much better integer formatting (less stack space, better precision handling)
parent
baf0dd4ca6
commit
e5a21382af
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@ -142,7 +142,8 @@ int main() {
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writefln(
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"\"%d\", \"%f\", \"%X\"", 123456789, 12345.6789123, 0x123456789ABCDEF
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);
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cout.imbue(std::locale{""});
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std::locale::global(std::locale{""});
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cout.imbue(std::locale{});
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writefln("\n-- number format with system locale --");
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writefln(
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"\"%d\", \"%f\", \"%X\"", 123456789, 12345.6789123, 0x123456789ABCDEF
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121
ostd/format.hh
121
ostd/format.hh
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@ -1017,9 +1017,9 @@ private:
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template<typename R, typename T>
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void write_int(R &writer, bool ptr, bool neg, T val) const {
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/* binary representation is the biggest, assume grouping */
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char buf[sizeof(T) * CHAR_BIT * (detail::MaxMultibyte + 1)];
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std::size_t n = 0;
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/* binary representation is the longest */
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char buf[sizeof(T) * CHAR_BIT];
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std::size_t ndig = 0;
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char isp = spec();
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if (isp == 's') {
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@ -1033,46 +1033,56 @@ private:
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int cmask = ((isp >= 'a') << 5);
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int base = detail::fmt_bases[specn];
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bool zval = !val;
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if (zval) {
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buf[n++] = '0';
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if (!val) {
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ndig = 1;
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buf[0] = '0';
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} else {
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for (; val; val /= base) {
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T vb = val % base;
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buf[ndig++] = (vb + "70"[vb < 10]) | cmask;
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}
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}
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/* this is bullshit */
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auto const &fac = std::use_facet<std::numpunct<wchar_t>>(p_loc);
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auto const &grp = fac.grouping();
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char tseps[detail::MaxMultibyte];
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int ntsep = wctomb(tseps, fac.thousands_sep());
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auto grpp = reinterpret_cast<unsigned char const *>(grp.data());
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unsigned char grpn = *grpp;
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for (; val; val /= base) {
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if (!ptr && *grpp) {
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if (!grpn) {
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for (int i = ntsep - 1; i >= 0; --i) {
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buf[n++] = tseps[i];
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}
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if (*(grpp + 1)) {
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++grpp;
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}
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grpn = *grpp;
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}
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if (grpn) {
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--grpn;
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}
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}
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T vb = val % base;
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buf[n++] = (vb + "70"[vb < 10]) | cmask;
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}
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std::size_t tn = n;
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std::size_t tdig = ndig;
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if (has_precision()) {
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int prec = precision();
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if (std::size_t(prec) > tn) {
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tn = std::size_t(prec);
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} else if (!prec && zval) {
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tn = 0;
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if (std::size_t(prec) > tdig) {
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tdig = std::size_t(prec);
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} else if (!prec && !val) {
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tdig = 0;
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}
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}
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/* here starts the bullshit */
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auto const &fac = std::use_facet<std::numpunct<wchar_t>>(p_loc);
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char tseps[detail::MaxMultibyte];
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int ntsep = wctomb(tseps, fac.thousands_sep());
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auto const &grp = fac.grouping();
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auto grpp = reinterpret_cast<unsigned char const *>(grp.data());
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std::size_t nseps = 0, sreps = 0;
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std::size_t total = tdig;
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if (!ptr && (ntsep >= 0)) {
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int cndig = int(ndig);
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while (*grpp) {
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cndig -= *grpp;
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if (cndig > 0) {
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++nseps;
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if (!grpp[1]) {
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++sreps;
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continue;
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}
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} else {
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break;
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}
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++grpp;
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}
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total += nseps * ntsep;
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}
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/* here ends the bullshit */
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int fl = flags();
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bool lsgn = fl & FMT_FLAG_PLUS;
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bool lsp = fl & FMT_FLAG_SPACE;
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@ -1084,28 +1094,53 @@ private:
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pfx = ("XB"[(specn == 3)]) | cmask;
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}
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/* leading spaces if they apply */
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if (!zero) {
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write_spaces(writer, tn + (!!pfx * 2) + sign, true, ' ');
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write_spaces(writer, total + (!!pfx * 2) + sign, true, ' ');
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}
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/* sign (either forced or a minus) */
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if (sign) {
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writer.put(neg ? '-' : *((" \0+") + lsgn * 2));
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}
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/* prefix such as 0x */
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if (pfx) {
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writer.put('0');
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writer.put(pfx);
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}
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/* if we chose to pad with leading zeroes instead */
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if (zero) {
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write_spaces(writer, tn + (!!pfx * 2) + sign, true, '0');
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write_spaces(writer, total + (!!pfx * 2) + sign, true, '0');
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}
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if (tn) {
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for (std::size_t i = 0; i < (tn - n); ++i) {
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/* number itself (with potential thousands grouping) */
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if (total) {
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/* potential higher precision, no grouping applies */
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for (std::size_t i = 0; i < (tdig - ndig); ++i) {
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writer.put('0');
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}
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for (std::size_t i = 0; i < n; ++i) {
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writer.put(buf[n - i - 1]);
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/* the rest of the number, with thousands grouping */
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unsigned char grpn = *grpp;
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for (std::size_t i = 0; i < ndig; ++i) {
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if (nseps) {
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if (!grpn) {
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for (int j = 0; j < ntsep; ++j) {
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writer.put(tseps[j]);
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}
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if (sreps) {
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--sreps;
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} else {
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--grpp;
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}
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grpn = *grpp;
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--nseps;
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}
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if (grpn) {
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--grpn;
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}
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}
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writer.put(buf[ndig - i - 1]);
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}
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}
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write_spaces(writer, tn + sign + (!!pfx * 2), false);
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write_spaces(writer, total + sign + (!!pfx * 2), false);
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}
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/* floating point */
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