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FLOW CHART COMIPLER MANUAL
version 1.0
PLEASE SEND ANY PROBLEM REPORTS TO:
Mark Falleroni
1029E. 4750S.
Ogden, Utah
84403
PLEASE INCLUDE A DESCRIPTION OF THE PROBLEM, ALONG WITH THE FLOW CHART
SOURCE FILE THAT CAUSED THE PROBLEM
System Requirements: 512K, Color Monitor, Gemini 10X or compatible
PURPOSE AND OBJECTIVES
The purpose of this program was to determine a
method to solve the problem of the manual generation of
flowcharts. The objective is to develop software that
will automate the flowchart design and development
process.
PROPOSED SOLUTION
The solution to the problem was to develop a
unique flowchart design language that could be
compiled. The requirement to compile the flowchart
design language resulted in a flowchart compiler that
can compile a flowchart design language source file,
display the compiled file to a windowed environment,
and print the compiled file in a high resolution
graphics mode. There are example source files at the
end of this document to help familiarize you with the
language and compiler.
DEFINITION OF TERMS
FDL - Flowchart Design Language; a design language
used to describe a software design. The FDL is the
source language for the Flowchart Compiler.
FCC - acronym for the FlowChart Compiler.
Ellipses - Any menu item followed by an ellipses
(...) indicates that further input is required. The
ellipses usually follows menu items that prompt for
filenames, module names or page numbers.
Output File - a file created by the flowchart
compiler. This type of file is the result of a
successful compile of an ASCII text, flowchart design
language file. It contains commands for the drawing
module. These commands contain information that
determines the type of flowchart symbols that are
drawn, their positions, and connectivity relationships
with other flowchart blocks.
DESIGN
The flowchart compiler was written in the C
programming language. It takes full advantage of the
desktop metaphor features provided by the GEM
interface.
The compiler was designed to perform the following
functions:
1. Compile flowchart design language source code
2. Display a module complexity estimate
3. Display a compiled file to a scrollable window
4. Print a compiled file in a high resolution
5. Edit a flowchart design language source file
6. Display the amount of free system memory
7. Display the amount of free disk memory
8. Display help screens to the user
FLOWCHART DESIGN LANGUAGE (FDL)
A structured language was developed to facilitate
the development of flowcharts. It is simply called the
Flowchart Design Language and will be referred to
hereafter as the FDL. The language is similar to
modern day high level structured programming languages
and contains most of the other programming language
constructs. The language consists of control
statements, looping statements, a call subroutine
statement, assignment statement and page layout
commands. It does not support the use of a 'goto' or
the premature exit from a loop. The FDL was designed
to represent existing software or new designs of a
modular nature and it is best used in that manner.
The FDL is very flexible from a user perspective
in that it can be as detailed or as general as desired.
If a high level use is desired, statements similar to
those found in a program design language can be used.
If a low level use is desired, statements very close to
a programming language can be used.
KEYWORDS
The following is a list of FDL keywords:
^, if, while, for, call, then, else, endif,
endwhile, do, endfor, until, repeat, program,
endprg, module, endmod, ife, endelse, header,
footer, date
To be recognized as a keyword by the flowchart
compiler, the following FDL keywords must appear as the
first word in an FDL statement:
^, if, while, for, call, until, repeat, endif,
else, endwhile, endfor, ife, endelse
The keywords listed above can be used anywhere in the
string of a statement. If they are not used as the
first word, they are not recognized as keywords.
An example would be the use of the keyword 'for' in the
middle of the following high level assignment
statement:
"Set a = b for the next pass through the loop;"
All FDL statements must be terminated with a semicolon.
PAGE LAYOUT STATEMENTS
All page layout statements must begin with a
carrot '^'. Only the following keywords can appear
after a carrot:
program, endprg, module, endmod, header, footer, date
Program Statement
The program statement must be the first statement
of any FDL source file. It has the following form:
^program program_name;
The program_name string is required and must be less
than 15 characters in length. On printed or displayed
output, the program_name string is positioned in the
upper left corner of the flowchart page.
