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construct/ircd/fmt.cc

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C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
namespace ircd::fmt
{
using namespace ircd::spirit;
struct spec;
struct specifier;
struct bool_specifier extern const bool_specifier;
struct char_specifier extern const char_specifier;
struct signed_specifier extern const signed_specifier;
struct unsigned_specifier extern const unsigned_specifier;
struct float_specifier extern const float_specifier;
struct hex_uppercase_specifier extern const hex_uppercase_specifier;
struct hex_lowercase_specifier extern const hex_lowercase_specifier;
struct pointer_specifier extern const pointer_specifier;
struct string_specifier extern const string_specifier;
constexpr char SPECIFIER {'%'};
constexpr char SPECIFIER_TERMINATOR {'$'};
template<class generator>
static bool generate_string(char *&out, const size_t &max, generator&&, const arg &val);
template<class gen,
class... attr>
static bool generate(mutable_buffer &, gen&&, attr&&...);
template<class T,
class lambda>
static bool visit_type(const arg &val, lambda&& closure);
static void handle_specifier(mutable_buffer &out, const uint &idx, const spec &, const arg &);
}
/// Structural representation of a format specifier. The parse of each
/// specifier in the format string creates one of these.
struct [[gnu::visibility("internal")]]
ircd::fmt::spec
{
char sign {'+'};
char pad {' '};
ushort width {0};
ushort precision {0};
string_view name;
};
/// Reflects the fmt::spec struct to allow the spirit::qi grammar to directly
/// fill in the spec struct.
#pragma GCC visibility push(internal)
BOOST_FUSION_ADAPT_STRUCT
(
ircd::fmt::spec,
( decltype(ircd::fmt::spec::sign), sign )
( decltype(ircd::fmt::spec::pad), pad )
( decltype(ircd::fmt::spec::width), width )
( decltype(ircd::fmt::spec::precision), precision )
( decltype(ircd::fmt::spec::name), name )
)
#pragma GCC visibility pop
/// The format string parser grammar.
namespace ircd::fmt::parser
{
template<class R = unused_type>
struct [[gnu::visibility("internal")]] rule
:qi::rule<const char *, R>
{
using qi::rule<const char *, R>::rule;
};
const expr specsym
{
lit(SPECIFIER)
,"format specifier"
};
const expr specterm
{
lit(SPECIFIER_TERMINATOR)
,"specifier termination"
};
const expr name
{
raw[repeat(1,14)[char_("A-Za-z")]]
,"specifier name"
};
const rule<fmt::spec> spec
{
(specsym >> !specsym)
>> -(char_('+') | char_('-'))
>> (-char_('0') | attr(' '))
>> -ushort_
>> -(lit('.') >> ushort_)
>> name
>> -specterm,
"specifier"
};
}
/// A format specifier handler module. This allows a new "%foo" to be defined
/// with custom handling by overriding. This abstraction is inserted into a
/// mapping key'ed by the supplied names leading to an instance of this.
///
class [[gnu::visibility("hidden")]]
ircd::fmt::specifier
{
static std::map<string_view, const specifier *, std::less<>> registry;
std::set<std::string> names;
public:
virtual bool operator()(char *&out, const size_t &max, const spec &, const arg &) const = 0;
specifier(const std::initializer_list<std::string> &names);
specifier(const std::string &name);
virtual ~specifier() noexcept;
static bool exists(const string_view &name);
static const specifier &at(const string_view &name);
};
[[clang::always_destroy]]
decltype(ircd::fmt::specifier::registry)
ircd::fmt::specifier::registry;
struct [[gnu::visibility("hidden")]]
ircd::fmt::string_specifier
:specifier
{
static const std::tuple
<
const char *,
std::string,
std::string_view,
ircd::string_view,
ircd::json::string,
ircd::json::object,
ircd::json::array
>
types;
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::string_specifier
{
"s"s
};
decltype(ircd::fmt::string_specifier::types)
ircd::fmt::string_specifier::types;
struct [[gnu::visibility("hidden")]]
ircd::fmt::bool_specifier
:specifier
{
static const std::tuple
<
bool,
char, unsigned char,
short, unsigned short,
int, unsigned int,
long, unsigned long,
long long, unsigned long long
>
types;
