jdataencode.m

function jdata = jdataencode(data, varargin)
%
% jdata=jdataencode(data)
%    or
% jdata=jdataencode(data, options)
% jdata=jdataencode(data, 'Param1',value1, 'Param2',value2,...)
%
% Annotate a MATLAB struct or cell array into a JData-compliant data
% structure as defined in the JData spec: http://github.com/NeuroJSON/jdata.
% This encoded form servers as an intermediate format that allows unambiguous
% storage, exchange of complex data structures and easy-to-serialize by
% json encoders such as savejson and jsonencode (MATLAB R2016b or newer)
%
% This function implements the JData Specification Draft 3 (Jun. 2020)
% see http://github.com/NeuroJSON/jdata for details
%
% author: Qianqian Fang (q.fang <at> neu.edu)
%
% input:
%     data: a structure (array) or cell (array) to be encoded.
%     options: (optional) a struct or Param/value pairs for user
%              specified options (first in [.|.] is the default)
%         AnnotateArray: [0|1] - if set to 1, convert all 1D/2D matrices
%              to the annotated JData array format to preserve data types;
%              N-D (N>2), complex and sparse arrays are encoded using the
%              annotated format by default. Please set this option to 1 if
%              you intend to use MATLAB's jsonencode to convert to JSON.
%         Base64: [0|1] if set to 1, _ArrayZipData_ is assumed to
%                  be encoded with base64 format and need to be
%                  decoded first. This is needed for JSON but not
%                  UBJSON data
%         Prefix: ['x0x5F'|'x'] for JData files loaded via loadjson/loadubjson, the
%                      default JData keyword prefix is 'x0x5F'; if the
%                      json file is loaded using matlab2018's
%                      jsondecode(), the prefix is 'x'; this function
%                      attempts to automatically determine the prefix;
%                      for octave, the default value is an empty string ''.
%         UseArrayZipSize: [1|0] if set to 1, _ArrayZipSize_ will be added to
%                  store the "pre-processed" data dimensions, i.e.
%                  the original data stored in _ArrayData_, and then flaten
%                  _ArrayData_ into a row vector using row-major
%                  order; if set to 0, a 2D _ArrayData_ will be used
%         UseArrayShape: [0|1] if set to 1, a matrix will be tested by
%                  to determine if it is diagonal, triangular, banded or
%                  toeplitz, and use _ArrayShape_ to encode the matrix
%         MapAsStruct: [0|1] if set to 1, convert containers.Map into
%                  struct; otherwise, keep it as map
%         Compression: ['zlib'|'gzip','lzma','lz4','lz4hc'] - use zlib method
%                  to compress data array
%         CompressArraySize: [100|int]: only to compress an array if the
%                  total element count is larger than this number.
%         FormatVersion [2|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.
%
% example:
%     jd=jdataencode(struct('a',rand(5)+1i*rand(5),'b',[],'c',sparse(5,5)))
%
%     encodedmat=jdataencode(single(magic(5)),'annotatearray',1,'prefix','x')
%     jdatadecode(jsondecode(jsonencode(encodedmat)))  % serialize by jsonencode
%     jdatadecode(loadjson(savejson('',encodedmat)))   % serialize by savejson
%
%     encodedtoeplitz=jdataencode(uint8(toeplitz([1,2,3,4],[1,5,6])),'usearrayshape',1,'prefix','x')
%     jdatadecode(jsondecode(jsonencode(encodedtoeplitz)))  % serialize by jsonencode
%     jdatadecode(loadjson(savejson('',encodedtoeplitz)))   % serialize by savejson
%
% 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 == 0)
    help jdataencode;
    return
end

opt = varargin2struct(varargin{:});
if (isoctavemesh)
    opt.prefix = jsonopt('Prefix', '', opt);
else
    opt.prefix = jsonopt('Prefix', sprintf('x0x%X', '_' + 0), opt);
end
opt.compression = jsonopt('Compression', '', opt);
opt.nestarray = jsonopt('NestArray', 0, opt);
opt.formatversion = jsonopt('FormatVersion', 2, opt);
opt.compressarraysize = jsonopt('CompressArraySize', 100, opt);
opt.base64 = jsonopt('Base64', 0, opt);
opt.mapasstruct = jsonopt('MapAsStruct', 0, opt);
opt.usearrayzipsize = jsonopt('UseArrayZipSize', 1, opt);
opt.messagepack = jsonopt('MessagePack', 0, opt);
opt.usearrayshape = jsonopt('UseArrayShape', 0, opt) && exist('bandwidth');
opt.annotatearray = jsonopt('AnnotateArray', 0, opt);

jdata = obj2jd(data, opt);

