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// © 2016 and later: Unicode, Inc. and others.
// Copyright (C) 2009-2013, International Business Machines
// Corporation and others. All Rights Reserved.
//
// Copyright 2001 and onwards Google Inc.
// Author: Sanjay Ghemawat
// This code is a contribution of Google code, and the style used here is
// a compromise between the original Google code and the ICU coding guidelines.
// For example, data types are ICU-ified (size_t,int->int32_t),
// and API comments doxygen-ified, but function names and behavior are
// as in the original, if possible.
// Assertion-style error handling, not available in ICU, was changed to
// parameter "pinning" similar to UnicodeString.
//
// In addition, this is only a partial port of the original Google code,
// limited to what was needed so far. The (nearly) complete original code
// is in the ICU svn repository at icuhtml/trunk/design/strings/contrib
// (see ICU ticket 6765, r25517).
#ifndef __STRINGPIECE_H__
#define __STRINGPIECE_H__
/**
* \file
* \brief C++ API: StringPiece: Read-only byte string wrapper class.
*/
#include "unicode/utypes.h"
#if U_SHOW_CPLUSPLUS_API
#include <cstddef>
#include <type_traits>
#include "unicode/uobject.h"
#include "unicode/std_string.h"
// Arghh! I wish C++ literals were "string".
U_NAMESPACE_BEGIN
/**
* A string-like object that points to a sized piece of memory.
*
* We provide non-explicit singleton constructors so users can pass
* in a "const char*" or a "string" wherever a "StringPiece" is
* expected.
*
* Functions or methods may use StringPiece parameters to accept either a
* "const char*" or a "string" value that will be implicitly converted to a
* StringPiece.
*
* Systematic usage of StringPiece is encouraged as it will reduce unnecessary
* conversions from "const char*" to "string" and back again.
*
* @stable ICU 4.2
*/
class U_COMMON_API StringPiece : public UMemory {
private:
const char* ptr_;
int32_t length_;
public:
/**
* Default constructor, creates an empty StringPiece.
* @stable ICU 4.2
*/
StringPiece() : ptr_(nullptr), length_(0) { }
/**
* Constructs from a NUL-terminated const char * pointer.
* @param str a NUL-terminated const char * pointer
* @stable ICU 4.2
*/
StringPiece(const char* str);
#if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN)
/**
* Constructs from a NUL-terminated const char8_t * pointer.
* @param str a NUL-terminated const char8_t * pointer
* @stable ICU 67
*/
StringPiece(const char8_t* str) : StringPiece(reinterpret_cast<const char*>(str)) {}
#endif
/**
* Constructs an empty StringPiece.
* Needed for type disambiguation from multiple other overloads.
* @param p nullptr
* @stable ICU 67
*/
StringPiece(std::nullptr_t p) : ptr_(p), length_(0) {}
/**
* Constructs from a std::string.
* @stable ICU 4.2
*/
StringPiece(const std::string& str)
: ptr_(str.data()), length_(static_cast<int32_t>(str.size())) { }
#if defined(__cpp_lib_char8_t) || defined(U_IN_DOXYGEN)
/**
* Constructs from a std::u8string.
* @stable ICU 67
*/
StringPiece(const std::u8string& str)
: ptr_(reinterpret_cast<const char*>(str.data())),
length_(static_cast<int32_t>(str.size())) { }
#endif
/**
* Constructs from some other implementation of a string piece class, from any
* C++ record type that has these two methods:
*
* \code{.cpp}
*
* struct OtherStringPieceClass {
* const char* data(); // or const char8_t*
* size_t size();
* };
*
* \endcode
*
* The other string piece class will typically be std::string_view from C++17
* or absl::string_view from Abseil.
*
* Starting with C++20, data() may also return a const char8_t* pointer,
* as from std::u8string_view.
*
* @param str the other string piece
* @stable ICU 65
*/
template <typename T,
typename = typename std::enable_if<
(std::is_same<decltype(T().data()), const char*>::value
#if defined(__cpp_char8_t)
|| std::is_same<decltype(T().data()), const char8_t*>::value
#endif
) &&
std::is_same<decltype(T().size()), size_t>::value>::type>
StringPiece(T str)
: ptr_(reinterpret_cast<const char*>(str.data())),
length_(static_cast<int32_t>(str.size())) {}
/**
* Constructs from a const char * pointer and a specified length.
* @param offset a const char * pointer (need not be terminated)
* @param len the length of the string; must be non-negative
* @stable ICU 4.2
*/
StringPiece(const char* offset, int32_t len) : ptr_(offset), length_(len) { }
#if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN)
/**
* Constructs from a const char8_t * pointer and a specified length.
