savejson.m

function output = savejson(rootname, obj, varargin)
%
% json=savejson(obj)
%    or
% json=savejson(rootname,obj,filename)
% json=savejson(rootname,obj,opt)
% json=savejson(rootname,obj,'param1',value1,'param2',value2,...)
%
% convert a MATLAB object (cell, struct or array) into a JSON (JavaScript
% Object Notation) string
%
% author: Qianqian Fang (q.fang <at> neu.edu)
% initially created on 2011/09/09
%
% input:
%      rootname: the name of the root-object, when set to '', the root name
%           is ignored, however, when opt.ForceRootName is set to 1 (see below),
%           the MATLAB variable name will be used as the root name.
%      obj: a MATLAB object (array, cell, cell array, struct, struct array,
%           class instance).
%      filename: a string for the file name to save the output JSON data.
%      opt: a struct for additional options, ignore to use default values.
%           opt can have the following fields (first in [.|.] is the default)
%
%           FileName [''|string]: a file name to save the output JSON data
%           FloatFormat ['%.16g'|string]: format to show each numeric element
%                         of a 1D/2D array;
%           IntFormat ['%.0f'|string]: format to display integer elements
%                         of a 1D/2D array;
%           ArrayIndent [1|0]: if 1, output explicit data array with
%                         precedent indentation; if 0, no indentation
%           ArrayToStruct[0|1]: when set to 0, savejson outputs 1D/2D
%                         array in JSON array format; if sets to 1, an
%                         array will be shown as a struct with fields
%                         "_ArrayType_", "_ArraySize_" and "_ArrayData_"; for
%                         sparse arrays, the non-zero elements will be
%                         saved to _ArrayData_ field in triplet-format i.e.
%                         (ix,iy,val) and "_ArrayIsSparse_" will be added
%                         with a value of 1; for a complex array, the
%                         _ArrayData_ array will include two columns
%                         (4 for sparse) to record the real and imaginary
%                         parts, and also "_ArrayIsComplex_":1 is added.
%           NestArray    [0|1]: If set to 1, use nested array constructs
%                         to store N-dimensional arrays; if set to 0,
%                         use the annotated array format defined in the
%                         JData Specification (Draft 1 or later).
%           ParseLogical [0|1]: if this is set to 1, logical array elem
%                         will use true/false rather than 1/0.
%           SingletArray [0|1]: if this is set to 1, arrays with a single
%                         numerical element will be shown without a square
%                         bracket, unless it is the root object; if 0, square
%                         brackets are forced for any numerical arrays.
%           SingletCell  [1|0]: if 1, always enclose a cell with "[]"
%                         even it has only one element; if 0, brackets
%                         are ignored when a cell has only 1 element.
%           EmptyArrayAsNull  [0|1]: if set to 1, convert an empty array to
%                         JSON null object; empty cells remain mapped to []
%           ForceRootName [0|1]: when set to 1 and rootname is empty, savejson
%                         will use the name of the passed obj variable as the
%                         root object name; if obj is an expression and
%                         does not have a name, 'root' will be used; if this
%                         is set to 0 and rootname is empty, the root level
%                         will be merged down to the lower level.
%           Inf ['"$1_Inf_"'|string]: a customized regular expression pattern
%                         to represent +/-Inf. The matched pattern is '([-+]*)Inf'
%                         and $1 represents the sign. For those who want to use
%                         1e999 to represent Inf, they can set opt.Inf to '$11e999'
%           NaN ['"_NaN_"'|string]: a customized regular expression pattern
%                         to represent NaN
%           JSONP [''|string]: to generate a JSONP output (JSON with padding),
%                         for example, if opt.JSONP='foo', the JSON data is
%                         wrapped inside a function call as 'foo(...);'
%           UnpackHex [1|0]: convert the 0x[hex code] output by loadjson
%                         back to the string form
%           SaveBinary [1|0]: 1 - save the JSON file in binary mode; 0 - text mode.
%           Compact [0|1]: 1- out compact JSON format (remove all newlines and tabs)
%           Compression  'zlib', 'gzip', 'lzma', 'lzip', 'lz4' or 'lz4hc': specify array
%                         compression method; currently only supports 6 methods. The
%                         data compression only applicable to numerical arrays
%                         in 3D or higher dimensions, or when ArrayToStruct
%                         is 1 for 1D or 2D arrays. If one wants to
%                         compress a long string, one must convert
%                         it to uint8 or int8 array first. The compressed
%                         array uses three extra fields
%                         "_ArrayZipType_": the opt.Compression value.
%                         "_ArrayZipSize_": a 1D integer array to
%                            store the pre-compressed (but post-processed)
%                            array dimensions, and
%                         "_ArrayZipData_": the "base64" encoded
%                             compressed binary array data.
%           CompressArraySize [100|int]: only to compress an array if the total
%                         element count is larger than this number.
%           CompressStringSize [inf|int]: only to compress a string if the total
%                         element count is larger than this number.
%           FormatVersion [3|float]: set the JSONLab output version; since
%                         v2.0, JSONLab uses JData specification Draft 1
%                         for output format, it is incompatible with all
%                         previous releases; if old output is desired,
%                         please set FormatVersion to 1.9 or earlier.
%           Encoding ['']: json file encoding. Support all encodings of
%                         fopen() function
%           Append [0|1]: if set to 1, append a new object at the end of the file.
%           Endian ['n'|'b','l']: Endianness of the output file ('n': native,
%                         'b': big endian, 'l': little-endian)
%           PreEncode [1|0]: if set to 1, call jdataencode first to preprocess
%                         the input data before saving
%           BuiltinJSON [0|1]: if set to 1, this function attempts to call
%                         jsonencode, if presents (MATLAB R2016b or Octave
%                         6) first. If jsonencode does not exist or failed,
%                         this function falls back to the jsonlab savejson
%
%        opt can be replaced by a list of ('param',value) pairs. The param
%        string is equivalent to a field in opt and is case sensitive.
% output:
%      json: a string in the JSON format (see http://json.org)
%
% examples:
%      jsonmesh=struct('MeshNode',[0 0 0;1 0 0;0 1 0;1 1 0;0 0 1;1 0 1;0 1 1;1 1 1],...
%               'MeshElem',[1 2 4 8;1 3 4 8;1 2 6 8;1 5 6 8;1 5 7 8;1 3 7 8],...
%               'MeshSurf',[1 2 4;1 2 6;1 3 4;1 3 7;1 5 6;1 5 7;...
%                          2 8 4;2 8 6;3 8 4;3 8 7;5 8 6;5 8 7],...
%               'MeshCreator','FangQ','MeshTitle','T6 Cube',...
%               'SpecialData',[nan, inf, -inf]);
%      savejson('jmesh',jsonmesh)
%      savejson('',jsonmesh,'ArrayIndent',0,'FloatFormat','\t%.5g')
%
% license:
%     BSD or GPL version 3, see LICENSE_{BSD,GPLv3}.txt files for details
%
% -- this function is part of JSONLab toolbox (http://iso2mesh.sf.net/cgi-bin/index.cgi?jsonlab)
%