%% -------------------------------------------------------------------------
function newitem = obj2jd(item, varargin)

if (iscell(item))
    newitem = cell2jd(item, varargin{:});
elseif (isstruct(item))
    newitem = struct2jd(item, varargin{:});
elseif (isnumeric(item) || islogical(item))
    newitem = mat2jd(item, varargin{:});
elseif (ischar(item) || isa(item, 'string'))
    newitem = mat2jd(item, varargin{:});
elseif (isa(item, 'containers.Map'))
    newitem = map2jd(item, varargin{:});
elseif (isa(item, 'categorical'))
    newitem = cell2jd(cellstr(item), varargin{:});
elseif (isa(item, 'function_handle'))
    newitem = struct2jd(functions(item), varargin{:});
elseif (isa(item, 'table'))
    newitem = table2jd(item, varargin{:});
elseif (isa(item, 'digraph') || isa(item, 'graph'))
    newitem = graph2jd(item, varargin{:});
elseif (isobject(item))
    newitem = matlabobject2jd(item, varargin{:});
else
    newitem = item;
end

%% -------------------------------------------------------------------------
function newitem = cell2jd(item, varargin)

newitem = cellfun(@(x) obj2jd(x, varargin{:}), item, 'UniformOutput', false);

%% -------------------------------------------------------------------------
function newitem = struct2jd(item, varargin)

num = numel(item);
if (num > 1)  % struct array
    newitem = obj2jd(num2cell(item), varargin{:});
    try
        newitem = cell2mat(newitem);
    catch
    end
elseif (num == 1) % a single struct
    names = fieldnames(item);
    newitem = struct;
    for i = 1:length(names)
        newitem.(names{i}) = obj2jd(item.(names{i}), varargin{:});
    end
else
    newitem = item;
end

%% -------------------------------------------------------------------------
function newitem = map2jd(item, varargin)

names = item.keys;
if (varargin{1}.mapasstruct)  % convert a map to struct
    newitem = struct;
    if (~strcmp(item.KeyType, 'char'))
        data = num2cell(reshape([names, item.values], length(names), 2), 2);
        for i = 1:length(names)
            data{i}{2} = obj2jd(data{i}{2}, varargin{:});
        end
        newitem.(N_('_MapData_', varargin{:})) = data;
    else
        for i = 1:length(names)
            newitem.(N_(names{i}, varargin{:})) = obj2jd(item(names{i}), varargin{:});
        end
    end
else   % keep as a map and only encode its values
    if (strcmp(item.KeyType, 'char'))
        newitem = containers.Map();
    else
        newitem = containers.Map('KeyType', item.KeyType, 'ValueType', 'any');
    end
    for i = 1:length(names)
        newitem(names{i}) = obj2jd(item(names{i}), varargin{:});
    end
end

%% -------------------------------------------------------------------------
function newitem = mat2jd(item, varargin)

N = @(x) N_(x, varargin{:});
newitem = struct(N('_ArrayType_'), class(item), N('_ArraySize_'), size(item));

zipmethod = varargin{1}.compression;
minsize = varargin{1}.compressarraysize;

