346 lines
13 KiB
C++
346 lines
13 KiB
C++
/*
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* This file is part of the DXX-Rebirth project <https://www.dxx-rebirth.com/>.
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* It is copyright by its individual contributors, as recorded in the
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* project's Git history. See COPYING.txt at the top level for license
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* terms and a link to the Git history.
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*/
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#pragma once
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#include <array>
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#include <stdexcept>
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#include <iterator>
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#include <cstdio>
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#include <string>
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#include <type_traits>
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#include "fwd-partial_range.h"
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#include <memory>
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#include "dxxsconf.h"
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/* If no value was specified for DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE,
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* then define it to true for NDEBUG builds and false for debug builds.
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*
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* When DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE is true, the partial_range
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* exception is a global scope structure.
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*
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* When DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE is false, the
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* partial_range exception is nested in partial_range_t<I>, so that the
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* exception type encodes the range type.
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*
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* Encoding the range type in the exception produces a more descriptive
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* message when the program aborts for an uncaught exception, but
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* produces larger debug information and many nearly-redundant
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* instantiations of the report function. Using the global scope
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* structure avoids those redundant instances, but makes the exception
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* description less descriptive.
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*
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* Choose false if you expect to debug partial_range exceptions or
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* report them to someone who will debug them for you. Choose true if
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* you want a smaller program.
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*/
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#ifndef DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE
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#ifdef NDEBUG
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#define DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE 1
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#else
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#define DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE 0
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#endif
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#endif
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namespace partial_range_detail
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{
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namespace {
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#define REPORT_FORMAT_STRING "%s:%u: %s %lu past %p end %lu \"%s\""
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/* Round reporting into large buckets. Code size is more
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* important than stack space on a cold path.
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*/
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template <std::size_t NF, std::size_t NE>
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constexpr std::size_t required_buffer_size = ((sizeof(REPORT_FORMAT_STRING) + sizeof("65535") + (sizeof("18446744073709551615") * 2) + sizeof("0x0000000000000000") + (NF + NE + sizeof("begin"))) | 0xff) + 1;
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template <std::size_t N>
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__attribute_cold
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void prepare_error_string(std::array<char, N> &buf, unsigned long d, const char *estr, const char *file, unsigned line, const char *desc, unsigned long expr, const void *t)
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{
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std::snprintf(buf.data(), buf.size(), REPORT_FORMAT_STRING, file, line, desc, expr, t, d, estr);
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}
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#undef REPORT_FORMAT_STRING
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/*
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* These are placed out of line from the class and used as an
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* indirection, so that the compiler can pick std::begin/std::end or ADL
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* appropriate alternatives, if they exist.
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*/
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template <typename T>
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inline auto adl_begin(T &t)
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{
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using std::begin;
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return begin(t);
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}
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template <typename T>
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inline auto adl_end(T &t)
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{
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using std::end;
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return end(t);
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}
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}
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}
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#if DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE
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struct partial_range_error;
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#endif
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template <typename I>
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class partial_range_t
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{
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public:
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using range_owns_iterated_storage = std::false_type;
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typedef I iterator;
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/* When using the unminimized type, forward declare a structure.
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*
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* When using the minimized type, add a typedef here so that later
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* code can unconditionally use the qualified type name. Using a
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* typedef here instead of a preprocessor macro at the usage sites
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* causes the debug information to be very slightly bigger, but has
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* no effect on the size of the generated code and is easier to
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* maintain.
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*/
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#if DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE
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using partial_range_error =
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#endif
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struct partial_range_error;
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iterator m_begin, m_end;
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partial_range_t(iterator b, iterator e) :
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m_begin(b), m_end(e)
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{
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}
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partial_range_t(const partial_range_t &) = default;
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partial_range_t(partial_range_t &&) = default;
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partial_range_t &operator=(const partial_range_t &) = default;
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template <typename T>
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partial_range_t(T &t) :
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m_begin(partial_range_detail::adl_begin(t)), m_end(partial_range_detail::adl_end(t))
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{
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}
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template <typename T>
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partial_range_t(partial_range_t<T> &&t) :
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m_begin(t.begin()), m_end(t.end())
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{
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}
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__attribute_warn_unused_result
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iterator begin() const { return m_begin; }
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__attribute_warn_unused_result
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iterator end() const { return m_end; }
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bool empty() const __attribute_warn_unused_result
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{
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return m_begin == m_end;
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}
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__attribute_warn_unused_result
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std::size_t size() const { return std::distance(m_begin, m_end); }
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std::reverse_iterator<iterator> rbegin() const __attribute_warn_unused_result { return std::reverse_iterator<iterator>{m_end}; }
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std::reverse_iterator<iterator> rend() const __attribute_warn_unused_result { return std::reverse_iterator<iterator>{m_begin}; }
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partial_range_t<std::reverse_iterator<iterator>> reversed() const __attribute_warn_unused_result
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{
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return {rbegin(), rend()};
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}
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};
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#if DXX_PARTIAL_RANGE_MINIMIZE_ERROR_TYPE
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struct partial_range_error
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#else
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template <typename I>
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struct partial_range_t<I>::partial_range_error
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#endif
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final : std::out_of_range
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{
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DXX_INHERIT_CONSTRUCTORS(partial_range_error, out_of_range);
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template <std::size_t N>
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__attribute_cold
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__attribute_noreturn
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static void report(const char *file, unsigned line, const char *estr, const char *desc, unsigned long expr, const void *t, unsigned long d)
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{
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std::array<char, N> buf;
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partial_range_detail::prepare_error_string(buf, d, estr, file, line, desc, expr, t);
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throw partial_range_error(buf.data());
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}
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};
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namespace partial_range_detail
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{
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namespace {
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template <typename I, std::size_t required_buffer_size>
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inline void check_range_bounds(const char *file, unsigned line, const char *estr, const void *t, const std::size_t o, const std::size_t l, const std::size_t d)
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{
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#ifdef DXX_CONSTANT_TRUE
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/*
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* If EXPR and d are compile-time constant, and the (EXPR > d)
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* branch is optimized out, then the expansion of
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* PARTIAL_RANGE_COMPILE_CHECK_BOUND is optimized out, preventing
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* the compile error.