if (nargin == 1)
    varname = inputname(1);
    obj = rootname;
    rootname = varname;
else
    varname = inputname(2);
end
if (length(varargin) == 1 && (ischar(varargin{1}) || isa(varargin{1}, 'string')))
    opt = struct('filename', varargin{1});
else
    opt = varargin2struct(varargin{:});
end

opt.isoctave = isoctavemesh;

opt.compression = jsonopt('Compression', '', opt);
opt.nestarray = jsonopt('NestArray', 0, opt);
opt.compact = jsonopt('Compact', 0, opt);
opt.singletcell = jsonopt('SingletCell', 1, opt);
opt.singletarray = jsonopt('SingletArray', 0, opt);
opt.formatversion = jsonopt('FormatVersion', 3, opt);
opt.compressarraysize = jsonopt('CompressArraySize', 100, opt);
opt.compressstringsize = jsonopt('CompressStringSize', inf, opt);
opt.intformat = jsonopt('IntFormat', '%.0f', opt);
opt.floatformat = jsonopt('FloatFormat', '%.16g', opt);
opt.unpackhex = jsonopt('UnpackHex', 1, opt);
opt.arraytostruct = jsonopt('ArrayToStruct', 0, opt);
opt.parselogical = jsonopt('ParseLogical', 0, opt);
opt.arrayindent = jsonopt('ArrayIndent', 1, opt);
opt.emptyarrayasnull = jsonopt('EmptyArrayAsNull', 0, opt);
opt.inf = jsonopt('Inf', '"$1_Inf_"', opt);
opt.nan = jsonopt('NaN', '"_NaN_"', opt);
opt.num2cell_ = 0;
opt.nosubstruct_ = 0;

