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Get rid of 'null_terminating_iterator' in printf.h (#980)

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The iterator class itself and its helpers 'to_pointer' are removed after reformulating the formatting loop in terms of a 'basic_string_view<Char>::iterator'.

Signed-off-by: Daniela Engert <dani@ngrt.de>
This commit is contained in:
Daniela Engert 2018-12-31 16:21:45 +01:00 committed by Victor Zverovich
parent 39623a7400
commit f5cc77cea0
1 changed files with 58 additions and 176 deletions
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224
include/fmt/printf.h
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@ -16,130 +16,6 @@
FMT_BEGIN_NAMESPACE
namespace internal {
// An iterator that produces a null terminator on *end. This simplifies parsing
// and allows comparing the performance of processing a null-terminated string
// vs string_view.
template <typename Char>
class null_terminating_iterator {
public:
typedef std::ptrdiff_t difference_type;
typedef Char value_type;
typedef const Char* pointer;
typedef const Char& reference;
typedef std::random_access_iterator_tag iterator_category;
null_terminating_iterator() : ptr_(0), end_(0) {}
FMT_CONSTEXPR null_terminating_iterator(const Char *ptr, const Char *end)
: ptr_(ptr), end_(end) {}
template <typename Range>
FMT_CONSTEXPR explicit null_terminating_iterator(const Range &r)
: ptr_(r.begin()), end_(r.end()) {}
FMT_CONSTEXPR null_terminating_iterator &operator=(const Char *ptr) {
assert(ptr <= end_);
ptr_ = ptr;
return *this;
}
FMT_CONSTEXPR Char operator*() const {
return ptr_ != end_ ? *ptr_ : Char();
}
FMT_CONSTEXPR null_terminating_iterator operator++() {
++ptr_;
return *this;
}
FMT_CONSTEXPR null_terminating_iterator operator++(int) {
null_terminating_iterator result(*this);
++ptr_;
return result;
}
FMT_CONSTEXPR null_terminating_iterator operator--() {
--ptr_;
return *this;
}
FMT_CONSTEXPR null_terminating_iterator operator+(difference_type n) {
return null_terminating_iterator(ptr_ + n, end_);
}
FMT_CONSTEXPR null_terminating_iterator operator-(difference_type n) {
return null_terminating_iterator(ptr_ - n, end_);
}
FMT_CONSTEXPR null_terminating_iterator operator+=(difference_type n) {
ptr_ += n;
return *this;
}
FMT_CONSTEXPR difference_type operator-(
null_terminating_iterator other) const {
return ptr_ - other.ptr_;
}
FMT_CONSTEXPR bool operator!=(null_terminating_iterator other) const {
return ptr_ != other.ptr_;
}
bool operator>=(null_terminating_iterator other) const {
return ptr_ >= other.ptr_;
}
// This should be a friend specialization pointer_from<Char> but the latter
// doesn't compile by gcc 5.1 due to a compiler bug.
template <typename CharT>
friend FMT_CONSTEXPR_DECL const CharT *pointer_from(
null_terminating_iterator<CharT> it);
private:
const Char *ptr_;
const Char *end_;
};
template <typename T>
FMT_CONSTEXPR const T *pointer_from(const T *p) { return p; }
template <typename Char>
FMT_CONSTEXPR const Char *pointer_from(null_terminating_iterator<Char> it) {
return it.ptr_;
}
// DEPRECATED: Parses the input as an unsigned integer. This function assumes
// that the first character is a digit and presence of a non-digit character at
// the end.
