hasfield.m

function [ x,I ] = hasfield( s, fname, varargin)
% X = HASFIELD(S,FNAME) checks if the struct S has the fieldname FNAME. If
% S is not a struct, X will be false.
%
% [X,L] = HASFIELD(S,FNAME,LEVEL) checks LEVEL number of levels into possible
% nested structres for a field name. L returns the first level that the
% field name was found at.

L = 0;% level
I = 0;% level iteratios
x = 0;% default

if(~isstruct(s))
    warning('input is not a struct');
    return
end

if(length(varargin) > 0)
    if(~isnumeric(varargin{1}))
        error('LEVEL must be a numeric variable');
    end
    L = varargin{1};
end

recurseon({s});

    function recurseon(T)
        I = I+1;
        %return if max iterations
        if(L > 0 && I > L)
            I = I-1;
            return
        end
        
        %check for any matching fieldnames
        NEWT = {};
        for i=1:length(T)
            
            t = T{i};
            
            %detection
            x = isfield(t,fname);
            if(x) 
                return
            end
            
            %breadth first elaboration
            N = fieldnames(t);
            for j = 1:length(N)
                if(isstruct(t.(N{j})))
                    NEWT = vertcat(NEWT,t.(N{j}));
                end
            end
            
        end
        
        %if theres actually anything to recurse on
        if(~isempty(NEWT))
            recurseon(NEWT);
        end
        
    end
end