if (jsonopt('BuiltinJSON', 0, opt) && exist('jsonencode', 'builtin'))
    try
        obj = jdataencode(obj, 'Base64', 1, 'AnnotateArray', 1, 'UseArrayZipSize', 1, opt);
        if (isempty(rootname))
            json = jsonencode(obj);
        else
            json = jsonencode(struct(rootname, obj));
        end
        if (isempty(regexp(json, '^[{\[]', 'once')))
            json = ['[', json, ']'];
        end
        if (nargout > 0)
            output = json;
        end
        return
    catch
        warning('built-in jsonencode function failed to encode the data, fallback to savejson');
    end
end

if (jsonopt('PreEncode', 1, opt))
    obj = jdataencode(obj, 'Base64', 1, 'UseArrayZipSize', 0, opt);
end

dozip = opt.compression;
if (~isempty(dozip))
    if (~ismember(dozip, {'zlib', 'gzip', 'lzma', 'lzip', 'lz4', 'lz4hc'}) && isempty(regexp(dozip, '^blosc2', 'once')))
        error('compression method "%s" is not supported', dozip);
    end
    if (exist('zmat', 'file') ~= 2 && exist('zmat', 'file') ~= 3)
        try
            error(javachk('jvm'));
            try
                base64decode('test');
            catch
                matlab.net.base64decode('test');
            end
        catch
            error('java-based compression is not supported');
        end
    end
    opt.Compression = dozip;
end

rootisarray = 0;
rootlevel = 1;
forceroot = jsonopt('ForceRootName', 0, opt);
if ((isnumeric(obj) || islogical(obj) || ischar(obj) || isstruct(obj) || ...
     iscell(obj) || isobject(obj)) && isempty(rootname) && forceroot == 0)
    rootisarray = 1;
    rootlevel = 0;
else
    if (isempty(rootname))
        rootname = varname;
    end
end
if ((isa(obj, 'containers.Map') && ~strcmp(obj.KeyType, 'char')) || (isa(obj, 'dictionary') && ~strcmp(obj.types, 'string')))
    rootisarray = 0;
end
if ((isstruct(obj) || iscell(obj)) && isempty(rootname) && forceroot)
    rootname = 'root';
end

whitespaces = struct('tab', sprintf('\t'), 'newline', sprintf('\n'), 'sep', sprintf(',\n'));
if (opt.compact == 1)
    whitespaces = struct('tab', '', 'newline', '', 'sep', ',');
end
if (~isfield(opt, 'whitespaces_'))
    opt.whitespaces_ = whitespaces;
end

nl = whitespaces.newline;

json = obj2json(rootname, obj, rootlevel, opt);

if (rootisarray)
    json = sprintf('%s%s', json, nl);
else
    json = sprintf('{%s%s%s}\n', nl, json, nl);
end

jsonp = jsonopt('JSONP', '', opt);
if (~isempty(jsonp))
    json = sprintf('%s(%s);%s', jsonp, json, nl);
end

% save to a file if FileName is set, suggested by Patrick Rapin
filename = jsonopt('FileName', '', opt);
if (~isempty(filename))
    if (jsonopt('UTF8', 1, opt) && exist('unicode2native', 'builtin'))
        json = unicode2native(json);
    end

    encoding = jsonopt('Encoding', '', opt);
    endian = jsonopt('Endian', 'n', opt);
    mode = 'w';
    if (jsonopt('Append', 0, opt))
        mode = 'a';
    end
    if (jsonopt('SaveBinary', 1, opt) == 1)
        if (isempty(encoding))
            fid = fopen(filename, [mode 'b'], endian);
        else
            fid = fopen(filename, [mode 'b'], endian, encoding);
        end
        fwrite(fid, json);
    else
        if (isempty(encoding))
            fid = fopen(filename, [mode 't'], endian);
        else
            fid = fopen(filename, [mode 't'], endian, encoding);
        end
        fwrite(fid, json, 'char');
    end
    fclose(fid);
end

