jl.m

classdef jl
    %JL static class encapsulating matlab-side functionality for mexjulia

    methods (Static)
        % Call a MEX-like Julia function.
        %
        % nout - the number of expected return values
        % fn - the name of the function to call
        %
        % A MEX-like function is one that can be invoked with a value of type
        % `Vector{MxArray}` and returns a collection of values for which a
        % conversion to `MxArray` exists.
        function varargout = mexn(nout, fn, varargin)
            jl.check_initialized;
            outputs = cell(nout+1, 1);
            try
                [outputs{:}] = mexjulia('jl_mex', fn, varargin{:});
                varargout = outputs(2:end);
                result = outputs{1};
                if ~islogical(result)
                    throw(result);
                end
            catch err
                warning('Something went wrong')
                warning(err.message)
                warning('Stack trace follows:')
                w = warning('query');
                for i = 1:length(err.stack)
                    if ~strcmp(w(1).state,'off')
                        disp(err.stack(i))
                    end
                end
                varargout{1} = [];
            end
        end

        % Like mexn but assumes exactly one output
        function val = mex(fn, varargin)
            val = jl.mexn(1, fn, varargin{:});
        end

        % Interpret string(s) as Julia expression(s), returning value(s).
        function varargout = eval(varargin)
            varargout = cell(nargin, 1);
            [varargout{:}] = jl.mexn(nargin, 'Mex.jl_eval', varargin{:});
        end

        % Call a Julia function, possibly with keyword arguments, returning its
        % value.
        %
        % fn - the name of the function to call
        % npos - the number of arguments to be treated as positional
        %
        % Arguments beyond the first npos are assumed to come in key/value
        % pairs.
        %
        % If npos < 0 all arguments are assumed to be positional.
        function v = callkw(fn, npos, varargin)
            if npos >= 0
                nkw = length(varargin) - npos;
                if nkw < 0
                    error('The number of positional arguments exceeds the total number of arguments.');
                elseif mod(nkw,2) ~= 0
                    error('The number of keyword arguments is %u, but must be even.', nkw);
                end
            end
            v = jl.mex('Mex.jl_call_kw', fn, int32(npos), varargin{:});
        end

        % Call a Julia function with the given (positional) arguments, returning its value.
        %
        % fn - the name of the function to call
        function v = call(fn, varargin)
            v = jl.callkw(fn, -1, varargin{:});
        end

        % Wrap a Julia function in a matlab function handle.
        %
        % fn - the name of the function to wrap
        % ismex - whether the function is to be treated as MEX-like
        % npos - if provided, the number of arguments to be treated as
        % positional
        function hdl = wrap(fn, npos)
            if nargin < 2
                npos = -1;
            end
            hdl = @(varargin) jl.callkw(fn, npos, varargin{:});
        end

        % Wrap a MEX-like Julia function in a matlab function handle.
        %
        % fn - the name of the function to wrap
        % nout - if provided, the number of output values to expect (default=1)
        function hdl = wrapmex(fn, nout)
            if nargin < 2
                nout = 1;
            end
            hdl = @(varargin) jl.mexn(nout, fn, varargin{:});
        end

        % Include a file in the Julia runtime
        function include(fn)
            jl.eval(sprintf('include("%s"); nothing', jl.forward_slashify(fn)));
        end

        function repl(prompt, doneq)

            if nargin < 2
                doneq = @(expr)startsWith(expr,';');
                if nargin < 1
                    prompt = 'julia> ';
                end
            end

            while true
                expr = input(prompt, 's');
                if doneq(expr), break, end
                jl.eval(expr)
            end
        end

        function bl = is_initialized()
            try
                bl = mexjulia;
            catch
                bl = false;
            end
        end

        % Check that the Julia runtime is initialized (and initialize it, if
        % necessary).
        function check_initialized()
            if ~jl.is_initialized

                % check that the mexfunction exists
                if isempty(which('mexjulia'))
                    error('It appears the mexjulia MEX function is missing. Consider running "Jl.build".\n');
                end

