cpp

// cpp/qsn.h

#ifndef QSN_H

#define QSN_H

#include "mycpp/runtime.h"

namespace qsn {

inline bool IsUnprintableLow(Str* ch) {

  assert(len(ch) == 1);

  return ch->data_[0] < ' ';

}

inline bool IsUnprintableHigh(Str* ch) {

  assert(len(ch) == 1);

  // 255 should not be -1!

  // log("ch->data_[0] %d", ch->data_[0]);

  unsigned char c = static_cast<unsigned char>(ch->data_[0]);

  return c >= 0x7f;

}

inline bool IsPlainChar(Str* ch) {

  assert(len(ch) == 1);

  uint8_t c = ch->data_[0];

  switch (c) {

  case '.':

  case '-':

  case '_':

    return true;

  }

  return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') ||

         ('0' <= c && c <= '9');

}

inline Str* XEscape(Str* ch) {

  assert(len(ch) == 1);

  Str* result = NewStr(4);

  sprintf(result->data(), "\\x%02x", ch->data_[0] & 0xff);

  return result;

}

inline Str* UEscape(int codepoint) {

  // maximum length:

  // 3 for \u{

  // 6 for codepoint

  // 1 for }

  Str* result = OverAllocatedStr(10);

  int n = sprintf(result->data(), "\\u{%x}", codepoint);

  result->MaybeShrink(n);  // truncate to what we wrote

  return result;

}

}  // namespace qsn

#endif  // QSN_H