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Implement fill/align/width parsing in chrono formatter

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This commit is contained in:
Victor Zverovich 2018-12-16 07:00:57 -08:00
parent 1f92f8a9d8
commit 3e01376e08
3 changed files with 137 additions and 83 deletions
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56
include/fmt/chrono.h
View File

@ -370,12 +370,50 @@ template <> FMT_CONSTEXPR const char *get_units<std::ratio<3600>>() {
template <typename Rep, typename Period, typename Char>
struct formatter<std::chrono::duration<Rep, Period>, Char> {
private:
align_spec spec;
internal::arg_ref<Char> width_ref;
mutable basic_string_view<Char> format_str;
typedef std::chrono::duration<Rep, Period> duration;
struct spec_handler {
formatter &f;
basic_parse_context<Char> &context;
typedef internal::arg_ref<Char> arg_ref_type;
template <typename Id>
FMT_CONSTEXPR arg_ref_type make_arg_ref(Id arg_id) {
context.check_arg_id(arg_id);
return arg_ref_type(arg_id);
}
FMT_CONSTEXPR arg_ref_type make_arg_ref(internal::auto_id) {
return arg_ref_type(context.next_arg_id());
}
void on_error(const char *msg) { throw format_error(msg); }
void on_fill(Char fill) { f.spec.fill_ = fill; }
void on_align(alignment align) { f.spec.align_ = align; }
void on_width(unsigned width) { f.spec.width_ = width; }
template <typename Id>
void on_dynamic_width(Id arg_id) {
f.width_ref = make_arg_ref(arg_id);
}
};
public:
formatter() : spec() {}
FMT_CONSTEXPR auto parse(basic_parse_context<Char> &ctx)
-> decltype(ctx.begin()) {
auto begin = ctx.begin(), end = ctx.end();
if (begin == end) return begin;
spec_handler handler{*this, ctx};
begin = internal::parse_align(begin, end, handler);
if (begin == end) return begin;
begin = internal::parse_width(begin, end, handler);
end = parse_chrono_format(begin, end, internal::chrono_format_checker());
format_str = basic_string_view<Char>(&*begin, end - begin);
return end;
@ -386,13 +424,21 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
-> decltype(ctx.out()) {
auto begin = format_str.begin(), end = format_str.end();
if (begin == end || *begin == '}') {
memory_buffer buf;
if (const char *unit = get_units<Period>())
return format_to(ctx.out(), "{}{}", d.count(), unit);
if (Period::den == 1)
return format_to(ctx.out(), "{}[{}]s", d.count(), Period::num);
return format_to(ctx.out(), "{}[{}/{}]s",
d.count(), Period::num, Period::den);
format_to(buf, "{}{}", d.count(), unit);
else if (Period::den == 1)
format_to(buf, "{}[{}]s", d.count(), Period::num);
else
format_to(buf, "{}[{}/{}]s", d.count(), Period::num, Period::den);
typedef output_range<decltype(ctx.out()), Char> range;
basic_writer<range> w(range(ctx.out()));
internal::handle_dynamic_spec<internal::width_checker>(
spec.width_, width_ref, ctx);
w.write(buf.data(), buf.size(), spec);
return w.out();
}
// TODO: use fill and align
internal::chrono_formatter<FormatContext> f(ctx);
f.s = std::chrono::duration_cast<std::chrono::seconds>(d);
f.ms = std::chrono::duration_cast<std::chrono::milliseconds>(d - f.s);