if (nargout > 0 || isempty(filename))
    output = json;
end

%% -------------------------------------------------------------------------
function txt = obj2json(name, item, level, varargin)

if (iscell(item) || isa(item, 'string'))
    txt = cell2json(name, item, level, varargin{:});
elseif (isstruct(item))
    txt = struct2json(name, item, level, varargin{:});
elseif (isnumeric(item) || islogical(item))
    txt = mat2json(name, item, level, varargin{:});
elseif (ischar(item))
    if (~isempty(varargin{1}.compression) && numel(item) >= varargin{1}.compressstringsize)
        txt = mat2json(name, item, level, varargin{:});
    else
        txt = str2json(name, item, level, varargin{:});
    end
elseif (isa(item, 'function_handle'))
    txt = struct2json(name, functions(item), level, varargin{:});
elseif (isa(item, 'containers.Map') || isa(item, 'dictionary'))
    txt = map2json(name, item, level, varargin{:});
elseif (isa(item, 'categorical'))
    txt = cell2json(name, cellstr(item), level, varargin{:});
elseif (isa(item, 'table'))
    txt = matlabtable2json(name, item, level, varargin{:});
elseif (isa(item, 'graph') || isa(item, 'digraph'))
    txt = struct2json(name, jdataencode(item), level, varargin{:});
elseif (isobject(item))
    txt = matlabobject2json(name, item, level, varargin{:});
else
    txt = any2json(name, item, level, varargin{:});
end

%% -------------------------------------------------------------------------
function txt = cell2json(name, item, level, varargin)
txt = {};
if (~iscell(item) && ~isa(item, 'string'))
    error('input is not a cell or string array');
end
isnum2cell = varargin{1}.num2cell_;

if (isnum2cell)
    item = squeeze(item);
    if (~isvector(item))
        item = permute(item, ndims(item):-1:1);
    end
end

dim = size(item);
len = numel(item);
ws = varargin{1}.whitespaces_;
padding0 = repmat(ws.tab, 1, level);
nl = ws.newline;
bracketlevel = ~varargin{1}.singletcell;
if (len > bracketlevel)
    if (~isempty(name))
        txt = {padding0, '"', decodevarname(name, varargin{1}.unpackhex), '":[', nl};
        name = '';
    else
        txt = {padding0, '[', nl};
    end
elseif (len == 0)
    if (~isempty(name))
        txt = {padding0, '"' decodevarname(name, varargin{1}.unpackhex) '":[]'};
        name = '';
    else
        txt = {padding0, '[]'};
    end
    txt = sprintf('%s', txt{:});
    return
end
if (size(item, 1) > 1)
    item = num2cell(item, 2:ndims(item))';
end
idx = num2cell(1:length(item));
sep = {[',' nl], ''};
txt = [txt{:}, cellfun(@(x, id) [obj2json(name, x, level + (dim(1) > 1) + (len > bracketlevel), varargin{:}), sep{(id == length(item)) + 1}], item, idx, 'UniformOutput', false)];

if (len > bracketlevel)
    txt(end + 1:end + 3) = {nl, padding0, ']'};
end
txt = sprintf('%s', txt{:});

%% -------------------------------------------------------------------------
function txt = struct2json(name, item, level, varargin)
txt = {};
if (~isstruct(item))
    error('input is not a struct');
end
dim = size(item);
if (ndims(squeeze(item)) > 2) % for 3D or higher dimensions, flatten to 2D for now
    item = reshape(item, dim(1), numel(item) / dim(1));
    dim = size(item);
end
len = numel(item);
forcearray = (len > 1 || (varargin{1}.singletarray == 1 && level > 0));
ws = varargin{1}.whitespaces_;
padding0 = repmat(ws.tab, 1, level);
padding2 = repmat(ws.tab, 1, level + 1);
padding1 = repmat(ws.tab, 1, level + (dim(1) > 1) + forcearray);
nl = ws.newline;
if (isfield(item, encodevarname('_ArrayType_', varargin{1}.unpackhex)))
    varargin{1}.nosubstruct_ = 1;
end

