1f91efaea9
Change-Id: Idb0a0fc620ece33e7ed6bcec3cbd8a0a833b1e38 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/152314 Tested-by: Jenkins Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
394 lines
14 KiB
C++
394 lines
14 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#ifndef INCLUDED_RTL_STRINGCONCAT_HXX
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#define INCLUDED_RTL_STRINGCONCAT_HXX
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// This file is only included from LIBO_INTERNAL_ONLY
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#include "rtl/stringutils.hxx"
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#include "rtl/string.h"
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#include "rtl/ustring.h"
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#include <cassert>
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#include <cstddef>
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#include <memory>
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#include <string>
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#include <string_view>
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#include <type_traits>
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#include <utility>
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#include <string.h>
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#if defined RTL_STRING_UNITTEST_CONCAT
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extern bool rtl_string_unittest_invalid_concat;
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#endif
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#ifdef RTL_STRING_UNITTEST
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#define rtl rtlunittest
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#endif
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namespace rtl
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{
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#ifdef RTL_STRING_UNITTEST
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#undef rtl
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#endif
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/*
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Implementation of efficient string concatenation.
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The whole system is built around two basic template classes:
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- ToStringHelper< T > - for each T it can give the length of the resulting string representation and can write
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this string representation to a buffer
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- O(U)StringConcat< T1, T2 > - operator+ now, instead of creating O(U)String object, returns only this helper object,
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that keeps a reference to both operator+ operands; only when converted to O(U)String it will actually create
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the resulting string object using ToStringHelper, creating directly the resulting object without any string
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intermediate objects
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As all the code is inline methods, it allows for extensive optimization and will usually result in very effective code
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(even surpassing strlen/strcat and equalling handwritten), while allowing for very easy and intuitive syntax.
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*/
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/**
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@internal
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Helper class for converting a given type to a string representation.
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*/
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template< typename T >
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struct ToStringHelper
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{
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/// Return length of the string representation of the given object.
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// static std::size_t length( const T& );
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/// Add 8-bit representation of the given object to the given buffer and return position right after the added data.
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// char* operator()( char* buffer, const T& ) const SAL_RETURNS_NONNULL;
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/// Add Unicode representation of the given object to the given buffer and return position right after the added data.
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// sal_Unicode* operator()( sal_Unicode* buffer, const T& ) const SAL_RETURNS_NONNULL;
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};
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/// If true, T can be used in concatenation resulting in O(U)String.
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template<typename C, typename T, class Enable = void> constexpr bool allowStringConcat = false;
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template<typename C, typename T> constexpr bool allowStringConcat<C, T, std::enable_if_t<std::is_invocable_v<ToStringHelper<T>, C*, T>>> = true;
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template <typename C> inline
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C* addDataHelper( C* buffer, const C* data, std::size_t length )
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{
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if (length != 0) {
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memcpy( buffer, data, length * sizeof( C ));
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}
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return buffer + length;
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}
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inline
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sal_Unicode* addDataLiteral( sal_Unicode* buffer, const char* data, std::size_t length )
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{
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for( std::size_t i = 0; i != length; ++i )
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*buffer++ = *data++;
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return buffer;
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}
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template <typename C> inline
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C* addDataString( C* buffer, const C* str )
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{
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while( *str != '\0' )
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*buffer++ = *str++;
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return buffer;
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}
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template<>
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struct ToStringHelper< const char* >
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{
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static std::size_t length( const char* str ) {
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return str ? strlen( str ) : 0;
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}
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char* operator()( char* buffer, const char* str ) const {
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return str ? addDataString( buffer, str ) : buffer;
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}
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};
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template<>
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struct ToStringHelper< char* > : public ToStringHelper< const char* > {};
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template< std::size_t N >
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struct ToStringHelper< char[ N ] >
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{
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static std::size_t length( const char str[ N ] ) {
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return strlen( str );
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}
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char* operator()( char* buffer, const char str[ N ] ) const { return addDataString( buffer, str ); }
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};
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template< std::size_t N >
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struct ToStringHelper< const char[ N ] >
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{
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static std::size_t length( const char str[ N ] ) { (void)str; assert( strlen( str ) == N - 1 ); return N - 1; }
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char* operator()( char* buffer, const char str[ N ] ) const { return addDataHelper( buffer, str, N - 1 ); }
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sal_Unicode* operator()( sal_Unicode* buffer, const char str[ N ] ) const { return addDataLiteral( buffer, str, N - 1 ); }
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};
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template<>
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struct ToStringHelper<OStringChar>
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{
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static std::size_t length(OStringChar) { return 1; }
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char* operator()(char* buffer, OStringChar data) const
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{ return addDataHelper(buffer, &data.c, 1); }
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};
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template<>
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struct ToStringHelper< const sal_Unicode* >
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{
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static std::size_t length( const sal_Unicode* str ) {
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return str ? std::char_traits<char16_t>::length( str ) : 0;
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}
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sal_Unicode* operator()( sal_Unicode* buffer, const sal_Unicode* str ) const {
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return str ? addDataString( buffer, str ) : buffer;
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}
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};
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template<>
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struct ToStringHelper< sal_Unicode* > : public ToStringHelper< const sal_Unicode* > {};
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template<std::size_t N>
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struct ToStringHelper<sal_Unicode[ N ]>
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{
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static std::size_t length( const sal_Unicode str[ N ] ) {
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return std::char_traits<char16_t>::length( str );
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}
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sal_Unicode * operator()(sal_Unicode * buffer, sal_Unicode const str[N]) const
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{ return addDataHelper(buffer, str, N - 1); }
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};
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template<std::size_t N>
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struct ToStringHelper<sal_Unicode const[N]>
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{
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static std::size_t length( const sal_Unicode str[ N ] ) { (void)str; assert( std::char_traits<char16_t>::length( str ) == N - 1 ); return N - 1; }
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sal_Unicode * operator()(sal_Unicode * buffer, sal_Unicode const str[N]) const
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{ return addDataHelper(buffer, str, N - 1); }
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};
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template<>
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struct ToStringHelper<OUStringChar_>
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{
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static std::size_t length(OUStringChar_) { return 1; }
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sal_Unicode * operator()(sal_Unicode * buffer, OUStringChar_ literal) const
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{ return addDataHelper(buffer, &literal.c, 1); }
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};
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/**
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@internal
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Objects returned by operator+, instead of O(U)String. These objects (possibly recursively) keep a representation of the whole
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concatenation operation.
