upb/lex/round_trip.c

// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

#include "upb/lex/round_trip.h"

#include <float.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

// Must be last.
#include "upb/port/def.inc"

/* Miscellaneous utilities ****************************************************/

static void upb_FixLocale(char* p) {
  /* printf() is dependent on locales; sadly there is no easy and portable way
   * to avoid this. This little post-processing step will translate 1,2 -> 1.2
   * since JSON needs the latter. Arguably a hack, but it is simple and the
   * alternatives are far more complicated, platform-dependent, and/or larger
   * in code size. */
  for (; *p; p++) {
    if (*p == ',') *p = '.';
  }
}

void _upb_EncodeRoundTripDouble(double val, char* buf, size_t size) {
  assert(size >= kUpb_RoundTripBufferSize);
  if (isnan(val)) {
    snprintf(buf, size, "%s", "nan");
    return;
  }
  snprintf(buf, size, "%.*g", DBL_DIG, val);
  if (strtod(buf, NULL) != val) {
    snprintf(buf, size, "%.*g", DBL_DIG + 2, val);
    assert(strtod(buf, NULL) == val);
  }
  upb_FixLocale(buf);
}

void _upb_EncodeRoundTripFloat(float val, char* buf, size_t size) {
  assert(size >= kUpb_RoundTripBufferSize);
  if (isnan(val)) {
    snprintf(buf, size, "%s", "nan");
    return;
  }
  snprintf(buf, size, "%.*g", FLT_DIG, val);
  if (strtof(buf, NULL) != val) {
    snprintf(buf, size, "%.*g", FLT_DIG + 3, val);
    assert(strtof(buf, NULL) == val);
  }
  upb_FixLocale(buf);
}