if (isempty(item))
    if (~isempty(name))
        txt = {padding0, '"', decodevarname(name, varargin{1}.unpackhex), '":[]'};
    else
        txt = {padding0, '[]'};
    end
    txt = sprintf('%s', txt{:});
    return
end
if (~isempty(name))
    if (forcearray)
        txt = {padding0, '"', decodevarname(name, varargin{1}.unpackhex), '":[', nl};
    end
else
    if (forcearray)
        txt = {padding0, '[', nl};
    end
end
for j = 1:dim(2)
    if (dim(1) > 1)
        txt(end + 1:end + 3) = {padding2, '[', nl};
    end
    for i = 1:dim(1)
        names = fieldnames(item(i, j));
        if (~isempty(name) && len == 1 && ~forcearray)
            txt(end + 1:end + 5) = {padding1, '"', decodevarname(name, varargin{1}.unpackhex), '":{', nl};
        else
            txt(end + 1:end + 3) = {padding1, '{', nl};
        end
        if (~isempty(names))
            for e = 1:length(names)
                if (varargin{1}.nosubstruct_ && ischar(item(i, j).(names{e})) || ...
                    strcmp(names{e}, encodevarname('_ByteStream_')))
                    txt{end + 1} = str2json(names{e}, item(i, j).(names{e}), ...
                                            level + (dim(1) > 1) + 1 + forcearray, varargin{:});
                else
                    txt{end + 1} = obj2json(names{e}, item(i, j).(names{e}), ...
                                            level + (dim(1) > 1) + 1 + forcearray, varargin{:});
                end
                if (e < length(names))
                    txt{end + 1} = ',';
                end
                txt{end + 1} = nl;
            end
        end
        txt(end + 1:end + 2) = {padding1, '}'};
        if (i < dim(1))
            txt(end + 1:end + 2) = {',' nl};
        end
    end
    if (dim(1) > 1)
        txt(end + 1:end + 3) = {nl, padding2, ']'};
    end
    if (j < dim(2))
        txt(end + 1:end + 2) = {',' nl};
    end
end
if (forcearray)
    txt(end + 1:end + 3) = {nl, padding0, ']'};
end
txt = sprintf('%s', txt{:});

%% -------------------------------------------------------------------------
function txt = map2json(name, item, level, varargin)
txt = {};
itemtype = isa(item, 'containers.Map');
dim = size(item);

if (isa(item, 'dictionary'))
    itemtype = 2;
    dim = item.numEntries;
end
if (itemtype == 0)
    error('input is not a containers.Map or dictionary class');
end
names = keys(item);
val = values(item);

if (~iscell(names))
    names = num2cell(names, ndims(names));
end

if (~iscell(val))
    val = num2cell(val, ndims(val));
end

if ((itemtype == 1 && ~strcmp(item.KeyType, 'char')) || (itemtype == 2 && ~strcmp(item.types, 'string')))
    mm = cell(1, length(names));
    for i = 1:length(names)
        mm{i} = {names{i}, val{i}};
    end
    if (isempty(name))
        txt = obj2json('_MapData_', mm, level + 1, varargin{:});
    else
        temp = struct(name, struct());
        if (varargin{1}.isoctave)
            temp.(name).('_MapData_') = mm;
        else
            temp.(name).('x0x5F_MapData_') = mm;
        end
        txt = obj2json(name, temp.(name), level, varargin{:});
    end
    return
end

ws = varargin{1}.whitespaces_;
padding0 = repmat(ws.tab, 1, level);
nl = ws.newline;

if (isempty(item))
    if (~isempty(name))
        txt = {padding0, '"', decodevarname(name, varargin{1}.unpackhex), '":[]'};
    else
        txt = {padding0, '[]'};
    end
    txt = sprintf('%s', txt{:});
    return
end
if (~isempty(name))
    txt = {padding0, '"', decodevarname(name, varargin{1}.unpackhex), '":{', nl};
else
    txt = {padding0, '{', nl};
end

for i = 1:dim(1)
    if (isempty(names{i}))
        txt{end + 1} = obj2json('x0x0_', val{i}, level + 1, varargin{:});
    else
        txt{end + 1} = obj2json(names{i}, val{i}, level + 1, varargin{:});
    end
    if (i < length(names))
        txt{end + 1} = ',';
    end
    if (i < dim(1))
        txt{end + 1} = nl;
    end
end
txt(end + 1:end + 3) = {nl, padding0, '}'};
txt = sprintf('%s', txt{:});