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If you get a build error related to this class, you most probably need to explicitly convert the result of a string
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concatenation to O(U)String.
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*/
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template <typename C, typename T1, typename T2, std::enable_if_t<allowStringConcat<C, T1> && allowStringConcat<C, T2>, int> = 0 >
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struct StringConcat
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{
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public:
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StringConcat( const T1& left_, const T2& right_ ) : left( left_ ), right( right_ ) {}
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std::size_t length() const { return ToStringHelper< T1 >::length( left ) + ToStringHelper< T2 >::length( right ); }
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C* addData( C* buffer ) const SAL_RETURNS_NONNULL { return ToStringHelper< T2 >()( ToStringHelper< T1 >()( buffer, left ), right ); }
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// NOTE here could be functions that would forward to the "real" temporary O(U)String. Note however that e.g. getStr()
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// is not so simple, as the O(U)String temporary must live long enough (i.e. can't be created here in a function, a wrapper
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// temporary object containing it must be returned instead).
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private:
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const T1& left;
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const T2& right;
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};
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template <typename C, typename T1, typename T2> struct ToStringHelper<StringConcat<C, T1, T2>>
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{
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static std::size_t length(const StringConcat<C, T1, T2 >& c) { return c.length(); }
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C* operator()(C* buffer, const StringConcat<C, T1, T2>& c) const SAL_RETURNS_NONNULL { return c.addData(buffer); }
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};
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template <typename T1, typename T2> using OStringConcat = StringConcat<char, T1, T2>;
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template <typename T1, typename T2> using OUStringConcat = StringConcat<sal_Unicode, T1, T2>;
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template< typename T1, typename T2 >
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[[nodiscard]]
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inline
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OStringConcat< T1, T2 > operator+( const T1& left, const T2& right )
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{
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return OStringConcat< T1, T2 >( left, right );
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}
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// char[N] and const char[N] need to be done explicitly, otherwise the compiler likes to treat them the same way for some reason
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template< typename T, std::size_t N >
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[[nodiscard]]
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inline
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OStringConcat< T, const char[ N ] > operator+( const T& left, const char (&right)[ N ] )
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{
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return OStringConcat< T, const char[ N ] >( left, right );
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}
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template< typename T, std::size_t N >
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[[nodiscard]]
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inline
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OStringConcat< const char[ N ], T > operator+( const char (&left)[ N ], const T& right )
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{
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return OStringConcat< const char[ N ], T >( left, right );
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}
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template< typename T, std::size_t N >
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[[nodiscard]]
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inline
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OStringConcat< T, char[ N ] > operator+( const T& left, char (&right)[ N ] )
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{
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return OStringConcat< T, char[ N ] >( left, right );
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}
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template< typename T, std::size_t N >
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[[nodiscard]]
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inline
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OStringConcat< char[ N ], T > operator+( char (&left)[ N ], const T& right )
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{
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return OStringConcat< char[ N ], T >( left, right );
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}
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template< typename T1, typename T2 >
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[[nodiscard]]
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inline
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OUStringConcat< T1, T2 > operator+( const T1& left, const T2& right )
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{
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return OUStringConcat< T1, T2 >( left, right );
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}
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template< typename T1, typename T2 >
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[[nodiscard]]
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inline
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typename std::enable_if_t< libreoffice_internal::ConstCharArrayDetector< T1, void >::ok, OUStringConcat< T1, T2 > > operator+( T1& left, const T2& right )
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{
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return OUStringConcat< T1, T2 >( left, right );
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}
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template< typename T1, typename T2 >
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[[nodiscard]]
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inline
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typename std::enable_if_t< libreoffice_internal::ConstCharArrayDetector< T2, void >::ok, OUStringConcat< T1, T2 > > operator+( const T1& left, T2& right )
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{
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return OUStringConcat< T1, T2 >( left, right );
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}
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#ifdef RTL_STRING_UNITTEST_CONCAT
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// Special overload to catch the remaining invalid combinations. The helper struct must
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// be used to make this operator+ overload a worse choice than all the existing overloads above.
