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Optimize format string parsing

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This commit is contained in:
Victor Zverovich 2020-06-06 07:13:38 -07:00
parent 09737dd83b
commit f11e968708
5 changed files with 68 additions and 71 deletions
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40
include/fmt/compile.h
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@ -62,13 +62,15 @@ template <typename Char> struct part_counter {
if (begin != end) ++num_parts;
}
FMT_CONSTEXPR void on_arg_id() { ++num_parts; }
FMT_CONSTEXPR void on_arg_id(int) { ++num_parts; }
FMT_CONSTEXPR void on_arg_id(basic_string_view<Char>) { ++num_parts; }
FMT_CONSTEXPR int on_arg_id() { return ++num_parts, 0; }
FMT_CONSTEXPR int on_arg_id(int) { return ++num_parts, 0; }
FMT_CONSTEXPR int on_arg_id(basic_string_view<Char>) {
return ++num_parts, 0;
}
FMT_CONSTEXPR void on_replacement_field(const Char*) {}
FMT_CONSTEXPR void on_replacement_field(int, const Char*) {}
FMT_CONSTEXPR const Char* on_format_specs(const Char* begin,
FMT_CONSTEXPR const Char* on_format_specs(int, const Char* begin,
const Char* end) {
// Find the matching brace.
unsigned brace_counter = 0;
@ -116,25 +118,28 @@ class format_string_compiler : public error_handler {
handler_(part::make_text({begin, to_unsigned(end - begin)}));
}
FMT_CONSTEXPR void on_arg_id() {
FMT_CONSTEXPR int on_arg_id() {
part_ = part::make_arg_index(parse_context_.next_arg_id());
return 0;
}
FMT_CONSTEXPR void on_arg_id(int id) {
FMT_CONSTEXPR int on_arg_id(int id) {
parse_context_.check_arg_id(id);
part_ = part::make_arg_index(id);
return 0;
}
FMT_CONSTEXPR void on_arg_id(basic_string_view<Char> id) {
FMT_CONSTEXPR int on_arg_id(basic_string_view<Char> id) {
part_ = part::make_arg_name(id);
return 0;
}
FMT_CONSTEXPR void on_replacement_field(const Char* ptr) {
FMT_CONSTEXPR void on_replacement_field(int, const Char* ptr) {
part_.arg_id_end = ptr;
handler_(part_);
}
FMT_CONSTEXPR const Char* on_format_specs(const Char* begin,
FMT_CONSTEXPR const Char* on_format_specs(int, const Char* begin,
const Char* end) {
auto repl = typename part::replacement();
dynamic_specs_handler<basic_format_parse_context<Char>> handler(
@ -165,16 +170,15 @@ void format_arg(
basic_format_parse_context<typename Context::char_type>& parse_ctx,
Context& ctx, Id arg_id) {
ctx.advance_to(visit_format_arg(
arg_formatter<OutputIt, typename Context::char_type>(
ctx, &parse_ctx),
arg_formatter<OutputIt, typename Context::char_type>(ctx, &parse_ctx),
ctx.arg(arg_id)));
}
// vformat_to is defined in a subnamespace to prevent ADL.
namespace cf {
template <typename Context, typename OutputIt, typename CompiledFormat>
auto vformat_to(OutputIt out, CompiledFormat& cf, basic_format_args<Context> args)
-> typename Context::iterator {
auto vformat_to(OutputIt out, CompiledFormat& cf,
basic_format_args<Context> args) -> typename Context::iterator {
using char_type = typename Context::char_type;
basic_format_parse_context<char_type> parse_ctx(
to_string_view(cf.format_str_));
@ -227,10 +231,10 @@ auto vformat_to(OutputIt out, CompiledFormat& cf, basic_format_args<Context> arg
if (specs.precision >= 0) checker.check_precision();
advance_to(parse_ctx, part.arg_id_end);
ctx.advance_to(visit_format_arg(
arg_formatter<OutputIt, typename Context::char_type>(
ctx, nullptr, &specs),
arg));
ctx.advance_to(
visit_format_arg(arg_formatter<OutputIt, typename Context::char_type>(
ctx, nullptr, &specs),
arg));
break;
}
}

