Function MaskSubStr

be/src/exprs/mask-functions-ir.cc:96–111

Mask the substring in range [start, end) of the given string value. Using rules in 'MaskTransform'. Indices are counted in bytes.

/// Mask the substring in range [start, end) of the given string value. Using rules in
/// 'MaskTransform'. Indices are counted in bytes.
static StringVal MaskSubStr(FunctionContext* ctx, const StringVal& val,
    int start, int end, int masked_upper_char, int masked_lower_char,
    int masked_digit_char, int masked_other_char) {
  DCHECK_GE(start, 0);
  DCHECK_LT(start, end);
  DCHECK_LE(end, val.len);
  StringVal result(ctx, val.len);
  if (UNLIKELY(result.is_null)) return StringVal::null();
  Ubsan::MemCpy(result.ptr, val.ptr, start);
  if (end < val.len) Ubsan::MemCpy(result.ptr + end, val.ptr + end, val.len - end);
  for (int i = start; i < end; ++i) {
    result.ptr[i] = MaskTransform(val.ptr[i], masked_upper_char, masked_lower_char,
        masked_digit_char, masked_other_char);
  }
  return result;
}

/// Checks whether the unicode code point is malformed, i.e. illegal or incomplete, and
/// warns if it is. Returns true if any warning is added.