Endprg Statement
The endprg statement must be the last statement in
an FDL source file. It must immediately appear after
the last endmod statement since it signals the end of
the file. The endprg statement has the following form:
^endprg;
Module Statement
The module statement indicates the beginning of a
module and must immediately follow the program
statement or an endmod statement. The module statement
has the form:
^module module_name;
The module_name string is required and must be less
than 14 characters in length. The module_name string
is placed in the module ENTRY block. Each module
begins with a '^module module_name;' statement and ends
with an endmod statement.
Endmod Statement
The endmod statement indicates the end of a
module. It must match a prior module statement. It
has the form:
^endmod endmod_string;
An example of the use of the endmod statement follows:
^module One;
statement 1;
statement 2;
statement 3;
...
...
...
statement n;
^endmod Return To Caller;
The endmod string is required and must be less than 17
characters in length. The endmod string appears in the
exit block of the flowchart.
Header Statement
The header statement can appear anywhere in a
module. It has the form:
^header header_string;
The header string must be less than 35 characters in
length. On printed or displayed output, it appears
just to the right of the program name at the top of the
flowchart page. A header is a useful item that can be
used to display a module name at the top of each page.
If multiple header statements appear in a module, the
last header statement is considered legitimate and the
previous header statements are ignored. The header
statement is optional and need not appear in the source
file.
Footer Statement
The footer statement can appear anywhere within a
module. It has the form:
^footer footer_string;
The footer string must be less than 45 characters in
length. On printed or displayed output, it appears at
the bottom of the page, approximately 25 characters
from the left margin. A footer is a useful item that
can be used to display a module name at the bottom of
each page. If multiple footer statements appear in a
module, the last footer statement is considered
legitimate and the previous footer statements are
ignored. The footer statement is optional and need not
appear in the FDL source file.
Date Statement
The date statement is used to indicate the month,
day and year that the source file was developed. It is
an optional statement.The date statement has the form:
^date mon day year;
where mon = three character month (Dec, Nov, etc.) in
upper or lower case
day = two character day
year = four character year
The date appears in the upper right part of the
displayed or printed flowchart output.
CONDITIONAL STATEMENTS
The FDL supports two conditional statements; they
are if..then..endif, and ife..then..else..endelse. The
if..then..endif statement has the form:
if conditional_statement then
statement 1;
statement 2;
...
...
statement n;
endif;
The conditional statement must be less than 40
characters in length and any single word within the
conditional statement must be less than 17 characters.
Words that are greater than or equal to 17 characters
in length will cause a code generator error. The
'then' keyword must follow the conditional statement
and the 'endif' keyword terminates the 'if' conditional
statement. This statement is used to bypass processing
if the condition is false.
The second conditional statement is the
ife..then..else..endelse statement. This statement is
similar to the previous one with regards to the length
of the conditional statement and individual word
length. This statement is used to execute one
processing path if the condition is false and another
processing path if the condition is true.
It has the form:
ife conditional_statement then
statement 1;
statement 2;
..
statement n;
else
statement n + 1;
statement n + 2;
..
statement n + m;
endelse;
These conditional statements can be nested within each
other to a level that does not exceed the FCC
complexity limit of 15.
LOOPING STATEMENTS
The FDL supports three looping structures; they
are while, for, and repeat. There are restrictions on
their use due to the type of flowchart block each
statement generates.
While Statement
The while statement is used to execute processing
while a condition is true. Once the condition becomes
false, the loop is exited. The while statement has the
form:
while condition_statement do
statement 1;
...
statement n;
endwhile;
The 'do' keyword must follow the condition statement.
The 'endwhile' keyword terminates the while statement.
Due to the type of flowchart blocks that are generated
by a while statement, a while statement cannot
immediately follow another while statement. This is
demonstrated below:
while x > y do
while z > a do { THIS IS NOT ALLOWED }
{ THIS IS ALLOWED }
while x > y do
initialize z;
while z > a do
..
