generator.c: Optimize by combining calls to fbuffer_append

Author: LukeShu

ext/json/ext/generator/generator.c

@@ -43,7 +43,7 @@ static void convert_UTF8_to_JSON(FBuffer *out_buffer, VALUE in_string, bool out_
  unsigned long in_utf8_len = RSTRING_LEN(in_string);
  bool in_is_ascii_only = rb_enc_str_asciionly_p(in_string);
 
- unsigned long pos;
+ unsigned long beg = 0, pos;
 
  for (pos = 0; pos < in_utf8_len;) {
  uint32_t ch;
@@ -89,6 +89,9 @@ static void convert_UTF8_to_JSON(FBuffer *out_buffer, VALUE in_string, bool out_
 
  /* JSON encoding */
  if (should_escape) {
+ if (pos > beg)
+ fbuffer_append(out_buffer, &in_utf8_str[beg], pos - beg);
+ beg = pos + ch_len;
  switch (ch) {
  case '"': fbuffer_append(out_buffer, "\\\"", 2); break;
  case '\\': fbuffer_append(out_buffer, "\\\\", 2); break;
@@ -124,12 +127,12 @@ static void convert_UTF8_to_JSON(FBuffer *out_buffer, VALUE in_string, bool out_
  fbuffer_append(out_buffer, scratch, 12);
  }
  }
- } else {
- fbuffer_append(out_buffer, &in_utf8_str[pos], ch_len);
  }
 
  pos += ch_len;
  }
+ if (beg < in_utf8_len)
+ fbuffer_append(out_buffer, &in_utf8_str[beg], in_utf8_len - beg);
  RB_GC_GUARD(in_string);
 }