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::bool_specifier
{
{ "b"s }
};
decltype(ircd::fmt::bool_specifier::types)
ircd::fmt::bool_specifier::types;
struct [[gnu::visibility("hidden")]]
ircd::fmt::signed_specifier
:specifier
{
static const std::tuple
<
bool,
char, unsigned char,
short, unsigned short,
int, unsigned int,
long, unsigned long,
long long, unsigned long long
>
types;
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::signed_specifier
{
{ "d"s, "ld"s, "zd"s }
};
decltype(ircd::fmt::signed_specifier::types)
ircd::fmt::signed_specifier::types;
struct [[gnu::visibility("hidden")]]
ircd::fmt::unsigned_specifier
:specifier
{
static const std::tuple
<
bool,
char, unsigned char,
short, unsigned short,
int, unsigned int,
long, unsigned long,
long long, unsigned long long
>
types;
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::unsigned_specifier
{
{ "u"s, "lu"s, "zu"s }
};
struct [[gnu::visibility("hidden")]]
ircd::fmt::hex_lowercase_specifier
:specifier
{
static const std::tuple
<
bool,
char, unsigned char,
short, unsigned short,
int, unsigned int,
long, unsigned long,
long long, unsigned long long
>
types;
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::hex_lowercase_specifier
{
{ "x"s, "lx"s }
};
decltype(ircd::fmt::hex_lowercase_specifier::types)
ircd::fmt::hex_lowercase_specifier::types;
struct [[gnu::visibility("hidden")]]
ircd::fmt::hex_uppercase_specifier
:specifier
{
static const std::tuple
<
bool,
char, unsigned char,
short, unsigned short,
int, unsigned int,
long, unsigned long,
long long, unsigned long long
>
types;
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::hex_uppercase_specifier
{
{ "X"s, "lX"s }
};
decltype(ircd::fmt::hex_uppercase_specifier::types)
ircd::fmt::hex_uppercase_specifier::types;
decltype(ircd::fmt::unsigned_specifier::types)
ircd::fmt::unsigned_specifier::types;
struct [[gnu::visibility("hidden")]]
ircd::fmt::float_specifier
:specifier
{
static const std::tuple
<
char, unsigned char,
short, unsigned short,
int, unsigned int,
long, unsigned long,
float, double,
long double
>
types;
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::float_specifier
{
{ "f"s, "lf"s }
};
decltype(ircd::fmt::float_specifier::types)
ircd::fmt::float_specifier::types;
struct [[gnu::visibility("hidden")]]
ircd::fmt::char_specifier
:specifier
{
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::char_specifier
{
"c"s
};
struct [[gnu::visibility("hidden")]]
ircd::fmt::pointer_specifier
:specifier
{
bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
using specifier::specifier;
}
const ircd::fmt::pointer_specifier
{
"p"s
};
//
// snprintf::snprintf
//
[[gnu::visibility("protected")]]
ircd::fmt::snprintf::snprintf(internal_t,
const mutable_buffer &out,
const string_view &fmt,
const va_rtti &v)
try
:out{out}
,fmt{[&fmt]
{
// start the member fmt variable at the first specifier (or end)
const auto pos(fmt.find(SPECIFIER));
return pos != fmt.npos?
fmt.substr(pos):
string_view{};
}()}
,idx{0}
{
// If out has no size we have nothing to do, not even null terminate it.
if(unlikely(empty(out)))
return;
// If fmt has no specifiers then we can just copy the fmt as best as
// possible to the out buffer.
if(empty(this->fmt))
{
append(fmt);
return;
}
// Copy everything from fmt up to the first specifier.
assert(data(this->fmt) >= data(fmt));
append(string_view(data(fmt), data(this->fmt)));
// Iterate
auto it(begin(v));
for(size_t i(0); i < v.size() && !finished(); ++it, i++)
{
const void *const &ptr(get<0>(*it));
const std::type_index type(*get<1>(*it));
argument(std::make_tuple(ptr, type));
}
// Ensure null termination if out buffer is non-empty.
assert(size(this->out) > 0);
assert(this->out.remaining());
copy(mutable_buffer(this->out), '\0');
}
catch(const std::out_of_range &e)
{
throw invalid_format
{
"Format string requires more than %zu arguments.", v.size()
};
}
[[gnu::visibility("hidden")]]
void
ircd::fmt::snprintf::argument(const arg &val)
{
// The format string's front pointer is sitting on the specifier '%'
// waiting to be parsed now.