%% -------------------------------------------------------------------------
function txt = str2json(name, item, level, varargin)
txt = {};
if (~ischar(item))
    error('input is not a string');
end
item = reshape(item, max(size(item), [1 0]));
len = size(item, 1);
ws = varargin{1}.whitespaces_;
padding1 = repmat(ws.tab, 1, level);
padding0 = repmat(ws.tab, 1, level + 1);
nl = ws.newline;
sep = ws.sep;

if (~isempty(name))
    if (len > 1)
        txt = {padding1, '"', decodevarname(name, varargin{1}.unpackhex), '":[', nl};
    end
else
    if (len > 1)
        txt = {padding1, '[', nl};
    end
end
for e = 1:len
    if (strcmp('_ArrayZipData_', decodevarname(name, varargin{1}.unpackhex)) == 0)
        val = escapejsonstring(item(e, :), varargin{:});
    else
        val = item(e, :);
    end
    if (len == 1)
        obj = ['"' decodevarname(name, varargin{1}.unpackhex) '":' '"', val, '"'];
        if (isempty(name))
            obj = ['"', val, '"'];
        end
        txt(end + 1:end + 2) = {padding1, obj};
    else
        txt(end + 1:end + 4) = {padding0, '"', val, '"'};
    end
    if (e == len)
        sep = '';
    end
    txt{end + 1} = sep;
end
if (len > 1)
    txt(end + 1:end + 3) = {nl, padding1, ']'};
end
txt = sprintf('%s', txt{:});

%% -------------------------------------------------------------------------
function txt = mat2json(name, item, level, varargin)
if (~isnumeric(item) && ~islogical(item) && ~ischar(item))
    error('input is not an array');
end
opt = varargin{1};
ws = opt.whitespaces_;
padding1 = repmat(ws.tab, 1, level);
padding0 = repmat(ws.tab, 1, level + 1);
nl = ws.newline;
sep = ws.sep;

dozip = opt.compression;
zipsize = opt.compressarraysize;
format = opt.formatversion;
isnest = opt.nestarray;

if (~opt.nosubstruct_ && (((isnest == 0) && length(size(item)) > 2) || issparse(item) || ~isreal(item) || ...
                          (isempty(item) && any(size(item))) || opt.arraytostruct || (~isempty(dozip) && numel(item) > zipsize)))
    if (isempty(name))
        txt = sprintf('%s{%s%s"_ArrayType_":"%s",%s%s"_ArraySize_":%s,%s', ...
                      padding1, nl, padding0, class(item), nl, padding0, regexprep(mat2str(size(item)), '\s+', ','), nl);
    else
        txt = sprintf('%s"%s":{%s%s"_ArrayType_":"%s",%s%s"_ArraySize_":%s,%s', ...
                      padding1, decodevarname(name, opt.unpackhex), nl, padding0, class(item), nl, padding0, regexprep(mat2str(size(item)), '\s+', ','), nl);
    end
else
    numtxt = matdata2json(item, level + 1, varargin{:});
    if (isempty(name))
        txt = sprintf('%s%s', padding1, numtxt);
    else
        if (numel(item) == 1 && varargin{1}.singletarray == 0)
            txt = sprintf('%s"%s":%s', padding1, decodevarname(name, opt.unpackhex), numtxt);
        else
            txt = sprintf('%s"%s":%s', padding1, decodevarname(name, opt.unpackhex), numtxt);
        end
    end
    return
end

dataformat = '%s%s%s%s%s';