                % tweak path to find shared libs
                if ispc
                    % This is a hack for windows which lets the mex function
                    % find the julia dlls during initialization without requiring that
                    % julia be on the path.
                    old_dir = pwd;
                    cd(jl.julia_home);
                end

                % basic runtime initialization
                mexjulia('', jl.julia_home, jl.sys_image, jl.lib_path);

                % Make sure MATLAB_HOME points to _this_ version of matlab.
                setenv('MATLAB_HOME', jl.matlab_dir);

                % load the boot file
                mexjulia(0, ['include("' jl.boot_file '")']);

                % restore the path
                if ispc
                    cd(old_dir);
                end
            end
        end

        function config(exe)
            % get the path to the julia to build against
            if nargin < 1
                % try to guess the path of the julia executable
                if ispc
                    [~, exe] = system('where julia');
                else
                    [~, exe] = system('which julia');
                end
                exe = strtrim(exe);
                if ~exist(exe, 'file')
                    exe = 'julia';
                end

                % get path of julia executable
                if ispc
                    wc = '*.exe';
                else
                    wc = '*';
                end
                [exe, pathexe] = uigetfile(wc,'Select the Julia executable', exe);
                exe = [pathexe exe];
            end
            assert(exist(exe, 'file') == 2);
            jl.set('julia_bin', exe);

            % get JULIA_HOME
            jlhome = jl.eval_with_exe('unsafe_string(Base.JLOptions().julia_home)');
            assert(exist(jlhome, 'dir') == 7);
            jl.set('julia_home', jlhome);

            % get the path of the image file
            img = jl.eval_with_exe('unsafe_string(Base.JLOptions().image_file)');
            assert(exist(img, 'file') == 2);
            jl.set('sys_image', img);

            % check for debugging
            dbg = jl.eval_with_exe('ccall(:jl_is_debugbuild, Cint, ()) != 0');
            jl.set('is_debug', dbg);

            % check if threading is enabled
            thr = jl.eval_with_exe('ccall(:jl_threading_enabled, Cint, ()) != 0');
            jl.set('threading_enabled', thr);

            % get include directory
            incdir = fullfile(fileparts(jlhome), 'include', 'julia');
            assert(exist(incdir, 'dir') == 7);
            jl.set('inc_dir', incdir);

            % get julia lib
            if eval(dbg)
                lib_base = 'julia-debug';
            else
                lib_base = 'julia';
            end
            lib_path = jl.eval_with_exe(sprintf('Libdl.dlpath(\\\"lib%s\\\")', lib_base));
            if ispc
                lib_dir = fullfile(jlhome, '..', 'lib');
            else
                lib_dir = fileparts(lib_path);
            end
            jl.set('lib_base', lib_base);
            jl.set('lib_path', lib_path);
            jl.set('lib_dir', lib_dir);

            % set cflags
            if eval(dbg)
                cflags = '-g';
            else
                cflags = '-O';
            end
            cflags = [cflags ' -I' '"' jl.get('inc_dir') '"'];
            if eval(jl.get('threading_enabled'))
                cflags = [cflags ' -DJULIA_ENABLE_THREADING'];
            end
            jl.set('build_cflags', cflags);

            % set ldflags
            ldflags = ['-L"' jl.get('lib_dir') '"'];
            if ~ispc
                ldflags = [ldflags ' -Wl,-rpath "' jl.get('lib_dir') '"'];
            end
            jl.set('build_ldflags', ldflags);

            % set ldlibs
            if ispc
                % get full path to .dll.a file
                ldlibs = fullfile(jl.get('lib_dir'), [ 'lib' jl.get('lib_base') '.dll.a' ]);
            else
                ldlibs = [ '-l' jl.get('lib_base') ' -ldl' ];
            end
            jl.set('build_ldlibs', ldlibs);

            % set mex source file
            src = fullfile(jl.this_dir, 'mexjulia.cpp');
            jl.set('build_src', src);

            % show the contents of the dictionary
            disp(jl.get);