..
endwhile;
endwhile;
A while statement cannot immediately follow an
ife..then..else..endelse statement. This is
demonstrated below:
ife the condition is true then
while x < 100 do { THIS IS NOT ALLOWED }
{ THIS IS ALLOWED }
ife the condition is true then
initialize x;
while x < 100 do
..
..
endwhile;
else
..
endelse;
A while statement cannot immediately follow a
for..do..endfor statement. This is demonstrated below:
for x = 100 0 - 1 do
while a > 34 do { THIS IS NOT ALLOWED }
{ THIS IS ALLOWED }
for x = 100 0 - 1 do
initialize a;
while a > 34 do
..
..
endwhile;
endfor;
For Statement
The for statement is another looping statement
supported by the FDL. It has the following form:
for loop_var = init_val limit_val sign increment do
statement 1;
statement 2;
...
statement n;
endfor;
The loop_var can be any character or word. The
init_val can be a number or a character or word. The
init_val is the value given to the loop_var at the
beginning of the for loop. The limit_val can be a
character or a word or a number. The loop_var is
compared to the limit_val at the beginning of the for
loop. The sign must be either a '+' or '-'. The
increment must be a number. Based upon the sign, the
increment is added or subtracted to the loop_var at the
end of the for loop. If the sign is positive, the
loop_var is tested to see if it is less than the
limit_val. If the sign is negative, the loop_var is
tested to see if it is greater than the limit_val.
FOR statements can be nested to a level that does not
exceed the FCC complexity limit of 15.
Repeat Statement
The repeat statement allows the subsequent
processing that occurs within the loop to execute at
least once. The repeat statement has the form:
repeat
statement 1;
...
statement n;
until condition_statement;
The repeat statement cannot immediately follow a while
statement, a ife..then..else..endelse statement or a
for statement. This is demonstrated below:
while loopvar < limit do
repeat { THESE ARE NOT ALLOWED }
ife condition is true then
repeat
for a = 0 100 + 1 do
repeat
{ THESE ARE ALLOWED }
while loopvar < limit do
any legal statement;
repeat
..
until condition is false;
..
endwhile;
ife condition is true then
any legal statement;
repeat;
..
until condition is false;
else
..
endelse;
for a = 0 100 + 1 do
any legal statement;
repeat
..
until condition is false;
..
endfor;
The 'until' keyword, if used as the first word in a
statement, indicates the end of the repeat statement.
The conditional statement must be less than 40
characters in length. Any word within the conditional
statement cannot be longer than 16 characters.
ASSIGNMENT STATEMENT
The assignment statement is simply any string that
does not begin with a keyword. The minimum string size
is 2 words and the maximum is 60 characters. The
maximum word length in an assignment statement string
must be less than 19 characters. An assignment
statement can follow any other statement.
SUBROUTINE CALL STATEMENT
The call statement must begin with the keyword
'call'. It can be 49 characters in length. The
maximum word length within a call statement string is
17 characters or less. The call statement has the
form:
Call module get_char() to input the next letter;
When displayed or printed, the keyword 'call' is
spelled in all capital letters.
SYNTAX
FDL syntax was designed to be straightforward and
easy to remember. Most of the FDL syntax rules were
discussed above. Here are the remaining syntax rules
for the FDL:
1. Any statement that does not begin with a keyword is
considered to be an assignment statement.
2. All statements must terminate with a semicolon.
3. Each FDL source file must begin with the FDL
statement - '^program progname;' where progname is
the name of the program.
4. The program name must be less than 16 characters in
length.
5. Each FDL source file must terminate with the FDL
statement - '^endprg;'.
6. A '^module module_name;'
statement must immediately follow a program
statement.
7. FDL source statements can be upper or lower case
characters or a combination thereof.
8. Comment statements must begin with a '{' and end
with a '}'. Once a left curly brace is encountered by
the FCC scanner, all subsequent text is ignored by the
scanner until an End Of File or a right curly brace is
found.
FLOWCHART COMPILER PROGRAM DESIGN
Flowchart Compiler Menu Titles and Items
Title Choices
Desktop About the Flowchart Compiler...
