Method FindOperation

library/cpp/expression/expression.cpp:440–527

}

size_t TExpressionImpl::FindOperation(const TStringBuf& exp, std::array<TStringBuf, MaxOperands>& args, EOperation& oper) {
    size_t parenLevel = 0;
    size_t condLevel = 0;
    size_t condEnd = 0;
    size_t numArgs = 0;
    oper = O_END;
    for (size_t i = exp.size(); i > 0; --i) {
        SkipQuoted('"', exp, i);
        SkipQuoted('\'', exp, i);
        if (exp[i - 1] == ')') {
            ++parenLevel;
        } else if (exp[i - 1] == '(') {
            Y_ENSURE(parenLevel > 0, "TExpression: bad paren balance");
            --parenLevel;
        } else if (parenLevel == 0) {
            TStringBuf suffix = exp.substr(i - 1);

            if (FastHasPrefix(suffix, ":")) {
                ++condLevel;

                if (condLevel == 1) {
                    condEnd = i - 1;
                }
            } else if (FastHasPrefix(suffix, "?@")) {
                Y_ENSURE(condLevel > 0, "TExpression: bad conditional syntax");
                --condLevel;

                if (condLevel == 0) {
                    args[0] = exp.substr(0, i - 1);
                    args[1] = exp.substr(i + 1, condEnd - i - 1);
                    args[2] = exp.substr(condEnd + 1);
                    oper = O_STR_COND;
                    numArgs = 3;
                }
            } else if (FastHasPrefix(suffix, "?")) {
                if (i > 1 && FastHasPrefix(exp.substr(i - 2), ">")) {
                    continue;
                }

                Y_ENSURE(condLevel > 0, "TExpression: bad conditional syntax");
                --condLevel;

                if (condLevel == 0) {
                    args[0] = exp.substr(0, i - 1);
                    args[1] = exp.substr(i, condEnd - i);
                    args[2] = exp.substr(condEnd + 1);
                    oper = O_COND;
                    numArgs = 3;
                }
            } else if (oper != O_COND && oper != O_STR_COND) {
                for (EOperation o = O_BINARY_BEGIN; EOperationsPriority[o] < EOperationsPriority[oper]; o = static_cast<EOperation>(o + 1)) {
                    if (!FastHasPrefix(suffix, EOperationsStrings[o])) {
                        continue;
                    }
                    if (EqualToOneOf(o, O_SUBSTRACT, O_ADD)) { // check if it is unary operations
                        bool isUnary = false;
                        for (size_t j = 1; j < i - 1; ++j) {
                            if (EqualToOneOf(exp[i - 1 - j], ' ', '\n')) {