154
include/fmt/format.h
View File

@ -1342,7 +1342,7 @@ class arg_formatter_base {
void write(bool value) {
string_view sv(value ? "true" : "false");
specs_ ? writer_.write_str(sv, *specs_) : writer_.write(sv);
specs_ ? writer_.write(sv, *specs_) : writer_.write(sv);
}
void write(const char_type *value) {
@ -1350,7 +1350,7 @@ class arg_formatter_base {
FMT_THROW(format_error("string pointer is null"));
auto length = std::char_traits<char_type>::length(value);
basic_string_view<char_type> sv(value, length);
specs_ ? writer_.write_str(sv, *specs_) : writer_.write(sv);
specs_ ? writer_.write(sv, *specs_) : writer_.write(sv);
}
public:
@ -1426,7 +1426,7 @@ class arg_formatter_base {
if (specs_) {
internal::check_string_type_spec(
specs_->type, internal::error_handler());
writer_.write_str(value, *specs_);
writer_.write(value, *specs_);
} else {
writer_.write(value);
}
@ -1840,15 +1840,11 @@ struct precision_adapter {
SpecHandler &handler;
};
// Parses standard format specifiers and sends notifications about parsed
// components to handler.
template <typename Char, typename SpecHandler>
FMT_CONSTEXPR const Char *parse_format_specs(
const Char *begin, const Char *end, SpecHandler &&handler) {
if (begin == end || *begin == '}')
return begin;
// Parse fill and alignment.
// Parses fill and alignment.
template <typename Char, typename Handler>
FMT_CONSTEXPR const Char *parse_align(
const Char *begin, const Char *end, Handler &&handler) {
FMT_ASSERT(begin != end, "");
alignment align = ALIGN_DEFAULT;
int i = 0;
if (begin + 1 != end) ++i;
@ -1876,10 +1872,39 @@ FMT_CONSTEXPR const Char *parse_format_specs(
handler.on_fill(c);
} else ++begin;
handler.on_align(align);
if (begin == end) return begin;
break;
}
} while (i-- > 0);
return begin;
}
template <typename Char, typename Handler>
FMT_CONSTEXPR const Char *parse_width(
const Char *begin, const Char *end, Handler &&handler) {
FMT_ASSERT(begin != end, "");
if ('0' <= *begin && *begin <= '9') {
handler.on_width(parse_nonnegative_int(begin, end, handler));
} else if (*begin == '{') {
++begin;
if (begin != end)
begin = parse_arg_id(begin, end, width_adapter<Handler, Char>(handler));
if (begin == end || *begin != '}')
return handler.on_error("invalid format string"), begin;
++begin;
}
return begin;
}
// Parses standard format specifiers and sends notifications about parsed
// components to handler.
template <typename Char, typename SpecHandler>
FMT_CONSTEXPR const Char *parse_format_specs(
const Char *begin, const Char *end, SpecHandler &&handler) {
if (begin == end || *begin == '}')
return begin;
begin = parse_align(begin, end, handler);
if (begin == end) return begin;
// Parse sign.
switch (static_cast<char>(*begin)) {
@ -1909,20 +1934,8 @@ FMT_CONSTEXPR const Char *parse_format_specs(
if (++begin == end) return begin;
}
// Parse width.
if ('0' <= *begin && *begin <= '9') {
handler.on_width(parse_nonnegative_int(begin, end, handler));
begin = parse_width(begin, end, handler);
if (begin == end) return begin;
} else if (*begin == '{') {
++begin;
if (begin != end) {
begin = parse_arg_id(
begin, end, width_adapter<SpecHandler, Char>(handler));
}
if (begin == end || *begin != '}')
return handler.on_error("invalid format string"), begin;
if (++begin == end) return begin;
}
// Parse precision.
if (*begin == '.') {
@ -2251,8 +2264,6 @@ class basic_writer {
iterator out_; // Output iterator.
internal::locale_ref locale_;
iterator out() const { return out_; }
// Attempts to reserve space for n extra characters in the output range.
// Returns a pointer to the reserved range or a reference to out_.
auto reserve(std::size_t n) -> decltype(internal::reserve(out_, n)) {
@ -2263,7 +2274,28 @@ class basic_writer {
// <left-padding><value><right-padding>
// where <value> is written by f(it).
template <typename F>
void write_padded(const align_spec &spec, F &&f);
void write_padded(const align_spec &spec, F &&f) {
unsigned width = spec.width(); // User-perceived width (in code points).
