sub-string

C++ implementation

node {
    char* strBuff;
    char* subBuff;
    size_t maxlen;
    CStringView view;

    void evaluate(Context ctx) {

        if (isSettingUp() || isInputDirty<input_STR>(ctx) || isInputDirty<input_OFST>(ctx) || isInputDirty<input_LEN>(ctx)) {
            auto str = getValue<input_STR>(ctx);
            maxlen = length(str);
            char* strBuff = new char[maxlen+1];
            memset(strBuff, '\0', maxlen + 1);
            dump(str, strBuff);
            auto ofst = getValue<input_OFST>(ctx);
            auto len = getValue<input_LEN>(ctx);
            subBuff = new char[maxlen+1];
            memset(subBuff, '\0', maxlen + 1);
            if (ofst < maxlen) {
                if (ofst+len > maxlen) {
                    len = maxlen-ofst;
                }
                for (auto i = 0; i < len; i++) {
                    subBuff[i] = strBuff[ofst+i];
                }
            }
            view = CStringView(subBuff);
            emitValue<output_SUB>(ctx, XString(&view));
        }
    }
}