fmt::spec spec;
auto &start(begin(this->fmt));
const auto &stop(end(this->fmt));
if(ircd::parse<invalid_format>(start, stop, parser::spec, spec))
handle_specifier(this->out, idx++, spec, val);
string_view fmt
{
start, stop
};
if(size(fmt) >= 2 && fmt[0] == SPECIFIER && fmt[1] == SPECIFIER)
{
append({&SPECIFIER, 1});
consume(this->fmt, 2);
fmt = string_view
{
start, stop
};
}
const auto nextpos
{
fmt.find(SPECIFIER)
};
const string_view leg
{
fmt.substr(0, nextpos)
};
append(leg);
consume(this->fmt, size(leg));
}
[[gnu::visibility("hidden")]]
void
ircd::fmt::snprintf::append(const string_view &src)
{
out([&src](const mutable_buffer &buf)
{
return strlcpy(buf, src);
});
}
[[gnu::visibility("hidden")]]
size_t
ircd::fmt::snprintf::remaining()
const noexcept
{
return out.remaining()?
out.remaining() - 1:
0;
}
[[gnu::visibility("hidden")]]
bool
ircd::fmt::snprintf::finished()
const noexcept
{
return empty(fmt) || !remaining();
}
//
// fmt::specifier
//
ircd::fmt::specifier::specifier(const std::string &name)
:specifier{{name}}
{
}
ircd::fmt::specifier::specifier(const std::initializer_list<std::string> &names)
:names{names}
{
for(const auto &name : this->names)
if(exists(name))
throw error
{
"Specifier '%s' already registered\n", name
};
for(const auto &name : this->names)
registry.emplace(name, this);
}
ircd::fmt::specifier::~specifier()
noexcept
{
for(const auto &name : names)
registry.erase(name);
}
bool
ircd::fmt::specifier::exists(const string_view &name)
{
return registry.count(name);
}
const ircd::fmt::specifier &
ircd::fmt::specifier::at(const string_view &name)
{
return *registry.at(name);
}
//
// Utils
//
void
ircd::fmt::handle_specifier(mutable_buffer &out,
const uint &idx,
const spec &spec,
const arg &val)
try
{
auto &outp(std::get<0>(out));
assert(size(out));
const size_t max
{
size(out) - 1 // Leave room for null byte for later.
};
assert(spec.name);
const auto &type(get<1>(val));
const auto &handler(specifier::at(spec.name));
if(unlikely(!handler(outp, max, spec, val)))
throw invalid_type
{
"`%s' (%s) for format specifier '%s' for argument #%u",
demangle(type.name()),
type.name(),
spec.name,
idx
};
}
catch(const std::out_of_range &e)
{
throw invalid_format
{
"Unhandled specifier `%s' for argument #%u in format string",
spec.name,
idx
};
}
catch(const illegal &e)
{
throw illegal
{
"Specifier `%s' for argument #%u: %s",
spec.name,
idx,
e.what()
};
}
template<class T,
class lambda>
bool
ircd::fmt::visit_type(const arg &val,
lambda&& closure)
{
const auto &ptr(get<0>(val));
const auto &type(get<1>(val));
return type == typeid(T)? closure(*static_cast<const T *>(ptr)) : false;
}
template<class gen,
class... attr>
bool
ircd::fmt::generate(mutable_buffer &out,
gen&& g,
attr&&... a)
{
constexpr bool truncation
{
true
};
return ircd::generate<truncation>(out, std::forward<gen>(g), std::forward<attr>(a)...);
}
//
// Handlers
//
bool
ircd::fmt::pointer_specifier::operator()(char *&out,
const size_t &max,
const spec &spec,
const arg &val)
const
{
using karma::eps;
static const auto throw_illegal{[]
{
throw illegal
{
"Not a pointer"
};
}};
struct generator
:karma::grammar<char *, uintptr_t()>
{
karma::rule<char *, uintptr_t()> rule
{
lit("0x") << karma::hex
};
_r1_type width;
_r2_type pad;
karma::rule<char *, uintptr_t(ushort, char)> aligned_left
{
karma::left_align(width, pad)[rule]
,"left aligned"
};
karma::rule<char *, uintptr_t(ushort, char)> aligned_right
{
karma::right_align(width, pad)[rule]
,"right aligned"
};
karma::rule<char *, uintptr_t(ushort, char)> aligned_center
{
karma::center(width, pad)[rule]
,"center aligned"
};
generator(): generator::base_type{rule} {}
}
static const generator;
static const auto &ep
{
eps[throw_illegal]
};
const auto &ptr(get<0>(val));
const auto &type(get<1>(val));
const void *const p
{
*static_cast<const void *const *>(ptr)
};
bool ret;
mutable_buffer buf
{
out, max
};
if(!spec.width)
ret = fmt::generate(buf, generator | ep, uintptr_t(p));
else if(spec.sign == '-')
{