            % check if this directory is on the search path
            path_dirs = regexp(path, pathsep, 'split');
            if ispc
                on_path = any(strcmpi(jl.this_dir, path_dirs));
            else
                on_path = any(strcmp(jl.this_dir, path_dirs));
            end

            % if not, add it and save
            if ~on_path
                fprintf('%s is not on the MATLAB path. Adding it and saving...\n', jl.this_dir);
                path(jl.this_dir, path);
                savepath;
            end

            % rebuild the mex function, given the new configuration
            jl.build;
        end

        function build()
            try
                cflags = jl.get('build_cflags');
                ldflags = jl.get('build_ldflags');
                src = jl.get('build_src');
                ldlibs = jl.get('build_ldlibs');
            catch
                error('Failed to get mex build parameters. Run ''jl.config''.');
            end

            if ispc
                mex_ptrn = 'mex -v -largeArrayDims %s -outdir "%s" %s %s %s';
            else
                mex_ptrn = 'mex LDFLAGS=''%s $LDFLAGS'' -v -largeArrayDims -outdir "%s" %s %s %s';
            end
            src = ['"' src '"'];
            mex_cmd = sprintf(mex_ptrn, ldflags, jl.this_dir, cflags, src, ldlibs);
            fprintf('The mex command to be executed:\n%s\n', mex_cmd);
            eval(mex_cmd);
        end

        function clear()
            save jldict;
        end

        function check_dict()
            if exist('jldict.mat', 'file') ~= 2
                jl.clear;
            end
        end

        function value = get(key)
            jl.check_dict;

            if nargin > 0
                load('jldict', key);
                try
                    value = eval(key);
                catch
                    value = '';
                end
            else
                value = struct;
                keys = who(matfile('jldict'));
                nkeys = length(keys);
                for k = 1:nkeys
                    value.(keys{k}) = jl.get(keys{k});
                end
            end
        end

        function set(key__, value__)
            jl.check_dict;
            if ~ischar(key__)
                error('The key must be a string.');
            end

            if nargin < 2
                load jldict;
                eval(sprintf('clear %s', key__));
                clear key__ value__
                save jldict;
            else
                if ~ischar(value__)
                    error('The value must be a string.');
                end
                eval(sprintf('%s=''%s'';', key__, value__));
                eval(sprintf('save -append jldict %s', key__));
            end
        end

        % full path of the mexjulia directory
        function md = this_dir()
            md = fileparts(mfilename('fullpath'));
        end

        % path to the root of this version of matlab
        function mh = matlab_dir()
            mh = fileparts(fileparts(fileparts(fileparts(which('path')))));
        end

        function bf = boot_file()
            bf = jl.forward_slashify(fullfile(jl.this_dir, 'jl', 'boot.jl'));
        end

        function home = julia_home()
            home = jl.get('julia_home');
        end

        function img = sys_image()
            img = jl.get('sys_image');
        end
        
        function lib = lib_path()
            lib = jl.get('lib_path');
        end

        % replace backslashes with forward slashes on pcs (id fn otherwise)
        function p = forward_slashify(p)
            if ispc
                p = regexp(p, filesep, 'split');
                p = [sprintf('%s/', p{1:end-1}) p{end}];
            end
        end

        % remove leading, trailing whitespace
        function str = chomp(str)
            str = regexprep(str, '^\s*', '');
            str = regexprep(str, '\s$', '');
        end

        function [val, err] = eval_with_exe(expr)
            exe = jl.get('julia_bin');
            if ~ispc
                % hide the LD_LIBRARY_PATH as it can cause errors when running
                % julia from matlab
                save_ld_lib_path = getenv('LD_LIBRARY_PATH');
                setenv LD_LIBRARY_PATH;
            end
            [err, val] = system(sprintf('"%s" -e "println(%s)"', exe, expr));
            if ~ispc
                % restore the LD_LIBRARY_PATH
                setenv('LD_LIBRARY_PATH', save_ld_lib_path);
            end
            if err ~= 0
                error(val)
            end
            val = jl.chomp(val);
        end

    end

end