Function pj_param_exists

ThirdParty/libproj/vtklibproj/src/param.cpp:98–131

/

/**************************************************************************************/
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;
}


/************************************************************************/