File Compile
Display
Print
Edit
Delete
Quit
Options Display Next Page
Output
Set Edit Info
Browse Manual
Memory System
Disk
Help Compile
Display
Print
Edit
Set Edit Pathname
Browse Manual
Each menu title and menu item within a title will
now be discussed:
Desk
By convention, the desk menu contains one application
item choice, and up to six accessories.
File Menu
Under this title, there are items that manipulate files. There
is also a menu item that if selected, will exit the program.
Compile
The 'Compile...' item displays a dialog box that
prompts the user for the full pathname of the input
file, output file, temporary file, and error file. If
a valid input filename is entered and the file
successfully opened for reading, a window is opened.
Status messages and/or error messages are scrolled in
the window to inform the user of compilation progress.
The FCC scans, then parses the input file. If errors
are detected, a message is output to the screen and it
is also written to the error file. Modules that have
errors do not have code generated. If one module has
an error, the output file is assumed to be
corrupted.
Display
This menu item will display a successfully compiled file
in a window. 23% of the first flow chart page will
be displayed. The window can be scrolled vertically or
closed at any time. To view subsequent pages, choose
'Display Next Page' from the 'Options' menu.
Print
The Print item allows the user to print a compiled
file in 120 horizontal by 72 vertical resolution. The
user is prompted for a filename. If the file can be
successfully opened, the display window is opened. The
first page of the file is copied into the offscreen
buffer and approximately 23% is displayed in the
display window. The contents of the offscreen buffer
are then printed. The user can prematurely terminate
the print function by typing Control D.
Edit
This menu item allows an editor to be Pexec'd. You must
specify the full pathname of the editor you want to use in
the 'Set Edit Info' item from the 'Options' menu.
Delete
This menu item displays a standard file selector box and will
delete any selected file.
Options Menu
This menu contains items that allow the user to display pages
of a compiled flowchart file, specify a range for flowchart
output, specify editor information, or browse this manual.
Display Next Page
This menu item is enabled only when a flowchart
file is being displayed. It displays the next page of
the flowchart file to the screen.
Output
This selection displays a dialog
box that allows the user to select display or print
options. All pages, only a module, or only a page
range within a module will be displayed or printed. If
all pages are selected the user should then exit the
dialog. If a module is selected, then the user needs
to enter the name of the module (case sensitive) to be
displayed. If the user wants to print a page range
within a module, he/she should enter the module name,
and the start and stop page numbers.
Set Edit Info
This selection allows the user to name the work
file for a session. It also allows the user to specify
which editor should be invoked when the 'Edit' item is
selected from the 'File' menu. When the editor is invoked, it
will automatically load the named file.
Memory Menu
The memory menu item contains two choices; system
and disk.
System
This selection displays the amount
of free system memory in an alert box.
Disk
The user is prompted for a drive
letter. The amount of free space, used space and total
space is displayed in an alert box.
Help Menu
The items under this menu title display
information about the selection. The Browse Manual
selection invokes the editor and this documentation file is
automatically loaded. The user should write protect
this file to prevent any inadvertant modification.
************ Language (BNF) Accepted by the Flow Chart Compiler *********
There may be an error or two here...
