From 8f10fdf27eef4653821be60bff1f5ef62febf6d3 Mon Sep 17 00:00:00 2001 From: Alisdair Meredith Date: Sat, 3 Jun 2006 12:51:13 +0000 Subject: [PATCH] Support for zero length arrays [SVN r34154] --- array0.cpp | 107 ++++++++++++++++++++++++++++++++++++ include/boost/array.hpp | 119 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 224 insertions(+), 2 deletions(-) create mode 100644 array0.cpp diff --git a/array0.cpp b/array0.cpp new file mode 100644 index 0000000..e6e5e8b --- /dev/null +++ b/array0.cpp @@ -0,0 +1,107 @@ +/* tests for using class array<> specialization for size 0 + * (C) Copyright Alisdair Meredith 2006. + * Distributed under the Boost Software License, Version 1.0. (See + * accompanying file LICENSE_1_0.txt or copy at + * http://www.boost.org/LICENSE_1_0.txt) + */ + +#include +#include +#include + +namespace { +unsigned int failed_tests = 0; + +void fail_test( const char * reason ) { + ++failed_tests; + std::cerr << "Test failure " << failed_tests << ": " << reason << std::endl; +} + +template< class T > +void BadValue( const T & ) +{ + fail_test( "Unexpected value" ); +} + +template< class T > +void RunTests() +{ + typedef boost::array< T, 0 > test_type; + + // Test value and aggegrate initialization + test_type test_case = {}; + const boost::array< T, 0 > const_test_case = test_type(); + + test_case.assign( T() ); + + // front/back and operator[] must compile, but calling them is undefined + // Likewise, all tests below should evaluate to false, avoiding undefined behaviour + if( !test_case.empty() ) { + BadValue( test_case.front() ); + } + + if( !const_test_case.empty() ) { + BadValue( const_test_case.back() ); + } + + if( test_case.size() > 0 ) { + BadValue( test_case[ 0 ] ); + } + + if( const_test_case.max_size() > 0 ) { + BadValue( const_test_case[ 0 ] ); + } + + // Assert requirements of TR1 6.2.2.4 + if( test_case.begin() != test_case.end() ) { + fail_test( "Not an empty range" ); + } + if( const_test_case.begin() != const_test_case.end() ) { + fail_test( "Not an empty range" ); + } + + if( test_case.begin() == const_test_case.begin() ) { + fail_test( "iterators for different containers are not distinct" ); + } + + if( test_case.data() == const_test_case.data() ) { + // Value of data is unspecified in TR1, so no requirement this test pass or fail + // However, it must compile! + } + + + // Check can safely use all iterator types with std algorithms + std::for_each( test_case.begin(), test_case.end(), BadValue< T > ); + std::for_each( test_case.rbegin(), test_case.rend(), BadValue< T > ); + std::for_each( const_test_case.begin(), const_test_case.end(), BadValue< T > ); + std::for_each( const_test_case.rbegin(), const_test_case.rend(), BadValue< T > ); + + // Check swap is well formed + std::swap( test_case, test_case ); + + // Check assigment operator and overloads are well formed + test_case = const_test_case; + + // Confirm at() throws the std lib defined exception + try { + BadValue( test_case.at( 0 ) ); + } catch ( const std::range_error & ) { + } + + try { + BadValue( const_test_case.at( 0 ) ); + } catch ( const std::range_error & ) { + } +} + +} + +int main() +{ + RunTests< bool >(); + RunTests< void * >(); + RunTests< long double >(); + RunTests< std::string >(); + return failed_tests; +} + diff --git a/include/boost/array.hpp b/include/boost/array.hpp index ce9eda7..841ed76 100644 --- a/include/boost/array.hpp +++ b/include/boost/array.hpp @@ -52,7 +52,7 @@ namespace boost { typedef const T& const_reference; typedef std::size_t size_type; typedef std::ptrdiff_t difference_type; - + // iterator support iterator begin() { return elems; } const_iterator begin() const { return elems; } @@ -135,6 +135,7 @@ namespace boost { // direct access to data (read-only) const T* data() const { return elems; } + T* data() { return elems; } // use array as C array (direct read/write access to data) T* c_array() { return elems; } @@ -154,13 +155,127 @@ namespace boost { // check range (may be private because it is static) static void rangecheck (size_type i) { - if (i >= size()) { + if (i >= size()) { throw std::range_error("array<>: index out of range"); } } }; + template< class T > + class array< T, 0 > { + + public: + // type definitions + typedef T value_type; + typedef T* iterator; + typedef const T* const_iterator; + typedef T& reference; + typedef const T& const_reference; + typedef std::size_t size_type; + typedef std::ptrdiff_t difference_type; + + // iterator support + iterator begin() { return iterator( reinterpret_cast< T * >( this ) ); } + const_iterator begin() const { return const_iterator( reinterpret_cast< const T * >( this ) ); } + iterator end() { return begin(); } + const_iterator end() const { return begin(); } + + // reverse iterator support +#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) && !defined(BOOST_MSVC_STD_ITERATOR) && !defined(BOOST_NO_STD_ITERATOR_TRAITS) + typedef std::reverse_iterator reverse_iterator; + typedef std::reverse_iterator const_reverse_iterator; +#elif defined(_MSC_VER) && (_MSC_VER == 1300) && defined(BOOST_DINKUMWARE_STDLIB) && (BOOST_DINKUMWARE_STDLIB == 310) + // workaround for broken reverse_iterator in VC7 + typedef std::reverse_iterator > reverse_iterator; + typedef std::reverse_iterator > const_reverse_iterator; +#else + // workaround for broken reverse_iterator implementations + typedef std::reverse_iterator reverse_iterator; + typedef std::reverse_iterator const_reverse_iterator; +#endif + + reverse_iterator rbegin() { return reverse_iterator(end()); } + const_reverse_iterator rbegin() const { + return const_reverse_iterator(end()); + } + reverse_iterator rend() { return reverse_iterator(begin()); } + const_reverse_iterator rend() const { + return const_reverse_iterator(begin()); + } + + // operator[] + reference operator[](size_type i) + { + BOOST_ASSERT( "out of range" ); + failed_rangecheck(); + } + + const_reference operator[](size_type i) const + { + BOOST_ASSERT( "out of range" ); + failed_rangecheck(); + } + + // at() with range check + reference at(size_type i) { failed_rangecheck(); } + const_reference at(size_type i) const { failed_rangecheck(); } + + // front() and back() + reference front() + { + failed_rangecheck(); + } + + const_reference front() const + { + failed_rangecheck(); + } + + reference back() + { + failed_rangecheck(); + } + + const_reference back() const + { + failed_rangecheck(); + } + + // size is constant + static size_type size() { return 0; } + static bool empty() { return true; } + static size_type max_size() { return 0; } + enum { static_size = 0 }; + + void swap (array& y) { + } + + // direct access to data (read-only) + const T* data() const { return 0; } + T* data() { return 0; } + + // use array as C array (direct read/write access to data) + T* c_array() { return 0; } + + // assignment with type conversion + template + array& operator= (const array& ) { + return *this; + } + + // assign one value to all elements + void assign (const T& ) { } + + // check range (may be private because it is static) + static void failed_rangecheck () { + throw std::range_error("attempt to access element of an empty array"); + } + + }; + // comparisons template bool operator== (const array& x, const array& y) {