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EDIT :: stringpiece.h

// © 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 <string_view> #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 = std::enable_if_t< (std::is_same_v<decltype(T().data()), const char*> #if defined(__cpp_char8_t) || std::is_same_v<decltype(T().data()), const char8_t*> #endif ) && std::is_same_v<decltype(T().size()), size_t>>> 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); #ifndef U_HIDE_INTERNAL_API /** * Converts to a std::string_view(). * @internal */ inline operator std::string_view() const { return {data(), static_cast<std::string_view::size_type>(size())}; } #endif // U_HIDE_INTERNAL_API /** * 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__

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