// it: an iterator pointing to the beginning of the input range.
template <typename Iterator, typename ErrorHandler>
FMT_CONSTEXPR unsigned parse_nonnegative_int(Iterator &it, ErrorHandler &&eh) {
assert('0' <= *it && *it <= '9');
if (*it == '0') {
++it;
return 0;
}
unsigned value = 0;
// Convert to unsigned to prevent a warning.
unsigned max_int = (std::numeric_limits<int>::max)();
unsigned big = max_int / 10;
do {
// Check for overflow.
if (value > big) {
value = max_int + 1;
break;
}
value = value * 10 + unsigned(*it - '0');
// Workaround for MSVC "setup_exception stack overflow" error:
auto next = it;
++next;
it = next;
} while ('0' <= *it && *it <= '9');
if (value > max_int)
eh.on_error("number is too big");
return value;
}
// Checks if a value fits in int - used to avoid warnings about comparing
// signed and unsigned integers.
template <bool IsSigned>
@ -485,18 +361,15 @@ class basic_printf_context :
typedef internal::context_base<OutputIt, basic_printf_context, Char> base;
typedef typename base::format_arg format_arg;
typedef basic_format_specs<char_type> format_specs;
typedef internal::null_terminating_iterator<char_type> iterator;
void parse_flags(format_specs &spec, iterator &it);
static void parse_flags(format_specs &spec, const Char *&it, const Char *end);
// Returns the argument with specified index or, if arg_index is equal
// to the maximum unsigned value, the next argument.
format_arg get_arg(
iterator it,
unsigned arg_index = (std::numeric_limits<unsigned>::max)());
format_arg get_arg(unsigned arg_index = std::numeric_limits<unsigned>::max());
// Parses argument index, flags and width and returns the argument index.
unsigned parse_header(iterator &it, format_specs &spec);
unsigned parse_header(const Char *&it, const Char *end, format_specs &spec);
public:
/**
@ -520,9 +393,9 @@ class basic_printf_context :
template <typename OutputIt, typename Char, typename AF>
void basic_printf_context<OutputIt, Char, AF>::parse_flags(
format_specs &spec, iterator &it) {
for (;;) {
switch (*it++) {
format_specs &spec, const Char *&it, const Char *end) {
for (; it != end; ++it) {
switch (*it) {
case '-':
spec.align_ = ALIGN_LEFT;
break;
@ -539,7 +412,6 @@ void basic_printf_context<OutputIt, Char, AF>::parse_flags(
spec.flags |= HASH_FLAG;
break;
default:
--it;
return;
}
}
@ -547,9 +419,7 @@ void basic_printf_context<OutputIt, Char, AF>::parse_flags(
template <typename OutputIt, typename Char, typename AF>
typename basic_printf_context<OutputIt, Char, AF>::format_arg
basic_printf_context<OutputIt, Char, AF>::get_arg(
iterator it, unsigned arg_index) {
(void)it;
basic_printf_context<OutputIt, Char, AF>::get_arg(unsigned arg_index) {
if (arg_index == std::numeric_limits<unsigned>::max())
return this->do_get_arg(this->parse_context().next_arg_id());
return base::get_arg(arg_index - 1);
@ -557,15 +427,15 @@ typename basic_printf_context<OutputIt, Char, AF>::format_arg
template <typename OutputIt, typename Char, typename AF>
unsigned basic_printf_context<OutputIt, Char, AF>::parse_header(
iterator &it, format_specs &spec) {
const Char *&it, const Char *end, format_specs &spec) {
unsigned arg_index = std::numeric_limits<unsigned>::max();
char_type c = *it;
if (c >= '0' && c <= '9') {
// Parse an argument index (if followed by '$') or a width possibly
// preceded with '0' flag(s).
internal::error_handler eh;
unsigned value = parse_nonnegative_int(it, eh);
if (*it == '$') { // value is an argument index
unsigned value = parse_nonnegative_int(it, end, eh);
if (it != end && *it == '$') { // value is an argument index
++it;
arg_index = value;
} else {
@ -579,15 +449,17 @@ unsigned basic_printf_context<OutputIt, Char, AF>::parse_header(
}
}
}
parse_flags(spec, it);
parse_flags(spec, it, end);
// Parse width.