% 2d numerical (real/complex/sparse) arrays with _ArrayShape_ encoding enabled
if (varargin{1}.usearrayshape && ndims(item) == 2 && ~isvector(item))
    encoded = 1;
    if (~isreal(item))
        newitem.(N('_ArrayIsComplex_')) = true;
    end
    symmtag = '';
    if (isreal(item) && issymmetric(double(item)))
        symmtag = 'symm';
        item = tril(item);
    elseif (~isreal(item) && ishermitian(double(item)))
        symmtag = 'herm';
        item = tril(item);
    end
    [lband, uband] = bandwidth(double(item));
    newitem.(N('_ArrayZipSize_')) = [lband + uband + 1, min(size(item, 1), size(item, 2))];
    if (lband + uband == 0) % isdiag
        newitem.(N('_ArrayShape_')) = 'diag';
        newitem.(N('_ArrayData_')) = diag(item).';
    elseif (uband == 0 && lband == size(item, 1) - 1) % lower triangular
        newitem.(N('_ArrayShape_')) = ['lower' symmtag];
        item = item.';
        newitem.(N('_ArrayData_')) = item(triu(true(size(item)))).';
    elseif (lband == 0 && uband == size(item, 2) - 1) % upper triangular
        newitem.(N('_ArrayShape_')) = 'upper';
        item = item.';
        newitem.(N('_ArrayData_')) = item(tril(true(size(item)))).';
    elseif (lband == 0) % upper band
        newitem.(N('_ArrayShape_')) = {'upperband', uband};
        newitem.(N('_ArrayData_')) = spdiags(item.', -uband:lband).';
    elseif (uband == 0) % lower band
        newitem.(N('_ArrayShape_')) = {sprintf('lower%sband', symmtag), lband};
        newitem.(N('_ArrayData_')) = spdiags(item.', -uband:lband).';
    elseif (uband < size(item, 2) - 1 || lband < size(item, 1) - 1) % band
        newitem.(N('_ArrayShape_')) = {'band', uband, lband};
        newitem.(N('_ArrayData_')) = spdiags(item.', -uband:lband).';
    elseif (all(toeplitz(item(:, 1), item(1, :)) == item))  % Toeplitz matrix
        newitem.(N('_ArrayShape_')) = 'toeplitz';
        newitem.(N('_ArrayZipSize_')) = [2, max(size(item))];
        newitem.(N('_ArrayData_')) = zeros(2, max(size(item)));
        newitem.(N('_ArrayData_'))(1, 1:size(item, 2)) = item(1, :);
        newitem.(N('_ArrayData_'))(2, 1:size(item, 1)) = item(:, 1).';
    else  % full matrix
        newitem = rmfield(newitem, N('_ArrayZipSize_'));
        encoded = 0;
    end

    % serialize complex data at last
    if (encoded && isstruct(newitem) && ~isreal(newitem.(N('_ArrayData_'))))
        item = squeeze(zeros([2, size(newitem.(N('_ArrayData_')))]));
        item(1, :) = real(newitem.(N('_ArrayData_'))(:));
        item(2, :) = imag(newitem.(N('_ArrayData_'))(:));
        newitem.(N('_ArrayZipSize_')) = size(item);
        newitem.(N('_ArrayData_')) = item;
    end

    % wrap _ArrayData_ into a single row vector, and store preprocessed
    % size to _ArrayZipSize_ (force varargin{1}.usearrayzipsize=true)
    if (encoded)
        if (isstruct(newitem) && ~isvector(newitem.(N('_ArrayData_'))))
            item = newitem.(N('_ArrayData_'));
            item = permute(item, ndims(item):-1:1);
            newitem.(N('_ArrayData_')) = item(:).';
        else
            newitem = rmfield(newitem, N('_ArrayZipSize_'));
        end
        newitem.(N('_ArrayData_')) = full(newitem.(N('_ArrayData_')));
        return
    end
end

% no encoding for char arrays or non-sparse real vectors
if (isempty(item) || isa(item, 'string') || ischar(item) || varargin{1}.nestarray || ...
    ((isvector(item) || ndims(item) == 2) && isreal(item) && ~issparse(item) && ...
     ~varargin{1}.annotatearray))
    newitem = item;
    return
end

if (isa(item, 'logical'))
    item = uint8(item);
end

if (isreal(item))
    if (issparse(item))
        fulldata = full(item(item ~= 0));
        newitem.(N('_ArrayIsSparse_')) = true;
        newitem.(N('_ArrayZipSize_')) = [2 + (~isvector(item)), length(fulldata)];
        if (isvector(item))
            newitem.(N('_ArrayData_')) = [find(item(:))', fulldata(:)'];
        else
            [ix, iy] = find(item);
            newitem.(N('_ArrayData_')) = [ix(:)', iy(:)', fulldata(:)'];
        end
    else
        if (varargin{1}.formatversion > 1.9)
            item = permute(item, ndims(item):-1:1);
        end
        newitem.(N('_ArrayData_')) = item(:)';
    end
else
    newitem.(N('_ArrayIsComplex_')) = true;
    if (issparse(item))
        fulldata = full(item(item ~= 0));
        newitem.(N('_ArrayIsSparse_')) = true;
        newitem.(N('_ArrayZipSize_')) = [3 + (~isvector(item)), length(fulldata)];
        if (isvector(item))
            newitem.(N('_ArrayData_')) = [find(item(:))', real(fulldata(:))', imag(fulldata(:))'];
        else
            [ix, iy] = find(item);
            newitem.(N('_ArrayData_')) = [ix(:)', iy(:)', real(fulldata(:))', imag(fulldata(:))'];
        end
    else
        if (varargin{1}.formatversion > 1.9)
            item = permute(item, ndims(item):-1:1);
        end
        newitem.(N('_ArrayZipSize_')) = [2, numel(item)];
        newitem.(N('_ArrayData_')) = [real(item(:))', imag(item(:))'];
    end
end

