parseEnum(myStr, varargin)

function val = parseEnum(myStr, varargin)
%val = parseEnum(myStr, str1,val1, str2,val2, ..., strn,valn)
%   Takes MYSTR and searches for the STRI string that matches it.  Returns
%   the corresponding VALI.  Returns an empty array if not match is found.  
%   Uses STRCMP to do the matching.
%
%Examples:
%   parseEnum('foo', 'foo',1, 'bar',2) --> 1
%   parseEnum('bar', 'foo',1, 'bar',2) --> 2
%   parseEnum('baz', 'foo',1, 'bar',2) --> []
%
%Motiving scenario:
%   This function was written to clean up and compact code where I wanted 
%   to look up a mapping from a string to a value.  For example, before I 
%   might have had someting like the following (using Matlab 7 FIND 
%   enhancements)
%       function code = getFruitCode(fruit)
%       names = {'apple', 'orange', 'banana'};
%       values = [-1 0 1];
%       code = values(find(strcmp(names, fruit), 1)); 
%   and with PARSEENUM, we can condense it down to
%       function code = getFruitCode(fruit)
%       code = parseEnum(fruit,  'apple',-1, 'orange',0, 'banana',1);
%
%Changes:
%   2006-02-18: Uses faster STRCMP implementation as suggested by Duane
%       Hanselman.  Removed boilerplate copyright.  Returns an empty array
%       instead of generating an error when no match is found.  Added a
%       motivating scenario to docs.
%
%by Gerald Dalley

if (mod(length(varargin),2) ~= 0)
    error('String-value pairs must be supplied.');
end

matches = find(strcmp({varargin{1:2:end}}, myStr));
if (length(matches) == 0), 
    val = []; 
else
    val = varargin{(matches(1))*2};
end