Function evaluate

plugins/prefetch/evaluate.cc:231–316

* @brief Evaluate a math addition or subtraction expression. * * @param v string containing an expression, i.e. "3 + 4" * @return string containing the result, i.e. "7" */

 * @return string containing the result, i.e. "7"
 */
String
evaluate(const StringView view, const EvalPolicy policy)
{
  if (view.empty()) {
    return String("");
  }

  // short circuit
  if (policy == EvalPolicy::Bignum) {
    return evaluateBignum(view);
  }

  StringView v = view;

  /* Find out if width is specified (hence leading zeros are required if the width is bigger then the result width) */
  String                stmt;
  uint32_t              len = 0;
  StringView::size_type pos = v.find_first_of(':');
  if (v.npos != pos) {
    stmt.assign(v.substr(0, pos));
    std::istringstream iss(stmt);
    iss >> len;
    v = v.substr(pos + 1);
  }
  PrefetchDebug("statement: '%s', formatting length: %" PRIu32, stmt.c_str(), len);

  uint64_t result = 0;
  pos             = v.find_first_of("+-");

  if (v.npos == pos) {
    stmt.assign(v.substr(0, pos));
    std::istringstream iss(stmt);

    if (policy == EvalPolicy::Overflow64) {
      iss >> result;
    } else {
      uint32_t tmp32;
      iss >> tmp32;
      result = tmp32;
    }

    PrefetchDebug("Single-operand expression: %s -> %" PRIu64, stmt.c_str(), result);
  } else {
    const String       leftOperand(v.substr(0, pos));
    std::istringstream liss(leftOperand);
    uint64_t           a64 = 0;

    if (policy == EvalPolicy::Overflow64) {
      liss >> a64;
    } else {
      uint32_t a32;
      liss >> a32;
      a64 = a32;
    }
    PrefetchDebug("Left-operand expression: %s -> %" PRIu64, leftOperand.c_str(), a64);

    const String       rightOperand(v.substr(pos + 1));
    std::istringstream riss(rightOperand);