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*
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* If EXPR and d are compile-time constant, and the (EXPR > d)
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* branch is not optimized out, then this function is guaranteed to
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* throw if it is ever called. In that case, the compile fails,
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* since the program is guaranteed not to work as the programmer
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* intends.
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*
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* If they are not compile-time constant, but the compiler can
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* optimize based on constants, then it will optimize out the
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* expansion of PARTIAL_RANGE_COMPILE_CHECK_BOUND, preventing the
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* compile error. The function might throw on invalid inputs,
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* including constant inputs that the compiler failed to recognize
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* as compile-time constant.
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*
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* If the compiler cannot optimize based on the result of
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* __builtin_constant_p (such as at -O0), then configure tests do
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* not define DXX_CONSTANT_TRUE and the macro expands to nothing.
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*/
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#define PARTIAL_RANGE_COMPILE_CHECK_BOUND(EXPR,S) \
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(DXX_CONSTANT_TRUE(EXPR > d) && (DXX_ALWAYS_ERROR_FUNCTION(partial_range_will_always_throw_##S, #S " will always throw"), 0))
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#else
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#define PARTIAL_RANGE_COMPILE_CHECK_BOUND(EXPR,S) static_cast<void>(0)
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#endif
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#define PARTIAL_RANGE_CHECK_BOUND(EXPR,S) \
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PARTIAL_RANGE_COMPILE_CHECK_BOUND(EXPR,S), \
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((EXPR > d) && (I::template report<required_buffer_size>(file, line, estr, #S, EXPR, t, d), 0))
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PARTIAL_RANGE_CHECK_BOUND(o, begin);
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PARTIAL_RANGE_CHECK_BOUND(l, end);
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#undef PARTIAL_RANGE_CHECK_BOUND
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#undef PARTIAL_RANGE_COMPILE_CHECK_BOUND
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}
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#ifdef DXX_HAVE_BUILTIN_OBJECT_SIZE
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template <typename I, std::size_t required_buffer_size, typename P>
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inline void check_range_object_size(const char *file, unsigned line, const char *estr, P &ref, const std::size_t o, const std::size_t l)
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{
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const auto ptr = std::addressof(ref);
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const std::size_t bos = __builtin_object_size(ptr, 1);
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if (bos != static_cast<std::size_t>(-1))
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check_range_bounds<I, required_buffer_size>(file, line, estr, ptr, o, l, bos / sizeof(P));
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}
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/* When P refers to a temporary, this overload is picked. Temporaries
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* have no useful address, so they cannot be checked. A temporary would
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* be present if iterator.operator*() returns a proxy object, rather
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* than a reference to an element in the container.
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*/
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template <typename I, std::size_t required_buffer_size, typename P>
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void check_range_object_size(const char *, unsigned, const char *, const P &&, std::size_t, std::size_t) {}
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#endif
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}
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}
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namespace {
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template <typename I, std::size_t required_buffer_size>
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__attribute_warn_unused_result
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inline partial_range_t<I> (unchecked_partial_range)(const char *const file, const unsigned line, const char *const estr, I range_begin, const std::size_t o, const std::size_t l)
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{
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#ifdef DXX_CONSTANT_TRUE
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/* Compile-time only check. Runtime handles (o > l) correctly, and
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* it can happen in a correct program. If it is guaranteed to
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* happen, then the range is always empty, which likely indicates a
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* bug.