if (issparse(item))
    [ix, iy] = find(item);
    data = full(item(find(item)));
    if (~isreal(item))
        data = [real(data(:)), imag(data(:))];
        if (size(item, 1) == 1)
            % Kludge to have data's 'transposedness' match item's.
            % (Necessary for complex row vector handling below.)
            data = data';
        end
        txt = sprintf(dataformat, txt, padding0, '"_ArrayIsComplex_":', 'true', sep);
    end
    txt = sprintf(dataformat, txt, padding0, '"_ArrayIsSparse_":', 'true', sep);
    if (~isempty(dozip) && numel(data * 2) > zipsize)
        if (size(item, 1) == 1)
            % Row vector, store only column indices.
            fulldata = [iy(:), data'];
        elseif (size(item, 2) == 1)
            % Column vector, store only row indices.
            fulldata = [ix, data];
        else
            % General case, store row and column indices.
            fulldata = [ix, iy, data];
        end
        txt = sprintf(dataformat, txt, padding0, '"_ArrayZipSize_":', regexprep(mat2str(size(fulldata)), '\s+', ','), sep);
        txt = sprintf(dataformat, txt, padding0, '"_ArrayZipType_":"', dozip, ['"' sep]);
        compfun = str2func([dozip 'encode']);
        txt = sprintf(dataformat, txt, padding0, '"_ArrayZipData_":"', base64encode(compfun(typecast(fulldata(:), 'uint8'))), ['"' nl]);
    else
        if (size(item, 1) == 1)
            % Row vector, store only column indices.
            fulldata = [iy(:), data'];
        elseif (size(item, 2) == 1)
            % Column vector, store only row indices.
            fulldata = [ix, data];
        else
            % General case, store row and column indices.
            fulldata = [ix, iy, data];
        end
        txt = sprintf(dataformat, txt, padding0, '"_ArrayData_":', ...
                      matdata2json(fulldata', level + 2, varargin{:}), nl);
    end
else
    if (format > 1.9)
        item = permute(item, ndims(item):-1:1);
    end
    if (~isempty(dozip) && numel(item) > zipsize)
        if (isreal(item))
            fulldata = item(:)';
            if (islogical(fulldata) || ischar(fulldata))
                fulldata = uint8(fulldata);
            end
        else
            txt = sprintf(dataformat, txt, padding0, '"_ArrayIsComplex_":', 'true', sep);
            fulldata = [real(item(:)) imag(item(:))]';
        end
        txt = sprintf(dataformat, txt, padding0, '"_ArrayZipSize_":', regexprep(mat2str(size(fulldata)), '\s+', ','), sep);
        txt = sprintf(dataformat, txt, padding0, '"_ArrayZipType_":"', dozip, ['"' sep]);
        encodeparam = {};
        if (~isempty(regexp(dozip, '^blosc2', 'once')))
            compfun = @blosc2encode;
            encodeparam = {dozip, 'nthread', jsonopt('nthread', 1, opt), 'shuffle', jsonopt('shuffle', 1, opt), 'typesize', jsonopt('typesize', length(typecast(fulldata(1), 'uint8')), opt)};
        else
            compfun = str2func([dozip 'encode']);
        end
        txt = sprintf(dataformat, txt, padding0, '"_ArrayZipData_":"', char(base64encode(compfun(typecast(fulldata(:), 'uint8'), encodeparam{:}))), ['"' nl]);
    else
        if (isreal(item))
            txt = sprintf(dataformat, txt, padding0, '"_ArrayData_":', ...
                          matdata2json(item(:)', level + 2, varargin{:}), nl);
        else
            txt = sprintf(dataformat, txt, padding0, '"_ArrayIsComplex_":', 'true', sep);
            txt = sprintf(dataformat, txt, padding0, '"_ArrayData_":', ...
                          matdata2json([real(item(:)) imag(item(:))]', level + 2, varargin{:}), nl);
        end
    end
end

txt = sprintf('%s%s%s', txt, padding1, '}');

%% -------------------------------------------------------------------------
function txt = matlabobject2json(name, item, level, varargin)
try
    if numel(item) == 0 % empty object
        st = struct();
    elseif numel(item) == 1 %
        txt = str2json(name, char(item), level, varargin{:});
        return
    else
        propertynames = properties(item);
        for p = 1:numel(propertynames)
            for o = numel(item):-1:1 % array of objects
                st(o).(propertynames{p}) = item(o).(propertynames{p});
            end
        end
    end
    txt = struct2json(name, st, level, varargin{:});
catch
    txt = any2json(name, item, level, varargin{:});
end

%% -------------------------------------------------------------------------
function txt = matlabtable2json(name, item, level, varargin)
st = containers.Map();
st('_TableRecords_') = table2cell(item);
st('_TableRows_') = item.Properties.RowNames';
st('_TableCols_') = item.Properties.VariableNames;
if (isempty(name))
    txt = map2json(name, st, level, varargin{:});
else
    temp = struct(name, struct());
    temp.(name) = st;
    txt = map2json(name, temp.(name), level, varargin{:});
end