Legend:
<...> non-terminals, | or, + after non-terminal is considered
superscript
<program> ::= ^program <string>; <modules> ^endprog;
<modules> ::= ^module <string>;<statements> ^endmod<string>; <modules> |
/\
<statements> ::= <statement> <statements> | /\
<statement>::= if <condition> then <statements> endif ; |
ife <condition> then <statements> else <statements>
endelse;|
<assignment statement>; |
while <condition> do <statements> endwhile
; |
repeat <statements> until <condition> ;
| /\ (NULL string); |
for <loop var> = <initial val> <limit val>
<sign> <increment val> do <statements> endfor ; |
<layout command> ;|
call <string>; |
{<comment>}
<condition> ::= <string>
<string> ::= <char><string> | /\
<char> ::= a|b|c|d..z|A|B|C|D..Z|0..9|!|"|#|$|%|&|'|(|)|space|
*|+|,|-|.|/|:|?|@|[|\|]|^|_|`|{|}
<assignment statement> ::= <string>
<loop var> ::= <string>
<digit> ::= 0..9
<initial val> ::= +<digit>+ | -<digit>+ | <digit>+
<limit val> ::= <initial val>
<sign> ::= + | -
<increment val> ::= <digit>+
<layout command> ::= ^<command> <string> | ^date <month> <day> <year>
<command> ::= header | footer
<month> ::= jan | feb | mar | apr | may | jun | jul | aug | sep |
oct | nov | dec
<day> ::= <digit>2
<year> ::= <digit>4
<comment> ::= <string>
The Flow Chart Design Language (FDL) Keywords are:
^, if, ife, endelse, while, for, call, then, else, endif,
endwhile, do, endfor, until, repeat, program, endprg, module, endmod
Flow chart string length capacity is less than 60 characters for any
block. All statements are terminated with a semicolon.
Comments can be placed anywhere within the source file.
************** Compiler Error Messages ************************
"Expected '^' for Module statement." - the compiler expected to find a '^'
before a module statement
"Missing '^ENDPRG;' statement." - an end of file was read before the
'^ENDPRG' statement was found
"Expected '^' for PROGRAM statement." - the compiler expected to find a
'^' before a PROGRAM statement
"PROGRAM statement expected." - compiler expected to find a PROGRAM
statement
"Missing program NAME." - the compiler parsed a semicolon instead of a
program name
"Program NAME expected; keyword found." - the compiler parsed a keyword
instead of a program name
"Program NAME exceeds 15 character limit." - the program name exceeded the
maximum length
"MODULE keyword expected." - the compiler expected to find a MODULE
keyword
"Module NAME exceeds 13 character limit." - the module name exceeded the
maximum length
"Missing module NAME." - the compiler expected to find a module name but
found a semicolon instead
"HEADER string length exceeds 35 characters." - the HEADER string exceeded
the allowable limit
"FOOTER string length exceeds 45 characters." - the FOOTER string exceeded
the allowable limit
"Page number string string length exceeds 4 characters." - page number
string length exceeded the allowable limit
"Invalid character in page number." - page number contained a non numeric
character
"PROGRAM statement should be the first statement in the file." - the
program keyword was used incorrectly, it can only be used to declare
a program at the beginning of the FDL source file
"ENDMOD string length exceeds 17 character limit." - the string length
exceeded the allowable limit
"MODULE statement must follow ENDMOD statement." - MODULE keyword can only
be used to declare a module in a FDL source file
"ENDPRG statement must follow ENDMOD statement." - the ENDPRG keyword can
only be used after an ENDMOD statement to terminate the FDL source file
"Invalid MONTH in DATE statement." - the month string in a DATE statement
did not match the first 3 characters of any month
"Invalid DAY in DATE statement." - day field in date statement is not a
number or the length is > 2 characters
"Invalid YEAR in DATE statement." - the year field in a date statement is
is not a number or the length is > 4 characters
"Missing semicolon." - compiler expected to parse a semicolon
"String length exceeds 60 character limit." - string length for an operand
exceeds the maximum string length limit.
"No Text String Found." - compiler expected to parse a string but instead
parsed a semicolon
"REPEAT statement cannot immediately follow WHILE." - a repeat statement
immediately followed a while statement in the source file
"REPEAT statement cannot immediately follow IFE." - a repeat statement
immediately followed the start of an IF..THEN..ELSE..ENDELSE structure
"REPEAT statement cannot immediately follow FOR." - repeat statement
immediately followed a FOR statement
"Expected COMMAND statement." - the compiler expected to parse a command
statement after a '^' keyword
"IF condition string length exceeds 40 characters." - the string length
for the conditional part of an IF statement exceeded the maximum length
allowed
"WHILE statement cannot immediately follow WHILE." - a while statement
immediately followed another while statement
"WHILE statement cannot immediately follow FOR." - a while statement
immediately followed a for statement
"WHILE statement cannot immediately follow IFE." - a while statement
immediately followed an ife statement
"WHILE condition string length exceeds 40 characters." - the conditional
string length of a while statement exceeded the maximum limit
"THEN keyword improperly used." - the then keyword was not used as the
terminator of an IF or IFE statement
"No matching IFE statement." - an ELSE keyword was used incorrectly, the
compiler couldn't find a matching IFE statement
"No matching IF statement." - an ENDIF statement was used incorrectly, the
compiler parsed an ENDIF and couldn't find the corresponding IF statement.