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struct StringConcatInvalid
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{
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template< typename T >
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StringConcatInvalid( const T& ) {}
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};
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template< typename T >
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inline
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int operator+( const StringConcatInvalid&, const T& )
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{
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rtl_string_unittest_invalid_concat = true;
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return 0; // doesn't matter
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}
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#endif
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// Lightweight alternative to O(U)String when a (temporary) object is needed to hold
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// an O(U)StringConcat result that can then be used as a std::(u16)string_view:
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template <typename C> class StringConcatenation {
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public:
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template <class Concat>
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explicit StringConcatenation(Concat const& c):
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length_(c.length()),
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buffer_(new C[length_])
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{
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auto const end = c.addData(buffer_.get());
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assert(end == buffer_.get() + length_); (void)end;
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}
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operator std::basic_string_view<C>() const { return {buffer_.get(), length_}; }
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private:
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std::size_t length_;
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std::unique_ptr<C[]> buffer_;
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};
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template <typename C, typename T1, typename T2> auto Concat2View(StringConcat<C, T1, T2> const& c)
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{
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return StringConcatenation<C>(c);
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}
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/**
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* O(U)StringNumber implementation
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Objects returned by O(U)String::number(), instead of O(U)String. These objects keep a representation of the number() operation.
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If you get a build error related to this class, you most probably need to explicitly convert the result of calling
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O(U)String::number() to O(U)String.
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*/
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template <typename C, std::size_t nBufSize> struct StringNumber
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{
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template <typename Func, typename... Args,
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std::enable_if_t<std::is_invocable_r_v<sal_Int32, Func, C*, Args...>, int> = 0>
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StringNumber(Func func, Args... args) { length = func(buf, args...); }
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// O(U)String::number(value).getStr() is very common (writing xml code, ...),
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// so implement that one also here, to avoid having to explicitly convert
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// to O(U)String in all such places
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const C* getStr() const SAL_RETURNS_NONNULL { return buf; }
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StringNumber&& toAsciiUpperCase() &&
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{
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if constexpr (sizeof(C) == sizeof(char))
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rtl_str_toAsciiUpperCase_WithLength(buf, length);
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else
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rtl_ustr_toAsciiUpperCase_WithLength(buf, length);
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return std::move(*this);
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}
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operator std::basic_string_view<C>() const { return std::basic_string_view<C>(buf, length); }
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C buf[nBufSize];
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sal_Int32 length;
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};
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template<std::size_t nBufSize> using OStringNumber = StringNumber<char, nBufSize>;
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template<std::size_t nBufSize> using OUStringNumber = StringNumber<sal_Unicode, nBufSize>;
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template< typename C, std::size_t nBufSize >
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struct ToStringHelper< StringNumber< C, nBufSize > >
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{
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static std::size_t length( const StringNumber< C, nBufSize >& n ) { return n.length; }
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C* operator()( C* buffer, const StringNumber< C, nBufSize >& n ) const SAL_RETURNS_NONNULL { return addDataHelper( buffer, n.buf, n.length ); }
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};
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template<typename C> struct ToStringHelper<std::basic_string_view<C>> {
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static constexpr std::size_t length(std::basic_string_view<C> s) { return s.size(); }
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C * operator()(C * buffer, std::basic_string_view<C> s) const SAL_RETURNS_NONNULL
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{ return addDataHelper(buffer, s.data(), s.size()); }
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};
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// An internal marker class used by O(U)String::Concat:
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template<typename C> struct StringConcatMarker {};
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using OStringConcatMarker = StringConcatMarker<char>;
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using OUStringConcatMarker = StringConcatMarker<sal_Unicode>;
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template<typename C> constexpr bool allowStringConcat<C, StringConcatMarker<C>> = true;
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#if defined __GNUC__ && !defined __clang__
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template <typename C, typename T2>
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struct StringConcat<C, StringConcatMarker<C>, T2>
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#else
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template <typename C, typename T2, std::enable_if_t<allowStringConcat<C, T2>, int> Dummy>
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struct StringConcat<C, StringConcatMarker<C>, T2, Dummy>
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#endif
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{
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public:
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StringConcat( const T2& right_ ) : right( right_ ) {}
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std::size_t length() const { return ToStringHelper< T2 >::length( right ); }
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C* addData( C* buffer ) const SAL_RETURNS_NONNULL { return ToStringHelper< T2 >()( buffer, right ); }
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private:
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const T2& right;
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};
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} // namespace
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#endif
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