos;
const size_t ulen = length_;
if (s.length_ == 0) return std::min(ulen, pos);
const char* last = ptr_ + std::min(ulen - s.length_, pos) + s.length_;
const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_);
return result != last ? result - ptr_ : npos;
}
size_type rfind(char c, size_type pos = npos) const {
if (length_ == 0) return npos;
for (int i = std::min(pos, static_cast<size_type>(length_ - 1));
i >= 0; --i) {
if (ptr_[i] == c) {
return i;
}
}
return npos;
}
StringPiece substr(size_type pos, size_type n = npos) const {
if (pos > static_cast<size_type>(length_)) pos = length_;
if (n > length_ - pos) n = length_ - pos;
return StringPiece(ptr_ + pos, n);
}
int Compare(const StringPiece& rhs) const {
const int r = memcmp(data(), rhs.data(), std::min(size(), rhs.size()));
if (r != 0) {
return r;
}
if (size() < rhs.size()) {
return -1;
} else if (size() > rhs.size()) {
return 1;
}
return 0;
}
private:
// Pointer to char data, not necessarily zero terminated.
const char* ptr_;
// Length of data.
size_type length_;
};
// 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==(const StringPiece& x, const StringPiece& y) {
StringPiece::size_type len = x.size();
if (len != y.size()) {
return false;
}
const char* p1 = x.data();
const char* p2 = y.data();
if (p1 == p2) {
return true;
}
if (len == 0) {
return true;
}
// Test last byte in case strings share large common prefix
if (p1[len-1] != p2[len-1]) return false;
if (len == 1) return true;
// At this point we can, but don't have to, ignore the last byte. We use
// this observation to fold the odd-length case into the even-length case.
len &= ~1;
return memcmp(p1, p2, len) == 0;
}
inline bool operator==(const StringPiece& x, const char* y) {
if (y == nullptr) {
return x.size() == 0;
} else {
return strncmp(x.data(), y, x.size()) == 0 && y[x.size()] == '\0';
}
}
inline bool operator!=(const StringPiece& x, const StringPiece& y) {
return !(x == y);
}
inline bool operator!=(const StringPiece& x, const char* y) {
return !(x == y);
}
inline bool operator<(const StringPiece& x, const StringPiece& y) {
return x.Compare(y) < 0;
}
inline bool operator>(const StringPiece& x, const StringPiece& y) {
return y < x;
}
inline bool operator<=(const StringPiece& x, const StringPiece& y) {
return !(x > y);
}
inline bool operator>=(const StringPiece& x, const StringPiece& y) {
return !(x < y);
}
inline std::ostream& operator<<(std::ostream& o, const StringPiece& piece) {
o.write(piece.data(), piece.size());
return o;
}
} // namespace art
#endif // ART_LIBARTBASE_BASE_STRINGPIECE_H_