size_t size = f.size(); // The number of code units.
size_t num_code_points = width != 0 ? f.width() : size;
if (width <= num_code_points)
return f(reserve(size));
auto &&it = reserve(width + (size - num_code_points));
char_type fill = static_cast<char_type>(spec.fill());
std::size_t padding = width - num_code_points;
if (spec.align() == ALIGN_RIGHT) {
it = std::fill_n(it, padding, fill);
f(it);
} else if (spec.align() == ALIGN_CENTER) {
std::size_t left_padding = padding / 2;
it = std::fill_n(it, left_padding, fill);
f(it);
it = std::fill_n(it, padding - left_padding, fill);
} else {
f(it);
it = std::fill_n(it, padding, fill);
}
}
template <typename F>
struct padded_int_writer {
@ -2525,15 +2557,6 @@ class basic_writer {
}
};
// Writes a formatted string.
template <typename Char>
void write_str(const Char *s, std::size_t size, const align_spec &spec) {
write_padded(spec, str_writer<Char>{s, size});
}
template <typename Char>
void write_str(basic_string_view<Char> str, const format_specs &spec);
template <typename Char>
friend class internal::arg_formatter_base;
@ -2543,6 +2566,8 @@ class basic_writer {
Range out, internal::locale_ref loc = internal::locale_ref())
: out_(out.begin()), locale_(loc) {}
iterator out() const { return out_; }
void write(int value) { write_decimal(value); }
void write(long value) { write_decimal(value); }
void write(long long value) { write_decimal(value); }
@ -2602,9 +2627,20 @@ class basic_writer {
it = std::copy(value.begin(), value.end(), it);
}
template <typename... FormatSpecs>
void write(basic_string_view<char_type> str, FormatSpecs... specs) {
write_str(str, format_specs(specs...));
// Writes a formatted string.
template <typename Char>
void write(const Char *s, std::size_t size, const align_spec &spec) {
write_padded(spec, str_writer<Char>{s, size});
}
template <typename Char>
void write(basic_string_view<Char> s,
const format_specs &spec = format_specs()) {
const Char *data = s.data();
std::size_t size = s.size();
if (spec.precision >= 0 && internal::to_unsigned(spec.precision) < size)
size = internal::to_unsigned(spec.precision);
write(data, size, spec);
}
template <typename T>
@ -2617,42 +2653,6 @@ class basic_writer {
}
};
template <typename Range>
template <typename F>
void basic_writer<Range>::write_padded(const align_spec &spec, F &&f) {
unsigned width = spec.width(); // User-perceived width (in code points).
size_t size = f.size(); // The number of code units.
size_t num_code_points = width != 0 ? f.width() : size;
if (width <= num_code_points)
return f(reserve(size));
auto &&it = reserve(width + (size - num_code_points));
char_type fill = static_cast<char_type>(spec.fill());
std::size_t padding = width - num_code_points;
if (spec.align() == ALIGN_RIGHT) {
it = std::fill_n(it, padding, fill);
f(it);
} else if (spec.align() == ALIGN_CENTER) {
std::size_t left_padding = padding / 2;
it = std::fill_n(it, left_padding, fill);
f(it);
it = std::fill_n(it, padding - left_padding, fill);
} else {
f(it);
it = std::fill_n(it, padding, fill);
}
}
template <typename Range>
template <typename Char>
void basic_writer<Range>::write_str(
basic_string_view<Char> s, const format_specs &spec) {
const Char *data = s.data();
std::size_t size = s.size();
if (spec.precision >= 0 && internal::to_unsigned(spec.precision) < size)
size = internal::to_unsigned(spec.precision);
write_str(data, size, spec);
}
struct float_spec_handler {
char type;
bool upper;

8
test/chrono-test.cc
View File

@ -91,6 +91,14 @@ TEST(ChronoTest, FormatDefault) {
std::chrono::duration<int, std::ratio<15, 4>>(42)));
}
TEST(ChronoTest, Align) {
auto s = std::chrono::seconds(42);
EXPECT_EQ("42s ", fmt::format("{:5}", s));
EXPECT_EQ("42s ", fmt::format("{:{}}", s, 5));
EXPECT_EQ(" 42s", fmt::format("{:>5}", s));
EXPECT_EQ("**42s**", fmt::format("{:*^7}", s));
}
TEST(ChronoTest, FormatSpecs) {
EXPECT_EQ("%", fmt::format("{:%%}", std::chrono::seconds(0)));
EXPECT_EQ("\n", fmt::format("{:%n}", std::chrono::seconds(0)));