const auto &g(generator.aligned_left(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, uintptr_t(p));
} else {
const auto &g(generator.aligned_right(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, uintptr_t(p));
}
out = data(buf);
return ret;
}
bool
ircd::fmt::char_specifier::operator()(char *&out,
const size_t &max,
const spec &,
const arg &val)
const
{
using karma::eps;
static const auto throw_illegal{[]
{
throw illegal
{
"Not a printable character"
};
}};
struct generator
:karma::grammar<char *, char()>
{
karma::rule<char *, char()> printable
{
karma::print
,"character"
};
generator(): generator::base_type{printable} {}
}
static const generator;
const auto &ptr(get<0>(val));
const auto &type(get<1>(val));
if(type == typeid(const char))
{
mutable_buffer buf
{
out, max
};
const auto &c(*static_cast<const char *>(ptr));
fmt::generate(buf, generator | eps[throw_illegal], c);
out = data(buf);
return true;
}
else return false;
}
bool
ircd::fmt::bool_specifier::operator()(char *&out,
const size_t &max,
const spec &,
const arg &val)
const
{
using karma::eps;
static const auto throw_illegal{[]
{
throw illegal
{
"Failed to print signed value"
};
}};
const auto closure([&](const bool &boolean)
{
struct generator
:karma::grammar<char *, bool()>
{
karma::rule<char *, bool()> rule
{
karma::bool_
,"boolean"
};
generator(): generator::base_type{rule} {}
}
static const generator;
mutable_buffer buf
{
out, max
};
const auto ret
{
fmt::generate(buf, generator | eps[throw_illegal], boolean)
};
out = data(buf);
return ret;
});
return test(types, [&](const auto type)
{
return visit_type<decltype(type)>(val, closure);
});
}
bool
ircd::fmt::signed_specifier::operator()(char *&out,
const size_t &max,
const spec &spec,
const arg &val)
const
{
static const auto throw_illegal{[]
{
throw illegal
{
"Failed to print signed value"
};
}};
const auto closure([&out, &max, &spec, &val]
(const long &integer)
{
using karma::long_;
struct generator
:karma::grammar<char *, long()>
{
karma::rule<char *, long()> rule
{
long_
,"signed long integer"
};
_r1_type width;
_r2_type pad;
karma::rule<char *, long(ushort, char)> aligned_left
{
karma::left_align(width, pad)[rule]
,"left aligned"
};
karma::rule<char *, long(ushort, char)> aligned_right
{
karma::right_align(width, pad)[rule]
,"right aligned"
};
karma::rule<char *, long(ushort, char)> aligned_center
{
karma::center(width, pad)[rule]
,"center aligned"
};
generator(): generator::base_type{rule} {}
}
static const generator;
static const auto &ep
{
eps[throw_illegal]
};
bool ret;
mutable_buffer buf
{
out, max
};
if(!spec.width)
ret = fmt::generate(buf, generator | ep, integer);
else if(spec.sign == '-')
{
const auto &g(generator.aligned_left(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, integer);
} else {
const auto &g(generator.aligned_right(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, integer);
}
out = data(buf);
return ret;
});
return test(types, [&](const auto type)
{
return visit_type<decltype(type)>(val, closure);
});
}
bool
ircd::fmt::unsigned_specifier::operator()(char *&out,
const size_t &max,
const spec &spec,
const arg &val)
const
{
static const auto throw_illegal{[]
{
throw illegal
{
"Failed to print unsigned value"
};
}};
const auto closure([&out, &max, &spec, &val]
(const ulong &integer)
{
using karma::ulong_;
struct generator
:karma::grammar<char *, ulong()>
{
karma::rule<char *, ulong()> rule
{
ulong_
,"unsigned long integer"
};
_r1_type width;
_r2_type pad;
karma::rule<char *, ulong(ushort, char)> aligned_left
{
karma::left_align(width, pad)[rule]
,"left aligned"
};
karma::rule<char *, ulong(ushort, char)> aligned_right
{
karma::right_align(width, pad)[rule]
,"right aligned"
};
karma::rule<char *, ulong(ushort, char)> aligned_center
{
karma::center(width, pad)[rule]
,"center aligned"
};
generator(): generator::base_type{rule} {}
}
static const generator;
static const auto &ep
{
eps[throw_illegal]
};
bool ret;
mutable_buffer buf
{
out, max
};
if(!spec.width)