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*/
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if (DXX_CONSTANT_TRUE(!(o < l)))
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DXX_ALWAYS_ERROR_FUNCTION(partial_range_is_always_empty, "offset never less than length");
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#endif
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#ifdef DXX_HAVE_BUILTIN_OBJECT_SIZE
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/* Avoid iterator dereference if range is empty */
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if (l)
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{
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partial_range_detail::check_range_object_size<typename partial_range_t<I>::partial_range_error, required_buffer_size>(file, line, estr, *range_begin, o, l);
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}
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#else
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(void)file;
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(void)line;
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(void)estr;
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#endif
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auto range_end = range_begin;
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/* Use <= so that (o == 0) makes the expression always-true, so the
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* compiler will optimize out the test.
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*/
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if (o <= l)
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{
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using std::advance;
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advance(range_begin, o);
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advance(range_end, l);
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}
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return {range_begin, range_end};
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}
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template <typename I, typename UO, typename UL, std::size_t NF, std::size_t NE>
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__attribute_warn_unused_result
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inline partial_range_t<I> (unchecked_partial_range)(const char (&file)[NF], unsigned line, const char (&estr)[NE], I range_begin, const UO &o, const UL &l)
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{
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/* Require unsigned length */
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static_assert(std::is_unsigned<UO>::value, "offset to partial_range must be unsigned");
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static_assert(std::is_unsigned<UL>::value, "length to partial_range must be unsigned");
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return unchecked_partial_range<I, partial_range_detail::required_buffer_size<NF, NE>>(
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file, line, estr, range_begin, o, l
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);
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}
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template <typename I, typename UL, std::size_t NF, std::size_t NE>
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__attribute_warn_unused_result
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inline partial_range_t<I> (unchecked_partial_range)(const char (&file)[NF], unsigned line, const char (&estr)[NE], I range_begin, const UL &l)
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{
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return unchecked_partial_range<I, UL, UL>(file, line, estr, range_begin, 0, l);
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}
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template <typename T, typename UO, typename UL, std::size_t NF, std::size_t NE, typename I = decltype(std::begin(std::declval<T &>()))>
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__attribute_warn_unused_result
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inline partial_range_t<I> (partial_range)(const char (&file)[NF], unsigned line, const char (&estr)[NE], T &t, const UO &o, const UL &l)
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{
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partial_range_detail::check_range_bounds<typename partial_range_t<I>::partial_range_error, partial_range_detail::required_buffer_size<NF, NE>>(file, line, estr, std::addressof(t), o, l, std::size(t));
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return unchecked_partial_range<I, UO, UL>(file, line, estr, std::begin(t), o, l);
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}
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template <typename T, typename UL, std::size_t NF, std::size_t NE>
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__attribute_warn_unused_result
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inline auto (partial_range)(const char (&file)[NF], const unsigned line, const char (&estr)[NE], T &t, const UL &l)
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{
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return partial_range<T, UL, UL>(file, line, estr, t, 0, l);
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}
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template <typename T, typename UO, typename UL, std::size_t NF, std::size_t NE>
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__attribute_warn_unused_result
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inline auto (partial_const_range)(const char (&file)[NF], unsigned line, const char (&estr)[NE], const T &t, const UO &o, const UL &l)
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{
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return partial_range<const T, UO, UL>(file, line, estr, t, o, l);
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}
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template <typename T, typename UL, std::size_t NF, std::size_t NE>
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__attribute_warn_unused_result
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inline auto (partial_const_range)(const char (&file)[NF], unsigned line, const char (&estr)[NE], const T &t, const UL &l)
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{
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return partial_range<const T, UL>(file, line, estr, t, l);
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}
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template <typename T, typename I = decltype(std::begin(std::declval<T &>()))>
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__attribute_warn_unused_result
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inline partial_range_t<I> (make_range)(T &t)
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{
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return t;
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}
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}
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/* Explicitly block use on rvalue t because returned partial_range_t<I>
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* will outlive the rvalue.
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*/
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template <typename T, typename UO, typename UL, std::size_t NF, std::size_t NE, typename I = decltype(begin(std::declval<T &&>()))>
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partial_range_t<I> (partial_const_range)(const char (&file)[NF], unsigned line, const char (&estr)[NE], const T &&t, const UO &o, const UL &l) = delete;
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template <typename T, typename UL, std::size_t NF, std::size_t NE, typename I = decltype(begin(std::declval<T &&>()))>
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partial_range_t<I> (partial_const_range)(const char (&file)[NF], unsigned line, const char (&estr)[NE], const T &&t, const UL &l) = delete;
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#define unchecked_partial_range(T,...) unchecked_partial_range(__FILE__, __LINE__, #T, T, ##__VA_ARGS__)
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#define partial_range(T,...) partial_range(__FILE__, __LINE__, #T, T, ##__VA_ARGS__)
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#define partial_const_range(T,...) partial_const_range(__FILE__, __LINE__, #T, T, ##__VA_ARGS__)
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