Function pj_param_exists

src/param.cpp:72–107

/

/**************************************************************************************/
paralist *pj_param_exists(paralist *list, const char *parameter) {
    /***************************************************************************************
        Determine whether a given parameter exists in a paralist. If it does,
    return a pointer to the corresponding list element - otherwise return 0.

        In support of the pipeline syntax, the search is terminated once a
    "+step" list element is reached, in which case a 0 is returned, unless the
    parameter searched for is actually "step", in which case a pointer to the
    "step" list element is returned.

        This function is equivalent to the pj_param (...) call with the "opt"
    argument set to the parameter name preceeeded by a 't'. But by using this
    one, one avoids writing the code allocating memory for a new copy of
    parameter name, and prepending the t (for compile time known names, this is
    obviously not an issue).
    ***************************************************************************************/
    paralist *next = list;
    const char *c = strchr(parameter, '=');
    size_t len = strlen(parameter);
    if (c)
        len = c - parameter;
    if (list == nullptr)
        return nullptr;

    for (next = list; next; next = next->next) {
        if (0 == strncmp(parameter, next->param, len) &&
            (next->param[len] == '=' || next->param[len] == 0)) {
            next->used = 1;
            return next;
        }
        if (0 == strcmp(parameter, "step"))
            return nullptr;
    }

    return nullptr;
}

/************************************************************************/
/*                              pj_param()                              */