%% -------------------------------------------------------------------------
function txt = matdata2json(mat, level, varargin)

ws = varargin{1}.whitespaces_;
tab = ws.tab;
nl = ws.newline;
isnest = varargin{1}.nestarray;
format = varargin{1}.formatversion;
isnum2cell = varargin{1}.num2cell_;

if (~isvector(mat) && isnest == 1)
    if (format > 1.9 && isnum2cell == 0)
        mat = permute(mat, ndims(mat):-1:1);
    end
    varargin{1}.num2cell_ = 1;
    varargin{1}.singletcell = 0;
    txt = cell2json('', num2cell(mat, 1), level - 1, varargin{:});
    return
elseif (isvector(mat) && isnum2cell == 1)
    mat = mat(:).';
end

if (size(mat, 1) == 1)
    pre = '';
    post = '';
    level = level - 1;
else
    pre = sprintf('[%s', nl);
    post = sprintf('%s%s]', nl, repmat(tab, 1, level - 1));
end

if (isempty(mat))
    if (varargin{1}.emptyarrayasnull)
        txt = 'null';
    else
        txt = '[]';
    end
    return
end
if (isinteger(mat))
    floatformat = varargin{1}.intformat;
else
    floatformat = varargin{1}.floatformat;
end
if (numel(mat) == 1 && varargin{1}.singletarray == 0 && level > 0)
    formatstr = [repmat([floatformat ','], 1, size(mat, 2) - 1) [floatformat sprintf(',%s', nl)]];
else
    formatstr = ['[' repmat([floatformat ','], 1, size(mat, 2) - 1) [floatformat sprintf('],%s', nl)]];
end
if (nargin >= 2 && size(mat, 1) > 1 && varargin{1}.arrayindent == 1)
    formatstr = [repmat(tab, 1, level) formatstr];
end

txt = sprintf(formatstr, permute(mat, ndims(mat):-1:1));
txt(end - length(nl):end) = [];
if (islogical(mat) && (numel(mat) == 1 || varargin{1}.parselogical == 1))
    txt = regexprep(txt, '1', 'true');
    txt = regexprep(txt, '0', 'false');
end

txt = [pre txt post];
if (any(isinf(mat(:))))
    txt = regexprep(txt, '([-+]*)Inf', varargin{1}.inf);
end
if (any(isnan(mat(:))))
    txt = regexprep(txt, 'NaN', varargin{1}.nan);
end

%% -------------------------------------------------------------------------
function txt = any2json(name, item, level, varargin)
st = containers.Map();
st('_DataInfo_') = struct('MATLABObjectName', name, 'MATLABObjectClass', class(item), 'MATLABObjectSize', size(item));
st('_ByteStream_') = char(base64encode(getByteStreamFromArray(item)));

if (isempty(name))
    txt = map2json(name, st, level, varargin{:});
else
    temp = struct(name, struct());
    temp.(name) = st;
    txt = map2json(name, temp.(name), level, varargin{:});
end

%% -------------------------------------------------------------------------
function newstr = escapejsonstring(str, varargin)
newstr = str;
if (isempty(str) || isempty(regexp(str, '\W', 'once')))
    return
end
isoct = varargin{1}.isoctave;
if (isoct)
    vv = sscanf(OCTAVE_VERSION, '%f');
    if (vv(1) >= 3.8)
        isoct = 0;
    end
end
if (isoct)
    escapechars = {'\\', '\"', '\a', '\f', '\n', '\r', '\t', '\v'};
    for i = 1:length(escapechars)
        newstr = regexprep(newstr, escapechars{i}, escapechars{i});
    end
    newstr = regexprep(newstr, '\\\\(u[0-9a-fA-F]{4}[^0-9a-fA-F]*)', '\$1');
else
    escapechars = {'\\', '\"', '\a', '\b', '\f', '\n', '\r', '\t', '\v'};
    esc = {'\\\\', '\\"', '\\a', '\\b', '\\f', '\\n', '\\r', '\\t', '\\v'};
    for i = 1:length(escapechars)
        newstr = regexprep(newstr, escapechars{i}, esc{i});
    end
    newstr = regexprep(newstr, '\\\\(u[0-9a-fA-F]{4}[^0-9a-fA-F]*)', '\\$1');
end