diff options
Diffstat (limited to 'absl/strings/internal/str_format/parser.cc')
| -rw-r--r-- | absl/strings/internal/str_format/parser.cc | 75 |
1 files changed, 45 insertions, 30 deletions
diff --git a/absl/strings/internal/str_format/parser.cc b/absl/strings/internal/str_format/parser.cc index c3e16fceb15e..5e3d0d0547d1 100644 --- a/absl/strings/internal/str_format/parser.cc +++ b/absl/strings/internal/str_format/parser.cc @@ -84,16 +84,24 @@ bool ConsumeConversion(string_view *src, UnboundConversion *conv, const char *pos = src->data(); const char *const end = pos + src->size(); char c; - // Read the next char into `c` and update `pos`. Reads '\0' if at end. - const auto get_char = [&] { c = pos == end ? '\0' : *pos++; }; + // Read the next char into `c` and update `pos`. Returns false if there are + // no more chars to read. +#define ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR() \ + do { \ + if (ABSL_PREDICT_FALSE(pos == end)) return false; \ + c = *pos++; \ + } while (0) const auto parse_digits = [&] { int digits = c - '0'; - // We do not want to overflow `digits` so we consume at most digits10-1 + // We do not want to overflow `digits` so we consume at most digits10 // digits. If there are more digits the parsing will fail later on when the // digit doesn't match the expected characters. - int num_digits = std::numeric_limits<int>::digits10 - 2; - for (get_char(); num_digits && std::isdigit(c); get_char()) { + int num_digits = std::numeric_limits<int>::digits10; + for (;;) { + if (ABSL_PREDICT_FALSE(pos == end || !num_digits)) break; + c = *pos++; + if (!std::isdigit(c)) break; --num_digits; digits = 10 * digits + c - '0'; } @@ -101,14 +109,14 @@ bool ConsumeConversion(string_view *src, UnboundConversion *conv, }; if (is_positional) { - get_char(); - if (c < '1' || c > '9') return false; + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); + if (ABSL_PREDICT_FALSE(c < '1' || c > '9')) return false; conv->arg_position = parse_digits(); assert(conv->arg_position > 0); - if (c != '$') return false; + if (ABSL_PREDICT_FALSE(c != '$')) return false; } - get_char(); + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); // We should start with the basic flag on. assert(conv->flags.basic); @@ -119,32 +127,39 @@ bool ConsumeConversion(string_view *src, UnboundConversion *conv, if (c < 'A') { conv->flags.basic = false; - for (; c <= '0'; get_char()) { + for (; c <= '0';) { + // FIXME: We might be able to speed this up reusing the kIds lookup table + // from above. + // It might require changing Flags to be a plain integer where we can |= a + // value. switch (c) { case '-': conv->flags.left = true; - continue; + break; case '+': conv->flags.show_pos = true; - continue; + break; case ' ': conv->flags.sign_col = true; - continue; + break; case '#': conv->flags.alt = true; - continue; + break; case '0': conv->flags.zero = true; - continue; + break; + default: + goto flags_done; } - break; + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); } +flags_done: if (c <= '9') { if (c >= '0') { int maybe_width = parse_digits(); if (!is_positional && c == '$') { - if (*next_arg != 0) return false; + if (ABSL_PREDICT_FALSE(*next_arg != 0)) return false; // Positional conversion. *next_arg = -1; conv->flags = Flags(); @@ -153,12 +168,12 @@ bool ConsumeConversion(string_view *src, UnboundConversion *conv, } conv->width.set_value(maybe_width); } else if (c == '*') { - get_char(); + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); if (is_positional) { - if (c < '1' || c > '9') return false; + if (ABSL_PREDICT_FALSE(c < '1' || c > '9')) return false; conv->width.set_from_arg(parse_digits()); - if (c != '$') return false; - get_char(); + if (ABSL_PREDICT_FALSE(c != '$')) return false; + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); } else { conv->width.set_from_arg(++*next_arg); } @@ -166,16 +181,16 @@ bool ConsumeConversion(string_view *src, UnboundConversion *conv, } if (c == '.') { - get_char(); + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); if (std::isdigit(c)) { conv->precision.set_value(parse_digits()); } else if (c == '*') { - get_char(); + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); if (is_positional) { - if (c < '1' || c > '9') return false; + if (ABSL_PREDICT_FALSE(c < '1' || c > '9')) return false; conv->precision.set_from_arg(parse_digits()); if (c != '$') return false; - get_char(); + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); } else { conv->precision.set_from_arg(++*next_arg); } @@ -188,23 +203,23 @@ bool ConsumeConversion(string_view *src, UnboundConversion *conv, std::int8_t id = kIds[static_cast<unsigned char>(c)]; if (id < 0) { - if (id == none) return false; + if (ABSL_PREDICT_FALSE(id == none)) return false; // It is a length modifier. using str_format_internal::LengthMod; LengthMod length_mod = LengthMod::FromId(static_cast<LM>(~id)); - get_char(); + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); if (c == 'h' && length_mod.id() == LengthMod::h) { conv->length_mod = LengthMod::FromId(LengthMod::hh); - get_char(); + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); } else if (c == 'l' && length_mod.id() == LengthMod::l) { conv->length_mod = LengthMod::FromId(LengthMod::ll); - get_char(); + ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR(); } else { conv->length_mod = length_mod; } id = kIds[static_cast<unsigned char>(c)]; - if (id < 0) return false; + if (ABSL_PREDICT_FALSE(id < 0)) return false; } assert(CheckFastPathSetting(*conv)); |