* @param str a const char8_t * pointer (need not be terminated)
* @param len the length of the string; must be non-negative
* @stable ICU 67
*/
StringPiece(const char8_t* str, int32_t len) :
StringPiece(reinterpret_cast<const char*>(str), len) {}
#endif
/**
* Substring of another StringPiece.
* @param x the other StringPiece
* @param pos start position in x; must be non-negative and <= x.length().
* @stable ICU 4.2
*/
StringPiece(const StringPiece& x, int32_t pos);
/**
* Substring of another StringPiece.
* @param x the other StringPiece
* @param pos start position in x; must be non-negative and <= x.length().
* @param len length of the substring;
* must be non-negative and will be pinned to at most x.length() - pos.
* @stable ICU 4.2
*/
StringPiece(const StringPiece& x, int32_t pos, int32_t len);
/**
* Returns the string pointer. May be nullptr if it is empty.
*
* 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.
* @return the string pointer
* @stable ICU 4.2
*/
const char* data() const { return ptr_; }
/**
* Returns the string length. Same as length().
* @return the string length
* @stable ICU 4.2
*/
int32_t size() const { return length_; }
/**
* Returns the string length. Same as size().
* @return the string length
* @stable ICU 4.2
*/
int32_t length() const { return length_; }
/**
* Returns whether the string is empty.
* @return true if the string is empty
* @stable ICU 4.2
*/
UBool empty() const { return length_ == 0; }
/**
* Sets to an empty string.
* @stable ICU 4.2
*/
void clear() { ptr_ = nullptr; length_ = 0; }
/**
* Reset the stringpiece to refer to new data.
* @param xdata pointer the new string data. Need not be nul terminated.
* @param len the length of the new data
* @stable ICU 4.8
*/
void set(const char* xdata, int32_t len) { ptr_ = xdata; length_ = len; }
/**
* Reset the stringpiece to refer to new data.
* @param str a pointer to a NUL-terminated string.
* @stable ICU 4.8
*/
void set(const char* str);
#if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN)
/**
* Resets the stringpiece to refer to new data.
* @param xdata pointer the new string data. Need not be NUL-terminated.
* @param len the length of the new data
* @stable ICU 67
*/
inline void set(const char8_t* xdata, int32_t len) {
set(reinterpret_cast<const char*>(xdata), len);
}
/**
* Resets the stringpiece to refer to new data.
* @param str a pointer to a NUL-terminated string.
* @stable ICU 67
*/
inline void set(const char8_t* str) {
set(reinterpret_cast<const char*>(str));
}
#endif
/**
* Removes the first n string units.
* @param n prefix length, must be non-negative and <=length()
* @stable ICU 4.2
*/
void remove_prefix(int32_t n) {
if (n >= 0) {
if (n > length_) {
n = length_;
}
ptr_ += n;
length_ -= n;
}
}
/**
* Removes the last n string units.
* @param n suffix length, must be non-negative and <=length()
* @stable ICU 4.2
*/
void remove_suffix(int32_t n) {
if (n >= 0) {
if (n <= length_) {
length_ -= n;
} else {
length_ = 0;
}
}
}
/**
* Searches the StringPiece for the given search string (needle);
* @param needle The string for which to search.
* @param offset Where to start searching within this string (haystack).
* @return The offset of needle in haystack, or -1 if not found.
* @stable ICU 67
*/
int32_t find(StringPiece needle, int32_t offset);
/**
* Compares this StringPiece with the other StringPiece, with semantics
* similar to std::string::compare().
* @param other The string to compare to.
* @return below zero if this < other; above zero if this > other; 0 if this == other.
* @stable ICU 67
*/
int32_t compare(StringPiece other);
/**
* Maximum integer, used as a default value for substring methods.
* @stable ICU 4.2
*/
static const int32_t npos; // = 0x7fffffff;
/**
* Returns a substring of this StringPiece.
* @param pos start position; must be non-negative and <= length().
* @param len length of the substring;
* must be non-negative and will be pinned to at most length() - pos.
* @return the substring StringPiece
* @stable ICU 4.2
*/
StringPiece substr(int32_t pos, int32_t len = npos) const {
return StringPiece(*this, pos, len);
}
};
/**
* Global operator == for StringPiece
* @param x The first StringPiece to compare.
* @param y The second StringPiece to compare.
* @return true if the string data is equal
* @stable ICU 4.8
*/
U_EXPORT UBool U_EXPORT2
operator==(const StringPiece& x, const StringPiece& y);
/**
* Global operator != for StringPiece
* @param x The first StringPiece to compare.
* @param y The second StringPiece to compare.
* @return true if the string data is not equal
* @stable ICU 4.8
*/
inline bool operator!=(const StringPiece& x, const StringPiece& y) {
return !(x == y);
}
U_NAMESPACE_END
#endif /* U_SHOW_CPLUSPLUS_API */
#endif // __STRINGPIECE_H__