waldyrious · February 26, 2018 23:36
diff --git a/log_entry.m b/log_entry.m
 % Return a formatted string that can be added to a log.

 % Available log levels and recommended use cases:
 % -- TRACE: Leave breadcrumbs of the program flow; provide context.
 %           Printed in blue.
 % -- DEBUG: Expose internal program state, for development or troubleshooting.
 %           Printed in purple
 % -- INFOR: Notify user of normal/expected actions and events.
 %           Printed in green
 % -- WARNG: Alert of incorrect/unexpected input; automatically recoverable.
 %           Printed in yellow.
 % -- ERROR: Issues fatal to the current operation, but not the entire program.
 %           Printed in orange.
 % -- FATAL: Issues that force immediate halting the program to avoid data loss.
 %           Printed in white on red.

 % Note: the ESC character must be inputted as `char(27)`:
 % Ref: http://octave.1599824.n4.nabble.com/Color-console-is-this-possible-in-near-future-tp4646309p4646312.html

 % TODO: add timestamp.
 % TODO: detect if ANSI escape codes are supported
 % TODO: wrapper script to print out directly as if fprintf(log_entry(...))
 % TODO: should also allow calling with extra parameters for printf-like params.

 function log_str = log_entry(message, level)

    levels = {'trace', 'debug', 'infor', 'warng', 'error', 'fatal'};
    colors = {'34',    '35',    '32',    '33',    '31',    '37;41'};

    log_str = ''; % Default return value

    % Process the "message" parameter
    if ~exist('message', 'var') || isempty(message)
        fprintf(cstrcat('[ERROR] No message provided. ' ...
            , 'Usage: log_entry(message, [level])\n' ...
        ));
        return;
    elseif ~strcmp(class(message), 'char')
        fprintf(cstrcat('[ERROR] log_entry(): Unsupported message type.\n\t' ...
            , 'Expected a string ("char" class), ' ...
            , 'got "', class(message), '" class instead.\n' ...
        ));
        return;
        fprintf('this should not show up.\n');
    end%if

    % Process the "level" parameter
    if ~exist('level', 'var') || isempty(level)
        level = 'infor';
    elseif ~strcmp(class(level), 'char')
        fprintf(cstrcat('[WARNG] log_entry(): Unsupported log level type.\n\t' ...
            , 'Expected a string ("char" class), ' ...
            , 'got "', class(level), '" class instead.\n' ...
        ));
        fprintf('[INFOR] log_entry(): Defaulting to "infor" level.\n');
        level = 'infor';
    elseif strcmp(level, 'info')
        level = 'infor';
    elseif strcmp(level, 'warn')
        level = 'warng';
    elseif ~any(ismember(levels, level))
        fprintf(cstrcat('[WARNG] log_entry(): Unsupported log level name.\n\t' ...
            , 'Expected one of: ', strjoin(levels,', '), '; ' ...
            , 'got "', level, '" instead.\n' ...
        ));
        fprintf('[INFOR] log_entry(): Defaulting to "infor" level.\n');

        level = 'infor';
    end%if

    % Get color at the same index as the log level
    color = colors{find(ismember(levels, level))};

    % Generate the formatted log entry string
    log_str = [ ...
        char(27) '[1;' color 'm' '[' upper(level) ']' char(27) '[0m ' ...
        message '\n' ...
    ];

 end%function
	% Return a formatted string that can be added to a log.

	% Available log levels and recommended use cases:
	% -- TRACE: Leave breadcrumbs of the program flow; provide context.
	% Printed in blue.
	% -- DEBUG: Expose internal program state, for development or troubleshooting.
	% Printed in purple
	% -- INFOR: Notify user of normal/expected actions and events.
	% Printed in green
	% -- WARNG: Alert of incorrect/unexpected input; automatically recoverable.
	% Printed in yellow.
	% -- ERROR: Issues fatal to the current operation, but not the entire program.
	% Printed in orange.
	% -- FATAL: Issues that force immediate halting the program to avoid data loss.
	% Printed in white on red.

	% Note: the ESC character must be inputted as `char(27)`:
	% Ref: http://octave.1599824.n4.nabble.com/Color-console-is-this-possible-in-near-future-tp4646309p4646312.html

	% TODO: add timestamp.
	% TODO: detect if ANSI escape codes are supported
	% TODO: wrapper script to print out directly as if fprintf(log_entry(...))
	% TODO: should also allow calling with extra parameters for printf-like params.

	function log_str = log_entry(message, level)

	levels = {'trace', 'debug', 'infor', 'warng', 'error', 'fatal'};
	colors = {'34', '35', '32', '33', '31', '37;41'};

	log_str = ''; % Default return value

	% Process the "message" parameter
	if ~exist('message', 'var') \|\| isempty(message)
	fprintf(cstrcat('[ERROR] No message provided. ' ...
	, 'Usage: log_entry(message, [level])\n' ...
	));
	return;
	elseif ~strcmp(class(message), 'char')
	fprintf(cstrcat('[ERROR] log_entry(): Unsupported message type.\n\t' ...
	, 'Expected a string ("char" class), ' ...
	, 'got "', class(message), '" class instead.\n' ...
	));
	return;
	fprintf('this should not show up.\n');
	end%if

	% Process the "level" parameter
	if ~exist('level', 'var') \|\| isempty(level)
	level = 'infor';
	elseif ~strcmp(class(level), 'char')
	fprintf(cstrcat('[WARNG] log_entry(): Unsupported log level type.\n\t' ...
	, 'Expected a string ("char" class), ' ...
	, 'got "', class(level), '" class instead.\n' ...
	));
	fprintf('[INFOR] log_entry(): Defaulting to "infor" level.\n');
	level = 'infor';
	elseif strcmp(level, 'info')
	level = 'infor';
	elseif strcmp(level, 'warn')
	level = 'warng';
	elseif ~any(ismember(levels, level))
	fprintf(cstrcat('[WARNG] log_entry(): Unsupported log level name.\n\t' ...
	, 'Expected one of: ', strjoin(levels,', '), '; ' ...
	, 'got "', level, '" instead.\n' ...
	));
	fprintf('[INFOR] log_entry(): Defaulting to "infor" level.\n');

	level = 'infor';
	end%if

	% Get color at the same index as the log level
	color = colors{find(ismember(levels, level))};

	% Generate the formatted log entry string
	log_str = [ ...
	char(27) '[1;' color 'm' '[' upper(level) ']' char(27) '[0m ' ...
	message '\n' ...
	];

	end%function