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https://github.com/matrix-construct/construct
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ircd::fmt: snprintf -> category.
This commit is contained in:
Jason Volk
parent
ccac92704d
commit
5dd280bb3b
2 changed files with 99 additions and 80 deletions
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@ -32,7 +32,7 @@ IRCD_EXCEPTION(error, invalid_type);
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IRCD_EXCEPTION(error, illegal);
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//
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// module/internal API
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// Module API
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//
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extern const char SPECIFIER;
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extern const char SPECIFIER_TERMINATOR;
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@ -66,37 +66,52 @@ class specifier
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};
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const std::map<std::string, specifier *> &specifiers();
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ssize_t _snprintf(char *const &, const size_t &, const char *const &, const ptrs &, const types &);
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//
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// public API
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// User API
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//
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// Implementation of the traditional snprintf(), as best as practical:
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// * The arguments are not restricted by va_list limitations. You can pass a real std::string.
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// * The function participates in the custom protocol-safe ruleset, and the behavior is non-standard.
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// To be sure to get truly /standard/ snprintf() behavior use ::snprintf() instead.
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template<class... Args> ssize_t snprintf(char *const &buf, const size_t &max, const char *const &fmt, Args&&... args);
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// * The arguments are not restricted by stdarg limitations. You can pass a real std::string.
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// * The function participates in the custom protocol-safe ruleset.
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class snprintf
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{
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const char *fstart; // Current running position in the fmtstr
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const char *fstop; // Saved state from the last position
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const char *fend; // past-the-end iterator of the fmtstr
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const char *obeg; // Saved beginning of the output buffer
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const char *oend; // past-the-end iterator of the output buffer
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char *out; // Current running position of the output buffer
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short idx; // Keeps count of the args for better err msgs
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protected:
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auto finished() const { return !fstart || fstop >= fend; }
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auto remaining() const { return (oend - out) - 1; }
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auto consumed() const { return size_t(out - obeg); }
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auto &buffer() const { return obeg; }
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void append(const char *const &begin, const char *const &end);
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void argument(const arg &);
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IRCD_OVERLOAD(internal)
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snprintf(internal_t, char *const &, const size_t &, const char *const &, const ptrs &, const types &);
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public:
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operator ssize_t() const { return consumed(); }
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template<class... A>
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snprintf(char *const &buf, const size_t &max, const char *const &fmt, A&&... args);
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};
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template<class... Args>
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ssize_t
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snprintf(char *const &buf,
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const size_t &max,
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const char *const &fmt,
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Args&&... args)
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snprintf::snprintf(char *const &buf,
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const size_t &max,
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const char *const &fmt,
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Args&&... args)
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:snprintf
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{
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internal, buf, max, fmt, ptrs{std::addressof(args)...}, types{typeid(Args)...}
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}
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{
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static const std::vector<std::type_index> types
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{
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typeid(Args)...
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};
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const std::vector<const void *> ptrs
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{
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std::addressof(args)...
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};
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return _snprintf(buf, max, fmt, ptrs, types);
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}
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} // namespace fmt
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116
ircd/fmt.cc
116
ircd/fmt.cc
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@ -210,75 +210,79 @@ fmt::parse::grammar<it, top>::grammar(qi::rule<it, top> &top_rule)
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})];
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}
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ssize_t
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fmt::_snprintf(char *const &buf,
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const size_t &max,
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const char *const &fmt,
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const ptrs &p,
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const types &t)
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fmt::snprintf::snprintf(internal_t,
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char *const &out,
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const size_t &max,
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const char *const &fstr,
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const ptrs &p,
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const types &t)
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try
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:fstart{strchr(fstr, SPECIFIER)}
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,fstop{fstr}
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,fend{fstr + strlen(fstr)}
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,obeg{out}
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,oend{out + max}
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,out{out}
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,idx{0}
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{
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if(unlikely(!max))
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return 0;
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char *out(buf); // Always points at next place to write
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const char *stop(fmt); // Saves the 'last' place to copy a literal from
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const char *start(strchr(fmt, SPECIFIER)); // The running position of the format string parse
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const char *const end(fmt + strlen(fmt)); // The end of the format string
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// Calculates remaining room in output buffer
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const auto remaining([&max, &buf, &out]() -> size_t
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{
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return max - std::distance(buf, out) - 1;
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});
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// Copies string data between format specifiers.
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const auto copy_literal([&stop, &out, &remaining]
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(const char *const &end)
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{
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const size_t len(std::distance(stop, end));
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const size_t &cpsz(std::min(len, remaining()));
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memcpy(out, stop, cpsz);
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out += cpsz;
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});
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size_t index(0); // The current position for vectors p and t (specifier count)
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for(; start; stop = start++, start = start < end? strchr(start, SPECIFIER) : nullptr)
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{
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// Copy literal data from where the last parse stopped up to the found specifier
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copy_literal(start);
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// Instantiate the format specifier grammar
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struct parser
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:parse::grammar<const char *, fmt::spec>
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{
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parser(): grammar{grammar::spec} {}
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}
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static const parser;
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// Parse the specifier with the grammar
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fmt::spec spec;
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if(!qi::parse(start, end, parser, spec))
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continue;
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// Throws if the format string has more specifiers than arguments.
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const arg val{p.at(index), t.at(index)};
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handle_specifier(out, remaining(), index, spec, val);
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index++;
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fstart = nullptr;
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return;
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}
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// If the end of the string is not a format specifier itself, it needs to be copied
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if(!start)
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copy_literal(end);
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if(!fstart)
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{
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append(fstr, fend);
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return;
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}
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*out = '\0';
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return std::distance(buf, out);
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append(fstr, fstart);
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for(size_t i(0); i < p.size(); ++i)
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argument(arg{p.at(i), t.at(i)});
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}
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catch(const std::out_of_range &e)
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{
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throw invalid_format("Format string requires more than %zu arguments.", p.size());
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}
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void
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fmt::snprintf::argument(const arg &val)
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{
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struct parser
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:parse::grammar<const char *, fmt::spec>
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{
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parser(): grammar{grammar::spec} {}
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}
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static const parser;
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if(finished())
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return;
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fmt::spec spec;
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if(qi::parse(fstart, fend, parser, spec))
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handle_specifier(out, remaining(), idx++, spec, val);
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fstop = fstart++;
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if(fstop < fend)
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{
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fstart = strchr(fstart, SPECIFIER);
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append(fstop, fstart?: fend);
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}
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else *out = '\0';
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}
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void
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fmt::snprintf::append(const char *const &begin,
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const char *const &end)
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{
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const size_t len(std::distance(begin, end));
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const size_t &cpsz(std::min(len, size_t(remaining())));
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memcpy(out, begin, cpsz);
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out += cpsz;
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*out = '\0';
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}
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const decltype(fmt::_specifiers) &
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fmt::specifiers()
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{
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