function [propargs, ch, strings] = process_inputs(leg,ax,argin,new_legend)

propargs = {}; % user-specified PV pairs 

ch = []; 

strings = {}; 

% @TODO - we need to remove this or start deprecating it.  We have 4

% options:

% 	a) do nothing: explicitly ignore ?-DynamicLegend?, i.e. remove it from the input args and continue (16a behavior).  If we do this the 16b behavior will actually be compatible with 14a, but in spite of ?-DynamicLegend? and not because of it.

% 	b) same as a), but also WARN that this arg is not longer needed because ?AutoUpdate? ?on? is the new default behavior.

% 	c) completely ignore ?-DynamicLegend?, legend(?-DynamicLegend?) will produce one item with this string, but also WARN

% 	d) completely ignore ?-DynamicLegend?, and don?t even WARN since this was never documented syntax.

if ~isempty(argin) && istextscalar(argin{1}) && strcmpi(argin{1},'-DynamicLegend') 

    argin(1) = [];

    if isempty(argin)

        return;

    end

end 

% Find PV Paris - assume any valid Legend property is the start of the P/V

% pair list

labelsInArray = false; 

children = []; 

if ~isempty(argin) 

    fieldnames = lower(get_legend_properties(leg)); 

    for i=1:numel(argin) 

        arg = argin{i}; 

        if istextscalarvector(arg) && ismember(lower(arg),fieldnames) 

            propargs = argin(i:end); 

            argin = argin(1:i-1); 

            break 

        end 

    end 

    if ~isempty(argin) 

        % Process leading (non-PV pair) inputs and determine strings, children and options

        n = 1; 

        nargs = numel(argin); 

        while n <= nargs 

            if istextscalar(argin{n}) 

                strings{end+1} = char(argin{n}); %#ok<AGROW> % single item string

            elseif isnumeric(argin{n}) && length(argin{n})==4 && ... 

                    (n > 1 || ~all(ishghandle(argin{n})))

                % to use position vector either it must not be the first argument,

                % or if it is, then the values must not all be handles - in which

                % case the argument will be considered to be the plot children

                % This is an undocumented API for backwards compatibility with

                % Basic Fitting.

                position = argin{n};

                fig = ancestor(ax,'figure');

                position = hgconvertunits(fig,position,'points','normalized', fig);

                center = position(1:2)+position(3:4)/2;

                % .001 is a small number so that legend will resize to fit and centered

                position = [center-.001 0.001 0.001];

                propargs = {propargs{:}, 'Position',position};

                propargs = {propargs{:}, 'Location','none'};

            elseif iscell(argin{n}) || isstring(argin{n})|| iscategorical(argin{n}) 

                labelsInArray = true;  

                if iscategorical(argin{n}) 

                    argin{n} = string(argin{n});

                end 

                strings = cellstr(argin{n}); 

                % prepend any remaining elements of argin to propargs

                if n < nargs 

                    propargs = [argin(n+1:end),propargs];

                    break;

                end 

            elseif n==1 && all(all(ishghandle(argin{n})))

                % found handles to put in legend

                % make sure to return objects, not doubles

                children=handle(argin{n});

            else

                error(message('MATLAB:legend:UnknownParameter'));

            end 

            n = n + 1; 

        end 

        strings = strings(:).'; 

    end 

end 

% Process plot children and legend labels

fewerStringsThanPlots = false; 

internalPropArgs = {}; 

removeEntries = false; 

if ~isempty(children) || ~isempty(strings) || new_legend 

    % process children and strings if either:

    %   - children or strings are passed in

    %   - a new legend is being created

    % this call removes all items from an existing legend

    if ~isempty(children) 

        % check that all children from user are Legendable

        validateLegendable(children);

        auto_children = false;

        ch = children;

        % get all Legendable objects

        ch_all = getLegendableChildren(ax);

        ch_exclude = setdiff(ch_all,ch);

    else 

        % if isempty(children), get children from axes

        auto_children = true; 

        ch = getLegendableChildren(ax); 

        ch_exclude = []; 

    end 

    % make sure we have column vectors

    ch = ch(:); 

    ch_exclude = ch_exclude(:); 

    % if str is empty, create strings

    if isempty(strings) 

        if auto_children && length(ch) > 50

            % only automatically add first 50 to cut down on huge lists

            ch = ch(1:50);

        end

        % flag when the user specifies fewer label strings than there are

        % legendable children.  This may be used in make_legend to provide

        % extra warning information.

        if numel(strings) < numel(ch)

            fewerStringsThanPlots = true;

        end

    else 

        % expand strings if possible

        % legend(p(1:2),['a';'b'])

        if (length(ch) ~= 1) && (length(strings) == 1) && (size(strings{1},1) > 1) 

            strings = cellstr(strings{1});

        end 

        % trim children or strings

        num_str = numel(strings); 

        num_ch = numel(ch); 