"No matching WHILE statement." - an ENDWHILE statement was used
incorrectly, the compiler parsed an ENDWHILE and couldn't find a matching
WHILE statement
"UNTIL condition string length exceeds 40 characters." - the conditional
string for an UNTIL block exceeded the maximum string length limit
"No matching REPEAT statement." - an UNTIL keyword was used incorrectly,
the compiler parsed an UNTIL keyword and could not find a matching REPEAT
statement
"No matching ELSE statement." - the ENDELSE keyword was used incorrectly,
the compiler parsed the ENDELSE keyword and could not find a matching ELSE
statement
"IFE condition string length exceeds 40 characters." - the conditional
string part of an IFE statement exceeded the maximum length limit
"No condition string found." - the compiler expected to parse a
conditional string and the string consisted of only 1 word or a semicolon
was parsed instead
"Missing DO keyword in a WHILE statement." - the compiler parsed a WHILE
statement without parsing the DO keyword after the conditional string
"Missing THEN keyword in IF statement." - the compiler parsed an IF
statement without parsing the THEN keyword after the conditional string
"Conditional string length exceeds 40 character limit." - during the parse
of a conditional string, the length exceeded the maximum length limit
"Expected to find a string." - during the parse for an assignment string,
a semicolon was found before a string
"ASSIGNMENT string length exceeds 60 characters." - the length of an
assignment string exceeded the maximum length limit
"CALL string length exceeds 56 characters." - the length of a CALL string
exceeded the maximum length limit
"Missing LOOP VARIABLE in FOR statement." - the compiler expected to parse
a loop variable for a FOR statement and found a keyword instead
"Missing '=' in FOR statement." - compiler expected to find an '=' for a
FOR statement
"Missing INITIAL VALUE in FOR statement." - compiler expected to find an
initial value for a FOR statement and instead found a keyword
"Missing LIMIT VALUE in FOR statement." - compiler expected to find a
limit value for a FOR statement and instead found a keyword
"Missing + or - operator in a FOR statement." - compiler expected to find
an increment/decrement sign for a FOR statement
"Missing INCREMENT VALUE in FOR statement." - compiler expected to find an
increment value for a FOR statement and instead found a keyword
"Missing DO keyword in a FOR statement." - compiler expected to find a DO
keyword in a FOR statement
"No matching FOR statement." - incorrect use of the ENDFOR keyword, the
compiler parsed an ENDFOR statement and could not find a matching FOR
statement
"Missing ENDIF statement." - there is an IF statement in the module that
is not terminated by an ENDIF statement. This error is discovered when
the ENDMOD statement is processed.
"Missing ENDFOR statement." - there is a FOR statement in the module that
is not terminated by an ENDFOR statement. This error is discovered when
the ENDMOD statement is processed
"Missing ENDWHILE statement." - there is a WHILE statement in the module
that is not terminated by an ENDWHILE statement. This error is discovered
when the ENDMOD statement is processed
"Missing UNTIL statement." - there is a REPEAT statement in the module
that is not terminated by an UNTIL statement. This error is discovered
when the ENDMOD statement is processed
"Code Generator: String -> <STRING> ... doesn't fit in block." - code
generator error; even though a string does not exceed the string length
limit, the string will not fit inside the specified block. Reword
(reduce the size) the string in the editor and recompile the source file
"Unmatched '{' caused early read of EOF." - a comment was started and not
finished with a closing '}'. The compiler searched to the end of file for
the missing '}'
