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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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59
include/fmt/format.h
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@@ -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];
};