        % flag when the user specifies fewer label strings than there are

        % legendable children.  This may be used in make_legend to provide

        % extra warning information.

        if num_str < num_ch 

            fewerStringsThanPlots = true;

        end 

        if num_str ~= num_ch 

            if ~auto_children || num_str > num_ch

                warning(message('MATLAB:legend:IgnoringExtraEntries'));

            end

            if num_str > num_ch

                strings = strings(1:num_ch);

            else

                % user passed in more objects than strings

                % add extra objects to the exclude list

                ch_exclude = [ch_exclude; ch(num_str+1:end)];

                ch = ch(1:num_str);

            end

        end 

    end 

    internalPropArgs = [internalPropArgs,{'PlotChildren_I'},{ch}]; 

    internalPropArgs = [internalPropArgs,{'PlotChildrenExcluded_I'},{ch_exclude}]; 

    internalPropArgs = [internalPropArgs,{'PlotChildrenSpecified'},{[]}]; 

    if ~auto_children 

        internalPropArgs = [internalPropArgs,{'PlotChildrenSpecified'},{ch}];

    end 

    removeEntries = true;  

end 

%%%%% Error checking before setting any state on legend

% validate and process user-specified PV pairs

if ~isempty(propargs) 

    % create local vars to support handling of special Location values

    % farther down.

    locations = {}; 

    locationAbbrevs = {}; 

    if any(strcmpi(propargs,'location')) 

        % Get location strings long and short form. The short form is the

        % long form without any of the lower case characters.

        % hard code the enumeration values until we can query the datatype directly

        locations = {'North','South','East', 'West','NorthEast','SouthEast','NorthWest','SouthWest','NorthOutside','SouthOutside','EastOutside','WestOutside','NorthEastOutside','SouthEastOutside','NorthWestOutside','SouthWestOutside','Best','BestOutside','none'}; 

        locationAbbrevs = cell(1,length(locations)); 

        for k=1:length(locations) 

            str = locations{k}; 

            locationAbbrevs{k} = str(str>='A' & str<='Z'); 

        end 

    end 

    % check that every p is a property

    % check for special Location values

    numPropArgs = numel(propargs); 

    for i=1:2:numPropArgs 

        if ~any(strcmpi(fieldnames,propargs{i})) 

            tryAddingWarningAboutLabelAmbiguity(labelsInArray,fewerStringsThanPlots,propargs{1});

            try

                m = message('MATLAB:legend:UnknownProperty', ['''' propargs{ i } '''']);

            catch 

                m = message('MATLAB:legend:UnknownProperty', '');

            end

            throw(MException(m));

        end 

        % Look for (...,'Location',POS) or (...,'Location',LOCATION_ABBREV)

        if strcmpi(propargs{i},'location') 

            if i < numPropArgs 

                if isnumeric(propargs{i+1}) && length(propargs{i+1})==4 

                    % found 'Location', POS

                    position = propargs{i+1};

                    propargs{i+1} = 'none';

                    propargs = {propargs{:}, 'Position',position};

                elseif istextscalar(propargs{i+1}) 

                    abbrevsCmp = strcmpi(propargs{i+1}, locationAbbrevs); 

                    if any(abbrevsCmp) 

                        % found 'Location', ABBREV

                        propargs{i+1} = locations{abbrevsCmp};

                    end 

                end 

            end 

        end 

    end 

end 

lcl_propargs = propargs; 

if ~isempty(lcl_propargs) 

    % first handle odd number of PV pairs

    if mod(numel(lcl_propargs),2) == 1 

        tryAddingWarningAboutLabelAmbiguity(labelsInArray,fewerStringsThanPlots,lcl_propargs{1});

        throw(MException(message('MATLAB:legend:NameValueMismatch')));

    end 

    % now try setting the pv pairs.  If the first pv pair errors try to add

    % a helpful warning since it may be because they meany the property to

    % be interpreted as a label.

    tmp_leg = matlab.graphics.illustration.Legend; 

    try 

        set(tmp_leg,lcl_propargs{1:2}); 

        lcl_propargs(1:2) = []; 

    catch ME

        delete(tmp_leg);

        tryAddingWarningAboutLabelAmbiguity(labelsInArray,fewerStringsThanPlots,lcl_propargs{1});

        throw(ME);

    end 

    % set remaining pv pairs, if any

    if ~isempty(lcl_propargs) 

        try

            set(tmp_leg,lcl_propargs{:});      

        catch ME

            delete(tmp_leg);

            throw(ME);

        end

    end 

    delete(tmp_leg); 

end 

% update legend state

if ~isempty(internalPropArgs) 

    set(leg,internalPropArgs{:}); 

end 

if removeEntries 

    removeAllEntries(leg);    

end