if (it != end) {
if (*it >= '0' && *it <= '9') {
internal::error_handler eh;
spec.width_ = parse_nonnegative_int(it, eh);
spec.width_ = parse_nonnegative_int(it, end, eh);
} else if (*it == '*') {
++it;
spec.width_ = visit_format_arg(
internal::printf_width_handler<char_type>(spec), get_arg(it));
internal::printf_width_handler<char_type>(spec), get_arg());
}
}
return arg_index;
}
@ -595,41 +467,43 @@ unsigned basic_printf_context<OutputIt, Char, AF>::parse_header(
template <typename OutputIt, typename Char, typename AF>
void basic_printf_context<OutputIt, Char, AF>::format() {
auto &buffer = internal::get_container(this->out());
auto start = iterator(this->parse_context());
const auto range = this->parse_context();
const Char * end = range.end();
const Char * start = range.begin();
auto it = start;
using internal::pointer_from;
while (*it) {
while (it != end) {
char_type c = *it++;
if (c != '%') continue;
if (*it == c) {
buffer.append(pointer_from(start), pointer_from(it));
if (it != end && *it == c) {
buffer.append(start, it);
start = ++it;
continue;
}
buffer.append(pointer_from(start), pointer_from(it) - 1);
buffer.append(start, it - 1);
format_specs spec;
spec.align_ = ALIGN_RIGHT;
// Parse argument index, flags and width.
unsigned arg_index = parse_header(it, spec);
unsigned arg_index = parse_header(it, end, spec);
// Parse precision.
if (*it == '.') {
if (it != end && *it == '.') {
++it;
if ('0' <= *it && *it <= '9') {
c = it != end ? *it : 0;
if ('0' <= c && c <= '9') {
internal::error_handler eh;
spec.precision = static_cast<int>(parse_nonnegative_int(it, eh));
} else if (*it == '*') {
spec.precision = static_cast<int>(parse_nonnegative_int(it, end, eh));
} else if (c == '*') {
++it;
spec.precision =
visit_format_arg(internal::printf_precision_handler(), get_arg(it));
visit_format_arg(internal::printf_precision_handler(), get_arg());
} else {
spec.precision = 0;
}
}
format_arg arg = get_arg(it, arg_index);
format_arg arg = get_arg(arg_index);
if (spec.has(HASH_FLAG) && visit_format_arg(internal::is_zero_int(), arg))
spec.flags = static_cast<uint_least8_t>(spec.flags & (~internal::to_unsigned<int>(HASH_FLAG)));
if (spec.fill_ == '0') {
@ -640,28 +514,36 @@ void basic_printf_context<OutputIt, Char, AF>::format() {
}
// Parse length and convert the argument to the required type.
c = it != end ? *it++ : 0;
char_type t = it != end ? *it : 0;
using internal::convert_arg;
switch (*it++) {
switch (c) {
case 'h':
if (*it == 'h')
convert_arg<signed char>(arg, *++it);
else
convert_arg<short>(arg, *it);
if (t == 'h') {
++it;
t = it != end ? *it : 0;
convert_arg<signed char>(arg, t);
} else {
convert_arg<short>(arg, t);
}
break;
case 'l':
if (*it == 'l')
convert_arg<long long>(arg, *++it);
else
convert_arg<long>(arg, *it);
if (t == 'l') {
++it;
t = it != end ? *it : 0;
convert_arg<long long>(arg, t);
} else {
convert_arg<long>(arg, t);
}
break;
case 'j':
convert_arg<intmax_t>(arg, *it);
convert_arg<intmax_t>(arg, t);
break;
case 'z':
convert_arg<std::size_t>(arg, *it);
convert_arg<std::size_t>(arg, t);
break;
case 't':
convert_arg<std::ptrdiff_t>(arg, *it);
convert_arg<std::ptrdiff_t>(arg, t);
break;
case 'L':
// printf produces garbage when 'L' is omitted for long double, no
@ -669,11 +551,11 @@ void basic_printf_context<OutputIt, Char, AF>::format() {
break;
default:
--it;
convert_arg<void>(arg, *it);
convert_arg<void>(arg, c);
}
// Parse type.
if (!*it)
if (it == end)
FMT_THROW(format_error("invalid format string"));
spec.type = static_cast<char>(*it++);
if (arg.is_integral()) {
@ -695,7 +577,7 @@ void basic_printf_context<OutputIt, Char, AF>::format() {
// Format argument.
visit_format_arg(AF(buffer, spec, *this), arg);
}
buffer.append(pointer_from(start), pointer_from(it));
buffer.append(start, it);
}
template <typename Buffer>