if (varargin{1}.usearrayzipsize == 0 && isfield(newitem, N('_ArrayZipSize_')))
    data = newitem.(N('_ArrayData_'));
    data = reshape(data, fliplr(newitem.(N('_ArrayZipSize_'))));
    newitem.(N('_ArrayData_')) = permute(data, ndims(data):-1:1);
    newitem = rmfield(newitem, N('_ArrayZipSize_'));
end

if (~isempty(zipmethod) && numel(item) > minsize)
    encodeparam = {};
    if (~isempty(regexp(zipmethod, '^blosc2', 'once')))
        compfun = @blosc2encode;
        encodeparam = {zipmethod, 'nthread', jsonopt('nthread', 1, varargin{1}), ...
                       'shuffle', jsonopt('shuffle', 1, varargin{1}), ...
                       'typesize', jsonopt('typesize', length(typecast(item(1), 'uint8')), varargin{1})};
    else
        compfun = str2func([zipmethod 'encode']);
    end
    newitem.(N('_ArrayZipType_')) = lower(zipmethod);
    if (~isfield(newitem, N('_ArrayZipSize_')))
        newitem.(N('_ArrayZipSize_')) = size(newitem.(N('_ArrayData_')));
    end
    newitem.(N('_ArrayZipData_')) = compfun(typecast(newitem.(N('_ArrayData_'))(:).', 'uint8'), encodeparam{:});
    newitem = rmfield(newitem, N('_ArrayData_'));
    if (varargin{1}.base64)
        newitem.(N('_ArrayZipData_')) = char(base64encode(newitem.(N('_ArrayZipData_'))));
    end
end

if (isfield(newitem, N('_ArrayData_')) && isempty(newitem.(N('_ArrayData_'))))
    newitem.(N('_ArrayData_')) = [];
end

%% -------------------------------------------------------------------------
function newitem = table2jd(item, varargin)

newitem = struct;
newitem.(N_('_TableCols_', varargin{:})) = item.Properties.VariableNames;
newitem.(N_('_TableRows_', varargin{:})) = item.Properties.RowNames';
newitem.(N_('_TableRecords_', varargin{:})) = table2cell(item);

%% -------------------------------------------------------------------------
function newitem = graph2jd(item, varargin)

newitem = struct;
nodedata = table2struct(item.Nodes);
if (isfield(nodedata, 'Name'))
    nodedata = rmfield(nodedata, 'Name');
    newitem.(N_('_GraphNodes_', varargin{:})) = containers.Map(item.Nodes.Name, num2cell(nodedata), 'UniformValues', false);
else
    newitem.(N_('_GraphNodes_', varargin{:})) = containers.Map(1:max(item.Edges.EndNodes(:)), num2cell(nodedata), 'UniformValues', false);
end
edgenodes = num2cell(item.Edges.EndNodes);
edgedata = table2struct(item.Edges);
if (isfield(edgedata, 'EndNodes'))
    edgedata = rmfield(edgedata, 'EndNodes');
end
edgenodes(:, 3) = num2cell(edgedata);
if (isa(item, 'graph'))
    if (strcmp(varargin{1}.prefix, 'x'))
        newitem.(genvarname('_GraphEdges0_')) = edgenodes;
    else
        newitem.(encodevarname('_GraphEdges0_')) = edgenodes;
    end
else
    newitem.(N_('_GraphEdges_', varargin{:})) = edgenodes;
end

%% -------------------------------------------------------------------------
function newitem = matlabobject2jd(item, varargin)
try
    if numel(item) == 0 % empty object
        newitem = struct();
    elseif numel(item) == 1 %
        newitem = char(item);
    else
        propertynames = properties(item);
        for p = 1:numel(propertynames)
            for o = numel(item):-1:1 % array of objects
                newitem(o).(propertynames{p}) = item(o).(propertynames{p});
            end
        end
    end
catch
    newitem = any2jd(item, varargin{:});
end

%% -------------------------------------------------------------------------
function newitem = any2jd(item, varargin)

N = @(x) N_(x, varargin{:});
newitem.(N('_DataInfo_')) = struct('MATLABObjectClass', class(item), 'MATLABObjectSize', size(item));
newitem.(N('_ByteStream_')) = getByteStreamFromArray(item);  % use undocumented matlab function
if (varargin{1}.base64)
    newitem.(N('_ByteStream_')) = char(base64encode(newitem.(N('_ByteStream_'))));
end

%% -------------------------------------------------------------------------
function newname = N_(name, varargin)

newname = [varargin{1}.prefix name];