function str = encodevarname(str,varargin)
%
% newname = encodevarname(name)
%
% Encode an invalid variable name using a hex-format for bi-directional
% conversions.
% This function is sensitive to the default charset
% settings in MATLAB, please call feature('DefaultCharacterSet','utf8')
% to set the encoding to UTF-8 before calling this function.
%
% author: Qianqian Fang (q.fang <at> neu.edu)
%
% input:
% name: a string, can be either a valid or invalid variable name
%
% output:
% newname: a valid variable name by converting the leading non-ascii
% letter into "x0xHH_" and non-ascii letters into "_0xHH_"
% format, where HH is the ascii (or Unicode) value of the
% character.
%
% if the encoded variable name CAN NOT be longer than 63, i.e.
% the maximum variable name specified by namelengthmax, and
% one uses the output of this function as a struct or variable
% name, the name will be trucated at 63. Please consider using
% the name as a containers.Map key, which does not have such
% limit.
%
% example:
% encodevarname('_a') % returns x0x5F_a
% encodevarname('a_') % returns a_ as it is a valid variable name
% encodevarname('变量') % returns 'x0xE58F98__0xE9878F_'
%
% this file is part of EasyH5 Toolbox: https://github.com/fangq/easyh5
%
% License: GPLv3 or 3-clause BSD license, see https://github.com/fangq/easyh5 for details
%
if(~isvarname(str(1)))
str=sprintf('x0x%X_%s',char(str(1))+0,str(2:end));
end
if(isvarname(str))
return;
end
if(exist('unicode2native','builtin'))
str=regexprep(str,'([^0-9A-Za-z_])','_0x${sprintf(''%X'',unicode2native($1))}_');
else
cpos=regexp(str,'[^0-9A-Za-z_]');
if(isempty(cpos))
return;
end
str0=str;
pos0=[0 cpos(:)' length(str)];
str='';
for i=1:length(cpos)
str=[str str0(pos0(i)+1:cpos(i)-1) sprintf('_0x%X_',str0(cpos(i))+0)];
end
if(cpos(end)~=length(str))
str=[str str0(pos0(end-1)+1:pos0(end))];
end
end
end
