Method BuildExpression

library/cpp/expression/expression.cpp:557–710

};

size_t TExpressionImpl::BuildExpression(TStringBuf str) {
    TStack<TFrame> stk;
    stk.push({str, Operations.size()});

    size_t result = 0;

    while (!stk.empty()) {
        auto& frame = stk.top();

        if (!frame.Processed) {
            TStringBuf s = StripString(frame.Str);
            frame.Order = Operations.size();
            frame.Processed = true;

            std::array<TStringBuf, MaxOperands> args;
            size_t numArgs = FindOperation(s, args, frame.Operation);
            if (numArgs) {
                Operations.push_back(TOperator(frame.Operation));
                frame.NumArgs = numArgs;
                frame.Args = TVector<TStringBuf>(args.begin(), args.begin() + numArgs);
                frame.ArgIndex = 0;
                frame.ArgResults.clear();
                stk.emplace(frame.Args[0], Operations.size());
                continue;
            } else if (s.size() == 0) {
                Operations.push_back(TOperator(O_TOKEN));
                Operations[frame.Order].Input.push_back(InsertOrUpdate(Tokens, ToString(s)));
                result = frame.Order;
                stk.pop();
                continue;
            } else if (s[0] == '(') {
                Y_ENSURE(s.back() == ')', "CalcExpression error: missing closing bracket.");
                stk.emplace(s.substr(1, s.size() - 2), Operations.size());
                continue;
            } else if (s[0] == '"') {
                Y_ENSURE(s.back() == '"' && s.size() >= 2, "CalcExpression error: missing closing quote.");
                Operations.push_back(TOperator(O_CONST));
                Operations[frame.Order].Input.push_back(InsertOrUpdate(Consts, ToString(s.substr(1, s.size() - 2))));
                result = frame.Order;
                stk.pop();
                continue;
            } else if (s[0] == '\'') {
                Y_ENSURE(s.back() == '\'' && s.size() >= 2, "CalcExpression error: missing closing singular quote.");
                Operations.push_back(TOperator(O_TOKEN));
                Operations[frame.Order].Input.push_back(InsertOrUpdate(Tokens, ToString(s.substr(1, s.size() - 2))));
                result = frame.Order;
                stk.pop();
                continue;
            } else if (s[0] == '-') {
                Operations.push_back(TOperator(O_MINUS));
                frame.Args = {s.substr(1)};
                frame.ArgIndex = 0;
                frame.NumArgs = 1;
                frame.ArgResults.clear();
                stk.emplace(frame.Args[0], Operations.size());
                continue;
            } else if (s[0] == '!') {
                Operations.push_back(TOperator(O_NOT));