59
include/fmt/format.h
View File

@ -2466,15 +2466,17 @@ inline bool find<false, char>(const char* first, const char* last, char value,
}
template <typename Handler, typename Char> struct id_adapter {
FMT_CONSTEXPR void operator()() { handler.on_arg_id(); }
FMT_CONSTEXPR void operator()(int id) { handler.on_arg_id(id); }
Handler& handler;
int arg_id;
FMT_CONSTEXPR void operator()() { arg_id = handler.on_arg_id(); }
FMT_CONSTEXPR void operator()(int id) { arg_id = handler.on_arg_id(id); }
FMT_CONSTEXPR void operator()(basic_string_view<Char> id) {
handler.on_arg_id(id);
arg_id = handler.on_arg_id(id);
}
FMT_CONSTEXPR void on_error(const char* message) {
handler.on_error(message);
}
Handler& handler;
};
template <bool IS_CONSTEXPR, typename Char, typename Handler>
@ -2508,17 +2510,17 @@ FMT_CONSTEXPR_DECL FMT_INLINE void parse_format_string(
++p;
if (p == end) return handler.on_error("invalid format string");
if (static_cast<char>(*p) == '}') {
handler.on_arg_id();
handler.on_replacement_field(p);
handler.on_replacement_field(handler.on_arg_id(), p);
} else if (*p == '{') {
handler.on_text(p, p + 1);
} else {
p = parse_arg_id(p, end, id_adapter<Handler, Char>{handler});
auto adapter = id_adapter<Handler, Char>{handler, 0};
p = parse_arg_id(p, end, adapter);
Char c = p != end ? *p : Char();
if (c == '}') {
handler.on_replacement_field(p);
handler.on_replacement_field(adapter.arg_id, p);
} else if (c == ':') {
p = handler.on_format_specs(p + 1, end);
p = handler.on_format_specs(adapter.arg_id, p + 1, end);
if (p == end || *p != '}')
return handler.on_error("unknown format specifier");
} else {
@ -2548,7 +2550,6 @@ template <typename ArgFormatter, typename Char, typename Context>
struct format_handler : detail::error_handler {
basic_format_parse_context<Char> parse_context;
Context context;
int arg_id;
format_handler(typename ArgFormatter::iterator out,
basic_string_view<Char> str,
@ -2563,23 +2564,20 @@ struct format_handler : detail::error_handler {
context.advance_to(out);
}
void on_arg_id() { arg_id = parse_context.next_arg_id(); }
void on_arg_id(int id) {
parse_context.check_arg_id(id);
arg_id = id;
}
void on_arg_id(basic_string_view<Char> id) { arg_id = context.arg_id(id); }
int on_arg_id() { return parse_context.next_arg_id(); }
int on_arg_id(int id) { return parse_context.check_arg_id(id), id; }
int on_arg_id(basic_string_view<Char> id) { return context.arg_id(id); }
void on_replacement_field(const Char* p) {
void on_replacement_field(int id, const Char* p) {
advance_to(parse_context, p);
auto arg = get_arg(context, arg_id);
auto arg = get_arg(context, id);
context.advance_to(
visit_format_arg(ArgFormatter(context, &parse_context), arg));
}
const Char* on_format_specs(const Char* begin, const Char* end) {
const Char* on_format_specs(int id, const Char* begin, const Char* end) {
advance_to(parse_context, begin);
auto arg = get_arg(context, arg_id);
auto arg = get_arg(context, id);
detail::custom_formatter<Context> f(parse_context, context);
if (visit_format_arg(f, arg)) return parse_context.begin();
basic_format_specs<Char> specs;
@ -2632,26 +2630,24 @@ class format_string_checker {
public:
explicit FMT_CONSTEXPR format_string_checker(
basic_string_view<Char> format_str, ErrorHandler eh)
: arg_id_(-1),
context_(format_str, num_args, eh),
: context_(format_str, num_args, eh),
parse_funcs_{&parse_format_specs<Args, parse_context_type>...} {}
FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
FMT_CONSTEXPR void on_arg_id() { arg_id_ = context_.next_arg_id(); }
FMT_CONSTEXPR void on_arg_id(int id) {
arg_id_ = id;
context_.check_arg_id(id);
}
FMT_CONSTEXPR void on_arg_id(basic_string_view<Char>) {
FMT_CONSTEXPR int on_arg_id() { return context_.next_arg_id(); }
FMT_CONSTEXPR int on_arg_id(int id) { return context_.check_arg_id(id), id; }
FMT_CONSTEXPR int on_arg_id(basic_string_view<Char>) {
on_error("compile-time checks don't support named arguments");
return 0;
}
FMT_CONSTEXPR void on_replacement_field(const Char*) {}
FMT_CONSTEXPR void on_replacement_field(int, const Char*) {}
FMT_CONSTEXPR const Char* on_format_specs(const Char* begin, const Char*) {
FMT_CONSTEXPR const Char* on_format_specs(int id, const Char* begin,
const Char*) {
advance_to(context_, begin);
return arg_id_ < num_args ? parse_funcs_[arg_id_](context_) : begin;
return id < num_args ? parse_funcs_[id](context_) : begin;
}
FMT_CONSTEXPR void on_error(const char* message) {
@ -2665,7 +2661,6 @@ class format_string_checker {
// Format specifier parsing function.
using parse_func = const Char* (*)(parse_context_type&);
int arg_id_;
parse_context_type context_;
parse_func parse_funcs_[num_args > 0 ? num_args : 1];
};