ret = fmt::generate(buf, generator | ep, integer);
else if(spec.sign == '-')
{
const auto &g(generator.aligned_left(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, integer);
} else {
const auto &g(generator.aligned_right(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, integer);
}
out = data(buf);
return ret;
});
return test(types, [&](const auto type)
{
return visit_type<decltype(type)>(val, closure);
});
}
bool
ircd::fmt::hex_lowercase_specifier::operator()(char *&out,
const size_t &max,
const spec &spec,
const arg &val)
const
{
static const auto throw_illegal{[]
{
throw illegal
{
"Failed to print hexadecimal value"
};
}};
const auto closure([&](const ulong &integer)
{
struct generator
:karma::grammar<char *, ulong()>
{
karma::rule<char *, ulong()> rule
{
karma::lower[karma::hex]
,"unsigned lowercase hexadecimal"
};
_r1_type width;
_r2_type pad;
karma::rule<char *, ulong(ushort, char)> aligned_left
{
karma::left_align(width, pad)[rule]
,"left aligned"
};
karma::rule<char *, ulong(ushort, char)> aligned_right
{
karma::right_align(width, pad)[rule]
,"right aligned"
};
karma::rule<char *, ulong(ushort, char)> aligned_center
{
karma::center(width, pad)[rule]
,"center aligned"
};
generator(): generator::base_type{rule} {}
}
static const generator;
static const auto &ep
{
eps[throw_illegal]
};
bool ret;
mutable_buffer buf
{
out, max
};
if(!spec.width)
ret = fmt::generate(buf, generator | ep, integer);
else if(spec.sign == '-')
{
const auto &g(generator.aligned_left(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, integer);
} else {
const auto &g(generator.aligned_right(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, integer);
}
out = data(buf);
return ret;
});
return test(types, [&](const auto type)
{
return visit_type<decltype(type)>(val, closure);
});
}
bool
ircd::fmt::hex_uppercase_specifier::operator()(char *&out,
const size_t &max,
const spec &spec,
const arg &val)
const
{
static const auto throw_illegal{[]
{
throw illegal
{
"Failed to print hexadecimal value"
};
}};
const auto closure([&](const ulong &integer)
{
struct generator
:karma::grammar<char *, ulong()>
{
karma::rule<char *, ulong()> rule
{
karma::upper[karma::hex]
,"unsigned uppercase hexadecimal"
};
_r1_type width;
_r2_type pad;
karma::rule<char *, ulong(ushort, char)> aligned_left
{
karma::left_align(width, pad)[rule]
,"left aligned"
};
karma::rule<char *, ulong(ushort, char)> aligned_right
{
karma::right_align(width, pad)[rule]
,"right aligned"
};
karma::rule<char *, ulong(ushort, char)> aligned_center
{
karma::center(width, pad)[rule]
,"center aligned"
};
generator(): generator::base_type{rule} {}
}
static const generator;
static const auto &ep
{
eps[throw_illegal]
};
bool ret;
mutable_buffer buf
{
out, max
};
if(!spec.width)
ret = fmt::generate(buf, generator | ep, integer);
else if(spec.sign == '-')
{
const auto &g(generator.aligned_left(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, integer);
} else {
const auto &g(generator.aligned_right(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, integer);
}
out = data(buf);
return ret;
});
return test(types, [&](const auto type)
{
return visit_type<decltype(type)>(val, closure);
});
}
//TODO: note long double is narrowed to double for now otherwise
//TODO: valgrind loops somewhere in here and eats all the system's RAM.
bool
ircd::fmt::float_specifier::operator()(char *&out,
const size_t &max,
const spec &spec,
const arg &val)
const
{
static const auto throw_illegal{[]
{
throw illegal
{
"Failed to print floating point value"
};
}};
thread_local uint _precision_;
_precision_ = spec.precision;
const auto closure([&](const double &floating)
{
using karma::double_;
struct generator
:karma::grammar<char *, double()>
{
struct policy
:karma::real_policies<double>
{
static uint precision(const double &)
{
return _precision_;
}
static bool trailing_zeros(const double &)
{
return _precision_ > 0;
}
static int floatfield(const double &)
{
return _precision_ > 0?
