343 lines
10 KiB
C++
343 lines
10 KiB
C++
// © 2016 and later: Unicode, Inc. and others.
|
|
// License & terms of use: http://www.unicode.org/copyright.html
|
|
// 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 UBool operator!=(const StringPiece& x, const StringPiece& y) {
|
|
return !(x == y);
|
|
}
|
|
|
|
U_NAMESPACE_END
|
|
|
|
#endif /* U_SHOW_CPLUSPLUS_API */
|
|
|
|
#endif // __STRINGPIECE_H__
|