20
test/format
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@ -596,23 +596,20 @@ struct format_handler : detail::error_handler {
context.advance_to(out);
}
void on_arg_id() {
arg = context.arg(parse_ctx.next_arg_id());
}
void on_arg_id(unsigned id) {
parse_ctx.check_arg_id(id);
arg = context.arg(id);
}
void on_arg_id(fmt::basic_string_view<Char>) {}
int on_arg_id() { return parse_ctx.next_arg_id(); }
int on_arg_id(unsigned id) { return parse_ctx.check_arg_id(id), id; }
int on_arg_id(fmt::basic_string_view<Char>) { return 0; }
void on_replacement_field(const Char* p) {
parse_ctx.advance_to(parse_ctx.begin() + (p - &*parse_ctx.begin()));
void on_replacement_field(int id, const Char* p) {
auto arg = context.arg(id);
parse_ctx.advance_to(parse_ctx.begin() + (p - &*parse_ctx.begin()));
custom_formatter<Context> f(parse_ctx, context);
if (!visit_format_arg(f, arg))
context.advance_to(visit_format_arg(ArgFormatter(context, &parse_ctx), arg));
}
const Char* on_format_specs(const Char* begin, const Char* end) {
const Char* on_format_specs(int id, const Char* begin, const Char* end) {
auto arg = context.arg(id);
parse_ctx.advance_to(parse_ctx.begin() + (begin - &*parse_ctx.begin()));
custom_formatter<Context> f(parse_ctx, context);
if (visit_format_arg(f, arg)) return &*parse_ctx.begin();
@ -630,7 +627,6 @@ struct format_handler : detail::error_handler {
basic_format_parse_context<Char> parse_ctx;
Context context;
basic_format_arg<Context> arg;
};
template <typename T, typename Char>

9
test/format-test.cc
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@ -2223,13 +2223,14 @@ TEST(FormatTest, ConstexprSpecsChecker) {
struct test_format_string_handler {
FMT_CONSTEXPR void on_text(const char*, const char*) {}
FMT_CONSTEXPR void on_arg_id() {}
FMT_CONSTEXPR int on_arg_id() { return 0; }
template <typename T> FMT_CONSTEXPR void on_arg_id(T) {}
template <typename T> FMT_CONSTEXPR int on_arg_id(T) { return 0; }
FMT_CONSTEXPR void on_replacement_field(const char*) {}
FMT_CONSTEXPR void on_replacement_field(int, const char*) {}
FMT_CONSTEXPR const char* on_format_specs(const char* begin, const char*) {
FMT_CONSTEXPR const char* on_format_specs(int, const char* begin,
const char*) {
return begin;
}

11
test/scan.h
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@ -169,14 +169,15 @@ struct scan_handler : error_handler {
scan_ctx_.advance_to(it + size);
}
void on_arg_id() { on_arg_id(next_arg_id_++); }
void on_arg_id(int id) {
int on_arg_id() { return on_arg_id(next_arg_id_++); }
int on_arg_id(int id) {
if (id >= args_.size) on_error("argument index out of range");
arg_ = args_.data[id];
return id;
}
void on_arg_id(string_view) { on_error("invalid format"); }
int on_arg_id(string_view) { return on_error("invalid format"), 0; }
void on_replacement_field(const char*) {
void on_replacement_field(int, const char*) {
auto it = scan_ctx_.begin(), end = scan_ctx_.end();
switch (arg_.type) {
case scan_type::int_type:
@ -208,7 +209,7 @@ struct scan_handler : error_handler {
}
}
const char* on_format_specs(const char* begin, const char*) {
const char* on_format_specs(int, const char* begin, const char*) {
if (arg_.type != scan_type::custom_type) return begin;
parse_ctx_.advance_to(begin);
arg_.custom.scan(arg_.custom.value, parse_ctx_, scan_ctx_);