fmtflags::fixed:
fmtflags::scientific;
}
};
karma::rule<char *, double()> rule
{
karma::real_generator<double, policy>()
,"floating point real"
};
_r1_type width;
_r2_type pad;
karma::rule<char *, double(ushort, char)> aligned_left
{
karma::left_align(width, pad)[rule]
,"left aligned"
};
karma::rule<char *, double(ushort, char)> aligned_right
{
karma::right_align(width, pad)[rule]
,"right aligned"
};
karma::rule<char *, double(ushort, char)> aligned_center
{
karma::center(width, pad)[rule]
,"center aligned"
};
generator(): generator::base_type{rule} {}
}
static const generator;
static const auto ep
{
eps[throw_illegal]
};
bool ret;
mutable_buffer buf
{
out, max
};
if(!spec.width)
ret = fmt::generate(buf, generator | ep, floating);
else if(spec.sign == '-')
{
const auto &g(generator.aligned_left(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, floating);
} else {
const auto &g(generator.aligned_right(spec.width, spec.pad));
ret = fmt::generate(buf, g | ep, floating);
}
out = data(buf);
return ret;
});
return test(types, [&](const auto type)
{
return visit_type<decltype(type)>(val, closure);
});
}
bool
ircd::fmt::string_specifier::operator()(char *&out,
const size_t &max,
const spec &spec,
const arg &val)
const
{
using karma::char_;
using karma::eps;
using karma::unused_type;
static const auto throw_illegal{[]
{
throw illegal
{
"Not a printable string"
};
}};
struct generator
:karma::grammar<char *, string_view>
{
karma::rule<char *, string_view> string
{
*(~ascii::cntrl)
,"string"
};
_r1_type width;
_r2_type pad;
karma::rule<char *, string_view (ushort, char)> aligned_left
{
karma::left_align(width, pad)[string]
,"left aligned"
};
karma::rule<char *, string_view (ushort, char)> aligned_right
{
karma::right_align(width, pad)[string]
,"right aligned"
};
karma::rule<char *, string_view (ushort, char)> aligned_center
{
karma::center(width, pad)[string]
,"center aligned"
};
generator() :generator::base_type{string} {}
}
static const generator;
static const auto ep
{
eps[throw_illegal]
};
if(!spec.width)
return generate_string(out, max, generator | ep, val);
if(spec.sign == '-')
{
const auto &g(generator.aligned_left(spec.width, spec.pad));
return generate_string(out, max, g | ep, val);
}
const auto &g(generator.aligned_right(spec.width, spec.pad));
return generate_string(out, max, g | ep, val);
}
template<class generator>
bool
ircd::fmt::generate_string(char *&out,
const size_t &max,
generator&& gen,
const arg &val)
{
using karma::eps;
bool ret;
mutable_buffer buf
{
out, max
};
const auto &ptr(get<0>(val));
const auto &type(get<1>(val));
if(type == typeid(ircd::string_view) ||
type == typeid(ircd::json::string) ||
type == typeid(ircd::json::object) ||
type == typeid(ircd::json::array))
{
const auto &str(*static_cast<const ircd::string_view *>(ptr));
ret = fmt::generate(buf, std::forward<generator>(gen), str);
}
else if(type == typeid(std::string_view))
{
const auto &str(*static_cast<const std::string_view *>(ptr));
ret = fmt::generate(buf, std::forward<generator>(gen), str);
}
else if(type == typeid(std::string))
{
const auto &str(*static_cast<const std::string *>(ptr));
ret = fmt::generate(buf, std::forward<generator>(gen), string_view{str});
}
else if(type == typeid(const char *))
{
const char *const &str{*static_cast<const char *const *>(ptr)};
ret = fmt::generate(buf, std::forward<generator>(gen), string_view{str});
} else {
// This for string literals which have unique array types depending on their size.
// There is no reasonable way to match them. The best that can be hoped for is the
// grammar will fail gracefully (most of the time) or not print something bogus when
// it happens to be legal.
const auto &str(static_cast<const char *>(ptr));
ret = fmt::generate(buf, std::forward<generator>(gen), string_view{str});
}
out = data(buf);
return ret;
}